Case Study:

Custom built robots to solve real world problems
The Djedi Project: Part 1

Author:

Robert Richardson

Published:

02/03/2020

Case Study:

Custom built robots to solve real world problems
The Djedi Project: Part 1

Author:

Robert Richardson

Published:

02/03/2020
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Case Studies

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The Djedi Project: Part 1

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Introduction

 

The Djedi Project is not just the new mission to explore the pyramid shafts – it truly is the next generation in robotic archaeology.  Beginning with Waynman Dixon’s iron rods, researchers have been probing the Great Pyramid’s mysterious claustrophobic passageways for 140 years.  But now, using technology designed for uses as divergent as space exploration and terrestrial search and rescue, we are finally able to explore the chamber behind Gantenbrink’s Door.

This case study covers how the Djedi Team won the “Robot Olympics in the Desert”, the members who make up the team, the specifics of the robot’s design, and the results of Djedi’s maiden voyage up QCS and into the chamber behind the first blocking stone. Through interviews and exchanges with the Djedi Project manager, Shaun Whitehead, as well as other team members, this article promises to be the resource for the published Djedi material to date.

 

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Pyramid Rover Recap

Pyramid Rover was a successful reconnaissance mission into the southern shaft coming out of the Queen’s Chamber (QCS).  The mission had confirmed that the 20 x 20 cm blocking slab and the final section of U-block were made of a higher quality type of limestone than the rest of the shaft, most likely the fine limestone quarried at Tura rather than the rougher local yellow limestone.  The blocking slab and final U-block were also smoother and of higher craftsmanship than the rest of the shaft blocks.  The Rover mission also confirmed that the blocking slab was affixed with two copper pins that were bent downward at a 90-degree angle.

Regarding the white circular patches observable behind the pins, Pyramid Rover’s close-up analysis revealed that these were most likely mortar patches rather than royal seals, one of the possibilities offered up by the Upuaut Project. Rover’s impact-echo probe had shown that the blocking slab was only 5-9 cm thick, which placed it within the capabilities of Rover’s drill and probe-mounted camera.

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Pyramid Rover
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Broken Pins

Rover successfully drilled a small hole in the slab, about 2 cm in diameter, while inflicting as little damage as possible.  The probe-mounted fiber optic camera was successfully deployed and gave us our first look behind Gantenbrink’s Door.  What the Pyramid Rover team discovered was a small chamber formed by the Tura limestone U-block, the basal stone, the blocking slab/door, and a rough block of the local limestone on the opposite side, about 19 cm away from the “door.”

But the probe camera had its limitations.  It was fixed inside a rigid tube and had no tilt or pan capabilities—all it could do was look straight ahead.  The LED array on the probe did not provide much ambient light, so Rover was unable to examine the walls and floor of the chamber, much less the back of the blocking slab.  Even the view of the opposite block was limited by the quality of the light.  With the center being overly reflective and the periphery fading into darkness, details were hard to make out.  What appeared to be cracks could just as easily be tool marks, mason’s lines, flaking, or just shadows.

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Rover drill
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Cracked stone

Larger, more structural questions presented themselves as well.  Was the opposing block another blocking slab/door?  Did the shaft continue on the opposite side, or come to an abrupt end against the core masonry of the pyramid?  Was the block inserted into the shaft like a cork, or did it sit flush against the end of the shaft like a lid?

The Pyramid Rover had also made a remarkable discovery in the northern shaft of the Queen’s Chamber —another door, nearly identical to the one Gantenbrink discovered, and at about the same elevation.  The QCN door also had copper pins and also appeared to be made of the higher-quality limestone and exhibited superior workmanship.  Could there be another chamber in QCN?

To even begin assessing these questions would require another mission and another robot.  But this meant asking new questions. Who should design the next robot?  How could they improve on the previous missions?  What would be the scope of the project? Zahi Hawass, the Secretary of the Supreme Council of Antiquities, had some decisions to make.

Zahi Hawass
Zahi Hawass

Selecting a New Mission Team:
Robot Olympics in the Desert

Initial planning for the next mission into the Queen’s Chamber shafts began soon after the conclusion of the Pyramid Rover Project, and at one point it seemed that a team from Singapore University had been selected as early as August, 2004.  Speaking with Chinese reporters at that time, Dr. Hawass talked as if the Singaporean mission was a done deal.  “The manufacturing of the robot will start in October,” Hawass said, “with the university [of Singapore] footing the bill.  The exploration will likely start next year” (People’s Daily Online, New robot to uncover pyramid mysteries, August 12, 2004).

By mid October, 2005, the Singaporean project, called Tomb Trekker, appeared to be on schedule. According to The Independent,  Singapore University had been working on Tomb Trekker for two years and Dr. Hawass would be inspecting the robot within a week (The Independent, Robot to explore Great Pyramid’s secret chamber, by Anne Penketh, October 12, 2005). But apparently he was not entirely convinced with what he saw and decided to open the project up to competition. In 2006 and 2007 Tomb Trekker would have to face off with a competing team from Leeds University for the right to explore the pyramid shafts.

The next mission into the Queen’s Chamber shafts would have two primary objectives:

  • Send a robot crawler up QCS to explore the space behind the first blocking slab using the same opening Pyramid Rover had drilled, determine if the rough block at the opposite side was the end of the shaft or another blocking slab, and if the latter, drill a hole through it and see what is behind it.
  • Send a robot crawler up QCN to drill a hole through that blocking slab and see what is on the other side.

To accomplish these objectives, the mission would have to meet certain criteria as well.  The tube-mounted camera on Pyramid Rover was unable to look around the inside of the chamber and the light quality was not fully up to task.  The next robot would need to be able to look up and down and from side to side, as well as take a look at the back of the blocking slab.  One of the most curious features of the shafts is the copper pins in the two blocking slabs.  To have a better understanding of these pins the new robot would need to be able to examine the backs of these slabs.

Another consideration would be scale.  The impact-echo probe used by Pyramid Rover covered nearly half the surface area of the blocking slab.  Obviously, something of comparable size would not be able to fit through the hole in the first blocking slab, and minimizing damage meant the team could not drill a larger hole.  The next mission would have to employ a probe that could fit through the tiny hole already made by Rover.

