When it comes to machinery, ‘seeing’ its surroundings is one thing — but being able to interpret this information usefully is another altogether. Here, Ross Turnbull, Director of Business Development and Product Engineering at ASIC company Swindon Silicon Systems explains the importance and benefits of ASIC-driven proximity sensors in a smart facility. 

Proximity sensors are responsible for detecting the presence of an object and converting this into an electrical signal. As a result, they’re found in a wealth of applications, effectively acting as the machinery’s eyes. In an industrial setting, proximity sensors play a vital role in enabling factory automation, whether it’s the conveyer belt transporting goods throughout, or to provide calibration functionalities within computer numerical control (CNC) and coordinate measuring machines (CMMs).

There’s a safety aspect to their use too. Proximity sensors placed around hazardous processes can notify workers that may be too close and warn them to move away. In a situation where the worker is seriously at risk of harm, the sensor can also provide an automatic shutoff.

Spatial sensing

So, how do proximity sensors work? There are a few types of proximity sensors available, depending on the required sensitivity and material of the object they must detect.

A popular type is the capacitive proximity sensor, which detects changes in capacitance caused by the presence of an object near the sensor. Metallic objects are typically easier to detect thanks to their conducting properties, but it’s possible for non-metal objects to be picked up by the sensor too. The success of non-metal object detection depends largely on three factors: the size of the sensor’s surface, the dielectric constant of the target material, and the size of the target object.

Another option is the inductive proximity sensor. Inductive-type proximity sensors use the principles of electromagnetism and Eddy currents to detect the presence of other objects, meaning they’re only suitable for detecting metallic objects. Though this does limit the use cases of inductive sensors, it can be an advantage in some scenarios. For example, environments that only require the detection of metal objects will benefit from the use of an inductive sensor, as the sensor is unlikely to give off false alerts due to dirt and debris.

Enhanced electronics

But selecting the right basis for your sensor system is only half the battle. While these proximity sensing elements can detect the presence of other objects, there’s still a need for this information to be processed and transformed into a meaningful output.

The signals generated by these sensing elements — whether they’re capacitive or inductive — are typically analogue. For these to be communicated and understood by other elements in an electronic system, they must be converted from an analogue to a digital signal.

This process of signal conditioning and conversion may be performed by one or more standard off-the-shelf ICs. But for a truly optimised system, design engineers should consider the benefits an Application Specific IC, or ASIC has to offer.

An ASIC is a custom IC that has been designed specifically for its destined application. This approach offers a superior design, giving manufacturers both the technical and commercial advantage over their competition. By considering the application right from the very beginnings of design, it’s possible to produce a fully optimised chip.

With the ability to embed microprocessors, memory and communication protocols within the ASIC, it’s possible for an experienced custom IC manufacturer to offer a fully integrated sensor interface, combining multiple functions onto a single chip for performance benefits as well as savings on space.

Once you’ve gained a competitive edge over your competition, you don’t want to lose it. IP protection is another key strength of ASIC design, and here at Swindon, we provide our customers with full ownership of their completed design. This means your IP won’t be sold onto other customers or used in-house within a standard product, helping you to retain your advantage.

As Industry 4.0 technologies mature and we look towards the next era of industrialisation, automation will play a major role. As a result, proximity sensors will likely be just another crucial tool in the arsenal of sensor system manufacturers. With the power and performance benefits of custom electronics, an ASIC could be what sets one sensor system apart from its competition.