Gauge based collision detection mechanism for a new three-degree-of-freedom flexible robot (*).

Flexible robots have given rise to numerous investigations and their use is easily justified in two main cases: 1) when the weight of the robot has to be minimized 2) when collisions of the robot with the environment are to be foreseen. as a flexible lightweight robot delivers less impact energy. There is a lot of work done by different authors on the position control of flexible robots by using feedback of the tip position or tip acceleration. However the use of these sensing devices is problematic in practical applications of flexible arms: 3-D tip position sensing is very expensive, and occlusions appear at some arm configurations; and accelerometers can not be used when contact of the tip with the environment is expected because these sensors can not stand the high negative accelerations produced at the impact (unless very low speed motions were performed). In most up to date analysis the force control is performed beginning from a known contact point at a given collision time. But in a more realistic approach an accurate detection of the collision would be needed before dealing with the force control. This paper analyzes the possibility of carrying out the collision detection as a first step towards the position/force control of a three-degree-of-freedom flexible arm by using gauges placed at some distance of the tip (where contact is expected) in such way that they can easily stand the impact. Simulated results over a prototype three-degree-of-freedom flexible arm are presented.