Configuration-based compliance control of kinematically redundant robot arm Part I: Theoretical framework

This paper presents theoretical and experimental aspects of Jacobian nullspace use in kinematically redundant robots for achieving kinetostatically consistent control of their compliant behavior. When the stiffness of the robot endpoint is dominantly influenced by the compliance of the robot joints, generalized stiffness matrix can be mapped into joint space using appropriate congruent transformation. Actuation stiffness matrix achieved by this transformation is generally nondiagonal. Off-diagonal elements of the actuation matrix can be generated by redundant actuation only (polyarticular actuators), but such kind of actuation is very difficult to realize practically in technical systems. The approach of solving this problem which is proposed in this paper is based on the use of kinematic redundancy and nullspace of the Jacobian matrix. Evaluation of the developed analytical model was done numerically by a minimal redundant robot with one redundant d.o.f. and experimentally by a 7 d.o.f. Yaskawa SIA 10F robot arm.

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Design and Analysis of a Fully Actuated Cable-Driven Joint for Hyper-Redundant Robots with Optimal Cable Routing

Journal of Mechanisms and Robotics ◽

10.1115/1.4052332 ◽

2021 ◽

pp. 1-13

Author(s):

Paolo Guardiani ◽

Daniele Ludovico ◽

Alessandro Pistone ◽

Haider Abidi ◽

Isiah Zaplana ◽

...

Keyword(s):

Genetic Algorithm ◽

Optimization Method ◽

Robot Arm ◽

Redundant Robot ◽

Redundant Robots ◽

Routing Optimization ◽

Novel Design

Abstract Cable-driven hyper-redundant robots have been adopted in many fields for accessing harsh and confined environments that maybe inaccessible or dangerous for humans. The cable actuation strategy makes the robot hardware safer and increases the robot payload reducing its weight. In this paper, a novel design of a fully actuated cable-driven hyper-redundant robot has been proposed. This solution is a pulleyless design that decreases the mechanical complexity, allowing to reduce the robot arm diameter and avoid tension losses on the cables during the motion. Three different joint designs have been taken into account and experiments have been carried to study their performances. The kinematics for n-joint robot has been formulated and a cable routing optimization method based on genetic algorithm have been proposed and applied to a five-joints robot.

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Robust tracking control of kinematically redundant robot manipulators subject to multiple self-motion criteria

Robotica ◽

10.1017/s0263574708004293 ◽

2008 ◽

Vol 26 (6) ◽

pp. 711-728 ◽

Cited By ~ 25

Author(s):

Ufuk Özbay ◽

H. Türker Şahin ◽

Erkan Zergeroğlu

Keyword(s):

Controller Design ◽

Robot Manipulators ◽

Parametric Uncertainty ◽

Robot Arm ◽

Robust Tracking Control ◽

Planar Case ◽

Redundant Robot ◽

Six Degree Of Freedom ◽

Joint Limits ◽

Self Motion

SUMMARYIn this study, we consider a model based robust control scheme for kinematically redundant robot manipulators that also enables the use of self motion of the manipulator to perform multiple sub-tasks (e.g., maintaining manipulability, avoidance of mechanical joint limits, and obstacle avoidance). The controller proposed ensures uniformly ultimately bounded end-effector and sub-task tracking despite the parametric uncertainty associated with the dynamic model. A Lyapunov based approach has been utilized in the controller design and extension to a non minimum set of parameters for orientation representation has been presented to illustrate the flexibility of the approach. Extensive simulation studies performed initially on a 3 link planar robot arm (for the planar case) and on a six degree of freedom (DOF) Puma type robot arm (for the 3D case with quaternion feedback) are presented to demonstrate the capabilities and the performance of the controller. The results were then experimentally tested on an actual Puma 560 robot to illustrate the feasibility of the proposed method.

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