Damage prevention was not just a consideration with the blocking slab, it had become one of the main criteria of the mission.  The tank-like treads used by Upuaut-2 and Pyramid Rover had left scuff marks on the shafts.  There is an old adage that cave explorers use—take only pictures, leave only footprints.  But the pyramid shafts are a different type of spelunking and the Supreme Council of Antiquities was determined that whoever they selected for the next mission would leave no footprints at all.

To select which team—Singapore or Leeds—was best able to fulfill the mission and meet all the criteria, Zahi Hawass arranged for the two sides to face off in a sort of robot Olympics in the desert.  The SCA had a group of Egyptologists and engineers from Cairo University design a limestone “competition tunnel” in the desert that mimicked the actual pyramid shafts as nearly as possible in terms of size, slope, and conditions.  The panel of judges was an impressive list of experts.  According to the Official Report of the mission findings:

The trials were supervised and witnessed by a team that included a group from the Faculty of Engineering at Cairo University; Dr. Ali Radwan, a professor of Egyptology at Cairo University; Dr. Sabri Abdel Aziz, Head of the Pharaonic Sector of the SCA; and Mr. Hisham El Leithy from the SCA.  (Hawass, Whitehead, et. al, p. 206)

The competition was exciting, but not without some anxiety for both sides.  For the Singapore team it meant defending a concession to do the work which they had thought had already been won back in 2004.  For the Leeds team it meant testing an entirely new crawler design against one that had held up fairly well with Upuaut and Rover. Dr. TC Ng, one of the members of the Leeds team, describes the moment:

While our team’s rover was doing the test and we were sweating like Indiana Jones under the Egyptian sun, a dozen disciplined Singaporean engineers marched in like soldiers with identical T-shirts. They seemed good…Their robot was brilliant and exceptionally well made (South China Morning Post, Dentist digs deep to discover Giza secret, by Adrian Wan, September 28, 2010).

Djedi top with bucket
Djedi top with bucket

Both robots were equipped with the tools they would need to achieve the mission goals, but in the end one particular criterion set the Leeds robot above Trekker.  Tomb Trekker had relied on the same type of over-and-under tread system that had propelled Upuaut-2 and Pyramid Rover, which uses pressure against the floor and ceiling of the shaft to hold the robot in place.  But this is also the same design that had damaged the pyramid shafts.  At the end of the competition, under the guidance of the star panel he had assembled, Dr. Hawass pronounced the Leeds team the victors.

The Leeds robot had proved that innovation and evolution sometimes prevail over convention and tradition, these latter two often being the bread and butter of Egyptology.  But the emerging field of robot archaeology was about to make a quantum leap from crawlers that looked like something from a WWII battlefield to a sleek new design that would be at home on a space exploration mission.  And as we shall see, that was no coincidence.

Before we get into the details of Djedi’s design and the results of its maiden voyage, let’s take some time to get to know the Leeds team and how they came together.

The Djedi Team

On pronouncing the Leeds team the victors, Dr. Hawass dubbed the mission robot Djedi, after the magician Pharaoh Khufu attempted to trick into showing him the secrets of the Sanctuary of Thoth.  It was now the mission of the Djedi team to tease out the secrets of the shafts in Khufu’s pyramid, and in doing so maybe learn more about how the pyramid was built.  The team itself was composed of modern magi—scientists, engineers, and technicians from the top ranks of their respective fields.

The Djedi Team had its early genesis with the efforts of Dr. Ng “TC” Tze Chuen, who began dreaming of his own project to explore the Queen’s Chamber shafts when he saw the broadcast of Pyramid Rover’s first peek behind the blocking slab.  Dr. Ng worked as a dentist in Hong Kong, but he had made his real mark designing precision tools for space exploration.  TC Ng knew that a third mission into the Queen’s Chamber shafts was inevitable, and he believed that space exploration technology might offer the best solutions to many of the problems Pyramid Rover and Upuaut-2 had faced.

A more productive meeting - TC NG with Dr. Zahi Hawass of the SCA (courtesy TC NG/Hong Kong dental assoc)
A more productive meeting – TC NG with Dr. Zahi Hawass of the SCA (courtesy TC NG/Hong Kong dental assoc)

Dr. Ng tried to get the ball rolling by cold calling on the Supreme Council of Antiquities, attempting to convince Dr. Hawass to hear his proposal.  At first his cold calls got him the cold shoulder.  As he describes it:

Winning the operation rights for the third attempt took me more than a dozen trips knocking on the doors of SCA uninvited.  It was a bitter experience in the early stage.  I still remember being pushed out of the main gate of SCA for not having a valid appointment.

Hong Kong Dental Association Newsletter, (Second Door? by Dr. Ng Tze Chuen, November/December 2010. Pp. 30-1).

But persistence paid off, and after hearing TC’s proposal Dr. Hawass gave him the go-ahead to begin assembling a team.  At first Dr. Ng attempted to work with the team he would eventually compete with—the University of Singapore.  But when that relationship failed to thrive, he turned to a friend he had made while working on a Mars lander project, Shaun Whitehead.

Shaun was a respected inventor and the founder of Scoutek UK, a company specializing in robotic technology for space and terrestrial exploration.  TC recalled Shaun’s drive and ability to generate enthusiasm for a project and knew that he was the ideal person for building the sort of interdisciplinary team that the Djedi Project would require.  Whitehead was immediately taken with the project.  “As soon as TC told me what he was trying to do,” he says, “I jumped at the opportunity.”

Shaun began looking for potential team members in the UK.  He knew that the team would require a balance of academic and technical expertise, and an understanding of the conditions in which Djedi would have to perform.  The robot would have to be small, but tough.  As with space exploration, where every ounce counts, the crawler would need to be light enough to navigate the shafts without damaging them, delicate enough to enter and work behind the small hole in the blocking slab, and durable enough that it wouldn’t break down where it would be impossible to repair or retrieve.

The challenges of the Djedi project are very similar to space exploration.  The rover has to be mass-optimized, to minimize damage to the shaft walls (higher weight = more brace force required for grip), and there also is very little opportunity for maintenance when the rover is deployed over sixty meters up into the shaft, just as we can’t repair space robots!  So everything needs to work right first time.  It’s a real “systems engineering” task, and consequently the robot is a lot more advanced than most people imagine.

