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. Tactile Sensors and their Robotic
Applications
Mentor : Prof. Himanshu Patel
Prepared by : Aasheesh
Tandon(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 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 (magnetic, 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 :

21. A Case Study

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

25. A Taxel

26. Electronic Circuit of a single
Taxel

27. Robotic Applications

28. 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.

30. 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

32. Application : Manipulation
 Contact Detection
 Moving a hand to grasp the desired object
 Deciding the force required to grasp the object
 Moving the object

33. Tactile Sensors as
Manipulators

34. Proximity Sensors on
Finger Tip

35. Tracking a Moving Object

36. 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

37. A Big Thank You!

38. 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

39. 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/artactile.htm
 en.wikipedia.org/wiki/Tactile_sensor