What is a force torque sensor?

Fundamentals
Force torque sensors play an important role in grinding and polishing applications. (Fanuc)

A force torque (FT) sensor is an electronic device that is designed to monitor, detect, record and regulate linear and rotational forces exerted upon it. In other words, the FT sensor in a robotic or mechanical system can be compared to the micro-receptors in skin that equip animals with the sense of “touch.” 

As a contact sensor, it is specifically designed to interact with physical objects in its environment. In order to mitigate interference from sound waves and debris, this sensor is designed to operate in a variety of climates and external conditions. Depending on the model and intended function, a force torque sensor is able to send digital or analog signals, and measure static or dynamic forces.

Figure 1. Measurement of external forces and moments by a six-axis force/torque sensor.
Figure 1. Measurement of external forces and moments by a six-axis force/torque sensor. (ResearchGate)
The most popular type of force torque sensor is the six-axis sensor. This particular FT sensor is capable of measuring forces in every direction. A six-axis FT sensor generally utilizes strain gauge technology; when pressure is applied, the resistance within the gauge increases or decreases proportionally to the force it receives. This is how the sensor measures the movement of its external frames in relation to one another. Six-axis sensors can be found in robotic arms at the “joint.”

Force torque sensors are implemented in a myriad of applications and mechanisms. Most notably, FT sensors have advanced “cobot” or “collaborative robot” technology. Cobots are designed to work in tandem with human beings, taking on both the time-consuming work such as driving screws in an efficient manner, and physically demanding tasks such as lifting automobile parts in assembly lines. 

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Figure 2: Force torque sensors are used in polishing applications to protect mechanical components from strain.
Figure 2: Force torque sensors are used in polishing applications to protect mechanical components from strain. (Fanuc)

Force torque sensors are also used in the polishing, testing, and medical industries to ensure the precision of mechanical systems. For example, FT sensors are used in polishing applications in order to protect mechanical components from strain, and apply enough force to successfully polish or sand metal and wood. 

The demand for FT sensor technology is expected to grow in the upcoming decade, as advances in robotics, mass production, and automation continue to transform the modern era, and “touch” the lives of millions around the globe.

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