(Em Hotep interview with Shaun Whitehead, January 8, 2012 )

The Djedi Team (cont)

He discovered that there was a small team at Manchester University that seemed to fit the bill. Dr. Robert Richardson, the Lecturer in Robotics at the School for Computer Science, was involved in a project to develop robots for urban search and rescue situations following natural disasters.  The types of crawlers Dr. Richardson was working on were both rugged and dexterous.  “Everything that’s in the building falls over, and most buildings tend to partially collapse,” he explains. “If you can’t interact with debris, you drive up and get stuck” (New Scientist, Mechanical mole could seek out disaster survivors, by Kurt Kleiner, September 17, 2007).

Shaun approached Dr. Richardson, who understood the mobility requirements for the pyramid shafts, and was happy to put himself and his team behind the project. Dr. Richardson had a highly skilled crew at Manchester who offered a wide range of experience and specialization. One was Stephen Rhodes, a computer science analyst for the Faculty of Engineering and Physical Sciences, and a gifted technician. Another was Andrew Pickering, who had been with the Manchester Robotics Group since 1994, and who had helped develop mobile robots that were designed to interact intelligently with their environment.

Prof Robert Richardson
Prof Robert Richardson

The team at Manchester was dedicated and they enjoyed working under Dr. Richardson, who Shaun describes as “very bright and very positive about the opportunity.”  Most importantly, they worked well together.  “I have great respect for the talent of those guys,” Whitehead continues.  “I have rarely known them to be stumped by any mechanical or electronic challenges.”  The team remained cohesive even after Dr Richardson moved to the University of Leeds, taking the project with him.  With the addition of Adrian Hildred, a researcher who develops and tests cars for Bentley, Shaun had his UK team.

For its own part, the University of Leeds has tremendously benefitted from its involvement in the Djedi Project, which has been a training ground for several generations of engineering students.  The enthusiasm, creativity, and commitment of these students have been vital to the project’s success, and Shaun particularly singled out the participation of Jason Liu and William Mayfield as “a particularly keen and hard-working pair who will stick with the project right to the end.”

Impact-Echo Probe (source: Tekron Services)
Impact-Echo Probe (source: Tekron Services)

From across the Atlantic, the team was joined by Ron Grieve, founder of the Canadian consultancy company Tekron and a trailblazer in the field of impact-echo testing.  Ron had developed technology for assessing the conditions of buildings and other structures, and specialized in creating miniature sensors to monitor stress, movement, humidity, temperature and corrosion. His innovations included micro-transducers capable of taking measurements from the smallest and roughest surfaces, which made him the best choice for helping solve the problem of how to analyze the rough surface of the second block behind the chamber door.

Mr. Grieve passed away in late December, 2010, but his contribution to the team was immeasurable.

He was the “non-destructive testing” expert in the team, responsible for assessing the condition of the blocking stones. We developed the miniature “Sonic Surveyor” together. This device uses an acoustic wave to measure stone thickness where there is access to just one side.  Ron was a very experienced member of the team, and was often called in to investigate things like bridge and power station failures. Most importantly, he was a very positive team-player and a very good friend. We miss him.

(Interview with Shaun Whitehead)

The team was rounded out with the addition of Mehdi Tayoubi, Richard Breitner, and Ben Willcocks from the French company Dassault Systèmes. Like Whitehead and Ng, Breitner had a background in aerospace technology, but readers may be most familiar with Mehdi and Richard from their work with Jean-Pierre Houdin on Project Khufu and Khufu Reborn Interactive. Using Dassault Systèmes’ scientific 3D/Virtual Reality software, CATIA, Project Khufu produced   the most complete survey of the Great Pyramid in history, modeling the pyramid in an immersive 3D/VR environment that allowed Jean-Pierre’s work to be effectively communicated to experts and laypersons alike.

To help model and fit-check the robot, Dassault Systèmes provided the powerful SolidWorks 3D software and the expert guidance of Ben Willcocks. The intuitive nature of SolidWorks 3D allowed students and team members to master the software quickly, to share models with each other around the globe, and to directly “print” parts of the robot using the software’s rapid prototyping capabilities. The modeling elements of the software also helped determine the best composition of materials to provide the maximum weight-to-strength ratio to allow Djedi to make the tortuous climb up the irregular geometry of the pyramid shafts.

DS shaft render
DS shaft render

Mehdi and Richard’s experience with modeling the Great Pyramid would also come in handy when it came time to model, analyze, and present the data culled by the robot crawler. Dassault Systèmes was able to help financially support the project through its <em>Passion for Innovation</em> program, which is specifically set up to help assist projects like Khufu and Djedi by providing funding, software, and technical assistance free of charge.

Through the dedication of the team members, the support of organizations like Leeds and Dassault Systèmes, and the commitment of Dr. Hawass and the Supreme Council of Antiquities, the third mission into the Queen’s Chamber shafts became a reality.  As it turns out, the actual robot itself was not prohibitively expensive, thanks to these efforts.

A popular misconception is that the Djedi robots cost a lot of money to produce, this is not true, mainly thanks to the generous contribution of manpower by individuals and organizations. Most funding was spent on travel and accommodation for the various tests and demonstrations.

(Interview with Shaun Whitehead)

Now that we know how the team came together, we will take a look at the Djedi robot itself before diving into the mission and its findings.

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The Djedi Project: Part 2

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Djedi – Creationeering the Next Generation in Robotic Archaeology

 

The Djedi robot won the competition with Tomb Trekker for a number of reasons, but ultimately the Leeds team was selected because Djedi represented the next generation of robotics while Trekker was stuck spinning its treads the old way.  If you peel the labels off, you might have a hard time distinguishing Trekker from Upuaut-2 and Pyramid Rover.  But Djedi is a whole new design, from the tools it carries to the way it carries them.  “Djedi has been custom-built from scratch to do this specific job,” explained Shaun Whitehead, “and to do it as well as possible while protecting the pyramid.”

 

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This is not to say that the Djedi team did not learn from the previous missions.  Both Upuaut-2 and Pyramid Rover had provided useful reconnaissance from QCN and QCS and gave the engineers from Leeds an idea of the challenges they were facing.  But part of the lesson came from learning what they did not want to reproduce in the robot.  Shaun Whitehead continues:

I always like to look at previous design solutions to challenges and see what we can learn from them.  In this case, there wasn’t much to be learned apart from the fact that I did not want to use a tracked robot.  However, we did use the findings of both robots to find out what challenges we might face in terms of inclinations, bends, steps, block thicknesses, etc., and have used those to drive the specification of our robot.

