Tactile sensors and their robotic applications

This presentation discusses about artificial tactile sensors, it's comparison with human tactile senses. Further different types of tactile sensors are enlisted ,with a few given in more detail.
Robotic applications are also discussed and then finally future developments in this area is mentioned.

1. Mentor : Prof. Himanshu Patel Prepared by : Aasheesh Tandon (12BIC044) Paxaj Shukla(12BIC056) Tactile Sensors and their Robotic Applications

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 measures information arising from physical interaction with its environment. What does it sense ? Deformation of bodies (strain) or fields (electric or magnetic).

6. Analogy with the Human Touch

7. Types of Human Touch Cutaneous Sensations - Cutaneous sense receives sensory inputs from the receptors embedded in the skin. Senses : temperature, pressure, pain Kinesthetic Sensations - Kinesthetic sense receives sensory inputs from the receptors located within muscles, tendons and joints. Senses : body position, movement, equilibrium Tactile Sensor  Cutaneous Sensory Receptors

8. From a Designer’s Perspective (An Approach to develop Artificial Touch Sensing) Strengths of Human Touch Sensors : Large number of Sensors Anticipation Drawbacks : Non-Linearity Hysteresis Low Frequency of Signals

9. Types of Signal in Human Touch Sensing Basis of Classification : Type of Signal Frequency of Signal

10. Contd.. Cutaneous Touch(Internal Sensing) – Tactel grid Kinesthetic Touch(External Sensing) - Force-Torque Sensor Strengths Weakness Linearity No Anticipation Low Hysteresis High Frequency of Signals

11. A grid of Tactels

12. A Thermal Image formed by a Tactel

13. Force-Torque Sensor

14. Tactile Sensors : How?

15. Tactile sensing: Methods of transduction Usually an array of discrete sensing elements. Sensing elements can be many types: Resistive : strain gauge, piezoresistive. Capacitive Piezoelectric & others like ( m agnetic, optical , conductive rubber, ultrasonic)

16. Resistive Sensing Elements : Strain gauge : a thin film having a metal pattern that changes resistance when strained. Piezoresistive element : Pressure on the element causes the material to compress, changing it’s resistance Advantages : very simple construction, durable, good dynamic range, easy readout Disadvantages: non-linearity, hysteresis, low sensitivity Strain gauge

17. Capacitive Sensing Elements : Mechanical deformation changes the capacitance of parallel conducting plates

18. Capacitive Sensing Elements : Main application area: Touchscreens . Advantages: good dynamic range, linearity Disadvantages: noise, measuring capacitance is hard! (compared to measuring resistance)

19. Other sensing methods: Piezoelectric: measures voltage created due to polarization under stress Magnetic: uses Hall effect to measure change in flux density List of other methods with their merits & demerits are as follows :

20. A Case Study

21. MEA based Tactel + Force-Torque Sensor First, a reference frame is defined Force-Torque Sensor Contact pin-pointed through Tactel The Approach

22. A Taxel

23. Electronic Circuit of a single Taxel

24. Robotic Applications

25. Applications : Manipulation : Grasp force control; contact locations and kinematics; stability assessment. Exploration : Surface texture, friction and hardness; thermal properties; local features. Response : Detection and reaction to contacts from external agents.

26. Application: Nasa’s Robonaut 2 One of the examples directly related to planetary exploration. NASA wants to use this on the International Space Station, helping humans with repairing/maintenance tasks in cluttered environments. They tried many tactile sensors (initially Force-Sensitive-Resistors(FSR), now Quantum Tunneling Composites (QTC))

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 as Manipulators

29. Proximity Sensors on Finger Tip

30. Tracking a Moving Object

31. Directions for Future Research Flexible substrates for skin-like tactile sensors Materials with different surface properties (long lasting 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 Force Sensor for Robotics and Medicine." Sensors and Actuators A 50: 55-65. Berger, A. D. and P. K. Khosla (1991). "Using tactile data for real-time feedback." The Bicchi , A., J. K. Salisbury, et al. (1990). Augmentation of grasp robustness using intrinsic tactile sensing. IEEE International Conference on Robotics and Automation. Charlebois , M., K. Gupta, et al. (2000). "On Estimating Local Shape Using Contact Sensing." Journal of Robotic Systems 17(12): 643-658. Cheung, E. and V. L. Lumelsky (1992). "A Sensitive Skin System for Motion Control of Robot

34. References(contd.) Arm Manipulators." Journal of Robotics and Autonomous Systems 10: 9-32. Chu, Z., P. M. Sarro , et al. (1996). "Silicon Three-Axial Tactile Sensor." Sensors and Actuators Cutkosky , M. R. and I. Kao (1989). "Computing and controlling the compliance of a robotic hand." IEEE Transactions on Robotics and Automation 5(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 Sensing Arrays for Humanoid Robots using Piezo -Polymer-FET devices. 13th National Conference on Sensors . www.southampton.ac.uk/~rmc1/robotics/ar tactile .htm en.wikipedia.org/wiki/ Tactile _ sensor