Compared with traditional prosthesis, mechanical prosthesis has many advantages, but there are many shortcomings such as high cost, noise, poor range and so on. A team of scientists at the University of Texas at Dallas recently developed a new type of mechanical prosthesis that uses motors originally used in robotic pickups on the International Space Station to create a quieter, more flexible prototype of the prosthesis.
During the use of traditional prosthetic limbs, the user usually lifts and swings the hips at every step in order to lift the leg off the ground and move forward. This leads to an unnatural gait that not only is exhausting, but can cause pain and injury over time.
The mechanical prosthesis, on the other hand, consists of electric joints that automatically bend the legs and move forward each step. In order to accommodate the limited space, the motor is usually small and rotates fast. A series of gears are used to transfer torque from these motors to the joints.
But these mechanical prosthesms make a lot of noise, and they also increase resistance, preventing the joints from swinging freely. In addition, these motors consume a lot of battery power, limiting the user’s walking distance for a day.
The new prosthesis prototype developed by the scientific team is equipped with only two motors at the knees and ankles, which are powerful enough to require minimal transmissions – meaning the leg is quieter and swings freer than other robotic prosthetics.
In addition, the robot legs are integrated with a regenerative braking system that slows it down at the end of each step. This setting not only allows the foot not to touch the ground with the force of the shock, but also charges the battery with the captured energy. As a result, it is said that just one initial charge of the battery will be enough to meet the need for a full day’s walk, which is twice as long as the life of other robotic prosthetics.
Scientists are now improving the control algorithm so that the device can automatically adjust to changes in terrain, walking speed and activity. A paper on the study, led by Associate Professor Robert Gregg (now working at the University of Michigan) was recently published in the IEEE Transactions on Robotics journal.