Latest Papers

ASME Journal of Mechanisms and Robotics

  • An Improved Dual Quaternion Dynamic Movement Primitives-Based Algorithm for Robot-Agnostic Learning and Execution of Throwing Tasks
    on May 9, 2025 at 12:00 am

    AbstractInspired by human nature, roboticists have conceived robots as tools meant to be flexible, capable of performing a wide variety of tasks. Learning from demonstration methods allow us to “teach” robots the way we would perform tasks, in a versatile and adaptive manner. Dynamic movement primitives (DMP) aims for learning complex behaviors in such a way, representing tasks as stable, well-understood dynamical systems. By modeling movements over the SE(3) group, modeled primitives can be generalized for any robotic manipulator capable of full end-effector 3D movement. In this article, we present a robot-agnostic formulation of discrete DMP based on the dual quaternion algebra, oriented to modeling throwing movements. We consider adapted initial and final poses and velocities, all computed from a projectile kinematic model and from the goal at which the projectile is aimed. Experimental demonstrations are carried out in both a simulated and a real environment. Results support the effectiveness of the improved method formulation.

  • Chained Timoshenko Beam Constraint Model With Applications in Large Deflection Analysis of Compliant Mechanism
    on May 9, 2025 at 12:00 am

    AbstractAccurately analyzing the large deformation behaviors of compliant mechanisms has always been a significant challenge in the design process. The classical Euler–Bernoulli beam theory serves as the primary theoretical basis for the large deformation analysis of compliant mechanisms. However, neglecting shear effects may reduce the accuracy of modeling compliant mechanisms. Inspired by the beam constraint model, this study takes a step further to develop a Timoshenko beam constraint model (TBCM) for initially curved beams to capture intermediate-range deflections under beam-end loading conditions. On this basis, the chained Timoshenko beam constraint model (CTBCM) is proposed for large deformation analysis and kinetostatic modeling of compliant mechanisms. The accuracy and feasibility of the proposed TBCM and CTBCM have been validated through modeling and analysis of curved beam mechanisms. Results indicate that TBCM and CTBCM are more accurate compared to the Euler beam constraint model (EBCM) and the chained Euler beam constraint model (CEBCM). Additionally, CTBCM has been found to offer computational advantages, as it requires fewer discrete elements to achieve convergence.

Design and Development of the Transmission for a Fully Actuated 5-Degrees-of-Freedom Compliant Robot Manipulator With a Single Motor

Abstract

This article presents a novel architecture for the actuation and transmission system of a 5-degrees-of-freedom (DOFs) compliant robot manipulator. The compliant behavior of the robot is achieved using inherently compliant magneto-rheological (MR) clutches introduced in antagonistic pairs in every joint of the manipulator. All five antagonistic MR clutch pairs are driven using a single brushless DC motor located in the base of the robot. The MR clutch pairs are coupled to the motor through a system of shafts, belts, and gears. Several possible architectures for realizing a suitable drive train are presented, and the advantages and disadvantages of each concept are analyzed. The most efficient architecture for the drive train is selected to complete the design of the manipulator. The kinematics of the manipulator using the adopted architecture is further analyzed, and the workspace of the system is presented. To the best of our knowledge, this is the first 5-DOF, fully actuated, compliant robotic manipulator that uses a single DC motor to achieve five independent axes of rotations.

Read More

Journal of Mechanisms and Robotics Open Issues