The Flexible Robot Arm P.O.W.E.R.
Introduction
The Personal Occupied Woven Envelope Robot (P.O.W.E.R.) project is a joint effort of the University of Alabama in Huntsville (UAH) and Wyle Laboratories. This work is being performed under the Innovative Research Program for NASA.
POWER is a flexible robot arm. It will be used as an "extension" of the Space Station. POWER consists of 50 segments, and each segment has six degrees of freedom. The segments are based on the Stewart Table, which has six linear (individually controlled) actuators. A control pod is attached to the top of the flexible robot arm. A flexible tunnel connects the control pod to the habitat module of the Space Station, allowing a person to transfer from the Space Station to the pod without having to suit up for extra vehicular activity. The operator of the pod is able to move himself and the pod to almost any location within 50 meters of the base attachment to the Space Station. The operator has at his disposal remote manipulator arms and also a glove box type arrangement with space suit arms so that he can perform manipulations on equipment external to the pod.
Some of the applications of POWER are:
• Changing out and servicing payloads on the payload platform.
• Maintaining subsystems such as propulsion and attitude control.
• Providing satellite service.
• Performing inspections.
• Supporting shuttle cargo bay operations.
• Performing remote control operations for hazardous duty.
• Capturing satellites during final approach.
Wendell the Unicyclist premiered in 1988, and is the world’s only unicycle riding animatronic figure. He performs without any visible means of support.
Source: The Illusion of Life: Lifelike Robotics, Gene W. Poor, 1991
"… But the most impressive component Garner brings to the animation marketplace is an extraordinarily creative mind with superb problem-solving and operationalizing abilities.
The evidence of those qualities can be seen in his animated character "Wendell the Unicycle Rider." I saw this animated piece when I visited Garner's facility. It is spectacular! Like Kuebler's sculptings, a picture does not do Garner's work justice. If you are serious about three-dimensional animation, I encourage you to take a pilgrimage to San Bernardino to experience Garner's "Wendell" robot. If that's not possible–be patient. In the future, you're going to see a lot of Garner Holt!"
Wendell's clay head during the sculpting process.
The completed Wendell head prior to assembly on the robot body.
Follow the lives of Rikky, a talanted geologist, and her brother Pete, an off-the-wall mechanical genius. To find peace of mind they travel to the outbacks of Australia and meet up with a desert mining town full of zany individualists.
In the movie, Pete builds a newspaper folding and launching machine accessory for his Mini-Moke car to make his 'paper round' easy to do. He also exhibits a kinetic art piece at his sister Rikky's art show opening. It elevates and smashes eggs.
Later he heads off with Rikky to a mining town, and eventually they get a plot to mine. They need a rock drill so Pete builds the mechanical horse with multiple rock drilling heads at one end, and a hydraulic back hoe at the other.
Produced by
Bryce Menzies….executive producer
David Parker….producer
Nadia Tass….producer
Timothy White….co-producer
Writing credits
David Parker …. writer
Cast includes
Stephen Kearney…Pete Menzies
Nina Landis…Rikky Menzies
Art Department
Aaron Beaucaire….mechanical props assistant
Steve Mills….mechanical props assistant
Back in November 2004 I contacted David Parker at his film production company in Port Melbourne, Victoria, Australia. He still had the "Mechanical Horse" from his "Rikky and Pete" movie (released in 1988). In a small garage there were various props from various movies. Here's some pics of the walking machine as it was then.
The air-cooled engine above was a prop. The real motor was electric and is shown below.
Shadow Walker – Retired in 2002
A two legged human sized pneumatic powered walking robot.
Design and building started 1988.
Size – 5ft 6inches high, weight about 80lb
Operational area:- safety supporting frame 4ft * 8ft * 8ft plus host computer, a small compressor fits under the host computer's table.
Shadow Biped appearances:
1990 – the BBC TV program Tomorrow's World, live on 18th January 1990.
1990 – Robotix, The Robot Olympics Glasgow 1990 – Gold Medal for Best Robot at Robotix
1990 – The Garden Party, TV program 12th September 1990.
1996 – Robotix96, The Robot Olympics Glasgow 1996 voted 'Best Robot' by attendees.
2002 – Robodex (Japan). Invited by the organisers, voted favourite Robot by an exit poll.
