Force Sensors, also called Force Transducers, are devices used for the measurement, and subsequent translation, of primarily mechanical forces. Force sensors are finding increasing application across sectors, primarily owing to their accuracy, and the relative ease with which they can be integrated into digitized systems. At a very fundamental level, force sensors measure the force applied, with its value being reflected in the corresponding value of an electric parameter such as voltage or current.
Force sensors can, by virtue of being able to ascertain the magnitude of physical pressure on components to high degrees of accuracy, not only provide information to technicians that can help them better regulate operations on the assembly line, but also offer real-time information on the wear and tear of machine components, by analyzing the impact of tensile and compressive forces, which can, in turn, prove immensely beneficial in ‘Predictive Maintenance’ practices.
Wide range
Force sensors currently available in the market are spread across a wide range, with sensitivity to as little as a few kilograms to being able to measure forces to the tune of thousands of tons. Many state-of-the-art sensors developed by leading mechanical firms have a measuring range of 0 Newton (the SI unit of force) to 20,000 Newton. Given their small size, force sensors can be accommodated even in a set-up otherwise constrained in space.
Types of Force Sensors
Among the most commonly used force sensors are
- Load Cells: These are mostly used to measure the value of either the weight acting on a body or the amount of pressure applied to the same. A household example of a load cell is the weighing scale one uses to gauge one’s own weight. Load cells are further classified, based on their functionality and mode of operation, into:
- Pneumatic Load Cells
- Hydraulic Load Cells
- Strain Gauge
- Capacitive Load Cells
- Inductive Force Sensors: Used in a wide range of mostly electrical and electronic applications, the Inductive Force Sensor employs the principle of alternating current to measure parameters such as displacement, and position. The operation of these sensors is centered on the principle of ‘Electric Induction’, wherein there is a change or variation in the inductive reactance of an electric circuit in response to the passage of an electric current or a variation in the magnetic field.
- Force Sensing Resistors: Resistors are indispensable components in even the most basic electric circuits. As its name suggests, a resistor is a small device used to resist the easy flow of electric current through a circuit. In the manufacturing world today, the force sensing resistors are finding applications galore, owing in part to the degree of accuracy they guarantee and to their small size, which enables firms to use them even in assembly lines where there is little room for use of additional machinery owing to severe space constraints. A force sensing resistor is a thin film-like device sensitive to even the slightest application of any force. Variation in the value of the sensor’s resistance proportional to the magnitude of the force applied offers technicians in a manufacturing set-up the output value they need to assess and regulate operations.
- Optical Force Sensors: The operating principle of an optical force sensor is very similar to that of a load cell strain gauge sensor, with the only difference being that, while the latter measures the strain on the sensor on the application of force on the sensor, infrared light is used as the parameter to determine the amount of force applied.
Applications across sectors
From healthcare to robotics and aerospace, force sensors are finding applications across industries. On the one hand, ease of integration into existing manufacturing models is driving their widespread adoption, while the accuracy, coupled with increasing onus on digitization is accelerating their use even in unconventional sectors.
- Robotics: Force torque sensors are currently finding increased application in the robotics industry. Addition of these sensors to robots is now bringing many precise tasks previously not within the operational purview of a robot within its reach. Force torque sensors, often affixed to the end of the robotic arm, enable them to detect the application of force across directions. They have proven particularly useful in preventing accidents inside manufacturing plants, since these force torque sensor-powered robots can now pause operations immediately following a collision. Other applications of force torque sensors include operations such as dowel pin placement, sanding, etc.
- Healthcare: Force sensors have proven particularly beneficial to physiotherapy specialists, who are now in a positon to accurately assess the amount of force, and thereby its impact, on a patient’s muscles or bones being treated. Given that there have been instances of patients experiencing undue pressure from the therapist, a glove affixed with force sensors is being used by some practitioners in the United States of America to provide real-time information on the amount of pressure being applied on the muscles at the time of treatment. This has ensured that these exercises are carried out with utmost care lest the muscle or tissue sustain any damage owing to application of excess pressure. Force sensors are also being used by doctors to detect points of excess stress on the beds used by patients to prevent onset of bed sores.
- Manufacturing: The use of force sensors at various points on the manufacturing assembly line has helped companies register an uptick in the overall production efficiency at manufacturing plants. Force sensors are used for quality checks, tests conducted to ascertain the strength of materials used in production, and even monitor operations in the assembly line.
Amid increased thrust for digitization of industrial processes, it is likely that force sensors, particularly force sensing resistors, will find applications hitherto not thought of. Force sensors, coupled with other Industry 4.0 technologies such as Industrial Internet of Things, Edge Computing, among others, are likely to further enhance the overall efficiency of industrial processes, while driving productivity further.