{"id":3042,"date":"2021-03-15T16:15:34","date_gmt":"2021-03-15T16:15:34","guid":{"rendered":"https:\/\/novanta.com\/robotics-automation\/2021\/03\/15\/rotary-position-sensors\/"},"modified":"2026-02-04T10:19:32","modified_gmt":"2026-02-04T10:19:32","slug":"rotary-position-sensors","status":"publish","type":"post","link":"https:\/\/novanta.com\/robotics-automation\/articles\/rotary-position-sensors\/","title":{"rendered":"Types and Roles of Rotary Position Sensors"},"content":{"rendered":"\n
\n
\n

Position sensors are very diverse, but in the world of high performance automation, the encoder is a critical element. Position sensor encoders provide feedback for both rotary and linear servo motor control, as well as position information for metrology applications.<\/p>\n\n\n\n

What are Rotary Position Sensors?<\/h2>\n\n\n\n

Rotary position sensors are a type of encoder that measure the angular position or displacement of an object, such as a shaft or motor, in a circular or rotational motion. <\/p>\n\n\n\n

These sensors generate an output signal that varies depending on underlying technology and principle of operation. It is based on the same basic principle as a linear position sensor<\/a>, except the device translates angular positions into useful output signals. Rotary encoders<\/a> may be absolute or incremental. Read the article linked below to learn more about the working principles of rotary position sensors:<\/p>\n\n\n\n

How Rotary Encoders Work<\/strong><\/a><\/p><\/p>\n\n\n\n

Types of Rotary Position Sensors<\/strong><\/h2>\n\n\n\n

There are many different types of rotary position sensors, each with their own unique properties and functionality. This includes:<\/p>\n\n\n\n

Rotary Potentiometers<\/strong><\/h3>\n\n\n\n

Rotary potentiometers are a type of sensor consisting of a resistive element and a wiper which is connected to a rotating shaft. As the shaft rotates, the wiper moves along the resistive element, changing the level of electrical resistance.<\/p>\n\n\n\n

These sensors are most commonly used in devices that require precise position feedback, such as joysticks, steering systems, volume controls, and a variety of industry control systems.<\/p>\n\n\n\n

Rotary Encoders<\/strong><\/h3>\n\n\n\n

A rotary encoder<\/a> is a sensor that measures the rotational movement of a shaft and converts this into an electrical signal output. This signal can be used to indicate the precise positioning and speed of the shaft\/object.<\/p>\n\n\n\n

Absolute<\/strong><\/h4>\n\n\n\n

An absolute rotary encoder provides a unique code corresponding to each distinct angular position of the shaft. This ensures that the exact position of the shaft is always known, even after power loss.<\/p>\n\n\n\n

Incremental<\/strong><\/h4>\n\n\n\n

An incremental rotary encoder generates signals in the form of pulses that track the relative movement of the shaft. However, it does not assign a specific code to each angle of rotation, meaning the exact position of the shaft is not retained – only changes in movement are recorded.<\/p>\n\n\n\n

Hall Effect Sensors<\/strong><\/h3>\n\n\n\n

Aptly named after the Hall Effect, Hall Effect sensors detect angular position and speed by measuring the voltage difference that occurs when a conductor is exposed to a magnetic field. The key advantage of these sensors is that they don’t require direct electrical contact to measure positioning, as they rely on magnetic fields. However, this also makes them more susceptible to interference from nearby electrical wires and magnets.<\/p>\n\n\n\n

Hall Effect sensors are commonly used in vehicles to measure wheel speed and in smartphones to detect screen orientation.<\/p>\n\n\n\n

Resolvers<\/strong><\/h3>\n\n\n\n

Resolvers operate similarly to transformers. They contain 3 coils; two which are stationary (known as stators) and one that rotates (known as the rotor). Resolvers in motion control systems measure the angular position of rotating shafts by generating two output signals: a sine and a cosine wave, based on the rotor’s position relative to the stator. These signals allow the system to calculate the exact angular position of the rotor by taking the ratio of the sine and cosine values. From the rate of change in position, velocity and direction can also be found.<\/p>\n\n\n\n

What are the Common Applications of Rotary Position Sensors?<\/strong><\/h2>\n\n\n\n

Rotary position sensors are used in a wide variety of sensing applications, within a range of industries. Here are some of the most common applications of these sensors:<\/p>\n\n\n\n

Automotive Systems<\/strong><\/h3>\n\n\n\n

Used in vehicles for functions like throttle position sensing, steering angle detection, and transmission control.<\/p>\n\n\n\n

Industrial Automation<\/strong><\/h3>\n\n\n\n

Employed in machinery for monitoring and controlling rotational movements, such as in robotics, CNC machines, and conveyor systems. In warehouse automation, these sensors play a crucial role in automated guided vehicles (AGVs) and autonomous mobile robots (AMRs), ensuring accurate navigation, positioning, and movement.<\/p>\n\n\n\n

Field Robotics<\/strong><\/h3>\n\n\n\n

Critical in agricultural and construction robotics, rotary position sensors help monitor and manage robotic arm positions and vehicle steering, enhancing precision and efficiency in challenging outdoor environments.<\/p>\n\n\n\n

Surgical Robotics<\/strong><\/h3>\n\n\n\n

Integrated into surgical robots to enable precise control of robotic arms and tools, ensuring accuracy and reliability during minimally invasive procedures and complex surgeries.<\/p>\n\n\n\n

Humanoid Robotics<\/strong><\/h3>\n\n\n\n

Used to replicate human-like movements in humanoid robots, these sensors assist in controlling joint angles, arm positions, and balance, enabling realistic motion and interaction.<\/p>\n\n\n\n

Consumer Electronics<\/strong><\/h3>\n\n\n\n

Found in devices like joysticks, video game console controllers, smartphones, and digital cameras for functions such as user input and image stabilisation.<\/p>\n\n\n\n

Home Appliances<\/strong><\/h3>\n\n\n\n

Integrated into devices like washing machines and dishwashers to manage and monitor motor positions and settings.<\/p>\n\n\n\n

And much more.<\/p>\n\n\n\n

Position Sensor Technologies<\/h2>\n\n\n\n

Rotary position sensors can be further defined based on the underlying technologies. Several sensor types can be used for both absolute and incremental position monitoring. The following is a brief selection of some of the primary types of sensor technologies:<\/p>\n\n\n\n