The robotic hand exoskeleton fits the need of seniors with quadriplegia because it takes into account both of the problems that the pre-existing products had including the verbal voice activation robot and the EMG controlled input robot. The robotic hand exoskeleton has altered the faults of the verbal activation robot as well as the EMG control input robot. It now consists of EEG and EMG signals being sent from the brain through the senior patient’s visual feedback, which generates signals. This was to improve the design for the seniors, but can still be improved.
The robotic hand exoskeleton consists of a pinching motion in the hand with the index finger and the thumb. “The exoskeleton has three aluminum rings fixed on the three joints in the index finger with the four degrees of freedom. For the pointing end of the finger, the joints include the distal interphalangeal (DIP), proximal interphalangeal (PIP), and metacarpophalangeal (MCP). The DIP and PIP joints have the flexion/extension degrees of freedom, while the MCP has both the flexion/extension and abduction/adduction degrees of freedom (all four)” (Lucas, DiCicco, Matsuoka 2). In order for a successful, steady pinching motion with the thumb, all three joints are required flexion and extension. The flexion and extension aspects of the DIP and POP joints are coupled, but the DIP/PIP and MCP flexion and extension are independent. “Abduction/adduction (active) activities of the index finger are not used to allow the end of the index finger to meet the thumb, but instead, passive abduction/adduction is used. This is to aid the senior’s finger in conforming to its targeted item” (Lucas, DiCicco, Matsuoka 2). In order to maintain these movements, there needs to be:
· A coupled active degree of freedom for the DIP and PIP flexion/extension
· An active degree of freedom for MCP flexion/extension
· A passive degree of freedom for the MCP abduction/adduction
“Pneumatic pistons are used for both active degrees of freedom, which activates a cabling system. There are variable pressure pneumatic cylindrical valves, which the pistons are linked to. This shows that the movements can be accomplished by a linear actuation of 1 to 1.5 inches (depending on the hand size of the senior). The orthotic robotic hand exoskeleton consists of the machine-driven framework made out of aluminum anchoring plates fixed to the back of the hand with three aluminum rings fixed on each joint of the index finger” (TBI Rehabilitation). These three metal pieces on the joints will allow for an easy pinching form for the senior quadriplegic individual. The three aluminum rings are adjustable in size for seniors with differing index finger sizes. The flexion of the PIP and DIP joints in the index finger is shaped by the steel cables running along the front of each index finger band and behind the hand. The cables are pulled back by the pneumatic cylinders acting as a compression force. “When the extended pneumatic cylinders push the linking mechanism forward to the distal end, the MCP joint results in flexion of the senior’s finger. There is a flexible coupling between the base-plate and the first finger band to achieve a smooth, repeatable motion” (TBI Rehabilitation).