Variable Admittance Control Based on Human-Robot Collaboration Observer Using Frequency Analysis for Sensitive and Safe Interaction.

Hyomin Kim,Woosung Yang

doi:10.3390/s21051899

Abstract

A collaborative robot should be sensitive to the user intention while maintaining safe interaction during tasks such as hand guiding. Observers based on the discrete Fourier transform have been studied to distinguish between the low-frequency motion elicited by the operator and high-frequency behavior resulting from system instability and disturbances. However, the discrete Fourier transform requires an excessively long sampling time. We propose a human–robot collaboration observer based on an infinite impulse response filter to increase the intention recognition speed. By using this observer, we also propose a variable admittance controller to ensure safe collaboration. The recognition speed of the human–robot collaboration observer is 0.29 s, being 3.5 times faster than frequency analysis based on the discrete Fourier transform. The performance of the variable admittance controller and its improved recognition speed are experimentally verified on a two-degrees-of-freedom manipulator. We confirm that the improved recognition speed of the proposed human–robot collaboration observer allows us to timely recover from unsafe to safe collaboration.

Highlights

Collaborative robotics has become the new frontier for industrial robots by combining high-level motion accuracy and the repeatability of robots with the flexible cognitive judgment of humans [1,2]
The recognition speed of the human–robot collaboration observer is 0.29 s, being 3.5 times faster than frequency analysis based on the discrete Fourier transform
We propose a human–robot collaboration observer (HRCO) based on an infinite impulse response (IIR) Butterworth filter

Summary

Introduction

Collaborative robotics has become the new frontier for industrial robots by combining high-level motion accuracy and the repeatability of robots with the flexible cognitive judgment of humans [1,2]. Effective human–robot collaboration requires an intuitive user interface to maximize operation flexibility [3]. 10218-1/2 [4,5] In this mode, the operator directly sets the sequence of desired robot positions by moving the robot end effector without an intermediate interface. In addition to the intuitive interaction, the operator can manipulate the robot while receiving haptic feedback that guides or limits the trajectory. This mode evolves the interface bottleneck of traditional input devices such as mouse, keyboard, and joystick [6]. When the operator and the robot are in continuous contact, safety during the physical human–robot interaction is the most important consideration [7]. The robot must operate according to the operator intention while ensuring safety

Methods

Results

Conclusion