Revolute joint

About: Revolute joint is a research topic. Over the lifetime, 3835 publications have been published within this topic receiving 52995 citations.

Planning Collision- Free Motions for Pick-and-Place Operations:

Abstract: An efficient algorithm that finds collision-free paths for a manipulator with five or six revolute joints is described. It solves the problem for four-degree-of-freedom pick-and-place operations. Examples are given of paths found by the algorithm in tightly cluttered workspaces. The algorithm first describes free space in two ways: as freeways for the hand and payload ensemble and as freeways for the upper arm. Freeways match volumes swept out by manipulator motions and can be "inverted" to find a class of topologically equivalent path segments. The two freeway spaces are searched concurrently under projection of constraints deter mined by motion of the forearm.

Joint stiffness identification of six-revolute industrial serial robots

Abstract: Although robots tend to be as competitive as CNC machines for some operations, they are not yet widely used for machining operations. This may be due to the lack of certain technical information that is required for satisfactory machining operation. For instance, it is very difficult to get information about the stiffness of industrial robots from robot manufacturers. As a consequence, this paper introduces a robust and fast procedure that can be used to identify the joint stiffness values of any six-revolute serial robot. This procedure aims to evaluate joint stiffness values considering both translational and rotational displacements of the robot end-effector for a given applied wrench (force and torque). In this paper, the links of the robot are assumed to be much stiffer than its actuated joints. The robustness of the identification method and the sensitivity of the results to measurement errors and the number of experimental tests are also analyzed. Finally, the actual Cartesian stiffness matrix of the robot is obtained from the joint stiffness values and can be used for motion planning and to optimize machining operations.

Adaptive Regulation of Amplitude Limited Robot Manipulators With Uncertain Kinematics and Dynamics

Abstract: Common assumptions in most of the previous robot controllers are that the robot kinematics and manipulator Jacobian are perfectly known and that the robot actuators are able to generate the necessary level of torque inputs. In this note, an amplitude-limited torque input controller is developed for revolute robot manipulators with uncertainty in the kinematic and dynamic models. The adaptive controller yields semiglobal asymptotic regulation of the task-space setpoint error. The advantages of the proposed controller include the ability to actively compensate for unknown parametric effects in the dynamic and kinematic model and the ability to ensure actuator constraints are not breached by calculating the maximum required torque a priori

Kinematic stability issues in force control of manipulators

Abstract: In active force or compliance implementations for multi-link manipulators, there is typically a kinematic coordinate transformation in the feedback path. A coordinate transformation will affect the dynamics of the closed-loop system and possibly make it unstable. It is shown that the hybrid force/position control method of Raibert and Craig (1981) exhibits such kinematically induced instabilities for revolute manipulators, whereas other force control methods, such as the stiffness control and the operational space methods, do not. Both theoretical analyses and experimental results on the MIT Serial Link Direct Drive Arm are given.