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.

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