A Nonlinear Model-based Variable Impedance Parameters Control for Position-based Impedance Control System of Hydraulic Drive Unit

Ba, Kaixian; Ma, Guoliang; Yu, Bin; Jin, Zhengguo; Huang, Zhipeng; Zhang, Jun-Xiao; Kong, Xianwen

doi:10.1007/s12555-019-0151-0

Cited by 37 publications

(15 citation statements)

References 17 publications

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“…To sum up, the iterative equation of approximate Hessian matrix is expressed as follows: (21) 3) DESIGN OF POSITION CONTROL METHOD BASED ON…”

Section: ) Bfgs Algorithmmentioning

confidence: 99%

“…The authors' cooperation team has carried out preliminary studies on the mathematical modeling and sensitivity analysis of HDU position control, which lays an application foundation for the research method in this paper [21] . In addition, related control methods based on constant parameter PID control were also studied in the previous study by the authors' cooperation team [22] .…”

Section: Introductionmentioning

confidence: 99%

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An Improved DDPG and Its Application Based on the Double-Layer BP Neural Network

Zhang

Gao

et al. 2020

IEEE Access

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This paper focused on three application problems of the traditional Deep Deterministic Policy Gradient(DDPG) algorithm. That is, the agent exploration is insufficient, the neural network performance is unsatisfied, the agent output fluctuates greatly. In terms of agent exploration strategy, network training algorithm and overall algorithm implementation, an improved DDPG method based on double-layer BP neural network is proposed. This method introduces fuzzy algorithm and BFGS algorithm based on Armijo-Goldstein criterion, improves the exploration efficiency, learning efficiency and convergence of BP neural network, increases the number of layers of BP neural network to improve the fitting ability of the network, and adopts periodic update to ensure the stable operation of the algorithm. The experimental results show that the deep learning network based on the improved DDPG algorithm has greatly improved the performance compared with the traditional method after multiple rounds of self-learning under variable working conditions. This study lays a theoretical and experimental foundation for the extended application of deep learning algorithm.

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“…To sum up, the iterative equation of approximate Hessian matrix is expressed as follows: (21) 3) DESIGN OF POSITION CONTROL METHOD BASED ON…”

Section: ) Bfgs Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Improved DDPG and Its Application Based on the Double-Layer BP Neural Network

Zhang

Gao

et al. 2020

IEEE Access

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“…The mathematical model of each link of the HDU adopted in this article is the same as the mathematical model of each link of the HDU established by the author in the previous period. 30 –32 To reduce the length, this article will not repeat them. According to the mathematical model of the HDU established in the previous period, five linearly independent system variables are selected as the state variables of the control system for the position-based impedance control system.…”

Section: State Space Expression Of Impedance Control System For Hdumentioning

confidence: 99%

“…30 Aiming at the position-based impedance control system of the HDU, the disturbance rejection controller was designed based on the traditional PID controller to improve the control performance of the position inner loop. 31 When the HDU applied in each joint of the robot leg adopts impedance control, it should have high response ability and control accuracy, so that the robot leg can have better compliance to quickly buffer the excessive collision force during the time when the foot of the robot contacts with the ground and to improve the overall stability of robot movement. In this article, HDU was investigated.…”

Section: Introductionmentioning

confidence: 99%

State feedback-based impedance control for legged robot hydraulic drive unit via full-dimensional state observer

Zhu

Huang

et al. 2020

International Journal of Advanced Robotic Systems

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In this article, the hydraulic drive unit that drives the movement of the joint of a legged robot was researched, aiming at improving the control accuracy of the position-based impedance control system with dual input and single output. The state feedback control containing more state information of the system was adopted to replace the traditional output feedback and proportional-integral-derivative (PID) control, through the real-time calculation of the time-varying parameters of the servo valve flow, the nonlinear state space expression of the system was derived, the state feedback matrix and the input transformation amplifier were obtained and the full-dimensional state observer was designed. The experimental results show that the designed full-dimensional state observer can track the state variables of the actual system better. Compared with the traditional output feedback and PID control, state feedback control performs better in aspects of accuracy and system dynamics for the position-based impedance control system, which can further improve the compliance performance of the robot.

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“…This section establishes the mathematical model of the key components of PCDS, including servo motor, gear pump, oil supply loop and asymmetrical cylinder. The mathematical model of experimental platform of PCDS loading system and related high-accuracy position control have been carried out in the author's previous research [22][23][24]. Due to space limitation, it is not introduced repeatedly.…”

Section: Nonlinear Mathematical Modeling Of Pcdsmentioning

confidence: 99%

Design, Mathematical Modeling and Force Control for Electro-Hydraulic Servo System With Pump-Valve Compound Drive

Zhu

Yao

et al. 2020

IEEE Access

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Each joint of hydraulic drive legged robot adopts highly integrated electro-hydraulic servo system, and the system has two common forms, namely, valve-controlled cylinder system and pump-controlled cylinder system. The former has a large energy loss, which restricts the endurance of the legged robot in the field. Although the latter has the advantages of energy saving and high efficiency, the overall response ability of control system is unsatisfied. In this paper, a novel pump-valve compound drive system (PCDS) is designed. It combines the advantages of pump-controlled cylinder system and valve-controlled cylinder system, which can not only effectively reduce the energy loss of the system, but also ensure the electro-hydraulic servo system of the robot joint has the ideal response ability. This paper consists of three parts. In the first part, the mathematical model of nonlinear force control of PCDS is established, which takes into account the pressure-flow nonlinearity of servo valve, the asymmetry of servo cylinder and the complexity and variability of load. So this model has a high accuracy. In the second part, On the basis of the above model, a force control method combining tracking error compensation and load compensation control is designed. And this control method can improve the control accuracy of the robot. In the third part, the performance of the designed control method is verified by experiments. The experiments show that the designed force control method can effectively reduce the influence of external position disturbance on the tracking accuracy of the force control system and improve the control accuracy of the robot joint movement.

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A Nonlinear Model-based Variable Impedance Parameters Control for Position-based Impedance Control System of Hydraulic Drive Unit

Cited by 37 publications

References 17 publications

An Improved DDPG and Its Application Based on the Double-Layer BP Neural Network

An Improved DDPG and Its Application Based on the Double-Layer BP Neural Network

State feedback-based impedance control for legged robot hydraulic drive unit via full-dimensional state observer

Design, Mathematical Modeling and Force Control for Electro-Hydraulic Servo System With Pump-Valve Compound Drive

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