Abstract:  The joint resistant torque of extravehicular spacesuit is an important index to evaluate the ergonomic performance of spacesuit and to plan astronauts′ extravehicular mission.In order to study the hysteresis characteristics of spacesuits′ joint resistant torque，firstly，the causes of the joint resistant torque were summarized，and the hysteresis relationship between the joint resistant torque and the motion angle of lower limbs was obtained.Secondly，the Jiles-Atherton model was adopted to describe the hysteresis characteristics of the joint resistant torque.Meanwhile，based on the actual joint resistant torque data，the SA-PSO（simulated annealing-particle swarm optimization）algorithm was proposed to identify the Jiles-Atherton model parameters.Finally，compared with the modified particle swarm optimization algorithm，the convergence rate of the designed SA-PSO algorithm was improved by 15.58% and 10.91%，the computational accuracy was improved by 29.31% and 11.77%，and the prediction errors of the unknown joint resistant torque were reduced by 10.89%/25.73% and 0.96%/22.2%，respectively，which verified the effectiveness of the designed algorithm.In addition，an error compensation function was designed according to the characteristics of modeling errors，and the identified Jiles-Atherton model further reduced the prediction errors by 46.49%/10.95% after error compensation.The calculated model can serve as a theoretical basis for the subsequent research on joint-assisted technology of extravehicular spacesuit.

Key words: extravehicular spacesuit, joint resistant torque, hysteresis characteristics, Jiles-Atherton model, simulated annealing algorithm, particle swarm optimization algorithm