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.

Stiffness Evaluation of an Adsorption Robot for Large-Scale Structural Parts Processing


Efficient and economical processing of large-scale structural parts is in increasing need and is also a challenging issue. In this paper, an adsorption machining robot for processing of large-scale structural parts is presented. It has potential advantages in flexible, efficient, and economical processing of large-scale structural parts because of the adsorption ability. Stiffness is one of the most important performance for machining robots. In order to investigate the stiffness of the robot in the workspace, the kinematics of the adsorption manipulator, the five-axis machining manipulator, and the adsorption machining robot is derived step by step. Then with the help of finite element analysis (FEA), a stiffness modeling method considering the compliance of the base is proposed. A stiffness isotropy index is put forward to evaluate the robot’s overall stiffness performance by taking all possible working conditions into consideration. Based on the index, stiffness evaluation in the reachable workspace is carried out and an optimized workspace is identified considering the overall stiffness magnitude, stiffness isotropy, and workspace volume, which will be used in the machining process. The stiffness modeling method and stiffness isotropy index proposed in the paper are universal and can be applied to other parallel robots.
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