Development of A Three-state Clamper for Multi-joint Sequence-driven Exoskeleton

Assisted exoskeleton robots are gradually being used in industrial production in order to reduce the risk of workers suffering from work-related musculoskeletal disorders (WMSDs). To lower the weight of the exoskeleton and improve its applicability, the active degrees of freedom of exoskeletons are often reduced in prototype designs. However, this may decrease the exoskeleton's output power and working capacity. To address this, we propose a tendon-sheath-based multi-joint actuation method that uses a single motor to sequentially drive multiple degrees of freedom, and applies it to the design of the shoulder and elbow joints of the upper limb exoskeleton. To do this, we develop a clamper remotely controlled by a steering gear, which has three working modes and is used to switch the position of the end anchor point of the tendon sheath artificial muscle. The clamper can clamp wire ropes with diameters of 1-2 mm and provide a maximum clamping force of 800 N. The performance of the multi-joint exoskeleton and the clamper was tested by experiments. The results show that the clamper can quickly control the tendon sheath artificial muscle to achieve the sequential movement of the multiple joints, and it only takes about 100ms to 150ms to switch between the three working modes.