TY - JOUR
T1 - An improved method combined SMC and MLESO for impedance control of legged robots’ electro-hydraulic servo system
AU - Zhu, Qixin
AU - Huang, Dunhao
AU - Yu, Bin
AU - Ba, Kaixian
AU - Kong, Xiangdong
AU - Wang, Shoukun
N1 - Publisher Copyright:
© 2022 ISA
PY - 2022/11
Y1 - 2022/11
N2 - The electro-hydraulic servo system (EHSS) drives the hydraulic quadruped robot, which has the advantages such as high load capacity, fast response velocity, and powerful motion ability. EHSS of single leg consists of three sets of hydraulic drive unit (HDU), which is the joint driver. As a result, HDU control is the fundamental control of the hydraulic quadruped robot, and it controls the robot's motion performance directly. In order to improve the control accuracy and adaptability to different working conditions of impedance control for HDU, a composite control method combining sliding mode control (SMC) and model-based linear extended state observer (MLESO), which is called SMC-MLESO, is designed in this paper. Firstly, the chattering problem of SMC is improved by designing a novel composite reaching law and adding total disturbance to sliding mode control law. Secondly, the parameters of sliding mode surface are calculated by the optimal control. The parameters of MLESO are calculated by the bandwidth of the controller. And the known model of the system is added to observer to reduce the influence of sensor noise. Finally, comparative experiments show that SMC-MLESO has a good control effect. The maximum error of using SMC-MLESO is 0.101 mm and the biggest change of the maximum error is 36.5% under different working conditions, which is better than PI+Gcp and PI+Gcp+Gfp(The two controllers were designed by the author's previous research, which was published by Journal of the Franklin Institute).
AB - The electro-hydraulic servo system (EHSS) drives the hydraulic quadruped robot, which has the advantages such as high load capacity, fast response velocity, and powerful motion ability. EHSS of single leg consists of three sets of hydraulic drive unit (HDU), which is the joint driver. As a result, HDU control is the fundamental control of the hydraulic quadruped robot, and it controls the robot's motion performance directly. In order to improve the control accuracy and adaptability to different working conditions of impedance control for HDU, a composite control method combining sliding mode control (SMC) and model-based linear extended state observer (MLESO), which is called SMC-MLESO, is designed in this paper. Firstly, the chattering problem of SMC is improved by designing a novel composite reaching law and adding total disturbance to sliding mode control law. Secondly, the parameters of sliding mode surface are calculated by the optimal control. The parameters of MLESO are calculated by the bandwidth of the controller. And the known model of the system is added to observer to reduce the influence of sensor noise. Finally, comparative experiments show that SMC-MLESO has a good control effect. The maximum error of using SMC-MLESO is 0.101 mm and the biggest change of the maximum error is 36.5% under different working conditions, which is better than PI+Gcp and PI+Gcp+Gfp(The two controllers were designed by the author's previous research, which was published by Journal of the Franklin Institute).
KW - Hydraulic drive unit (HDU)
KW - Hydraulic legged robot
KW - Model-based linear extended state observer (MLESO)
KW - Position-based impedance control
KW - Sliding mode control (SMC)
UR - http://www.scopus.com/inward/record.url?scp=85127324656&partnerID=8YFLogxK
U2 - 10.1016/j.isatra.2022.03.009
DO - 10.1016/j.isatra.2022.03.009
M3 - Article
C2 - 35361486
AN - SCOPUS:85127324656
SN - 0019-0578
VL - 130
SP - 598
EP - 609
JO - ISA Transactions
JF - ISA Transactions
ER -