Designing Uniaxial Magnetorheological Damper-based Prosthetic Knee and CT+PD Trajectory Tracking Control
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摘要: 针对传统假肢膝关节存在阻尼无法连续可调、仿生性不佳及价格高昂等问题,提出一种以磁流变阻尼器(Magnetorheological damper, MRD)为控制器件的新型磁流变假肢膝关节(Magnetorheological damper-based prosthetic knee, MRPK)。基于健康人在平地行走的步态数据,对单轴式MRPK进行结构设计,并建立其处于摆动相内的动力学模型,得到MRD的阻尼力需大于208.6 N及行程需大于33.3 mm。对MRD进行结构设计并利用ANSYS对其进行电磁场仿真分析,同时建立MRD的正向、逆向力学模型并得到其性能曲线。采用联合仿真的方法建立磁流变假肢膝关节控制系统,设计CT+PD轨迹跟踪控制器并与PD控制器对比,仿真得到CT+PD控制器的最大误差为-4.6°,而PD控制器的最大误差为12.3°。初步证明了CT+PD轨迹跟踪控制对MRPK摆动控制的有效性。Abstract: To solve the problems of traditional prosthetic knees such as nonadjustable damping, low imitation and high price, a magnetorheological damper-based prosthetic knee (MRPK) using magnetorheological damper (MRD) as control device is designed. Based on the gait data of healthy people walking on the ground, the structural design of the uniaxial MRPK was carried out, and its dynamic model in the swing phase was established. The damping force required by MRD is greater than 208.6 N and the stroke is greater than 33.3 mm. The structure of the MRD was designed and the simulation of electromagnetic field of the designed MRD was performed with the ANSYS. At the same time, the forward and reverse mechanical models of the MRD were established and its performance curves were obtained. The control system of the designed MRPK was established with the co-simulation method, and the computing torque plus PD (CT+PD) trajectory tracking controller was designed and compared with the PD controller. The results show that the maximum error of the CT+PD controller is -4.6°, while that of the PD controller is 12.3°, therefore proving that the CT+PD trajectory tracking control is effective for the swing control of the designed MRPK.
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Key words:
- prosthetic knee /
- magnetorheological damper /
- structural design /
- CT+PD control
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表 1 大腿及小腿摆动角度拟合参数
i a1i a2i a3i b1i b2i b3i 1 9.169 23.88 0.582 2.798 0.495 -2.289 2 9.522 14.17 0.041 12.5 1.494 2.525 3 23.54 37.13 3.735 5.175 2.398 1.184 4 10.37 3.573 9.817 19.38 -6.663 -2.905 5 -13.07 3.119 5.362 24.8 0.200 2 -2.367 6 1.833 1.89 19.13 27.25 -6.367 -0.363 表 2 磁流变假肢关键参数
参数名称 数值 大腿质量m1 1 kg 小腿质量m2 2.4 kg 大腿长度l1 460 mm 小腿长度l2 430 mm 大腿质心到髋关节长度lp1 360 mm 小腿质心到膝关节长度lp2 165 mm 表 3 MRD关键参数
参数名称 数值 缸体内径D 30 mm 活塞头直径d1 28 mm 活塞杆直径d2 18 mm 有效阻尼长度L 10 mm 黏度η 0.8 Pa·s 匝数N 100 -
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