Design and impedance control of a hydraulic robot for paralyzed people

Abstract

One of the most restricting conditions for any living being is the loss of mobility. For humans, quadriplegia is the most extreme form. Different causes like spinal cord or brain injuries resulting in various degrees of paralysis of all four limbs. In the most serious cases even the ability to feel is gone below the injury resulting in an absolute dependency on others. Technical devices are already able to help those affected in many ways. To regain some of their independence, a robot actuating their body and giving them their mobility back could be one approach. Since their conditions affect the ability to interact with a device the choices for an interface controlling device are limited. In this paper, a design for a one degree of freedom device for paralyzed patients is presented. This device is focusing on the wrist extension and flexion. It is considered as a demonstration platform for a new actuation and comfort approaches for assistive devices. Since moving the human body for manipulation of objects will require high output forces, using a hydraulic system is a good option for actuating the device. Thus, after designing the device, a suitable actuator has to be chosen. One of the problems in using hydraulic systems is their hard controlling task. For controlling this hydraulic actuator, an impedance controller is proposed. For evaluating the controlling system, two different experiments are designed and their results are explored.