Design Of Wearable Cable-driven Assistive Systems Of Hand And Arm

The recent development of soft exoskeletons has allowed many patients who have suffered of a stroke or a spinal cord injury or who had an accident,and who have been paralyzed of a limb or part of it,to recover a major portion of their movement and independence.Nevertheless,there are still need for assistance in the movements.In this perspective,this essay,after reviewing existing systems and previous work on a hand exoskeleton,presents two main systems: a compact and light soft cable-driven hand exoskeleton and a prototype of cable-driven upper limb system.The first one can be used for the flexion and the extension of the fingers and to bend the wrist.The other one can bend the elbow and lift the arm.These systems aim to assist people with paralysis.The development of these devices has been realised depending on the problems encountered and the requirement to make the systems functional.The design of the hand exoskeleton is specific to each individual to increase its precision while the upper limb system can be used by everyone depending only on the motor output power.The hand exoskeleton is composed of two sections: an independent hand section for three fingers(thumb,index and middle)and a wrist section which use some parts of the hand device to bend the wrist.For the flexion and the extension of the fingers,a 6-stage pulley has been realised to provide smooth and precise movements.To bend the wrist,a linear motor is used to pull the hand section while a spring allows it to come back in position in line with the arm.The upper limb system is made up of a system that has already been tried and tested to bend the elbow and a new system to lift the arm.The two parts can be used simultaneously.The part to lift the arm has been studied,designed and simulated on Solid Works before being made in Aluminium alloy and tested.It has been designed to lift the arm with as little force as possible.Experimental results show that the systems are well developed to assist people in their movements.For the hand exoskeleton,the requirements for Activities of Daily Life(ADLs)are respected.Nevertheless,some improvements on other devices are necessary to be wearable and optimized.Future applications might allow these devices to be tested on people with real needs and adapted to electronic system to operate them more conveniently.