scholarly journals Constraint-Following Servo Control for the Trajectory Tracking of Manipulator with Flexible Joints and Mismatched Uncertainty

Machines ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 202
Author(s):  
Fangfang Dong ◽  
Bin Yu ◽  
Xiaomin Zhao ◽  
Shan Chen ◽  
Haijun Liu
Keyword(s):  
Trajectory Tracking ◽  
Dead Zone ◽  
Fundamental Equation ◽  
Servo Control ◽  
Flexible Joints ◽  
Constraint Force ◽  
Mismatched Uncertainty ◽  
Common Application ◽  
Flexible Joint Manipulator ◽  
Fractional Type

Trajectory tracking is a common application method for manipulators. However, the tracking performance is hard to improve if the manipulators contain flexible joints and mismatched uncertainty, especially when the trajectory is nonholonomic. On the basis of the Udwadia–Kalaba Fundamental Equation (UKFE), the prescribed position or velocity trajectories are creatively transformed into second-order standard differential form. The constraint force generated by the trajectories is obtained in closed form with the help of UKFE. Then, a high-order fractional type robust control with an embedded fictitious signal is proposed to achieve practical stability of the system, even if the mismatched uncertainty exists. Only the bound of uncertainty is indispensable, rather than the exact information. A leakage type of adaptive law is proposed to estimate such bound. By introducing a dead-zone, the control will be simplified when the specific parameter enters a certain area. Validity of the proposed controller is verified by numerical simulation with two-link flexible joint manipulator.

Trajectory and Vibration Control of a Single-Link Flexible-Joint Manipulator Using a Distributed Higher-Order Differential Feedback Controller

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
John T. Agee ◽  
Zafer Bingul ◽  
Selcuk Kizir
Keyword(s):  
Trajectory Tracking ◽  
Higher Order ◽  
Feedback Controller ◽  
Step Response ◽  
Position Measurement ◽  
Tracking Errors ◽  
Flexible Joint ◽  
Nonminimum Phase ◽  
Step Input ◽  
Flexible Joint Manipulator

The trajectory tracking in the flexible-joint manipulator (FJM) system becomes complicated since the flexibility of the joint of the FJM superimposes vibrations and nonminimum phase characteristics. In this paper, a distributed higher-order differential feedback controller (DHODFC) using the link and joint position measurement was developed to reduce joint vibration in step input response and to improve tracking behavior in reference trajectory tracking control. In contrast to the classical higher-order differential (HOD), the dynamics of the joint and link are considered separately in DHODFC. In order to validate the performance of the DHODFC, step input, trajectory tracking, and disturbance rejection experiments are conducted. In order to illustrate the differences between classical HOD and DHODFC, the performance of these controllers is compared based on tracking errors and energy of control signal in the tracking experiments and fundamental dynamic characteristics in the step response experiments. DHODFC produces better tracking errors with almost same control effort in the reference tracking experiments and a faster settling time, less or no overshoot, and higher robustness in the step input experiments. Dynamic behavior of DHODFC is examined in continuous and discontinues inputs. The experimental results showed that the DHODFC is successful in the elimination of the nonminimum phase dynamics, reducing overshoots in the tracking of such discontinuous input trajectories as step and square waveforms and the rapid damping of joint vibrations.

A Novel Robust Constraint Force Servo Control for Under-actuated Manipulator Systems: Fuzzy and Optimal

2017 ◽  
Vol 20 (5) ◽  
pp. 1818-1838 ◽  
Author(s):  
Fangfang Dong ◽  
Jiang Han ◽  
Ye-Hwa Chen ◽  
Lian Xia
Keyword(s):  
Servo Control ◽  
Constraint Force

scholarly journals Trajectory tracking control of two degrees-of-freedom helicopter based on Udwadia–Kalaba theory

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880893
Author(s):  
Yinfei Zhu ◽  
Han Zhao ◽  
Hao Sun ◽  
Kang Huang ◽  
Yinghui Dong
Keyword(s):  
Trajectory Tracking ◽  
Tracking Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Initial Conditions ◽  
Control Cost ◽  
Trajectory Tracking Control ◽  
Constraint Force ◽  
Two Degrees Of Freedom ◽  
High Control

In this article, by using Lagrange energy method, we establish the dynamical model of a two degrees-of-freedom helicopter, which is subject to holonomic constraints. A control method based on Udwadia–Kalaba theory is proposed to achieve the trajectory tracking control of the 2-degrees-of-freedom helicopter. Different from traditional methods, this method could solve the constraint force of the mechanical system without adding additional parameters such as Lagrange multipliers. When initial conditions are compatible, we can use the nominal control which is based on Udwadia–Kalaba equation to control 2-degrees-of-freedom helicopter in real time. But when initial conditions have incompatibility, the simulation result could produce divergence phenomenon. To solve the trajectory tracking control problem of 2-degrees-of-freedom helicopter under incompatible initial conditions, a modified controller is proposed. We also make simulation contrast by different control methods to validate the effectiveness and superiority of the modified controller. Simulation results show that the modified controller can drive the 2-degrees-of-freedom helicopter to perfectly track the desired trajectory with less control cost and high control accuracy.

Adaptive Sliding Mode Control for Depth Trajectory Tracking of Remotely Operated Vehicle with Thruster Nonlinearity

2016 ◽  
Vol 70 (1) ◽  
pp. 149-164 ◽  
Author(s):  
Zhenzhong Chu ◽  
Daqi Zhu ◽  
Simon X. Yang ◽  
Gene Eu Jan
Keyword(s):  
Sliding Mode Control ◽  
Trajectory Tracking ◽  
Sliding Mode ◽  
Dead Zone ◽  
Adaptive Sliding Mode Control ◽  
Remotely Operated Vehicle ◽  
Trajectory Tracking Control ◽  
Adaptive Sliding Mode ◽  
Saturation Nonlinearity ◽  
Mode Control

This paper focuses on depth trajectory tracking control for a Remotely Operated Vehicle (ROV) with dead-zone nonlinearity and saturation nonlinearity of thruster; an adaptive sliding mode control method based on neural network is proposed. Through the analysis of dead-zone nonlinearity and saturation nonlinearity of thruster, the depth trajectory tracking control system model of a ROV which uses thruster control signals as system input has been established. According to the principle of sliding mode control, an adaptive sliding mode depth trajectory tracking controller is built by using three-layer feed-forward neural network for online identification of unknown items. The selection method and update laws of the control parameters are also given. The uniform ultimate boundedness of trajectory tracking error is analysed by Lyapunov theorem. Finally, the effectiveness of the proposed method is illustrated by simulations.

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