  (Interview with Shaun Whitehead)

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Improvements

One of several improvements was the camera and lighting array.  For Djedi, the team used a miniature “micro snake” camera that was designed by Scoutek.  This camera uses a wide-angle lens surrounded by six high-intensity LEDs for optimum light.  Mounted on a snake-like appendage that uses miniature servos to operate its mechanical muscles and tendons, Djedi’s camera is capable of a full 360 degrees of motion (+/- 180 degrees pitch and yaw).  With a diameter of less than 8 mm, the snake-cam easily fits through the existing hole in the blocking slab.

Another improvement was in the size and technology of the impact-echo probe used to measure the thickness of the blocks in the shaft.  As we have noted, the probe used by Rover required a surface area nearly equal to half that of the blocking slab.  Rover also benefitted from the fact that the first blocking slab has a smooth, finished surface.  But the second blocking stone in QCS has a rough surface and lies 18 cm away, on the other side of a 2 cm hole.

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Djedi's snake camera
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Scoutek's microbot technology made Djedi's mission possible (source: Scoutek Ltd.)

The sonic surveyor designed for Djedi was a collaborative effort and an example of what Shaun calls creationeering – the fusion of creativity and engineering.  Ron Grieve and Shaun Whitehead both had expertise in micro-technology—Ron with creating micro-transducers capable of measuring stone up to 15 meters thick, and Shaun with fashioning beetle microbots that carry sensors into very tight spaces.  The Leeds team was adept at creating mobile robotic platforms to carry these tools past a multitude of obstacles, and Dassault Systèmes had the powerful software and 3D technology to analyze the data and model it in virtual reality.

The Djedi Project was a perfect alchemy of talented individuals presented with difficult but enjoyable challenges, and all the right tools and resources to innovate.  One of the most observable ways that Djedi was an evolutionary leap beyond Upuaut-2, Pyramid Rover, and Tomb Trekker, however, was in its mobility system.  All three previous crawlers had employed rubber tread belts that looped over two or more motorized drive wheels.  The belts provided the traction while the wheels provided the force that moved them.  This type of propulsion is called continuous track, or caterpillar mobility.

Caterpillar mobility is designed to maximize traction by distributing the weight of the vehicle over its entire length, and usually the vehicle’s weight helps increase traction.  But in the pyramid shafts, gravity is not your friend.  QCS has an average ascent of 39.6 degrees, while QCN averages around 36.7 degrees.  In this environment the weight of the vehicle does not provide sufficient traction to grip the floors—the crawlers have to be wedged into the shafts or they slide back down.  Upuaut-2, Rover, and Trekker all addressed this problem with over-and-under-mounted treads and chassis that could expand upward.

Pyramid Rover's under-and-over mounted caterpillar drive relied on an upward expanding chassis to hold it in place, as did Upuaut-2 and Tomb Trekker.
Pyramid Rover’s under-and-over mounted caterpillar drive relied on an upward expanding chassis to hold it in place, as did Upuaut-2 and Tomb Trekker.

The upward-expanding chassis wedged the robots between the floor and ceiling of the shaft, allowing the top and bottom treads to crawl along both surfaces.  This mitigated the downward pull of the slope, but created problems of its own.  The pressure created by the expanded chassis could result in the metal drive wheels exerting force directly onto the limestone surfaces.  In fact, the serrated wheels of Upuaut-2 appear specifically designed to bite into the shafts for traction.

Inspirations

Djedi’s designers understood that minimizing the weight of the crawler would reduce the amount of force needed for traction and propulsion, and less force meant that the robot was not as likely to damage the shafts.  Rather than something that looks like a bulky WWII tank, the Djedi team came up with a new model that benefitted from their collective experience in aerospace and terrestrial robotic navigation, but which also somewhat resembled a relic of Waynman Dixon’s era – the adjustable roller skate.

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Antique roller skates had a design that allowed their length and width to be adjusted.  They were made up of two carriages, each mounted over a pair of wheels, connected by an adjustable central rod that controlled the length of the skate.  The width was controlled by two sliding braces that extended from the sides of the front carriage.

dje22-computer-sim-back-carriage

Like the skate, Djedi’s chassis is also comprised of two carriages, each mounted over a pair of wheels, connect by a pair of sliding rods that control the length of the crawler.  Analogous to the side braces on the front of the skate, Djedi has extendable rods on the sides of both carriages, with a fifth rod that extends from the top of the front carriage.  Called bracing actuators, these rods control the width of the chassis, but whereas the side braces on the skate apply inward pressure for a snug fit around a foot, Djedi’s bracing actuators apply outward pressure to hold the crawler in place in the pyramid shafts.

Djedi’s mode of mobility is similar to that of an inchworm.  When an inchworm is stretched out to its full length, it moves by grasping with its front legs and contracting its body to pull its hind legs forward.  Once it reaches its shortest length, it grabs with its hind legs and pushes the front part of its body forward by stretching out.  Once again at full length, the inchworm grabs with its front legs, turns loose with its hind legs, and contracts again.  By repeating this series of motions it “inches” its way toward its destination.

Djedi inches along in a similar way.  When the crawler’s chassis is stretched out to its full length, the front carriage grabs the surfaces of the shaft by extending its bracing actuators.  The tips of the actuators have thick pads that protect the shaft surfaces from damage while providing the necessary traction to pull the back of the crawler forward.  The actuators in the rear carriage are in the retracted position, which leaves the back of the crawler free to move.  Djedi contracts its chassis by pulling the central connecting rods forward, moving the rear carriage up the shaft.

Once Djedi is in its contracted (shortest) position, it extends the bracing actuators in the rear carriage which then locks the back of the crawler in place, just like the inchworm grasping with its hind legs.  Djedi then withdraws the actuators in the front carriage, leaving the front end of the crawler free to move.  Now traction has been transferred from the front carriage to the back carriage.  The robot then expands its chassis by pushing the central connecting rods forward, moving the front carriage further up the shaft.  Once at full length, the front carriage extends its actuators, transferring the traction back to the front of the crawler, and the process begins again, thus “inching” Djedi up the shaft.

