Degrees Of Freedom Robot Manipulator Research Articles

Theoretical aspect of hybrid position /force control

This work presents a new theoretical approach to hybrid position/force control. It develops a method for the design of controllers of constrained manipulators. In this work also the robustness considerations are given. It can be shown that the proposed control system has robustness properties for a class of dynamic uncertainties. In order to improve the robustness property integral controller is applied to the force control loop. The usefulness of this hybrid control system is demonstrated through simulations of a constrained two degrees of freedom robot manipulator.

Robust Hybrid Position/Force Control for Robot Manipulators

This work presents a new robust control methodology for hybrid position/force control. The control input of this methodology consists of a nonlinear and a linear part. The nonlinear control part gives a new coordinate system. Using this coordinate system. robot dynamics is decoupled and input spaces are divided into two orthogonal spaces of position and force control. The linear control part improves robustness properties of the nonlinear hybrid control scheme. A model feedback control scheme is applied to the linear part or position control and integral control is used in the linear part of force control. The robustness properties of the nonlinear robust hybrid control algorithm are demonstrated through simulation of a constrained two degrees of freedom robot manipulator.

ロボットマニピュレータのロバストな位置と力のハイブリッド制御

Abstract This work presents a new robust control methodology for hybrid position/force control. The control input of this methodology consists of a nonlinear and a linear part. The nonlinear control part gives a new coordinate system. Using this coordinate system. robot dynamics is decoupled and input spaces are divided into two orthogonal spaces of position and force control. The linear control part improves robustness properties of the nonlinear hybrid control scheme. A model feedback control scheme is applied to the linear part or position control and integral control is used in the linear part of force control. The robustness properties of the nonlinear robust hybrid control algorithm are demonstrated through simulation of a constrained two degrees of freedom robot manipulator.

A Suboptimal Reference Generation Technique for Robotic Manipulators Following Specified Paths

The optimal reference generation problem deals with finding a tracking velocity versus time profile which will move the end effector of a multiple degree of freedom robotic manipulator through a general spatial curve in minimum time subject to hard actuator torque limits. While reference generation techniques exist which solve this problem, they are typically computationally intensive, limiting their usefulness in practical situations. In this technical brief, a modification is made to the formulation of the optimal reference generation problem, resulting in a slightly suboptimal solution which is numerically simpler than optimal methods. The method is applied to a computer simulation of a two link SCARA type manipulator following a circular path in joint space. Performance comparisons are made with an optimized constant velocity profile as with the true optimal solution.

A new simulation scheme for self-tuning adaptive control of robot manipulators

SUMMARYIn most dynamic adaptive control simulation of robotic manipulators, the Langrange–Euler (L–E) dynamic equations are first piecewise linearized about the desired reference and then discretized and rewritten in a state space form. This makes things very complicated and it is easy to make errors. What is more is that with a different reference this work must be done again. A new simulation scheme – Backward Recursive Self-Tuning Adaptive (BRSTA) – as it will be called, is suggested in this paper for adaptive controller design of robot manipulators. A two degree of freedom robot manipulator is used to verify the scheme in the condition of highly nonlinear and highly coupled system. A one degree of freedom robot manipulator is used for comparing both the forward and backward methods. The main advantages of this scheme include that it can be used for evaluating the self-tuning adaptive control laws and provide the initial process parameters for real-time control. And it is concluded here that the Newton–Euler (N–E) dynamic equations are equally well qualified as the Langrange–Euler (L-E) equations for the simulation of self-tuning adaptive control of robot manipulators.

Pole Placement Self-Tuning Control of Manipulators

The pole placement self-tuning (PPST) methods developed by Wellstead and his colleagues [1-3] are modified for application to a six degree of freedom robotic manipulator. The manipulator selected is the JPL-Stanford arm with five revolute joints and one prismatic joint. The results of two example applications demonstrate the clear superiority of the pole placement approach over previous minimum variance self-tuning attempts [4].