Active Touch Studies of a Flexible-beam Antenna Sensor with Controlled Movements

This article presents studies on active contact sensing of a controlled antenna sensor. The experimental antenna is a lab-scale flexible-beam made of carbon fibre that is attached to a force-torque sensor. The antenna tip precisely tracks a trajectory and recovers its position after a contact is made. The system actively controls the beam vibrational behaviour and allows for fast and precise movements after it touches an object. This controlled antenna system minimizes the time needed when the antenna has to perform specific tasks, such as when it must be pointed precisely or when it has to follow a search trajectory. The system damps the collision effects while keeping the antenna's tip error minimal which prevents the flexible-beam from touching points that are not within the range of our particular object. Controlled movements are thought to maximise the amount of useful contact information in the least amount of computational time. A simple contact identification method is proposed and consists on attaining the active touch information when the antenna touches an object. The contact point, time and normal force are obtained by processing force, torque and encoder measurements.