Robot Manipulator Control offers a complete survey of control systems for serial-link robot arms and acknowledges how robotic device performance hinges upon a well-developed control system. Containing over 750 essential equations, this thoroughly up-to-date Second Edition, the book explicates theoretical and mathematical requisites for controls design and summarizes current techniques in computer simulation and implementation of controllers. It also addresses procedures and issues in computed-torque, robust, adaptive, neural network, and force control. New chapters relay practical information on commercial robot manipulators and devices and cutting-edge methods in neural network control.

Robot Manipulator Control: Theory and Practice

The Stewart platform manipulator: a review

This paper presents a systematic methodology for solving the inverse dynamics of a Stewart-Gough manipulator. Based on the principle of virtual work and the concept of link Jacobian matrices, a methodology for deriving the dynamical equations of motion is developed. It is shown that the dynamics of the manipulator can be reduced to solving a system of six linear equations in six unknowns. A computational algorithm for solving the inverse dynamics of the manipulator is developed and several trajectories of the moving platform are simulated.

Solving the Inverse Dynamics of a Stewart-Gough Manipulator by the Principle of Virtual Work

The Stewart platform is a six-axis parallel robot manipulator with a force-to-weight ratio and positioning accuracy far exceeding that of a conventional serial-link arm. Its stiffness and accuracy approach that of a machine tool yet its workspace dexterity approaches that of a conventional manipulator. In this article, we study the dynamic equations of the Stewart platform manipulator. Our derivation is closed to that of Nguyen and Pooran because the dynamics are not explicitly given but are in a step-bystep algorithm. However, we give some insight into the structure and properties of these equations: We obtain compact expressions of some coefficients. These expressions should be interesting from a control point of view. A stiffness control scheme is designed for milling application. Some path-planning notions are discussed that take into account singularity positions and the required task. The objective is to make the milling station into a semiautonomous robotic tool needing some operator interaction but having some intelligence of its own. It should interface naturally with part delivery and other higher-level tasks. 0 1993 John Wiley & Sons, Inc.

Dynamic analysis and control of a Stewart platform manipulator

This paper presents the motion control of a six degree-of-freedom tendon-based parallel manipulator, which moves a platform with high speed using seven cables. To control the motion of the platform along desired trajectories in space, nonlinear feedforward control laws in the cable length coordinates are used. Taking account of the effect of redundancy on actuation, the optimal tension distribution should be considered to the advantage of the control laws. Using a method based on the analysis of the workspace condition, tension constraints and limiting torque constraints of actuators, an analytical solution for optimum tension distribution was found and used to compute the force in each cable for compensation of dynamic errors. It is experimentally demonstrated that the proposed control laws reduce the energy consumption of the actuators and satisfy the path tracking accuracy.

Motion control of a tendon-based parallel manipulator using optimal tension distribution

The Stewart platform manipulator is a fully parallel kinematic linkage system that has major mechanical differences over typical serial link robots. Its closed kinematic chain and parallel linkage structure give it great rigidity and a high force-to-weight ratio. In this paper, based on the forward and inverse kinematic analysis, the Jacobian matrix and the dynamic equations of the six-degree-of-freedom Stewart platform are derived. The singularities of the Stewart platform are also studied. Four singular positions are proved and some other conditions under which the possible singular positions may occur are given. These results provide us with the necessary information to avoid passing through singular points. The dynamic equations in Cartesian space appear in a very simple form. Especially in some applications if there is no rotation about the fixed X-axis, then the ‘inertia matrix’ reduces to a constant, diagonal matrix and the ‘Coriolis and centrifugal matrix’ goes to zero, which makes the Stewart platform become a decoupled, linear system in Cartesian space.

Guy Lebret

Papers

Dynamic analysis and control of a Stewart platform manipulator

The singularities and dynamics of a Stewart platform manipulator