Design of virtual stiffness for human operated robot considering external force in safety enhancement

R. M.Maheshi Ruwanthika, Seiichiro Katsura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Precise force control and position control is essential for many robotic applications. During unilateral or bilateral object handling remote applications, human operators apply excess forces on the actuators with the intention of better grip and it is possible to damage the handled objects. This paper proposes position control and force control techniques when human applies excess force. The controllers consist of predefined force and equilibrium position which are correspond to remote environmental object safety. The operator applied excess force is modeled as a spring force through a virtual stiffness model. The paper introduces proportional derivative position control loop to conventional virtual stiffness controller. The force control loop and the position control loop references are combined in the common dimension of acceleration to produce current reference to the actuator. The sensorless sensing techniques of disturbance observer and reaction force observer are utilized to disturbance suppression and external force estimation. In the force controller, estimated reaction force is reduced to desired value by introducing virtual force loop between reaction force observer output and reaction force feedback input. The position control is achieved by introducing a scaling factor to reaction force feedback path. The switching between force control and position control is possible with scaling factor value. The performances of proposed methods are compared with conventional method and validity of the proposed methods is verified by simulations and experiments.

Original languageEnglish
Title of host publicationProceedings IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages7596-7601
Number of pages6
Volume2017-January
ISBN (Electronic)9781538611272
DOIs
Publication statusPublished - 2017 Dec 15
Event43rd Annual Conference of the IEEE Industrial Electronics Society, IECON 2017 - Beijing, China
Duration: 2017 Oct 292017 Nov 1

Other

Other43rd Annual Conference of the IEEE Industrial Electronics Society, IECON 2017
CountryChina
CityBeijing
Period17/10/2917/11/1

Keywords

  • disturbance observer
  • force control
  • human
  • position control
  • reaction force observer
  • virtual stiffness model

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering
  • Control and Optimization
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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  • Cite this

    Ruwanthika, R. M. M., & Katsura, S. (2017). Design of virtual stiffness for human operated robot considering external force in safety enhancement. In Proceedings IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society (Vol. 2017-January, pp. 7596-7601). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/IECON.2017.8217331