With the increasing degree of automation in all walks of life, the importance of motion control is becoming increasingly prominent. In order to drive the motor effectively, control inputs describing speed and position are essential. However, there are a variety of technologies to achieve this sensing, each with different characteristics and application scenarios.

This article will compare the different rotation sensing techniques and discuss the reasons for choosing them. Then, we’ll look at some of the latest devices on the market.

Position sensing applications

In order to improve accuracy, improve yield, and reduce operating costs, many processes that previously required manual operation have been automated, which has led to a rapid growth in location sensing applications. In fact, as long as there is some form of motion, there needs to be sensors that provide position information to the controller.

IS215ACLEH1BB Industry 4.0 has driven many advances in automation in the industrial market. Robotics is becoming increasingly common, enabling “unmanned” operation around the clock without fatigue or error – which requires a sensor for each axis of motion. The same goes for “collaborative robots” that work alongside humans in traditional factories.

Today, many parts are made by machine-some using numerical control (CNC) machines, some using laser cutters, and some using 3D printers. These machines have moving parts and require precise position control to meet quality objectives. Once parts are machined, they are often transported via automated material handling or conveyor belts, which also require position sensing.

Position control is also needed in many places outside the factory, such as large medical equipment that can move patients or scanners. In addition, robots are now able to perform surgery, which also requires very precise control.

In the transportation sector, every application involves motion. Whether it is traditional transportation such as trains, agricultural machinery, construction machinery, or emerging applications such as autonomous mobile robots (AMRs) in warehousing and thousands of drones, location sensing is required.

As passenger cars with all modes of drive (internal combustion engine (ICE), pure electric drive (EV) and hybrid) are moving towards electrification, mechanical control solutions are being replaced by systems such as “drive-by-wire” and “steering-by-wire”. For these systems to function properly, the position information of the accelerator pedal (accelerator) must be transmitted to the electronic control unit (ECU), or the position information of the steering wheel must be transmitted to the steering control system.

As electronic control extends to almost all aspects of vehicle operation, position sensing technology is also widely used in suspension components (for level/ride control), powertrains, and power Windows, sunroofs, door locks, and more.

IS215ACLEH1BB Comparison of position sensing techniques

Rotary position sensing mainly uses three technologies – optical, magnetic and inductive technologies, each of which has its own different operating modes, advantages, disadvantages and application scenarios.

Optical encoders, often considered the most accurate (though not in all cases), work by passing light through a disk with holes, using pulses of light to detect motion as the disk rotates.