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New Force/Torque sensor based on optical technology for robot applications

Force/torque and tactile sensing array have been implemented into medical devices, robot applications, and prosthetic hands to interact with environments. For example, during surgical operations, excessive forces by medical devices may damage soft tissues. Robot hands and prosthetic hands for amputees grasp and manipulate an object dextrously without damaging it.

A variety of force/torque sensors based on piezoresistive materials, strain gauges, polyvinylidene fluoride (PVDF) films, fiber Bragg grating (FBG), and fibre-optics have so far been proposed in the literature. Those sensing elements are attached to a mechanical structure. When external force/moment components are applied on it, by measuring its direct deformation, they can be estimated.

However, those approaches are sensitive to temperature variation, so temperature compensation circuits are essential, and electrical noise is generated by those sensing elements, so a low-pass filter is required to reduce high-frequency noise.

For this reason, a low-cost tactile and force/torque sensor using optoelectronics has been proposed. Contrary to the direct deformation measurement, optoelectronic components are mounted below the surface of a mechanical structure, and it can measure a tiny distance between the sensor and the surface, thereby indirectly measuring its deformation. The advantages of the use of optoelectronics are its immunity to electrical noise, low power consumption, low-level noise, no need for any electronic filtering, and low cost.

In addition, force/torque and tactile sensors can be designed with optical fibres and optoelectronic components, and the light intensity can be transmitted through a pair of optical fibres to the optoelectronic components placed at the remote site.

This method is suitable for extremely hazardous environments where electronics is prohibited to use such as nuclear waste dump, magnetic resonance imaging (MRI) system, and the deep ocean.

Furthermore, not only recent advances have produced diminutive sized photoelectric sensors, but also Today’s 3D printing technologies allow fabricating miniaturised complex sensor structures in metal material at low cost. Hence, the overall size of the sensor structure can also be reduced and miniaturised in comparison with commercially available force/torque and tactile sensors.





Related Research Group(s)

Digital Manufacturing

Digital Manufacturing - Being at the forefront of solutions for building smart machines, we create an operational framework for the digital transformation to Industry 4.0.

Robotics and Automation

Robotics and Automation - We carry out world-class research in robotics and autonomous systems, exploiting and exploring opportunities to develop innovative solutions for industrial and societal applications.

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Project last modified 10/09/2021