Weight-perception-based fixed and variable admittance control algorithms for unimanual and bimanual lifting of objects with a power assist robotic system

S M Mizanoor Rahman,Ryojun Ikeura

doi:10.1177/1729881416678131

S M Mizanoor Rahman, Ryojun Ikeura

Open Access

https://doi.org/10.1177/1729881416678131

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Abstract

Weight-perception-based fixed admittance control algorithm and variable admittance control algorithm are proposed for unimanual and bimanual lifting of objects with a power assist robotic system. To include weight perception in controls, the mass parameter for the inertial force is hypothesized as different from that for the gravitational force in the dynamics model for lifting objects with the system. For the bimanual lift, two alternative approaches of force sensor arrangements are considered: a common force sensor and two separate force sensors between object and human hands. Computational models for power assistance, excess in load forces, and manipulation efficiency and precision are derived. The fixed admittance control algorithm is evaluated in a 1-degree-of-freedom power assist robotic system. Results show that inclusion of weight perception in controls produce satisfactory performance in terms of power assistance, system kinematics and kinetics, human–robot interactions, and manipulation efficiency and precision. The fixed admittance control algorithm is then augmented to variable admittance control algorithm as a tool of active compliance to vary the admittance with inertia instead of with gravity. The evaluation shows further improvement in the performance for the variable admittance control algorithm. The evaluation also shows that bimanual lifts outperform unimanual lifts and bimanual lifts with separate force sensors outperform bimanual lifts with a common force sensor. Then, the results are proposed to develop power assist robotic systems for handling heavy objects in industries.

Highlights

Workers in industries such as manufacturing and assembly, mining, construction, logistics, transport, rescue and disaster operations, military, timber, and so on, frequently manipulate heavy objects
We argue that human–robot systems such as power assist robotic systems (PARSs) may be perfectly used for heavy object manipulation where the combination of mechanical strength of a robot and flexibility of a human may make the system far better than the individual robot or the human.[3]
The results showed that the reduction in perceived weight (RPW) and PAL had linear relationships with m2, the power assistance was higher for the bimanual lifts than that for the unimanual lift, and the force sensors arrangement in the design did not affect the power assistance level

Summary

Introduction

Workers in industries such as manufacturing and assembly, mining, construction, logistics, transport, rescue and disaster operations, military, timber, and so on, frequently manipulate heavy objects. The PARSs can be operated with less experiences and skills.[4]

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Discussion

Conclusion