A Basic Study on Biological Signal of Operator During Master-Slave System Control

In a master-slave system, operators control the master device based on visual information and sensory feedback. This suggests that the position sensors on the slave side are not always necessary. However, position signals are required to estimate the acting force conveyed to the slave using an observer which realize the force sensorless control. In this paper, we focused on the biological signals of the operator to estimate the slave side’s condition which can be used to estimate the external force. In the early stage of the research, we investigate biological signals just with 1-DOF masterslave system. First, we measured electromyographic (EMG) and gripping force of operators when pushing objects. We verified that predictive signals can be used for estimation of touching the objects. Second, we propose a method, which uses wrist joint torque and Total Contraction Level (TCL) calculated by the EMG when pushing the virtual elastic films, of estimating the acting force conveyed to the slave. We verify that the proposed method can estimate external force under specific conditions with a trained subject.

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Implementing pseudo haptic feedback in a semi-isometric master interface for robotic surgery

International Journal of Advanced Robotic Systems ◽

10.1177/1729881417733885 ◽

2017 ◽

Vol 14 (5) ◽

pp. 172988141773388

Author(s):

In Kim ◽

Kotaro Tadano ◽

Takahiro Kanno ◽

Kenji Kawashima

Keyword(s):

External Force ◽

Haptic Feedback ◽

Position Control ◽

Wrist Joint ◽

Control Technique ◽

Slave System ◽

Velocity Control ◽

Reference Velocity ◽

And Control ◽

Master Slave System

We have developed a master interface that uses an isometric velocity control technique for translation and an anisometric position control technique for rotation. Using the developed interface, the operator can concentrate on the slave side and control the robot without repositioning required in conventional master arm due to the workspace limitation. However, it cannot display haptic to the operator for the translation directions with the manipulator. In this article, we propose a method to feedback the external force on the slave side to the master manipulator without using actuators or link mechanism but using a pseudo haptic effect. A flexible wrist joint with a spring is used at the tip of the slave forceps to enhance visual effect. The spring stiffness is pneumatically controlled. At the same time, we change the reference velocity of the slave according to the external force applied to the slave manipulator. The changed velocity caused by the external force restrains the slave motion. Using both the visual feedback and the motion restrain, the master–slave system is able to display force to the operator as pseudo haptic feedback without actuators. Experiments of pulling suture threads are executed using the developed master–slave surgical robot. It is confirmed that the master–slave system with pseudo haptic feedback can decrease the variance of force.

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A master–slave control method with gravity compensation for a hydraulic teleoperation construction robot

Advances in Mechanical Engineering ◽

10.1177/1687814017709701 ◽

2017 ◽

Vol 9 (7) ◽

pp. 168781401770970

Author(s):

Lingtao Huang ◽

Hironao Yamada ◽

Tao Ni ◽

Yanan Li

Keyword(s):

External Force ◽

Driving Force ◽

Control Method ◽

Compensation Method ◽

Slave System ◽

Gravity Compensation ◽

Master Slave System

This research develops a gravity compensation method that determines the mass of a task object easily and compensates for the external force caused by the task object when it is conveyed by a hydraulic teleoperation construction robot. Moreover, this study establishes a master–slave system for this robot; two joysticks act as the master, and an excavator with four links (fork glove, swing, boom, and arm) represents the slave. To compensate for the influence of gravity, a previous gravity compensation method is proposed and applied to the boom and arm. However, it is ineffective during the conveyance process especially when the task object is heavy because the driving force is influenced by gravity of the task object. Therefore, this research presents a gravity compensation method that can effectively determine the mass of a grasped object and compensate for the external force induced by its gravity, as verified through pressing, grasping, and conveying experiments.

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