Sit-stand movement is one of the most common movement behaviors of the human body. The knee joint is the main bearing joint of this movement. Thus, the dynamic analysis of knee joint during this movement has deeply positive influences. According to the principle of moment balance, the dynamics of the knee joint during the movement were analyzed. Furthermore, combined with the data obtained from optical motion capture and six-dimensional ground reaction force test, the curve of knee joint torque was calculated. To verify the accuracy of the analysis of dynamic, the human body model was established, the polynomial equations of angle and angular velocity were fitted according to the experimental data, and the knee joint simulation of the movement was carried out. The result revealed that in terms of range and trend, the theoretical data and simulation data were consistent. The relationship between knee joint torque and ground reaction force was revealed based on the variation law of knee joint torque. During the sit-stand movement, the knee joint torque and the ground reaction force were directly proportional to each other, and the ratio was 5 to 6. In the standing process, the acceleration first increased and then decreased and finally increased in reverse, and the maximum knee torque occurred at an angle of about 140°. In the sitting process, the torque was maximized in the initial stage. The results of the dynamics analysis of knee joint during sit-stand movement are beneficial to the optimal design and force feedback control of seated rehabilitation aids, and can provide theoretical guidance for knee rehabilitation training.
坐立运动是人体最常见的运动行为之一，膝关节是人体坐立运动的主要承力关节，因此进行坐立运动过程的膝关节动力学研究具有重要意义。基于力矩平衡原理对坐立运动的膝关节动力学进行分析，结合光学动作捕捉和六维支撑力测试所得数据，计算求得膝关节力矩曲线。为了验证实验数据和动力学分析的准确性，建立人体模型，根据实验数据拟合角度和角速度多项式方程，进行坐立运动的膝关节动力学仿真。结果显示计算数据和仿真数据在范围和变化趋势方面一致。综合膝关节力矩变化规律，揭示了膝关节力矩与地面反作用力的关系。坐立运动中膝关节力矩和地面反作用力成正比关系，比值为5～6，且由坐到立过程中，加速度先增大后减小最后反向增加，力矩最大值发生在膝关节夹角约140°时，而由立到坐过程中，力矩在初始阶段最大。坐立运动的膝关节动力学研究结果有益于坐立康复辅具的优化设计及力反馈控制，并可为膝关节康复训练提供理论指导。.
Keywords: Dynamic model; Ground reaction force; Joint torque; Motion capture; Sitting and standing movement.