Robot Muscles are not strong enough...

Robots and exoskeletons seem to be in the news lately, considering that new CGI films can make it possible to show the hyper reality of what a sophisticated robot can do in a fire fight. The reality is far from the fantasy. As always movement is restricted by the limited technology, while electric motors rule the mini robots that dominate the toy shelves. The use of these motors will have a limiting strength with or with out a gear system.
Consider The Hybrid Assistive Limb (also known as HAL) is a powered exoskeleton suit currently in development by Japan's Tsukuba University and the robotics company Cyberdyne. It has been designed to support and expand the physical capabilities of its users, particularly people with physical disabilities. There are currently two versions of the system: HAL 3, which has bulkier electric servo-motors and only has the leg function, and HAL 5, which is a full-body exoskeleton for the arms, legs, and torso. HAL 5 is currently capable of allowing the operator to lift and carry about five times as much weight as he or she could lift and carry unaided.
When a person attempts to move their body, nerve signals are sent from the brain to the muscles through the motor neurons, moving the musculoskeletal system. When this happens, small biosignals can be detected on the surface of the skin. The HAL suit registers these signals through a sensor attached to the skin of the wearer. Based on the signals obtained, the power unit moves the joint simultaneously with the wearer's muscle movement, supporting and amplifying the wearer's motion. The HAL suit possesses both a user-activated “voluntary control system” and a “robotic autonomous control system” for automatic motion support. The use of biosignals from the limbs allows freedom of moment, as nerve impulses is greatly amplified to each servo motor joint. But while the elderly and other people with restricted movement are benefiting with this type of technology in Japan. The super human strength and speed and agility in such a machine with limited battery time can not out perform a robot attack.
Consider hydraulic-power, in fluid or air used for the generation, control and transmission of power. Human Universal Load Carrier, or HULC, is an un-tethered, hydraulic-powered anthropomorphic exoskeleton developed by Professor H. Kazerooni and his team at Ekso Bionics. It is intended to help soldiers in combat carry a load of up to 200 pounds at a top speed of 10 miles per hour for extended periods of time. After being under development at Berkeley Robotics and Human Engineering Laboratory since 2000, the system was announced publicly at the AUSA Winter Symposium on February 26, 2009 when an exclusive licensing agreement was reached with Lockheed Martin.

Sensors in the foot pads relay information to an on-board microcomputer that moves the hydraulic system to amplify and enhance the wearer's movement. The flexibility of the system allows soldiers to run, walk, kneel, crawl, and even go into low squats. There is no joystick or control mechanism, instead sensors detect movement and, using an on-board micro-computer, make the suit move in time with the body. The system's titanium structure and hydraulic power augments the soldier's ability, strength and performance, whereas its modularity allows components to be switched and replaced with ease. Hydraulic power can provide speed and power to a human, but the large power pack even for a simple machine like the HULC system may limit its combat superiority. As the kicking power from this machine may provide enough damage to break bones, however it maybe top heavy. The likelyhood is that after attempting to kick the center of balance is distorted enough to topple over the user rendering him helpless as a turtle.

 Current systems of actuators hydraulics and servo motors have strengths and weaknesses all of which seem to have limited success on mobile systems. Even for a exoskeleton system to win a bar room fight, punching and kicking movements would be slightly delayed, due to sluggish mechanics and electronics. Considering that a quick few punches is need to subdue your opponent.
Only recently the tiny artificial muscles created by an international team of researchers are 200 times stronger than human muscle fibers of comparable size. Ray Baughman, a nanotechnology researcher at the University of Texas at Dallas, led the team that made the new muscle, which he sometimes calls a yarn because of the way it's woven. The muscles would work well in small medical devices, he said. His lab in Texas has thought of another creative use for them, too: "We've been playing with yarns to open and close blinds depending on the temperature of the room," he told TechNewsDaily.

Baughman's new muscles are made of ropes of carbon nanotubes, a super-tiny, high-tech material that researchers are adding to everything from water filters to experimental airplane parts. Baughman said he and his team twisted the nanotubes "quite similarly to the way people insert twists into common wool or cotton fibers" into thicker yarns. They then filled the hollow space in the nanotubes with different materials, including paraffin, the wax that goes in candles.
To get the muscles to contract, researchers heated them briefly. When heated, the paraffin wax expanded, pushing against the nanotube walls and making them fatter and shorter. As the wax cooled again, it shrank, and the nanotubes became narrower and longer. The muscles were able to shorten and then lengthen again every 25 milliseconds, or 25 thousandths of a second, Baughman said. Such fast contractions mean the muscles are able to perform a lot of work, he said.