Using its bracing actuators to hold its carriages in place, Djedi expands and contracts its chassis on the central connecting rods, inchworming its way around a difficult turn and up the pyramid shaft. (courtesy: Dassault Systems/Djedi Team)
Using its bracing actuators to hold its carriages in place, Djedi expands and contracts its chassis on the central connecting rods, inchworming its way around a difficult turn and up the pyramid shaft. (courtesy: Dassault Systems/Djedi Team)

With this type of mobility, Djedi protects the shaft surfaces by containing the force almost entirely to the central connecting rods, rather than to a set of metal drive wheels that might accidentally—or by design—transfer both force and traction directly to the limestone surfaces.  Unlike the drive wheels in the caterpillar systems, Djedi’s wheels are not motorized, they are light weight and free rolling.  The protective padding on the actuator feet can be thicker than a tread belt because the belt has to be thin enough to move with the drive wheels.  As Dr. Richardson explains:

[The] Djedi robot climbs the shaft walls using soft pads on its ‘feet’ that grip but leave no trace. This is in complete contrast to other climbing robots that rely on tracks to move upwards on sloping surfaces, leaving scuff marks in their wake.”

dje25-Close-up-of-the-bracing-actuators
dje26-Djedi-with-scoop

For any crawler to move within the pyramid shafts, they have to apply both traction and force to the surfaces.  But using a motorized set of telescoping connector rods to provide movement rather than multiple motorized drive wheels keeps weight to a minimum and applies force in the direction of least resistance.  Whereas a track system can be left spinning and biting into the surfaces to surmount a step, Djedi’s fixed-point actuators keep traction at a constant, allowing the carriages to be pulled or pushed over steps with ease.

Exclusive video

Now that we know how the Djedi robot crawler is designed we are ready to see how it performed on its first trip up QCS, through the hole, and behind Door Number One, continuing in Part Three.

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The Djedi Project: Part 3

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Introduction

 

The final part of this case study explores the construction of the chamber we needed to access and what the future holds. 

 

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General construction of the Chamber

The floors of the shafts are made of flat limestone blocks, the thicknesses of which are unknown.  The walls and ceilings are formed by sections of inverted u-blocks that resemble upside down gutters.  Although it is uncertain what the blocks above and below the shafts look like, the shafts run at a sloping angle through the horizontal layers of the pyramid, so it is believed that the u-blocks and basal blocks rest under and on blocks that are wedge-shaped.

Block construction
Block construction

The first blocking slab in QCS (i.e., “Gantenbrink’s Door”) is located 63.6 meters from the shaft’s entrance in the Queen’s Chamber, plus or minus .4 meters.  Its position was determined by a combination of Djedi’s odometers—sensors that estimate the distance the crawler moves over time—and the length of the crawler’s umbilical cable.  Djedi confirmed Pyramid Rover’s measurement of the thickness of the first blocking slab as about 60 mm.

DS shaft render
DS shaft render

As discovered by Upuaut-2, and now confirmed by both Pyramid Rover and Djedi, the final section of u-block leading up to the blocking slab is made of a higher quality limestone than the rest of the shaft blocks, most likely the fine white Tura limestone originally used to provide the external surface of the pyramid with a smooth face.  The blocking slab also appears to be made of the Tura limestone, and both the final u-block and the blocking slab have finished surfaces, unlike the rest of the shaft.  The basal (floor) stone of the final section of the shaft is not made of the Tura limestone and has not been polished.

Composite image of the QCS Chamber as facing the second blocking stone
Composite image of the QCS Chamber as facing the second blocking stone

Although we learned from Pyramid Rover’s look behind the blocking slab that there was a small chamber behind the “door”, it was not known whether the walls and ceiling of the chamber were a continuation of the same u-block as the shaft leading up to it, or the beginning of a new section.  Thanks to Djedi’s ability to look upward and back toward the door, this question was answered.  In the shaft ceiling leading up to the door there are two crisscrossing cracks or veins which continue on the other side of the door, which confirms that the u-block continues on the other side of the slab.

The width of the shaft in front of the blocking slab was measured by the side bracing actuators in Djedi’s front carriage.  After correcting for the padding on the tips of the actuators, the shaft was determined to be 230 mm wide, plus or minus 10 mm.  Since the chamber is formed by the same u-block as the final section of shaft, it stands to reason that the chamber has the same width as the shaft.  This was confirmed when Djedi was able to look at the back of the blocking stone and observe that the gaps between the edges of the slab and the chamber walls were the same on both sides, front and back.

There is a small triangular chip in the lower right hand side of the blocking slab that allows us to see a narrow 2-3 mm lip, or ledge, against which the blocking stone rests.  The blocking slab is about 3 mm wider than the u-block, which has been cut slightly wider at this point to accommodate the “door”, thus forming the ledge.   The tool marks where this widening of the u-block took place are still visible on the right hand chamber wall behind the blocking slab.  Although less visible, the team believes there is a corresponding ledge on the left hand side, but none at the top or bottom.  There is no sign of mortar holding the slab in place, it simply rests on these narrow ledges jutting out from the side.

Chamfer photo
Chamfer photo

The back wall of the chamber is formed by the second blocking stone.  Unlike the u-block and the first blocking stone, the second blocking stone has a rough unfinished surface and appears to be made of the lower-quality local yellow limestone.  The height of the chamber was determined by scaling the height of the second blocking stone.  After adjusting for perspective, the Djedi team estimated the height of the second blocking stone to be about 230 mm—more or less equal to the width of the chamber.  Thus, both the width and height of the chamber is about 23 cm.

dje34-Front-and-back-of-the-first-blocking-stone

To judge the length, or depth, of the chamber, the team put marks on the tube probe on which the snake camera is mounted.  By comparing the snake camera’s field of view with its depth of field, they were able to determine when its tip was about 50 mm from the second blocking stone.  Using the chassis-mounted camera, the team could see from the tube probe that the tip of the snake cam was 200 mm from the front of the blocking slab, meaning that the back wall of the chamber is about 250 mm from the front surface of the “door”.  Given that that blocking slab is about 60 mm thick, the chamber was determined to be about 19 cm long (+/- 15 mm).

So by a variety of measurements, the Djedi team was able to determine that the interior of the chamber is about 190 mm by 230 mm by 230 mm (LWH).