Back in 1988 when the Shadow Group was new, Richard Greenhill, the founder and funder of the Group, was working on a shrugging shoulder which he thought was necessary for a robot or human to lift heavy weights such as suitcases. For David this wasn't a very fascinating aspect of robotics and he suggested that in order to attract members the group needed an appealing and challenging project such as the full sized biped robot they had often talked about. Rather than wait until everything was developed, the group could start with the legs and add the other parts as they went on. So the project to build the first Shadow Biped Walker was set in motion.
David Buckley drew up plans for the skeleton, researched medical texts for muscle placements and designed the electronics so the group could run the walker from an Acorn Archimedes computer. Richard Moyle and David Buckley built the skeleton and the electronics were built by various other members of the group. Richard Greenhill designed and built the muscles (his development of the McKibben muscle) and attached them to the legs. All the joints had potentiometers attached for position feedback and all the muscles had tension sensors. The next step was to build the pneumatic valve sets to drive the muscles.
David Buckley was working abroad and when he came back others in the group had built the two sets of air valves and switches seen in the photograph. They took up all of the body space leaving no room for any arm mechanism at all! David was very disappointed but what was built was built, maybe it was his fault for not drawing up the arms, he thought to himself. David Tricket built a pressure sensor panel with modified pressure dial gauges so everyone and the computer could read the pressure in each muscle and this was attached to the back of the robot.
Richard Walker took over writing software experimenting with all sorts of neural nets trying to get the walker to learn how to stand.
Since the robot used McKibben muscles David Buckley hoped it would be quite flexible but Richard Greenhill kept pressing for more force from the muscles and in the end it was very highly strung and could nearly stand up without any compressed air in the muscles at all!
During this time David Buckley was spending time working abroad so had little control of what went on with the robot and one time when he returned the group had decided that since some of the potentiometer fixings had come loose instead of securing them they would take off all of them and replace them with analog optical sensors.
After a lot of work especially by Richard Greenhill, in getting the sensors to work, Richard Walker discovered they were not monotonic and so more time and effort was expended on them.
The original valves were 110vac (used because Richard Greenhill bought them cheaply from Proops at around £1 each) but Richard Walker thought they didn't have enough through flow to fill the muscles fast enough for his control software to work. So they were all changed for 12v washing machine valves with enormous flow capacity. In doing so it was discovered that the reason the old valves couldn't supply the necessary air was that most of the connections in the pressure sensor panel virtually sealed off the supply and simply making them good would have been sufficient. The new valves required large fittings and only cast-iron ones were available, this set another problem because the group member who modified them didn't clean them thoroughly and they all went rusty and particles stopped the valves from working. An all night session stripping and cleaning everything was required so the robot could be shown, probably at the Robot Olympics 1996.
The new valves brought their own problems, they had rubber diaphragms and pressure bleed holes and didn't respond well to being pulsed, but Richard Walker eventually managed to tame them.
In 1998 David Buckley moved into a new house in the North of England and the walker was transferred from the Shadow labs in London with the idea that he could continue to work on it at home. However after inspecting it he realised that it would take as much work to refurbish as to build a new walker and so it was decided to retire it. The walker now hangs on the wall of the Shadow labs.
Sadly after returning from Robodex 2002 the Biped was never put back together. In 2008 the valve blocks were in a store cupboard… and the rest?…
valve blocks.
A good place for Biped links is androidworld.com – see Biped Projects
[photographs of the Shadow Biped by Richard Greenhill]
Shadow leg
Robotic-Leg for medical research into powered prosthetics, North Carolina A & T University 2005 by David Buckley.
The human sized Leg was made for the Shadow Robot Co. as part of a contract from North Carolina A & T University and my understanding is that it was to be used at North Carolina A & T University in a research program which would investigate myoelectric control of powered prosthetic legs. The program was to be overseen by Dr. Gary L. Lebby, a Research Professor in the Department of Electrical and Computer Engineering.
The actuators are Shadow Air muscles, a development of the McKibben artificial muscle.
Material – white acetal plate.
The leg was fitted with the control system used by the Shadow Hand
See David Buckley's website for further photos, video clip and other details.
Shadow Hands
There are two types of hand built by Shadow.
The McKibben Shadow hand
The Electrically actuated Shadow hand.
Shadow C6M Smart Motor Hand
Electric conversion for Shadow Pneumatic Dextrous Hand. Summer 2008 by David Buckley.
