State of the art of actuator and damper for micro-processor controlled prosthetic knee

According to the data calculation of the second national handicapped person sampling survey, the sum of disabled people in China is 82.96 million, including 24.12 million physical disabilities and 2.26 million amputees.1 The number of lower limb amputee is about 1.58 million.2 To cope with daily life activities, lower limb amputees require to install lower limb prosthesis. Lower limb prosthesis for a person with transfemoral (above-knee) limb loss includes, at a minimum, a socket, knee, foot, and the necessary pylons or adapters to connect these components.3 The part that has taken the biggest efforts in its development is the knee prosthesis. The knee performs a key role during the whole gait cycle, and this is basically due to the fact that the knee joint sets a leg made of two bodies, articulated between each other through it. This is the case in human body between thigh and shank, being this leg configuration from which it is understood a natural gait. Moreover, this last feature, leaving aside damping and impulse functions of feet, is what makes human gait the most efficient mode of moving human body from one place to another.4 The prosthetic knee is separated by the complexity of their control: mechanically passive, microprocessor controlled passive, and microprocessor controlled active.5 Damping of mechanically passive control knee cannot be changed with different speeds and often characterized by abnormal gait, increasing energy expenditure of amputees to walk. Microprocessor-controlled prosthetic knee are the research focus. The classification of microprocessor-controlled prosthetic knee is shown in Figure 1.