The First Blocking Slab and the Metal Pins

Composite image
Composite image

Among the most interesting features of the Queen’s Chamber shafts are the copper pins affixed to the blocking slabs of both QCN and QCS.  Since we are specifically discussing the aspects of the Djedi Project which have been published so far, we will limit our observations to the pins in QCS.  The pins are judged to be copper, or mostly copper, due to their greenish coloration.  Before the installation of the ventilation system during Project Upuaut, the atmosphere inside the Great Pyramid was extremely hot and humid, conditions that are very corrosive to copper, causing it to turn green.

Both pins protrude through the front (outer) surface of the blocking stone and have been hammered downward into a 90 degree position against the blocking slab.  The bending of the pins appears to be deliberate, as they have been flattened where they were hammered.  The original ends of both pins have been broken off at points which coincide with mortar patches.  The left hand pin was broken off prior to the Upuaut Project, and the right hand pin was broken off by Pyramid Rover.  Both of the broken off ends, estimated to be about 12 mm long, were observed by Djedi and will be collected by the crawler in a future mission.

Computer rendering of the front of the first blocking stone
Computer rendering of the front of the first blocking stone

The pins are surrounded by a black material where they pass through the blocking stone.  The material seems to anchor them in place within the holes, and is itself apparently held in by mortar.  It is unclear whether this is a different substance than the pins, constitutes a separate part through which the pins were inserted, or is a wider section of the pins themselves.  It will take additional analysis to answer these questions.

(A) front of left-hand pin (B) front of right-hand pin (C) back of left-hand pin (D) back of right-hand pin
(A) front of left-hand pin (B) front of right-hand pin (C) back of left-hand pin (D) back of right-hand pin

Djedi allowed us to observe the back of the blocking slab for the first time.  Like the front, the back of the first blocking stone has been polished to a smooth surface, and the pins protrude from this side as well.  The back of the left hand pin appears nearly pristine, seems to exit the block and is then bent downward into a neat loop, with the bottom end of the pin flush to the block, and no mortar visible. The back of the right hand pin appears more fragile and or corroded, seems to be held in place with mortar at both the top and bottom of the loop, with the bottom inserted back into the mortar.

Computer rendering of the back of the first blocking stone
Computer rendering of the back of the first blocking stone

There is no explanation as of yet for the more corroded appearance of the right hand loop, and what practical function they may have served, if any, remains a mystery.  As noted by the official report:

The loops are very small and would only permit an approximately 3 mm diameter object to pass through them.  They do not appear to be very well positioned for functional purposes, as they are high up on the block.  (Hawass, Whitehead, et at, p. 210)

Shaun Whitehead continues:

We also realize that there are lots of theories about what the shafts are for, ranging from practical explanations such as ventilation, to the more esoteric, such as part of a giant electricity generating power plant or a hidden hall of records.  However, it’s not our part to speculate, we just want to gather as much information, and the best quality information as possible…We now know that these pins end in small, beautifully made loops, indicating that they were more likely ornamental rather than electrical connections or structural features. (Correspondence with the writer)

Composite image of the back of the first blocking stone
Composite image of the back of the first blocking stone

Djedi also showed that on the floor immediately behind the blocking slab there was a concentration of debris on the right hand side (as viewed from behind).  The debris appears to be a combination of material from the construction of the shaft and dust produced by Pyramid Rover drilling through the door.  The location and concentration of floor debris in the chamber is helping the Djedi team precisely determine the orientation and roll of the shaft, and additional details of these findings will be published in the future.

The Chamber Floor, Walls & Ceiling

The Chamber Floor and Its Markings

Just as the same u-block forms the walls and ceiling for both the chamber and the final (known) section of the southern shaft, the same basal block constitutes the floor in both the chamber and the section of QCS leading up to the blocking slab.  In addition to the floor debris along the bottom of the blocking slab (mentioned above), there is a dark chip on the floor that appears to correspond to a cavity located on the left hand wall, which will be detailed further below.

Composite image of the Chamber floor
Composite image of the Chamber floor

One of the most exciting discoveries by the Djedi Project so far has been the markings found on the floor of the chamber.  One of the marks is a straight red line that runs parallel to the right hand wall, extending from just behind the first blocking stone all the way to the base of the second blocking stone.  The line has the same appearance as other red ochre mason’s lines that appear elsewhere in the shafts.  There is an additional black mark on the floor where the red line meets the second blocking stone.  These lines usually mark where blocks were to be cut, and why this particular line was not used is one of the unanswered questions about the chamber.

The source of no small amount of speculation is a series of three red glyphs drawn at about 45 degrees to the red line, between the line and the wall.  Two other less distinct red marks occur on this side of the line, closer to the back of the chamber.  The three glyphs appear to be mason’s marks written in hieratic, a form of shorthand hieroglyphs.  The official report suggests that central and left hand glyphs appear similar to the hieratic figures for 20 and 1, respectively, or 21 when read together (p. 211).  The right hand glyph is inconclusive and is left uninterpreted by the official report.

dje43-Detail-of-the-glyps-and-masons-line-on-the-floor

One theory that has been put forth by Luca Miatello, an independent researcher in Egyptian mathematics, who is unassociated with the Djedi project, is that the right hand figure is the hieratic figure for 100.  Referring to the three glyphs, in an interview with Discovery News Miatello stated:

The markings are hieratic numerical signs. They read from right to left, meaning 100, 20, 1. The builders simply recorded the total length of the shaft: 121 cubits.  (Discovery News: Pyramid hieroglyphs likely engineering numbers, by Rosella Lorenzi, June 7, 2011)

While this is one possible interpretation of the glyphs, it is far from conclusive.  The central and left hand glyphs do appear to be hieratic for 20 and 1, but in this writer’s lay opinion, the right hand glyph is not clear enough for interpretation, and in any case, looks more similar to the hieratic figure for 200 than 100.  The hieratic glyph for 200 has a mark in the crook of its “elbow”, the glyph for 100 does not.  The right hand glyph on the floor appears to me to have a mark in its crook.  Miatello’s theory is a good one, and may ultimately be vindicated with further analysis, but at this point I do not feel the evidence allows for a conclusive interpretation.

dje44-Detail-of-the-three-hieratic-characters

Regarding the glyphs, Dr. Richardson has gone on record already, stating “We believe that if these hieroglyphs could be deciphered they could help Egyptologists work out why these mysterious shafts were built” (Response to media enquiries, p. 1).  Shaun Whitehead would only add “Experts have had the opportunity to comment on the marks, and it is still generally agreed that they are hieratic characters.  It would be very exciting to find similar characters behind the first blocking stone in QCN” (Interview with Shaun Whitehead).

