Tracking Control of a Robotic System with Initial Constraint Violation and Actuator Faults

Author(s):  
Yu Zhang ◽  
Linghuan Kong ◽  
Pengxin Yang ◽  
Shuo Yuan ◽  
Shuang Zhang
Author(s):  
Yu Zhang ◽  
Linghuan Kong ◽  
Shuang Zhang ◽  
Xinbo Yu ◽  
Pengxin Yang

Author(s):  
AM Shafei ◽  
H Mirzaeinejad

This article establishes an innovative and general approach for the dynamic modeling and trajectory tracking control of a serial robotic manipulator with n-rigid links connected by revolute joints and mounted on an autonomous wheeled mobile platform. To this end, first the Gibbs–Appell formulation is applied to derive the motion equations of the mentioned robotic system in closed form. In fact, by using this dynamic method, one can eliminate the disadvantage of dealing with the Lagrange Multipliers that arise from nonholonomic system constraints. Then, based on a predictive control approach, a general recursive formulation is used to analytically obtain the kinematic control laws. This multivariable kinematic controller determines the desired values of linear and angular velocities for the mobile base and manipulator arms by minimizing a point-wise quadratic cost function for the predicted tracking errors between the current position and the reference trajectory of the system. Again, by relying on predictive control, the dynamic model of the system in state space form and the desired velocities obtained from the kinematic controller are exploited to find proper input control torques for the robotic mechanism in the presence of model uncertainties. Finally, a computer simulation is performed to demonstrate that the proposed algorithm can dynamically model and simultaneously control the trajectories of the mobile base and the end-effector of such a complicated and high-degree-of-freedom robotic system.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amin Mihankhah ◽  
Ali Doustmohammadi

Purpose The purpose of this paper, is to solve the problem of finite-time fault-tolerant attitude synchronization and tracking control of multiple rigid bodies in presence of model uncertainty, external disturbances, actuator faults and saturation. It is assumed that the rigid bodies in the formation may encounter loss of effectiveness and/or bias actuator faults. Design/methodology/approach For the purpose, adaptive terminal sliding mode control and neural network structure are used, and a new sliding surface is proposed to guarantee known finite-time convergence not only at the reaching phase but also on the sliding surface. The sliding surface is then modified using a proposed auxiliary system to maintain stability under actuator saturation. Findings Assuming that the communication topology between the rigid bodies is governed by an undirected connected graph and the upper bounds on the actuators’ faults, estimation error of model uncertainty and external disturbance are unknown, not only the attitudes of the rigid bodies in the formation are synchronized but also they track the time-varying attitude of a virtual leader. Using Lyapunov stability approach, finite-time stability of the proposed control algorithms demonstrated on the sliding phase as well as the reaching phase. The effectiveness of the proposed algorithm is also validated by simulation. Originality/value The proposed controller has the advantage that the need for any fault detection and diagnosis mechanism and the upper bounds information on estimation error and external disturbance is eliminated.


2020 ◽  
Vol 53 (7-8) ◽  
pp. 1309-1317
Author(s):  
Bei Liu ◽  
Yang Yi ◽  
Hong Shen ◽  
Chengbo Niu

This brief proposes a novel composite observer-based integral sliding mode tracking control algorithm for a class of nonlinear systems affected by both actuator faults and mismatched disturbances. First, different types of observers, including the extended state observer, the fault diagnosis observer, and the disturbance observer, are integrated to estimate the unknown system state, actuator faults, and mismatched disturbances timely. Then, in accordance with the estimation information, the integral sliding surface and the integral sliding mode controller are proposed, which can tolerate the actuator faults and reject the mismatched disturbances. Meanwhile, the state trajectories can be driven into the specified sliding surface in a finite time. Furthermore, not only the stability, but the favorable dynamical tracking and the output constraints of closed-loop augmented systems can be guaranteed. Finally, the validities of the proposed algorithm are embodied by the simulation results of typical A4D systems.


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