A LOWER LIMB EXOSKELETON WITH ACTIVE HIP, KNEE, ANKLE JOINT FOR LOAD AUGMENTATION AND MOBILITY REGENERATION FOR PERSONS WITH MOBILITY DISORDER AND FOR MILITARY PURPOSES AND PROCESS FOR CONTROLLING THE SAME

摘要

The invented system is a multipurpose lower limb robotic exoskeleton which can be used as a mobility generator as well as performance enhancer serving both pathological and normal usage. Active lower limb exoskeleton system consists of hip, knee and ankle joints actuated in sagital plane along with proper adjustable links and braces, actuator mechanism, sensing system, embedded control unit and Li ion battery unit (3S-2P). Developed system can also be independently used as hip exoskeleton, knee exoskeleton or ankle exoskeleton as per user’s need. The joints are specially designed using Ball screw based linear actuation at hip and knee joint and lead screw actuation at the ankle joint. In house high power dedicated motor controller unit has also been developed with current control, over current protection and thermal shutdown mode. The system is initiated, controlled and terminated using user’s intention and is adaptive to surface variation, velocity variation and anthropomorphic variation. Sensory system includes a potentiometer and optical encoder at each joint for absolute and incremental joint position information, myoelectric sensors and acquisition units for intention estimation and gait cycle phase calculation and pressure sensor based foot insole to detect, terminate gait cycle and calculate Centre of pressure. The lower limb exoskeleton structure consists of six actuated joints in sagital plane namely Hip joint (X), knee joint (Y) and ankle joint (Z). The hip joint has three degree of freedom (DoF), one active and two passive, knee joint and ankle joint have one DoF. The lower limb active exoskeleton works based on two independent control algorithms namely ‘intention based adaptive trajectory control and ‘interaction torque control’.