Disturbance Compensation Strategy for Fifth-order Joint Servomechanism Based on Characteristic Model

doi:10.12382/bgxb.2022.0941

Abstract

Abstract:

A control strategy combining the linear extended state observer and full coefficient adaptive control based on characteristic model is proposed for the time-varying load and model uncertainties of industrial robot joint servomechanism. A two-inertia flexible joint dynamics model is established, and the equation of the fifth-order extended state of joint servomechanism was obtained. A fifth-order linear extended state observer is designed based on the model, through which the total disturbance of the system is estimated and compensated, and the convergence of the observer is proved. Based on the method of characteristic modeling, the characteristic parameters are identified by experimental data and gradient descent method, and the full coefficient adaptive control law is designed based on the parameter values. A control strategy is designed to accurately control the system by combining the control law with the linear extended state observer. The experimental results show that the proposed control strategy is used to make the positioning accuracy of the system reach 0.003° under the condition of variable load disturbance and the sinusoidal signal tracking error keep within 0.92°. The system has strong robustness and control accuracy.

Key words: joint servomechanism, fifth-order linear extended state observer, characteristic modeling, full coefficient adaptive control, disturbance compensation

CLC Number:

TP242.2

ZHANG Tianyi, ZHENG Ying, QIU Xinguo, JI Xingjian, JIN Xiaohang. Disturbance Compensation Strategy for Fifth-order Joint Servomechanism Based on Characteristic Model[J]. Acta Armamentarii, 2024, 45(1): 276-287.

Figures/Tables 21

Fig.1 Two-inertia model of joint servomechanism

Fig.2 Dynamic model of joint servomechanism

Fig.3 Error verification of characteristic model

Table 1 Parameters of servomechanism

参数	数值
反电动势C_e/(V·rad·s^-1)	0.0764
转矩常数K_t/(N·m·A^-1)	0.112
转动惯量J_m/(kg·m²)	0.175×10^-4
定子电阻R_s/Ω	0.15
黏滞摩擦系数B/(N·m·(rad·s^-1)^-1)	0.3
减速比i	100:1
PWM功放系数K_u	8.32
额定负载惯量J_L/(kg·m²)	0.025
联轴器刚度系数k_s/(N·m·rad^-1)	3000
齿隙2θ/rad	0.00175

Table 2 Identification results of characteristic parameters

信号	$\hat{f}_{1}$	$\hat{f}_{2}$	$\hat{g}_{0}$	$\tilde{Y} /\left(^{\circ}\right) $
	1.3461	-0.3465	3.0659×10^-5	0.026
2	1.3472	-0.3469	6.6071×10^-4	0.021
3	1.3475	-0.3481	5.8614×10^-4	0.035

Fig.4 Control structure of joint servomechanism

Fig.5 Frequency domain characteristic curve of position feedback quantity

Fig.6 Frequency domain characteristic curve of controller output

Fig.7 Experimental platform

Fig.8 Step response curve

Fig.9 Step tracking error

Fig.10 Characteristic model error

Fig.11 Position and velocity estimated errors of C4

Fig.12 Continuous step response curves

Fig.13 Continuous step tracking error

Fig.14 Sinusoidal tracking curve

Fig.15 Sinusoidal tracking error

Table 3 Performance indicators(°)

控制器	指标
控制器	M_e	μ	σ
C1	9.025	5.155	2.394
C2	8.736	0.821	0.842
C3	4.699	1.285	0.939
C4	1.952	0.594	0.295

Fig.16 Sinusoidal tracking curve

Fig.17 Sinusoidal tracking error

Table 4 Performance indicators(°)

控制器	指标
控制器	M_e	μ	σ
C1	25.436	15.698	7.026
C2	14.176	8.926	3.977
C3	11.461	2.834	1.850
C4	10.221	0.629	1.193

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