Thursday, 18 October 2012

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...


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