Transcript Slides

Summary of
Tactile sensors for robotics
applications
Student Talk – Di Zhu
Background

Science has long been trying to provide robots with the basic human sensing
capabilities: hearing, sight, smell, taste and touch.
The Human Touch

Based on four kinds of receptors.

1. Meissner Corpuscles.

2. Merkel Cells. (most sensitive to vibrations)

3. Ruffini Endings. (kinaesthetic)

4. Pacinian corpuscles. (deep pressure and high frequency
vibrations)
Two main research areas on tactile sensors
 1.
Lifting and Grasping
 2.
Characterizing different surface textures.
Concept: Taxels

An array of touch sensitive sites.

Simple, reliable and durable solutions are better and less cost
than complex solutions.
Tactile Sensors :

Mechanically based sensors

Resistive based sensors

Capacitive based sensors
Good Design:
Small dimension taxels, maximum capacitance and high
sensitivity.
Optical Sensor

Two ways to modulate the intensity of light:
1.
By moving an obstacle into the light path.
2.
By moving a reflective surface into the light path.
Another One: Optical fiber based sensors.
Piezoelectric Sensors:

Applying a thin layer of metallization to both sides of the piezoelectric
material, constituting the whole a parallel plate capacitor.
Magnetic Based Sensors

Based on the change of the magetic flux density.

Although they have high sensitivity and physical robustness,
they still fails to be a valuable alternative to the types of tactile
sensors.
Deformation Based Sensors

The surface of a material changes in length when it is subjected
to external forces can be used for tactile sensing.
Tactile sensors are attractive

Because touch screen is very popular now.

Medicine and virtual reality applications.
But the tactile sensors that humanoid robots need are not in a
particularly oriented way…
Polymer-based Sensors

Usually use piezoresistive rubber as force sensing element.

Advantage: Low fabrication cost per unit area.

Disadvantage: Low spatial resolution.
Silicon Micromachined Sensors

Advantages: silicon high tensile strength, reduced mechanical
hysteresis, low thermal coefficient of expansion.

Allow higher spatial resolution.
Industry Applications

Surface acoustic waves (SAWs) sensing

Advantages: 100% light throughput.

Disadvantage: no multi-touch.
Car Industry:

Brake pads Monitor

Door mounting monitor

Wind shield wiper
Robots

Goals: provide robots manipulators (hand/fingers) with as accurate
information as possible about the objects to grab, hold and handle.

Enable robots to grasp real-world objects without crashing or dropping
them.
video
Thank you!