Right now, Baughman's lab knows how to make a muscle fiber that's one kilometer (0.62 miles) long, but Baughman hopes one day to weave fabrics that require miles of fiber. He also is looking to make the muscles react to chemicals instead of heat. Heat-driven motors are energy-inefficient, so chemical-driven muscles might be more practical.
Alternatively SRI International, Menlo Park, Calif.created a electronic muscle or a passive dielectrics which are a variant of artificial muscle activated by the movement of electrons. In an actuator, two flexible conducting plates form a sandwich with the passive dielectric, a springy, insulating plastic, as a filling. When the plates are given opposite charges, their mutual attraction flattens and expands the filling. Also electro active polymers already been reported to show a significant actuation strain, and although they were not strong enough to amplify body movements, they prove to be useful on small scale robotics.
Other alternatives might be a Ionic polymer metal composites are a form of artificial muscle that depends on the movement of ions for motion. Flexible metal foils sandwich a wet polymer filling. With the foils charged, free ions flow toward one side, expanding it and bending the actuator.

Its still early days for a practical actuator to replace the motors and hydraulics, that we have in current exoskeleton systems. Adding super strength to a machine would mean tethering it to a large power source. While agility of the human body cant quite be matched, as is unlikely at this time to see a exoskeleton perform the same movements of a gymnast.
Excluding the military applications of hand to hand combat or mimicking the fire power of fiction character Iron-man, although the real world applications for replacing damaged limbs is too important to miss. While electro-neural connections are becoming a reality. The progress for artificial muscles is quite slow in comparison to Moore's Law. As emerging technologies that are designed to replace the human element, so will those technologies will find a way to mimic muscle fibers or at-least replace electric servos. The end result will probably be a system that will help aid humans. While there might be a slight need for combat situations, its hard to think that there will be a suit or exoskeleton that will be able to perform superhuman martial arts on an opponent...

ExoSkeletons, robot power for normal people

I enjoy watching the hyper reality of a man using a fictional power source to make light work of heavy lifting and carrying. Its fun to see the not so strong nerd engineer turn fictional engineering into superhero action. But in the back of my mind I knew that heavy actuators and expensive electronics would be a problem or even a difficult challenge. The main problem is heavy machinery or exoskeletons designed give the operator super human strength would probably need to be tethered to a large power source.

The first General Electric designs the “Hardiman” exoskeleton in 1965, but never demonstrates the full suit in action. Due to problems with motor control and the fact the legs could not work without support.
The project was not successful. Any attempt to use the full exoskeleton resulted in a violent uncontrolled motion, and as a result the exoskeleton was never turned on with a person inside. Further research concentrated on one arm. Although it could lift its specified load of 750 pounds (340 kg), it weighed three quarters of a ton, just over twice the liftable load. Without getting all the components to work together the practical uses for the Hardiman project were limited.
Since the Stan Lee creation in recent films, exoskeletons have been appearing in the news. One example Raytheon’s second-generation exoskeleton (XOS 2), essentially a wearable robotics suit, has been named one of the Best Inventions of 2010 by Time Magazine. The suit was unveiled for the first time in September during an event at the company’s Salt Lake City research facility. XOS 2 is lighter, stronger and faster than its predecessor, yet it uses 50 percent less power, and its new design makes it more resistant to the environment.

