1. Tactile Sensors and their RoboticApplicationsMentor : Prof. Himanshu PatelPrepared by : AasheeshTandon(12BIC044)Paxaj Shukla(12BIC056)

2. Welcome! 3. Overview : What is Tactile Sensor? Analogy with the Human Touch Tactile Sensing : How? A Case Study Robotic Applications Directions for Future Research 4. What is Tactile Sensor? 5. A tactile sensor is a device that measuresinformation arising from physical interactionwith its environment. What does it sense ?Deformation of bodies (strain) or fields(electric or magnetic). 6. Analogy with the HumanTouch 7. Types of Human Touch Cutaneous Sensations - Cutaneous sensereceives sensory inputs from the receptorsembedded in the skin. Senses : temperature, pressure, pain Kinesthetic Sensations - Kinesthetic sensereceives sensory inputs from the receptorslocated within muscles, tendons and joints. Senses : body position, movement, equilibrium Tactile Sensor Cutaneous SensoryReceptors 8. From a Designers Perspective(An Approach to developArtificial Touch Sensing)Strengths of Human Touch Sensors : Large number of Sensors AnticipationDrawbacks : Non-Linearity Hysteresis Low Frequency of Signals 9. Types of Signal in Human TouchSensingBasis of Classification : Type of Signal Frequency of Signal 10. Contd.. Cutaneous Touch(Internal Sensing) Tactel grid Kinesthetic Touch(External Sensing) - Force-Torque SensorStrengths Weakness Linearity No Anticipation Low Hysteresis High Frequency of Signals 11. A grid of Tactels 12. A Thermal Image formed by aTactel 13. Force-Torque Sensor 14. Tactile Sensors : How? 15. Tactile sensing: Methods oftransduction Usually an array of discrete sensing elements. Sensing elements can be many types: Resistive: strain gauge, piezoresistive. Capacitive Piezoelectric & others like (magnetic, optical, conductive rubber,ultrasonic) 16. Resistive Sensing Elements : Strain gauge: a thin film having a metal patternthat changes resistance when strained. Piezoresistive element : Pressure on the elementcauses the material to compress, changing itsresistance Advantages: very simple construction, durable,good dynamic range, easy readout Disadvantages: non-linearity, hysteresis, lowsensitivityStrain gauge 17. Capacitive Sensing Elements: Mechanical deformation changes the capacitance ofparallel conducting plates 18. Capacitive Sensing Elements : Main application area: Touchscreens. Advantages: good dynamic range, linearity Disadvantages: noise, measuring capacitance ishard! (compared to measuring resistance) 19. Other sensing methods: Piezoelectric: measures voltage created dueto polarization under stress Magnetic: uses Hall effect to measure changein flux density List of other methods with their merits &demerits are as follows : 20. A Case Study 21. The Approach MEA based Tactel + Force-Torque Sensor First, a reference frame is defined Force-Torque Sensor Contact pin-pointed through Tactel 22. A Taxel 23. Electronic Circuit of a singleTaxel 24. Robotic Applications 25. Applications : Manipulation: Graspforce control; contactlocations and kinematics;stability assessment. Exploration: Surfacetexture, friction andhardness; thermalproperties; local features. Response: Detection andreaction to contacts fromexternal agents. 26. Application: Nasas Robonaut 2 One of the examples directlyrelated to planetaryexploration. NASA wants to use this onthe International SpaceStation, helping humans withrepairing/maintenance tasksin cluttered environments. They tried many tactilesensors (initially Force-Sensitive-Resistors(FSR),now Quantum Tunneling 27. Application : Manipulation Contact Detection Moving a hand to grasp the desired object Deciding the force required to grasp the object Moving the object 28. Tactile Sensors asManipulators 29. Proximity Sensors onFinger Tip 30. Tracking a Moving Object 31. Directions for FutureResearch Flexible substrates for skin-like tactile sensors Materials with different surface properties (longlasting materials, self cleaning) Different display mediums (acoustic) Improved dynamic tactile sensing 32. A Big Thank You! 33. References Beebe, D. J., A. S. Hsieh, et al. (1995). "A Silicon ForceSensor for Robotics and Medicine." Sensors and Actuators A 50: 55-65. Berger, A. D. and P. K. Khosla (1991). "Using tactile datafor real-time feedback." The Bicchi, A., J. K. Salisbury, et al. (1990). Augmentation ofgrasp robustness using intrinsic tactile sensing. IEEE International Conference onRobotics and Automation. Charlebois, M., K. Gupta, et al. (2000). "On EstimatingLocal Shape Using Contact Sensing." Journal of Robotic Systems 17(12): 643-658. Cheung, E. and V. L. Lumelsky (1992). "A Sensitive SkinSystem for Motion Control of Robot 34. References(contd.) Arm Manipulators." Journal of Robotics and AutonomousSystems 10: 9-32. Chu, Z., P. M. Sarro, et al. (1996). "Silicon Three-AxialTactile Sensor." Sensors and Actuators Cutkosky, M. R. and I. Kao (1989). "Computing andcontrolling the compliance of a robotic hand." IEEE Transactions on Robotics and Automation5(2): 151-165. Dahiya, R. S., G. Metta, et al. (2008). "Tactile Sensing:From Humans to Humanoids." IEEE Transactions on Robotics (unpublished). Dahiya, R. S., M. Valle, et al. (2008). Tactile SensingArrays for Humanoid Robots using Piezo-Polymer-FET devices. 13th National Conferenceon Sensors . www.southampton.ac.uk/~rmc1/robotics/artactile.htm en.wikipedia.org/wiki/Tactile_sensor