Robust tuning of robot control systems

The computed torque control problem is examined for a robot arm with flexible, geared, joint drive systems which are typical in many industrial robots. The standard computed torque algorithm is not directly applicable to this class of manipulators because of the dynamics introduced by the joint drive system. The proposed approach to computed torque control combines a computed torque algorithm with torque controller at each joint. Three such control schemes are proposed. The first scheme uses the joint torque control system currently implemented on the robot arm and a novel form of the computed torque algorithm. The other two use the standard computed torque algorithm and a novel model following torque control system based on model following techniques. Standard tasks and performance indices are used to evaluate the performance of the controllers. Both numerical simulations and experiments are used in evaluation. The study shows that all three proposed systems lead to improved tracking performance over a conventional PD controller

Evaluation of automated decisionmaking methodologies and development of an integrated robotic system simulation

A generic computer simulation for manipulator systems (ROBSIM) was implemented and the specific technologies necessary to increase the role of automation in various missions were developed. The specific items developed are: (1) capability for definition of a manipulator system consisting of multiple arms, load objects, and an environment; (2) capability for kinematic analysis, requirements analysis, and response simulation of manipulator motion; (3) postprocessing options such as graphic replay of simulated motion and manipulator parameter plotting; (4) investigation and simulation of various control methods including manual force/torque and active compliances control; (5) evaluation and implementation of three obstacle avoidance methods; (6) video simulation and edge detection; and (7) software simulation validation

Parameter identification and model based control of direct drive robots

Imperial Users onl

Decoupling and adaptive control and stabilization of two-link elastic robotic arm

In this thesis the control and stabilization of a two link flexible robotic arm is considered. The first scheme is based on nonlinear inversion, a nonlinear controller is designed for the trajectory control of the joint angles using joint torquers. The inverse controller includes a servocompensator for robustness. A simplified controller has also been designed neglecting the Coriolis and Centrifugal forces; In the second scheme the control system design is based on nonlinear adaptive control and linear stabilization. First a nonlinear adaptive control law is derived such that in the closed-loop system the joint-angles are precisely controlled to track reference trajectories. A linear stabilizer designed based on a linear model of the arm is switched to accomplish the final capture of the desired state; Simulation results are presented for all cases to show that in the closed-loop system accurate joint angle trajectory tracking and elastic mode stabilization can be accomplished inspite of the uncertainity in the payload. (Abstract shortened with permission of author.) ftn*This research was supported by the U.S. Army Research Office under ARO Grant No. DAAL03-87-G-004

Model-Based Robot Control and Multiprocessor Implementation

Model-based control of robot manipulators has been gaining momentum in recent years. Unfortunately there are very few experimental validations to accompany simulation results and as such majority of conclusions drawn lack the credibility associated with the real control implementation

A survey of adaptive control technology in robotics

Previous work on the adaptive control of robotic systems is reviewed. Although the field is relatively new and does not yet represent a mature discipline, considerable attention has been given to the design of sophisticated robot controllers. Here, adaptive control methods are divided into model reference adaptive systems and self-tuning regulators with further definition of various approaches given in each class. The similarity and distinct features of the designed controllers are delineated and tabulated to enhance comparative review