Two-dimensional team lifting prediction with floating-base box dynamics and grasping force coupling
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Two-dimensional team lifting prediction with floating-base box dynamics and grasping force coupling Yujiang Xiang1
· Asif Arefeen1
Received: 29 October 2019 / Accepted: 3 May 2020 © Springer Nature B.V. 2020
Abstract An optimization-based multibody dynamics modeling method is proposed for two-dimensional (2D) team lifting prediction. The box itself is modeled as a floating-base rigid body in Denavit–Hartenberg representation. The interactions between humans and box are modeled as a set of grasping forces which are treated as unknowns (design variables) in the optimization formulation. An inverse-dynamics-based optimization is used to simulate the team lifting motion where the dynamic effort of two humans is minimized subjected to physical and task-based constraints. The design variables are control points of cubic Bsplines of joint angle profiles of two humans and the box, and the grasping forces between humans and the box. Analytical sensitivities are derived for all constraints and objective functions including the varying unknown grasping forces. Two numerical examples are successfully simulated: one is to lift a 10 kg box with the center of mass (COM) in the middle, and the other is the same weight box with the COM off the center. The humans’ joint angle, torque, ground reaction force, and grasping force profiles are reported. Reasonable team lifting motion, kinematics, and kinetics are predicted using the proposed multibody dynamic modeling approach and optimization formulation. Keywords Team lifting · Manual material handling · Inverse-dynamics-based optimization · Recursive Lagrangian equation · Grasping force coupling
1 Introduction Two-person or team lifting is a popular manual handling strategy that is routinely used when the lifting capacity of the single worker is expected to be exceeded by the lifting tasks and also when mechanical assistance is not available. Due to the variety of lifting situations it would be difficult to provide a mechanical device, but team lifting can be used in handling heavy and awkward or bulky objects. Team lifting is also often used in the furniture handling
B Y. Xiang
[email protected]
1
School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078, USA
Y. Xiang, A. Arefeen
industry, manufacturing and construction sectors [1], retail sales, and healthcare industry to transfer patients [2, 3]. In addition, it was reported that 53% of all lifts performed by military personnel were performed by more than one person [4]. In recent decades, there has been a great amount of work on developing guidelines for manual material handling (MMH) such as NIOSH lifting equations. Many researchers have conducted MMH studies, but these studies were mostly about single person lifting, although team lifting tasks are required in many workplaces. The experiment-based psychophysical and biomechanical approaches are the two basic methods for analyzing team lifting in the literature. The only predictive team lifting simulations are in the roboti
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