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.

Identification and Control of a 3-X Cable-Driven Manipulator Inspired From the Bird’s Neck

Abstract

This paper is devoted to the control and identification of a manipulator with three anti-parallelogram joints in series, referred to as X-joints. Each X-joint is a tensegrity one-degree-of-freedom mechanism antagonistically actuated with cables and springs in parallel. As compared to manipulators built with simple revolute joints in series, manipulators with tensegrity X-joint offer a number of advantages, such as an intrinsic stability, variable stiffness, and lower inertia. This design was inspired by the musculosleketon architecture of the bird’s neck, which is known to be very dextrous. A test-bed prototype is presented and used to test computed torque control laws. Friction and cable elasticity are modeled and identified. Their effect on the performance of control laws is analyzed. It is shown that in the context of antagonistic actuation and lightweight design, friction plays a leading role and the significance of modeling cable elasticity is discussed.
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