Skip to content

A key benefit of robotics and automation in industrial environments is the ability to improve throughput and efficiency. To enable this, it is necessary to have a scalable, repeatable and accurate method for detecting objects and making accurate measurements to locate those objects.

Fork sensors are a simple way of making these measurements. They operate on the principle of projecting a light source between the two arms of the fork, and when an object passes through, the resulting break in the light beam indicates presence. In addition, object measurement and precise location can be determined by simple calculations. The light beam in these optical fork sensors can be either infra-red or laser, but generally, laser enables much better precision and can detect smaller objects than is possible with infra-red.

So, what is a typical scenario that illustrates the benefit of optical fork sensors? Imagine you have a robot welding arm. It carries out a set task, and you know that for example it carries out that operation at a certain speed. If it normally takes 10 seconds to perform an operation, say to dip a tool, but suddenly it takes 9 seconds or 11 seconds, then this data provided by the fork sensor can trigger an alert for an operator or supervisor to investigate further and rectify any issues. The cause might be a tool that has moved out of position for example.

The fork light barrier sensors from CAPTRON, available in widths from 20mm to 220mm, can detect both metallic and non-metallic objects using a one-way light barrier based on laser light. The sensor itself houses both the transmitter and the receiver in the same metal housing; hence they have a fixed position and setting and require little additional calibration to ensure consistent measurement results.

Because they only require an input signal and an output signal, they can be integrated into an automation system easily by connecting directly into a PLC (programmable logic controller).

An important benefit is of these sensors is high accuracy enabled by a very high switching frequency of 10 kHz, and a high resolution of 0.05 mm. This means very small parts moving at high speed can be reliably detected. They can also be adjusted to for light or dark switching, and sensitivity can be fine-tuned using an adjustment screw.

Another key differentiator of the CAPTRON optical sensors is that they are made from Aluminum, making them very rugged. There is also a version with an integrated pressurized air system which prevents dust and dirt from collecting on the transmitter and receiver, ensuring that it is resilient to dusty environments. This makes it suitable for applications where there might be high levels of contamination, such as in the food industry, paper industry and mixing systems.

What is tool center point (TCP)?

The tool center point, or TCP, function is a way of ensuring a tool head, like a pick or a cutter, is always aligned with the surface it is working on, and avoiding crushing or gouging of the object it is picking or cutting. The TCP function defines the tip of the tool in three dimensions (X, Y and Z), so that it can be fed into program that controls it. Since the program also knows the contours of the surface it is working (say if there is a curve or it has a non-level surface), it can ensure the tool moves exactly along a path that maps that contour.

CAPTRON provides a TCP measurement technology for industrial robots that ensures a high level of precision for tool calibration, featuring a reproducibility of 0.01 mm. It is offered in a one-part structure within a compact housing, which makes it easy to install and assemble. These TCP laser measurement units can be used for measurement and robot calibration in many industrial automation applications, including dispensing technology, bonding technology, welding technology, soldering, and the food industry.

To learn more about our optical sensors please contact us via email: or give us a call at (914)-619-5422. We're excited to help you pick a sensing solution tailored to your needs!


Leave a Comment