Passive exoskeleton for assistance in heavy operation

Passive exoskeletons for industry are devices that can effectively facilitate the work performed by the wearer. One of the limitations of existing structures, used in various application fields, is not to correctly respond to normal human physiological movement, given by the non-direct correlation between robotic and human degrees of freedom. This generates discomfort, non-linear movements and often injury. To solve this problem, models based on shoulder rhythm have been presented and developed, focusing on a supporting exoskeleton for heavy operations of the upper limb member. Several geometric models have been proposed that are able to recover the potential energy of the movement of the arm with respect to its reference position (non-activated muscular system and arms parallel to the gravity vector). The first model involves the use of a space cam system, that involves the use of compression springs, for which the law of motion was sought for the most suitable target. The remaining two models have been simplified, covering different ranges of movement with respect to the global mobility range of the arm. These models exploit the elastic energy of a pressurized fluid through the use of pneumatic muscles (McKibben muscle). The strategy adopted was to study the natural dynamics of the shoulder and develop the energy needed to provide assistance during the flexion and abduction phases so as to reduce the metabolic consumption required by the muscles during the manipulation phases in the arm's working space, with the aim of creating an ergonomically better working condition. A test bench was run for models involving the use of McKibben muscles in order to assess the true functioning characteristic and muscle losses.