Latest Papers

ASME Journal of Mechanisms and Robotics

  • Single Task Optimization-Based Planar Box Delivery Motion Simulation and Experimental Validation
    by Xiang Y, Tahmid S, Owens P, et al. on February 23, 2021 at 12:00 am

    AbstractBox delivery is a complicated task and it is challenging to predict the box delivery motion associated with the box weight, delivering speed, and location. This paper presents a single task-based inverse dynamics optimization method for determining the planar symmetric optimal box delivery motion (multi-task jobs). The design variables are cubic B-spline control points of joint angle profiles. The objective function is dynamic effort, i.e., the time integral of the square of all normalized joint torques. The optimization problem includes various constraints. Joint angle profiles are validated through experimental results using root-mean-square-error (RMSE) and Pearson’s correlation coefficient. This research provides a practical guidance to prevent injury risks in joint torque space for workers who lift and deliver heavy objects in their daily jobs.

  • Identification of Non-Transversal Motion Bifurcations of Linkages
    by Müller A, López-Custodio PC, Dai JS. on February 23, 2021 at 12:00 am

    AbstractThe local analysis is an established approach to the study of singularities and mobility of linkages. The key result of such analyses is a local picture of the finite motion through a configuration. This reveals the finite mobility at that point and the tangents to smooth motion curves. It does, however, not immediately allow to distinguish between motion branches that do not intersect transversally (which is a rather uncommon situation that has only recently been discussed in the literature). The mathematical framework for such a local analysis is the kinematic tangent cone. It is shown in this paper that the constructive definition of the kinematic tangent cone already involves all information necessary to distinguish different motion branches. A computational method is derived by amending the algorithmic framework reported in previous publications.

  • Flexible-Joint Humanoid Balancing Augmentation via Full-State Feedback Variable Impedance Control
    by Spyrakos-Papastavridis E, Dai JS. on February 23, 2021 at 12:00 am

    AbstractThis paper attempts to address the quandary of flexible-joint humanoid balancing performance augmentation, via the introduction of the Full-State Feedback Variable Impedance Control (FSFVIC), and Model-Free Compliant Floating-base VIC (MCFVIC) schemes. In comparison to rigid-joint humanoid robots, efficient balancing control of compliant bipeds, powered by Series Elastic Actuators (or harmonic drives), requires the design of more sophisticated controllers encapsulating both the motor and underactuated link dynamics. It has been demonstrated that Variable Impedance Control (VIC) can improve robotic interaction performance, albeit by introducing energy-injecting elements that may jeopardize closed-loop stability. To this end, the novel FSFVIC and MCFVIC schemes are proposed, which amalgamate both collocated and non-collocated feedback gains, with power-shaping signals that are capable of preserving the system's stability/passivity during VIC. The FSFVIC and MCFVIC stably modulate the system's collocated state gains to augment balancing performance, in addition to the non-collocated state gains that dictate the position control accuracy. Utilization of arbitrarily low-impedance gains is permitted by both the FSFVIC and MCFVIC schemes propounded herein. An array of experiments involving the COmpliant huMANoid reveals that significant balancing performance amelioration is achievable through online modulation of the full-state feedback gains (VIC), as compared to utilization of invariant impedance control.

  • An Affordable Linkage-and-Tendon Hybrid-Driven Anthropomorphic Robotic Hand—MCR-Hand II
    by Yang H, Wei G, Ren L, et al. on February 23, 2021 at 12:00 am

    AbstractThis paper presents the design, analysis, and development of an anthropomorphic robotic hand coined MCR-hand II. This hand takes the advantages of both the tendon-driven and linkage-driven systems, leading to a compact mechanical structure that aims to imitate the mobility of a human hand. Based on the investigation of the human hand anatomical structure and the related existing robotic hands, mechanical design of the MCR-hand II is presented. Then, using D-H convention, kinematics of this hand is formulated and illustrated with numerical simulations. Furthermore, fingertip force is deduced and analyzed, and mechatronic system integration and control strategy are addressed. Subsequently, a prototype of the proposed robotic hand is developed, integrated with low-level control system, and following which empirical study is carried out, which demonstrates that the proposed hand is capable of implementing the grasp and manipulation of most of the objects used in daily life. In addition, the three widely used tools, i.e., the Kapandji score test, Cutkosky taxonomy, and Kamakura taxonomy, are used to evaluate the performance of the hand, which evidences that the MCR-hand II possesses high dexterity and excellent grasping capability; object manipulation performance is also demonstrated. This paper hence presents the design and development of a type of novel tendon–linkage-integrated anthropomorphic robotic hand, laying broader background for the development of low-cost robotic hands for both industrial and prosthetic use.

Simulation and Analysis of Microspines Interlocking Behavior on Rocky Surfaces: An In-Depth Study of the Isolated Spine


Microspine grippers address a large variety of possible applications, especially in field robotics and manipulation in extreme environments. Predicting and modeling the gripper behavior remains a major challenge to this day. One of the most complex aspects of these predictions is how to model the spine to rock interaction of the spine tip with the local asperity. This paper proposes a single spine model, in order to fill the gap of knowledge in this specific field. A new model for the anchoring resistance of a single spine is proposed and discussed. The model is then applied to a simulation campaign. With the aid of simulations and analytic functions, we correlated performance characteristics of a spine with a set of quantitative, macroscopic variables related to the spine, the substrate and its usage. Eventually, this paper presents some experimental comparison tests and discusses traversal phenomena observed during the tests.
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