Experimental Testing of a Gauge Based Collision Detection Mechanism for a New Three‐Degree‐of‐Freedom Flexible Robot

Abstract

The use of flexible robots can be easily justified in two main cases: (1) when the weight of the robot has to be minimized and (2) when collisions between the robot and the environment are foreseen, since a flexible, lightweight robot implies less impact energy. The position control of these robots has already been analyzed in previous communications. However, the second of these cases justifying the use of flexible robots requires further consideration, leading to the development of a force controller. In most up to date analysis the force control is studied beginning from a known contact point at a given collision time. In a more realistic approach, however, an accurate detection of the collision would be needed prior to dealing with the force control. After developing a reliable position controller for a three-degree-of-freedom flexible robot using strain gauges placed over the robot structure, in this paper we deal with the possibility of carrying out the collision detection for the same prototype. This has been easily achieved by analyzing some estimated signals such as tip position and tip velocity. However, a complete analysis of the information obtained with the sensors has been required to obtain those estimates and a signal processing scheme had to be devised for a previous filtering of the original signals from the sensors (encoders and strain gauges). This work has been carried out as a first step towards the position/force control. Experimental results on a three-degree-offreedom flexible arm prototype are presented to verify how well this method performs.

Collision detection and suspend control of parallel- structured single-link flexible arms

“…The collision is detected by using the difference between the actual input torques to the manipulator and its reference torques calculated based on the manipulator dynamics. Garca et al [3] have presented a method of collision detection based on difference between the tip-position and its reference. Kaneko, et al [4] developed an active antenna for mobile robots.…”

Collision Detection and Control of Single-link Flexible Arm Using Optimal Disturbance Decoupling and Kalman Filters

“…Several studies on collision detection methods for flexible arms have already been conducted [7][8][9][10][11]. Moorehead and Wang proposed a collision detection method for a flexible cantilevered beam by using two strain gauges to determine the intensity and position of the external force resulting from a collision [7].…”

Control of Flexible Manipulators. Theory and Practice

“…Another interesting and not very studied approach to the flexibility of manipulators consists of taking advantage of it for specific purposes. Flexibility is considered as a potential benefit instead of a disadvantage, showing some examples with margin of improvement in assembling (Whitney, 1982), collision (García et al, 2003), sensors (Ueno et al, 1998) or mobile robots (Kitagawa et al, 2002).…”