Knee joint exoskeleton with rigidity adjustment and energy recovery functions and training method thereof

The knee joint exoskeleton comprises a thigh support, a shank support, a thigh connecting plate and a shank connecting plate, the top of the shank connecting plate is rotationally connected with the bottom of the thigh connecting plate, and a driver mechanism is arranged on the front side face of the thigh support; the driver mechanism comprises a rack, a power input mechanism fixedly installed on the rack, a rigidity adjusting mechanism rotationally installed on the rack, and a power output mechanism connected with the rigidity adjusting mechanism and the shank connecting plate. The robot further comprises a sensing system and a control system electrically connected with the sensing system, and the sensing system comprises an encoder set arranged in the driver mechanism, an angle sensor arranged between the thigh connecting plate and the shank connecting plate and a pressure sensor arranged below the shank support. The output rigidity of the exoskeleton robot can be adjusted in real time according to the rig