FEATURE Sensors
Reaching for a better grip with robots
Ross Turnball, Director of Business Development and Product Engineering at ASIC design and supply company Swindon Silicon Systems, says enhanced sensors are essential for improved robotic grippers
T
he industrial robotics sector continues to experience strong growth, with operational stock at approximately four million
robots according to statistics from the International Federation of Robotics. Improvements in robotic grippers have helped accelerate industrial robot uptake, but is there room for further development? Whether it’s moving large, heavy goods
from point A to point B or assembling something small and fragile, industrial robots can be useful for a wide range of tasks. To give them the ability to hold and manipulate objects on their own, many robots will feature one or more grippers. But it isn’t as simple as directing the gripper to just open or close. These robots must be able to work with objects of all hardnesses — and adapt accordingly. This can be a challenge. The gripper needs to be able to sense the object to pick it up quickly and accurately, holding it securely to prevent it from being dropped. But it cannot close too tightly, as this could impair the gripper jaws themselves or damage fragile products. It’s also important to consider the electronics assembly. Thin connector wires in small electronic components can be easily bent and damaged through poor handling. To prevent damage while ensuring
proper operation, robotic grippers need to have at least one sensor. These sensors need both accuracy and precision to move, how can we build sensors capable of this? For the gripper to be able to move accurately, it needs to know its exact position to the same level of precision. This is where position sensors come into play. available: inductive and optical. Inductive position sensors rely on electromagnetic induction for non-contact detection of metallic objects. Conductive targets cause disturbances in the magnetic sensing element. Optical position sensors,
12 December 2024/January 2025 | Automation
be interpreted by the rest of the robot or digitised. The necessary processes of signal the-shelf IC, but there is a better solution available.
in contrast, make use of an LED and photodetector, with an optical scale to measure linear displacement accurately. Force or torque sensors are another important sensor type, as robots do not feel forces. Integration of a torque sensor can help give robots ‘feeling’. These typically make use of strain gauges, which convert pressure into a measurable electrical signal. Multiple gauges can be combined to determine not only the intensity but also the direction of the force. The result is a robot that can handle even fragile materials or precisely tighten a screw without going too far to cause damage.
The last key type for discussion here is
the proximity sensor. These are particularly helpful to check the angle of the jaw grippers for accurate movement, and can part is still inside the gripper. Proximity sensors for this application are commonly inductive. Using the principles of electromagnetism and Eddy currents, the sensors can detect the metal of the jaws or a metal target attached to the jaws. Whether systems contain just one of these sensor types or a combination, they’ll still have something in common: at least one or more ICs. The aforementioned sensor types will typically produce an analogue signal output. For this signal to
This takes the shape of an Application this case, a robotic gripper. The result of bespoke design means the IC can be fully optimised for superior closely with the manufacturer to discuss the current sensor system and identify the best areas for improvement for maximum processing functions can be included to improve signal quality and minimise noise to ensure the accuracy of data and therefore movement of the robot. Industrial grippers working with extremely small components such as printed circuit board latency and real-time decision-making. This is particularly important for robots working in a collaborative environment with humans. Products are growing in complexity while shrinking in size, making their manufacture more and more challenging. Custom ICs can help provide the dexterity and capabilities required for modern manufacturing.
Swindon Silicon Systems
www.swindonsilicon.com
automationmagazine.co.uk
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