The wearable robotics suit is being designed to help with the many logistics challenges faced by the military both in and out of theater. Repetitive heavy lifting can lead to injuries, orthopedic injuries in particular. The XOS 2 does the lifting for its operator, reducing both strain and exertion. It also does the work faster. One operator in an exoskeleton suit can do the work of two to three soldiers. Deploying exoskeletons would allow military personnel to be reassigned to more strategic tasks. The suit is built from a combination of structures, sensors, actuators and controllers, and it is powered by high pressure hydraulics.
The Raytheon exoskeleton designed for the soldier for tomorrow seems more likely a power suit for loading munitions into large guns rather then combat.
Alternatively research into exoskeletons have not been exclusive to the military.
In Japan there has been a surge of R and D into exoskeletons, largely because of the country's rapidly ageing population: more than 30 per cent may be over 65 by 2025. In a recent science and technology white paper the government emphasised the need for robotic devices in a society where increasingly "the elderly will be caring for the elderly". The muscle suit is one of a series of cybernetic exoskeletons developed by Hiroshi Kobayashi's team at the Tokyo University of Science in Japan. Scheduled for commercial release early next year, the wearable robot takes two forms: one augmenting the arms and back that is aimed at areas of commerce where heavy lifting is required. The other, a lighter, 5 kg version, will target the nursing industry to assist in lifting people in and out of bed, for example.
Kobayashi believes his suit will be different. It doesn't have heavy electric actuators and hydraulics, but instead comes with PAMs - pneumatic artificial muscles. These lightweight, mesh-encased rubber bladders are designed to contract when pressurised air is pumped in. The PAMs give up to 30 kg of instant support or more, depending on how far the weight is away from the body. "The power-to-weight ratio is 400 times greater than motor-driven suits," says Kobayashi, who adds that unlike motors, PAMs are unaffected by water and dirt. A regulator controls the compressed air output based on a signal given by a microprocessor, which in turn communicates with an acceleration sensor in the frame that detects and responds to movement.
As well as its high power-to-weight ratio, the muscle suit's huge advantage, Kobayashi says, are its simple controls, which are largely preprogrammed to mimic natural human movements. Walking or lifting are triggered via the jacket's sensor, which responds to both simple voice commands, such as "start or "stop", and the body's acceleration. If the wearer is standing upright or moving more slowly than the preset acceleration threshold then the device will not move. A simple dial can control the suit's speed. The exoskeleton will be available to rent from ¥15,000 (£115) per month, although Japan's health insurance will cover 90 per cent of the charge in many cases.
The medical benefits for exoskeletons are more practical then military combat, thus giving a new lease of life to people who are in need for assisted support. One example was the use of a exoskeleton used on a a small child whose underdeveloped muscles made life difficult. Emma suffers from Arthrogryposis Multiplex Congenita (AMC), a rare congenital disorders that sees the muscles and joints shortened, as well as the muscles being weakened. But duPont Hospital Department of Orthopedics developed WREX–the Wilmington Robotic Exoskeleton. It gives kids with muscle weakness much better movement and the ability to lift objects. The exoskeleton is cheap to make because it is made from 3D printed parts and requires no power to support the arms instead elastic bands have been the main support for this type of machine.

The para Olympics in london had one or two examples of cybernetic legs for the disabled. One system from Rex Bionics claims that their robot walking device is completely self supporting and that people with no control to their legs could easily operate the system. Despite the cumbersome design, the different modes for walking standing and transitioning from a seated position works very well. Although from the footage the action of walking looks very slow. Created by two New Zealanders whose mothers are confined to wheelchairs, REX allow users to self-transfer from chair to the exoskeleton, then control their movements via a joystick and control pad. It runs on a rechargeable battery that lasts about two hours during continuous use and is swappable in instances where the user wishes to move about on his or her feet for longer periods. At $150,000 USD, REX is by no means inexpensive, but it does offer wheelchair users a practical and (almost) readily available means of getting out of their chairs. Other technology is a company called Berkeley Bionics which are introducing two new exoskeletons to the market that augment mobility, strength and endurance: eLEGS powers wheelchair users up to get them standing and walking again; and HULCTM (Human Universal Load Carrier) enables users to carry up to 200 lbs. for hours and over all terrains, while reducing the likelihood of back-injuries. This system requires the uses of two crutches to walk as there is no stability in the system. Despite the lack of stability the system works well and intuitively as it computes the movement in the arms to determine the movement for the legs. Ekso is currently undergoing further development and clinical trials in rehabilitation centers. It should become lighter and more adaptable, and by 2013 should be available for private use at a cost of about $100,000.
The technology for electronic limbs is in its infancy, Cost for a pair of battery operated legs seems ridiculously high roughly the price for a medium home or decent car. Maybe in time the sophistication for legs to stand and hold still will improve. Perhaps instead of electric motors, a pneumatic version with self correcting balancing computer could be a better system. But for now there seems to be trend for electric legs which are currently fore-sale, in time the price and possibly the walking speed will get better. Mean while for lazy people or someone who needs extra assistance there is a cool looking Cyberdyne robot-suit "HAL" (Hybrid Assistive Limb). Already for rental in japan the suit or legs will allow anyone to quickly rehabilitate. The eventual acceptance for exoskeletons will, I think remain in the medical realm as there is much need for such systems. Despite parallels with superhero action films, the need to aid a disabled person with this technology seems more heroic...