Floor, Walls & Ceiling (cont)

The Chamber Walls and Ceiling

The walls and ceiling of the chamber are formed by the final section of u-block, partitioned off from the shaft by the first blocking stone, and terminated by the second blocking stone.  When talking about the walls and ceiling of the chamber, therefore, it must be kept in mind that they are not separate pieces, but are all parts of the same block.  For purposes of orientation, it is assumed that we are looking across (actually, upward) to the second blocking stone.  Thus, the right wall is the one on your right hand side as you face the second blocking stone, with your back to the “door”.

As stated above, there is a cavity on the left hand wall of the chamber that appears to correspond to a chip located on the floor nearby.  The Djedi team proposes that the damage was caused by a spall “where an underlying pressure point has been created, probably from a chemical reaction” (Hawass, Whitehead, et. al, p. 212).  There is also a patch of flaking limestone close to the second blocking stone.  There are two red mason’s marks on the very edge of the left hand wall where it abuts the second blocking stone.

Prof Robert Richardson
Prof Robert Richardson

The right hand wall is interesting only in that it is slightly rougher near the first blocking stone.  Whereas the rest of the inside of the final u-block is finely polished and shows no obvious tool marks, there is a section on the right hand side behind the “door” where there are some diagonal tool marks visible.  The section is still smooth, but for some reason the workers were unable to sand out the tool marks in this area.  There are no corresponding tool marks on the left hand wall.

dje46-Right-hand-wall-finish-before-and-after-the-first-blocking-stone

The Djedi team proposes that this is the result of the block being cut to form the ledge that the “door” rests on, visible on the outside of the blocking stone via the triangular chip in the lower right corner.  Because of the way the right hand wall angles slightly inward to form the ledge, it was thus difficult to reach this spot for polishing.  This shaved area may also have been necessary to allow the blocking slab to be angled into place, as the slab is otherwise wider than the u-block, as indicated by the ledge it nestles against.

[Note: as will be mentioned when we discuss the second blocking stone below, Shaun Whitehead indicated in the Em Hotep interview that there are some red ochre marks on the back of the right wall, near the second blocking stone, which may correspond to those on the left wall.]

The ceiling is unremarkable, other than the cracks which emerge from the other side of the blocking stone, confirming that it is the same section of u-block that comprises the final part of the shaft.  Regarding these cracks, Shaun Whitehead says “It is most likely that they occurred after the U-block was finished and positioned, as the rest of the construction is so careful in this region.” There is another large crack that angles inward from the back left corner, where the ceiling meets the second blocking stone.

The Second Blocking Stone

Composite image of the second blocking stone (the back wall)
Composite image of the second blocking stone (the back wall)

The second blocking stone, which forms the back wall of the chamber, has a rough unfinished surface and appears to be made of the same lower quality yellow limestone that is used in most of the shaft.  Other than the same tool marks seen on other similarly rough blocks, and a green “trickle line”, the block has no distinguishing marks.

The “trickle line” is of indeterminate nature.  It emerges from the top of the stone, just left of the center, and runs slightly diagonally to the left, stopping 3-4 cm above the floor.  It is greenish in tint, and the official report suggests that it could be either accidental, such as copper oxide leaching from a nearby copper object, or purposely painted onto the block using the “Egyptian blue” pigment created by calcium copper silicate (p. 213).  Both causes would result in the sort of green seen in the trickle line.

dje49-The-green-trickle-line-on-the-second-blocking-stone

However, the official report also states that in order to produce a streak of copper oxide as prominent as the “trickle line” there would have to be a “significant presence of water” (p. 213), any source of which would be pure speculation unsupported by the existing data.  Regarding the possibility that the line could be the result of minerals within the limestone itself, Shaun observes “So far I have not seen any similar marks anywhere else in the shafts, decreasing the possibility that it was a mark that naturally occurred at the quarry” (Interview with Shaun Whitehead).

Djedi also noted that there is vertical cracking one third of the way from the right hand side which is odd (but not unique) in that it does not seem to emanate from one edge or the other:

It stops and starts suddenly and ‘feathers’ midway. These features are normally more associated with drying shrinkage rather than structural loading, although similar cracking has been observed elsewhere in the shafts. (Hawass, Whitehead, et al, p. 213)

The big question regarding the second blocking stone is whether it is the end of the shaft, and if not, what is on the other side?  Does another section of shaft resume on the other side?  Could it open into another chamber, possibly another burial chamber, or a section of internal ramp?  Or is it the terminus of the shaft, plain and simple?  A couple of factors within the scope of the Djedi Project and the robot’s capabilities could help answer these questions.

First, how does the final blocking stone fit against the end of the shaft?  Does the block lay flat against the end of the final section of u-block, like a lid, or is it plugged into the shaft like a cork?  If the former, that would suggest that the u-block terminates against the second blocking stone.  If the latter, then the u-block may continue past the second blocking stone, depending on whether the second block has a sort of T-shape, with the thinner section inserted into the shaft, or whether it is small enough to be fully inserted into the u-block like the first blocking stone, which means the shaft could potentially continue beyond it.

dje50-Computer-rendering-of-the-red-marks-on-the-back-left-wall

This first question could possibly be answered by further analysis of the edges of the back end of the u-block.  As mentioned above, there are mason’s marks on the edges of the u-block, where it meets the second blocking stone.  These marks could simply be lines the workers made when cutting out sections of u-block.  But they could also have marked a section where the u-block was shaped to form a ledge, like the one against which the first blocking stone rests.  As the official report notes, this could mean that the second blocking stone is inserted into the shaft like a cork, rather than lying across it like a lid (p. 214).

Shaun Whitehead expanded on this question in the Em Hotep interview:

At a first glance, the second blocking stone just seems to be a large, relatively rough-hewn block sitting on the end of the U-block. However, the intriguing thing is that there appear to be red ochre mason’s marks on both walls at the far end where they meet the second blocking stone. This may suggest that this U-block has been cut back at this point, to form ledges on both sides. It’s possible to follow this reasoning to several logical conclusions, all currently speculation.