For The Shadow Robot Company.
Mechanical design of the forearm and wrist for the conversion of the Shadow Pneumatic Dextrous Hand to use electric motors together with force sensing feedback to achieve active compliance. Debugging and reworking of existing motor control boards and force sensors for use with the new arm. The project also required learning and becoming skilled in ProDesktop, the CAD program Shadow use.
A good example of the "big iron" approach to mobile robots is AMBLER (acronym for Autonomous MoBiLe Exploration Robot), developed by Carnegie Mellon University and the Jet Propulsion Laboratory. This behemoth stands about 5m (16.4ft) tall, is up to 7m (23.0ft) wide, and weights 2500 kg (5512 lb). It moves at a blistering 35 cm (13.8 in) per minute. Just sitting still, it consumes 1400 W of power. Ask it to walk and it sucks up just about 4000 W.
AMBLER showing time-lapse traces on one leg.
Some of the Carnegie-Mellon team with AMBLER highlight its immense size.
See a few pdf's describing AMBLER mainly here and here.
The Ambler robot was designed for walking under the particular constraints of planetary terrain, where there are meter-sized boulders, deep crevices, and steep slopes-an altogether inhospitable environment that defies humans and wheeled machines alike. Therefore, the six-legged Ambler travels over extremely rugged terrain without the close aid of humans. Autonomously, the Ambler builds detailed terrain maps; plans its own sequence and location of steps; and controls its movement, balance, and stability. In extensive tests, the Ambler has traveled thousands of meters, taken thousands of steps, and negotiated terrains that defy other robots.
Walking
Ambler walks like no other machine and like no other creature in nature: Stepping with any leg in any sequence, the Ambler has the patented capability to move its rear-most leg past all other legs in order to travel over extreme terrain as efficiently as possible. Also, while most animals bend their legs to step and walk, Ambler's legs remain vertical, while they swing horizontally, then lengthen themselves vertically, like a telescope, to touch the ground. Such legs do not rock or sway in the act of stepping, thus risking unnecessary collision with obstacles. More flexible, animal-like legs require substantially more sensing and planning from a robot, but the Ambler's unbendable legs decrease both the consequences and the extra planning that would be necessary for bendable legs.
The robot's height of 3.5 meters enables it to step over obstacles as high as one meter. At the same time, no matter how rough the terrain, the Ambler walks upright, keeping its legs vertical and its body horizontalÑand keeping its laser rangefinder steady. It is through data from the laser rangefinder that the Ambler's perception system builds computerized maps of the terrain. (See Terrain Mapping, Krotkov.) In fact, Ambler's walking design facilitates perception of the terrain by maintaining a steady and level posture (on a 30 degree slope). When the robotÕs perception system merges laser images from different viewpoints into a larger composite picture of the terrain, the robot's stability gives its laser images a good registrationÑthat is, leaves very little unintended overlap and no gaps between the various image viewpoints. The robot's height also gives the laser rangefinder a high-vantage with which to better view the terrain, and promotes a high quality of sensor data.
Planning
Although remote human operators tell the Ambler where to go, the robot itself plans the steps it must take to get there (see also, Gait Configuration of Legged Robots, Wettergreen). The robot's gait planner takes into account not only terrain constraints but also its own walking capabilities: how far the robot's legs can reach, how long the legs can extend, how far the robot's body can stray from its center of gravity, where the robot can move each leg without colliding into another leg, and how it can place its legs so that its body-which moves alternately with the legs-also has a clear path to move forward.
After the gait planner has intersected all of these constraints and determined a limited number of steps, the footfall planner considers which of the available steps offer the best footholds and are more efficient in time and energy. The footfall planner has learned, through a neural network, which footholds are optimal, having been presented examples during its development of good and bad footholds. The leg recovery planner finally determines how to move each leg without colliding into something mid-move. At the same time, the robot's planners must weigh the various constraints. For example, the robot's body must move as far forward as possible (to increase efficiency of speed), without moving beyond its center of gravity.
Integration
Getting the various on-board systems to interact efficiently involves the use of Task Control architecture (see Task-Level Communication and Control, Simmons). Like a switch-board operator, TCA facilitates communication between the Ambler's various systems, coordinates the robot's plans, sequences tasks, and monitors actions and recovers from problems. Task Control Architecture enables planning, perception, and real-time control to work concurrently.
