TouchDetect – Tactile arrays and soft interfaces

Tactile arrays and soft interfaces

PowerON’s soft tactile arrays use our patented elastomer switches and make robots feel. Soft and stretchable, our arrays give adaptive robotic grippers the sense of touch for lifelike interactions. Large area skins upgrade entire robots with tactile sense for natural interactions with human co-workers.

The widespread integration of robotic assistance systems, in industry, household or the service sector, fails today because conventional robotic systems can neither quickly adapt to changing processes, individual and flexible production, nor safely collaborate with humans. Safe interaction is difficult to achieve with conventional technology. TouchDetect is an easy-to-use tactile array for robotic finger tips that gives robotic grippers the ability to feel touch, adjust their gripping force accordingly and identify objects, their position and slipping of those. It comes either with Bluetooth low energy, industry standard CAN-bus or I/OlLink connectivity and is fully integrated. It is intended, to be used in state-of-the-art industrial grippers, to retrofit tactual sensation features.

Set-up:

TouchDetect is an array of pressure sensitive sensor points on top of a compliant body that can be adapted to the desired gripping task. The size of the array and the density of tactile sensor points can be adjusted; our standard array has 6×6 tactile points. The compliant 6×6 tactile skin and body are mounted with the interface & measurement electronics.

Depending on the selected communication protocol, the size of the sensor array can be chosen between 17 mm to 25 mm edge length with different heights and mechanical compliance. The electrodes of the tactile skin consist of Polydimethylsiloxan (PDMS) and conductive carbon fillers. The tactile skin is supported by a silicone body. The silicone body fulfils two functions: it separates the electronics from the tactile skin; and it contributes to the overall flexibility of the sensor, producing a robust system for difficult gripper conditions. The sensor array is supplied by 5V.

The sensor technology and manufacturing process allow for a wide range scaling, both of the sensor array size, as well as number of sensor points and fields of applications.

Connectivity:

When an object touches the surface, the array points are deformed, changing resistance between the corresponding electrodes and providing information about the object shape, direction and gripping force – amongst other factors. The embedded sensor electronics provide resolution of 4095 bits, encoded in an ISO 11898-1 / CAN 2.0B frame. Consequently, the sensor array can be integrated in any CAN message-based sensor network or used in a standalone application. Finally, the user gets the signal for every sensor point and can combine it with the array position of the point for a pressure map of the object.

Summary:

TouchDetect today is suitable for, e.g., two-fingered grippers for applications where pressures/forces normal to the sensor surface are generated. Lateral forces are not measured directly and can be recognized by processing the measured signals. Since the sensor points are arranged in an array-like structure the shape of an object can easily be estimated. A small number of sensor points can recognise known objects and to identify, say, random object shapes a larger number of sensor points can be added, or additional scanning strategies can be considered. Both are possible with the technology underlying TouchDetect.

The flexibility of TouchDetect facilitates its use especially in soft robotic systems where classic sensors based on semiconductors, and classic construction materials, such as metals, frequently fail.

TouchDetect is a step forward to soft robot grippers with sensing capacities comparable to the human hand. As nature needed millions of years to design our hands, TouchDetect still will be optimized in the future.

Applications: pick-and-place, agritech, service-, industry- and household-robots, collaborative robotics and soft user interfaces.