Latest Papers

ASME Journal of Mechanisms and Robotics

  • Dynamics of Mobile Manipulators Using Dual Quaternion Algebra
    on September 14, 2022 at 12:00 am

    AbstractThis article presents two approaches to obtain the dynamical equations of mobile manipulators using dual quaternion algebra. The first one is based on a general recursive Newton–Euler formulation and uses twists and wrenches, which are propagated through high-level algebraic operations and works for any type of joints and arbitrary parameterizations. The second approach is based on Gauss’s Principle of Least Constraint (GPLC) and includes arbitrary equality constraints. In addition to showing the connections of GPLC with Gibbs–Appell and Kane’s equations, we use it to model a nonholonomic mobile manipulator. Our current formulations are more general than their counterparts in the state of the art, although GPLC is more computationally expensive, and simulation results show that they are as accurate as the classic recursive Newton–Euler algorithm.

Connectivity Calculation-Based Automatic Synthesis of Planar Multi-Loop Mechanisms

Abstract

The creative design of kinematic structures with excellent performance remains an open issue in the quest for developing novel multi-loop mechanisms. This study presents an automatic method to synthesize all nonisomorphic planar multi-loop mechanisms satisfying the required connectivity between the base and the end-effector. First, based on the connectivity matrix calculation, all multi-loop mechanisms are generated from synthesized kinematic chains. Second, the concepts of perimeter, canonical, and characteristic graphs of multi-color topological graphs are addressed to acquire the simplified characteristic hybrid code (SCHC) in order to eliminate isomorphic multi-loop mechanisms. Then, an automatic method to synthesize all nonisomorphic planar multi-loop mechanisms with the required connectivity between the base and the end-effector is provided. Finally, a practical application of this synthesis method is illustrated by taking the mechanical arm of a face-shovel hydraulic excavator as an example to demonstrate the effectiveness of the method.
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