Haptic Perception

An aim of our research on haptic perception is to develop a system that can actively explore an object with touch while simultaneously learning its own sensory apparatus. During the proceeding of the project a series of more and more complex haptic systems will be built. So far a very simple robotic hand equipped with nine pressure sensors has been built together with a computational model of the human haptic system. Although simple, the robotic hand has shown ability to generate tactile signal patterns that contain enough information to allow categorization of objects, and the system, i.e. the robotic hand together with the computational model, has shown ability to learn to categorize objects according to size.

The LUCS Haptic Hand I is only capable of passive touch. Therefore we have developed its successor, the LUCS Haptic Hand II. The LUCS Haptic Hand II an eight d.o.f. robot hand equipped with 45 piezo electric touch sensors. The robot hand consists of three fingers, each with two phalanges, mounted on a triangular plastic plate. It is equipped with a wrist and a mechanism for vertical repositioning. The piezo electric touch sensors are distributed on the palmar side of the finger phalanges. The LUCS Haptic Hand I is employed in a sequence of artificial systems for haptic shape perception. These systems employs active explorations of the objects by several grasps with the robot hand in order to gather cutaneous and proprioceptive information. The systems make heavy use of tensor product operations or a novel neural network called Tensor Multiple Peak SOM (T-MPSOM) to code the tactile information in a useful way. The systems are strongly inspired by their biological counterparts and are able to learn to map different shapes in different parts of a self-organizing map. Currently we are trying to extend the system so that it can benefit from expectations provided with another modality (e.g. vision). A movie that shows the LUCS Haptic Hand II during the grasping of a ball is available here: MOVIE.