Omni-Wrist III - A new generation of pointing devices. I. Laser beam steering devices - mathematical modeling

Abstract

Omni-Wrist III is a newsensor mount developed with U.S. Air Force funding that emulates the kinematics of a human wrist. Driven by two linear motors and computer controlled, it is capable of a full 180 ± hemisphere of pitch/yaw motion. A comprehensive laboratory testing of one of the few existing devices of this type, installed in the Laser Communications Research Laboratory at Binghamton University, has resulted in the establishment of a complete mathematical model relating pitch/yaw coordinates of the sensor mount to the motor encoder signals. This paper presents the development of the model that incorporates inverse and forward pose kinematics solutions as well as the dynamics of the novel gimbal-like pointing system.

A Comparison of Robot Wrist Implementations for the iCub Humanoid †

“…A third alternative, represented in Figure 1d, is to achieve mass relocation by combining adjacent joints into multi-DOF (degree of freedom) parallel kinematics mechanisms. Examples of this approach can be found in [16,18,24,29]. A typical characteristic of parallel mechanisms is that their kinematic behavior tends to be more complex, often "non-uniform" (see [30,31]) with respect to their serial counterparts.…”

“…Parameters l 1 , l 2 and l 3 , were scaled in order to obtain a unit distance from the center of the moving platform (point P) to the center of the mechanism base (point O). The parameter values of α = 45°and γ = 90°, which are the ones normally employed for N-UU mechanisms with 4 limbs (4-UU) [18], were chosen for this study. Given α, γ and a unit OP distance the values of l 1 , l 2 and l 3 and their ratios were univocally determined.…”

“…Another one of the most prominent works, was the OmniWrist-III [18] mechanism by Ross-Hime Designs, Inc., which falls under the class of N-UU mechanism. Each limb of the mechanism comprises a pair of universal joints, which is mirror symmetric about a common plane [19,20].…”

“…• a spherical parallel mechanism with five curved links (bars) adapted from the one presented in [15]; • a spherical six bar mechanism as proposed in [16] • an implementation of a N-UU parallel mechanisms similar to the OmniWrist-III mechanism [18] developed by Ross-Hime Designs, Inc.; • a Quaternion joint, similar to the N-UU class, as proposed by Kim in [24] for the LIMS2-AMBIDEX robot.…”

Analysis of a mechanism with redundant drive for antenna pointing

“…Driven by two linear actuators, it is capable of a full hemisphere of pitch/yaw motion. 2 Two-DOF parallel wrists with two rotary motors have been presented by Carricato and Parenti-Castelli, 3 and Gogu, 4 respectively. The workspace and the kinematics of one type of the wrist mechanisms have been studied, 5 and the singularities have been analyzed by using a visual graphic approach.…”