Topic
Revolute joint
About: Revolute joint is a research topic. Over the lifetime, 3835 publications have been published within this topic receiving 52995 citations.
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01 Jan 2013
TL;DR: In this paper, the problem of integrated joint-type and dimensional synthesis of planar four-bar and six-bar linkages with revolute (R) and prismatic (P) joints for guiding through five specified task positions is addressed.
Abstract: This paper deals with the problem of integrated joint-type and dimensional synthesis of planar four-bar and six-bar linkages with revolute (R) and prismatic (P) joints for guiding through five specified task positions. In a recent work, we developed a simple algorithm for analyzing a set of given task positions to determine all feasible planar dyads with revolute and/or prismatic joints that can be used to guide through the given positions. The current paper extends this algorithm to the integrated joint-type and dimensional synthesis of Watt I and II and Stephenson I, II, and III six-bar linkages with a combination of R and P joints. We demonstrate this task driven synthesis approach with three examples including a novel six-bar linkage for lifting an individual with age disability from seating position to standing position.
23 May 1990
TL;DR: In this article, a model-reference adaptive control technique realized with Tap-Delay filters is presented for trajectory control of a simple two-link, planar robot with revolute joints.
Abstract: A Model-Reference Adaptive Control technique realized with Tap-Delay filters is presented. The adaptive logic is based upon Lyapunov stability with the Lyapunov function consisting of a quadratic sum of system errors and Tap-Delay filter weights. The problem of trajectory control of a robot manipulator consisting of a simple two-link, planar robot with revolute joints is selected to exemplify the method. The Tap-Delay filter allows a straightforward implementation of an inverse modeling control scheme which can be used in the initiation of robot motion, before the model reference system can effectively compensate. The resulting trajectory control systems is, computationally, very simple and requires adaptation of as few as five weights per each joint and measurement of only link angular orientation and rate. Robustness properties are examined and the control technique is evaluated in simulation. The proposed algorithm appears to have considerable potential for application to a variety of nonlinear control problems.
16 Aug 2017
TL;DR: The reciprocal of the condition number based on a dimensionally homogeneous Jacobian matrix is used to evaluate the dexterity by changing the operating height and radius ratios of the mechanism separately.
Abstract: This paper deals with the kinematic analysis and performance evaluation of a 2-URPR-UPR (U, R, P standing for universal, revolute and prismatic joint, respectively) redundantly actuated hybrid manipulator. First, the kinematic analysis of the proposed manipulator is presented, including mobility analysis, inverse kinematics, and singular analysis. Then, the reciprocal of the condition number based on a dimensionally homogeneous Jacobian matrix is used to evaluate the dexterity by changing the operating height and radius ratios of the mechanism separately. Finally, the global conditioning index is carried out to describe global dexterity performance with different radius ratios.
TL;DR: In this article, a high precision control system for the tip position of a robot link has been designed, which deals with a special measuementsystem based on a rotating laser-beam with a separate drive.
Posted Content•
TL;DR: This work introduces temporary constraints between near‐colliding links and adapts a randomized Poisson‐disk motion planner, which prevents local oversampling and widens the search, to ultra‐high dimensions, and shows that the sampling acceptance rate can increase from 16% to 70%, and that the conformational coverage in loop modeling measured as average closeness to existing loop conformations doubled.
Abstract: The function of protein, RNA, and DNA is modulated by fast, dynamic exchanges between three-dimensional conformations. Conformational sampling of biomolecules with exact and nullspace inverse kinematics, using rotatable bonds as revolute joints and non-covalent interactions as holonomic constraints, can accurately characterize these native ensembles. However, sampling biomolecules remains challenging owing to their ultra-high dimensional configuration spaces, and the requirement to avoid (self-) collisions, which results in low acceptance rates.
Here, we present two novel mechanisms to overcome these limitations. First, we introduced temporary constraints between near-colliding links. The resulting constraint varieties instantaneously redirect the search for collision-free conformations, and couple motions between distant parts of the linkage. Second, we adapted a randomized Poisson-disk motion planner, which prevents local oversampling and widens the search, to ultra-high dimensions. We evaluated our algorithm on several model systems. Our contributions apply to general high-dimensional motion planning problems in static and dynamic environments with obstacles.