Tactile sensing for robotic applications

Robotic devices – limited to the structured environment of manufacturing plants until few years ago – are slowly making way into human life, which has led to the emergence of interaction and learning issues in robots. Such issues are important for future robot to be able to learn autonomously and to interact safely with the environment i.e. without causing any harm to it or to the objects with which it is interacting. In this context, it becomes important to study the ways and means of robot’s interaction with the environment. Humans interact and explore the environment through five main sense modalities viz. touch, vision, hearing, olfaction and taste. Loss of any of these modalities will result in the incomplete information about the environment. Irrespective of their importance with respect to each other, the study of their individual contribution in collecting information from environment is important for improving the sensing capabilities of any future robotic system. This chapter provides an overview of tactile sensing in robotics. This chapter is an attempt to answer three basic questions: • What is meant by Tactile Sensing? • Why Tactile Sensing is important? • How Tactile Sensing is achieved? The chapter is organized to sequentially provide the answers to above basic questions. Tactile sensing has often been considered as force sensing, which is not wholly true. In order to clarify such misconceptions about tactile sensing, it is defined in section 2. Why tactile section is important for robotics and what parameters are needed to be measured by tactile sensors to successfully perform various tasks, are discussed in section 3. An overview of `How tactile sensing has been achieved’ is given in section 4, where a number of technologies and transduction methods, that have been used to improve the tactile sensing capability of robotic devices, are discussed. Lack of any tactile analog to Complementary Metal Oxide Semiconductor (CMOS) or Charge Coupled Devices (CCD) optical arrays has often been cited as one of the reasons for the slow development of tactile sensing vis-a-vis other sense modalities like vision sensing. Our own contribution – development of tactile sensing arrays using piezoelectric polymers and involving silicon micromachining is an attempt in the direction of achieving tactile analog of CMOS optical arrays. The first phase implementation of these tactile sensing arrays is discussed in section 5. Section 6 concludes the chapter with a brief discussion on the present status of tactile sensing and the challenges that remain to be solved. O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg