scholarly journals Decentralized robust control of robot manipulators with harmonic drive transmission and application to modular and reconfigurable serial arms

Robotica ◽  
2009 ◽  
Vol 27 (2) ◽  
pp. 291-302 ◽  
Author(s):  
Z. Li ◽  
W. W. Melek ◽  
C. Clark
Keyword(s):  
Robust Control ◽  
Degrees Of Freedom ◽  
Robot Manipulators ◽  
Robot Dynamics ◽  
Harmonic Drive ◽  
Robust Controller ◽  
Reconfigurable Robots ◽  
Independent Subsystem ◽  
Control Schemes ◽  
Decentralized Robust Control

SUMMARYIn this paper, we propose a decentralized robust control algorithm for modular and reconfigurable robots (MRRs) based on Lyapunov's stability analysis and backstepping techniques. In using decentralized control schemes with robot manipulators, each joint is considered as an independent subsystem, and the dynamical effects from the other links and joints are treated as disturbance. However, there exist many uncertainties due to unmodeled dynamics, varying payloads, harmonic drive (HD) compliance, HD complex gear meshing mechanisms, etc. Also, while the reconfigurability of MRRs is advantageous, modifying the configuration will result in changes to the robot dynamics parameters, thereby making it challenging to tune the control system. All of the above mentioned disturbances in addition to reconfigurability present a challenge in controlling MRRs. The proposed controller is well suited for MRR applications because of its simple structure that does not require the exact knowledge of the dynamic parameters of the configurations. Desired tracking performance can be achieved via tuning a limited set of parameters of the robust controller. If the numbers of degrees of freedom are held constant, these parameters are shown to be relatively independent of the configuration, and can be held constant between changes in configuration. This strategy is novel compared to existing MRR control methods. In order to validate the controller performance, experimental setup and results are also presented.

scholarly journals Neural Networks-based Adaptive State Feedback Control of Robot Manipulators

2007 ◽  
Vol 2 (4) ◽  
pp. 328 ◽  
Author(s):  
Ghania Debbache ◽  
Abdelhak Bennia ◽  
Noureddine Goléa
Keyword(s):  
Neural Networks ◽  
State Feedback ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
External Disturbance ◽  
Nonlinear Function ◽  
State Feedback Control ◽  
Robot Dynamics ◽  
Robust Controller ◽  
Control Scheme

This paper proposes an adaptive control suitable for motion control of robot manipulators with structured and unstructured uncertainties. In order to design an adaptive robust controller, with the ability to compensate these uncertainties, we use neural networks (NN) that have the capability to approximate any nonlinear function over a compact space. In the proposed control scheme, we need not derive the linear formulation of robot dynamic equation and tune the parameters. To reduce the NNs complexity, we consider the properties of robot dynamics and the decomposition of the uncertainties terms. The proposed controller is robust against uncertainties and external disturbance. The validity of the control scheme is demonstrated by computer simulations on a two-link robot manipulator.

scholarly journals Nonlinear pd controllers with gravity compensation for robot manipulators

2014 ◽  
Vol 14 (1) ◽  
pp. 141-150 ◽  
Author(s):  
Jianfeng Huang ◽  
Chengying Yang ◽  
Jun Ye
Keyword(s):  
Degrees Of Freedom ◽  
Position Control ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
Nonlinear Function ◽  
Step Response ◽  
Robot Dynamics ◽  
Gravity Compensation ◽  
Pd Controller ◽  
Globally Asymptotically Stable

Abstract A Nonlinear Proportional-Derivative (NPD) controller with gravity compensation is proposed and applied to robot manipulators in this paper. The proportional and derivative gains are changed by the nonlinear function of errors in the NPD controller. The closed-loop system, composed of nonlinear robot dynamics and NPD controllers, is globally asymptotically stable in position control of robot manipulators. The comparison of the simulation experiments in the position control (the step response) of a robot manipulator with two degrees of freedom is also presented to illustrate that the NPD controller is superior to the conventional PD controller in a position control system. The experimental results show that the NPD controller can obtain a faster response velocity and higher position accuracy than the conventional PD controller in the position control of robot manipulators because the proportional and derivative gains of the NPD controller can be changed by the nonlinear function of errors. The NPD controller provides a novel approach for robot control systems.

