Pneumatic muscle actuators (PMAs) are frequently used in a wide variety of biorobotic applications, such as robotic orthoses and wearable exoskeletons, due to their high power/weight ratio and significant compliance. However, the asymmetric hysteresis nonlinearity reduces their fidelity and cause difficulties in the accurate control procedure. In this paper, Bouc–Wen hysteresis model is modified to describe the asymmetric force/length hysteresis of the PMA. The effect of muscle length on hysteretic restoring force is considered in this modified model and experimental results show that the proposed model has a better performance to characterize the asymmetric hysteresis loop of pneumatic muscles. The nonlinear pressure/force model of these actuators also is modeled precisely and its performance is experimentally verified for different muscle lengths.

气动肌肉执行器（PMA）由于具有高功率/重量比和显着的顺应性，因此经常用于各种生物机器人应用中，例如机器人矫形器和可穿戴外骨骼。但是，非对称磁滞非线性降低了其保真度，并在精确控制过程中造成了困难。在本文中，修改了Bouc–Wen磁滞模型来描述PMA的非对称力/长度磁滞。在修改后的模型中考虑了肌肉长度对迟滞恢复力的影响，实验结果表明，该模型具有更好的性能来表征气动肌肉的非对称滞后回线。