The other question which lies within the scope of Djedi’s capabilities is:  how thick is the second blocking stone?  If it is, like the first “door”, more of a slab than a block, and if it is either inserted into the shaft or rests on a ledge, then this could be a pretty good indicator that there is something on the other side than the core material of the pyramid.  Again, Shaun explained the difficulties involved in taking this measurement in the Em Hotep interview:

The intention is to try to determine the thickness of the second blocking stone with the miniature “Sonic Surveyor” that I mentioned earlier. This uses a similar device to that used by Pyramid Rover, however it’s much, much more difficult to build.  Pyramid Rover’s device was so large that it covered about half the area of the blocking stone.  Ours has to fit through the existing hole in the first blocking stone, so can be no larger in diameter than a pen.  This includes the actuator for “tapping” the stone, the sensor for listening to the response and the electronics to process the signal.  We also have a much rougher stone to try to evaluate. It’s really tough to get it just right. The development was somewhat hindered by the sad death of Ron Grieve.

The Djedi team remains confident that these difficulties will be breached, and that when work in the Queen’s Chamber resumes, modifications currently being made to the robot crawler will allow them to get a good read of the thickness of the second blocking stone.  Until then the questions remain—if the shafts ends with the chamber, and the first blocking stone was simply the dressed facing stone for the end of the shaft, why was it inserted 190 mm down into the shaft rather than flush against the end of the final u-block, and, if the chamber is not the end of the shaft, why is the second blocking stone made of the rougher, unfinished limestone, rather than the dressed Tura limestone?

These questions will only be answered, if ever, with further analysis of the shaft and the chamber.

Other Marks Inside QCS

When the Djedi team was able to analyze the video footage from the southern shaft they made another interesting discovery.  On the lower right hand wall of the shaft, about 3.5 meters before the first blocking stone, there are some additional marks similar to the hieratic glyphs discovered inside the chamber.  Like the other glyphs, these marks appear to be made in red ochre and black paint.  According to the official report, the marks are about 3-4 cm tall, but “as the marks were found serendipitously, it was not possible to examine them closely” (p. 214).

55_Figure-18

The Future of the Djedi Project

Like all Egyptological fieldwork, the Djedi Project has been affected by the political environment in Egypt following the January 2011 revolution.  However, there is plenty of reason to be optimistic.  The team has resubmitted their formal application to resume work in the Great Pyramid, and Shaun reports that their application has been reviewed and they are awaiting approval by the various committees that have been established by the new government to help Egyptologists get back to work.  The Djedi team hopes to finish their work in one final season and then publish all the results as soon as possible.

The effects of the January 2011 Revolution continue to reverberate as Egypt forges a new destiny (Photo Tahrir Square, Friday 8 April 2011, by James X)
The effects of the January 2011 Revolution continue to reverberate as Egypt forges a new destiny
(Photo Tahrir Square, Friday 8 April 2011, by James X)

Meanwhile, there is still plenty to be done—and that is being done—to analyze the data gathered so far and to prepare for the resumption of fieldwork.  Specialists are working to complete the 3D reconstruction based on the various types of data collected from QCS and the chamber, and to integrate this into the larger picture.  As mentioned before, Dassault Systèmes has already worked with Jean-Pierre Houdin to create an incredibly accurate and detailed 3D virtual reconstruction of the Great Pyramid, and the mutually beneficial connections between Project Khufu and Djedi—having experts involved in both projects working together—are readily apparent.

dje55-The-next-horizon-for-Djedi-QCN

Djedi is also being refitted in preparation for returning to QCS and for its voyage into the more difficult Queen’s Chamber northern shaft.  QCN had to negotiate around other internal structures, such as the Grand Gallery, and presents a greater challenge for the agile little robot.  As Shaun explained to Em Hotep:

We have completely redesigned and rebuilt the brace actuators (that grip the walls), improving the climbing algorithms and techniques of the robot, [we are] designing tools to help the robot cope with the complex bends in the Northern shaft, extending the reach and agility of the snake camera, fitting a high definition camera, perfecting the Sonic Surveyor, working on 3D video reconstruction, multispectral imaging of the shafts inside and outside the pyramid if possible…

Djedi’s remaining work may be summarized as follows:

  • Determine the thickness of the second blocking stone in QCS, and if feasible, drill through it and see what lies beyond.
  • Determine the thickness of the blocking stone in QCN, and if feasible drill through it and see if there is a chamber in QCN like the one in QCS.
  • If there is another chamber in QCN, with a matching second blocking stone, analyze that block as well and hopefully drill through it and see what lies on the other side.

The next obvious question is: if there is another space behind the second blocking stone in QCS, and presumably, QCN, what then?  Eventually the shafts have to end, either in a final chamber or passageway, against the core of the pyramid, or out the other side of the pyramid’s surface.  And if there is something on the other side of the second blocking stone[s], Djedi will inevitably reach the end of its capabilities.  It is obviously too large to fit into the drill holes, and while a snake camera can feasibly be extended to an indefinite length, tube drill cannot—once it reaches a certain length the weight of the tube becomes too heavy.

But necessity is the mother of invention, and Scoutek is no stranger to creating smaller and smaller robots.  The Great Pyramid of Khufu may necessitate a leap into the next, next generation of robotic archaeology.

Works Cited
Zahi Hawass, Shaun Whitehead, TC Ng, Robert Richardson, Andrew Pickering, Stephen Rhodes, Ron Grieve, Adrian Hildred, Mehdi Tayoubi and Richard Breitner.  “First report: video survey of the southern shaft of the Queen’s Chamber in the Great Pyramid.”  Annales du Service des AntiquitÉs de l’Égypte .  Tome 84, 2010.  Pp. 203-16.

Copyright by Keith Payne, 2012.  All rights reserved.

All photographs and images watermarked “Courtesy of the Djedi Team” are copyrighted by the Djedi Project Team, all rights reserved, and are used with the permission of the copyright holders.  All photographs and images watermarked “Courtesy Dassault Systèmes/Djedi Team” are copyrighted by Dassault Systèmes and the Djedi Project Team, all rights reserved.  The photo Tahrir Square, Friday 8 April 2011, by James X , is used in accordance with the Creative Commons 2.0 license. 

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