A tuning procedure for stable PID control of robot manipulators

Robotica ◽  
1995 ◽  
Vol 13 (2) ◽  
pp. 141-148 ◽  
Author(s):  
Rafael Kelly
Keyword(s):  
Pid Control ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Robot Manipulators ◽  
Robot Dynamics ◽  
Closed Loop System ◽  
Torque Vector ◽  
Pid Tuning ◽  
Simple Rules ◽  
The Stability

SummaryIn this paper we propose some simple rules for PID tuning of robot manipulators. The procedure suggested requires the knowledge of the structure of the inertia matrix and the gravitational torque vector of the robot dynamics, but only upper bounds on the dynamics parameters are needed. This tuning procedure is extracted from the stability analysis by using a suitable Lyapunov function together with the LaSalle invariance principle. We show that with this guideline, the overall closed-loop system is asymptotically stable. This procedure is illustrated for a two degrees-of-freedom robot

scholarly journals Dynamical Modelling and Robust Control for an Unmanned Aerial Robot Using Hexarotor with 2-DOF Manipulator

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Li Ding ◽  
Hongtao Wu
Keyword(s):  
Robust Control ◽  
Trajectory Tracking ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Robot Dynamics ◽  
Detailed Knowledge ◽  
State Variables ◽  
Aerial Robot ◽  
Modelling Uncertainties ◽  
Dynamical Modelling

The robust control issues in trajectory tracking of an unmanned aerial robot (UAR) are challenging tasks due to strong parametric uncertainties, large nonlinearities, and high couplings in robot dynamics. This paper investigates the dynamical modelling and robust control of an aerial robot using a hexarotor with a 2-degrees-of-freedom (DOF) manipulator in a complex aerial environment. Firstly, the kinematic model and dynamic model of the aerial robot are developed by the Euler-Lagrange method. Afterwards, a linear active disturbance rejection control is designed for the robot to achieve a high-accuracy trajectory tracking goal under heavy lumped disturbances. In this control scheme, the modelling uncertainties and external disturbances are estimated by a linear extended state observer, and the high tracking precision is guaranteed by a proportion-differentiation (PD) feedback control law. Meanwhile, an artificial intelligence algorithm is applied to adjust the control parameters and ensure that the state variables of the robot converge to the references smoothly. Furthermore, it requires no detailed knowledge of the bounds on unknown dynamical parameters. Lastly, numerical simulations and experiments validate the efficiency and advantages of the proposed method.

Modeling of robot manipulators working under the sea and the design of a robust controller

Robotica ◽  
1996 ◽  
Vol 14 (2) ◽  
pp. 213-218 ◽  
Author(s):  
Choi Hyeung-Sik
Keyword(s):  
Robust Control ◽  
Sea Water ◽  
Robot Manipulators ◽  
Water Environment ◽  
Added Mass ◽  
Unmodeled Dynamics ◽  
Robust Controller ◽  
Control Scheme ◽  
Mass Moment ◽  
Mass Moment Of Inertia

SUMMARYThis paper presents a study of the dynamics of undersea robot manipulators in an unstructured sea water environment and a control scheme appropriate for manipulating them. Under the sea, the buoyancy and the added mass should be considered in modeling the dynamics of the robot manipulators. However, due to the complexity of the modeling of the added mass, the dynamics of the robot manipulators are treated as an unmodeled dynamics in this paper. In addition to the buoyancy and added mass/moment of inertia, disturbing forces due to drag, and current affecting the dynamics of the robot manipulators should be considered. In this paper, the forces due to the drag are defined as disturbance forces in addition to the frictional force of manipulator joints. In order to control the manipulator, a robust control scheme is devised to achieve trajectory tracking while regulating disturbance forces. A numerical example is shown.

An Observer-Based Design for Robust Control of Robot Manipulators

1990 ◽  
Author(s):  
Walter Grossman ◽  
Farshad Khorrami ◽  
Bernard Friedland
Keyword(s):  
Robust Control ◽  
Robot Manipulators
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