HEIDENHAIN Glossary of Terms



  • Absolute encoders – Absolute encoders provide motion unique position feedback at every point, i.e. when the system loses power and is turned on, the position is the same and does not need to be reset, even after drifting.
  • Absolute measuring method – The absolute measuring method is the measurement of total distance moved from a fixed datum point (called absolute zero or zero reference).
  • Accuracy – The degree to which it is possible to make measurements correctly with respect to a known standard that is true.
  • AC motor – AC induction motors are used with variable frequency drives and include an encoder. They offer high accuracy and torque density.
  • Angle encoders – Angle encoders are a type of rotary encoder that provides feedback in the form of precision angle measurements.
  • Angular acceleration – Angular acceleration (α) can be defined as angular velocity (ω) divided by acceleration time (t).
  • Brushless motor – In brushless DC motors, an electronic servo system replaces a mechanical commutator contacts. The advantages of a brushless motor over brushed motors are high power-to-weight ratio, high speed, electronic control, and low maintenance.
  • Continuous rotation servo motor – A continuous rotation servo motor can generate clockwise or counterclockwise motion for as long as necessary at controlled speeds
  • DC motor – DC motors have an internal power source, a positive and negative terminal. They are best used in longer length, smaller diameter motion.
  • Digital readout (DRO) – A simple keyboard and display of a machine’s position, typically using feedback provided by an encoder.
  • Direct drive motor – A direct drive motor is connected directly to the load and moves it without using any transmission mechanisms. They can be used for both rotary and linear motion. Linear and torque motors are versions of direct drive motors.
  • Enclosed encoders – Enclosed encoders, like sealed encoders, provide protection against contaminants.
  • Incremental encoders – Incremental encoders read equally spaced markings on a scale to track how far and how fast rotational motion occurs.
  • Incremental measuring method – A measurement between two successive points, such as on encoders where markings are evenly spaced and each send a signal.
  • Inductive scanning principle – Inductive scanning for encoders fits between resolvers and optical rotary encoders in terms of performance. They use absolute positioning. Inductive scanning is good for applications where accuracy requirements are relatively low.
  • Interferential scanning principle – The interferential scanning principle uses the diffraction and interference of light on a fine graduation to produce signals used to measure motion.
  • Length gauges – Length gauges are an alternative to calipers for measuring the length or diameter of a part.
  • Linear actuator – A linear actuator is a device that requires an energy source input, an external signal input, both of which then create an output usually in the form of push and pull linear motion.
  • Linear encoders – A linear encoder provides motion and position feedback along a straight line, using a reader head, sensor, that reads a marked scale.
  • Linear scale – A linear scale is a precisely ruled straight piece of glass (or, other materials) substrate, with a uniformly spaced pattern of lines, which allow light to pass through or reflect intermittently for the purpose of measurement.
  • Linear servo motor – Like a positional rotation servo, linear servo motors move about 180 degrees in each direction, but extra gears are used to convert circular motion to linear.
  • Machine control – A machine control refers to the interface used to set up, program and run a metalworking machine for processes like milling, drilling, grinding and turning.
  • Magnetic encoders – Magnetic encoders use magnetic poles around a disk or in a linear configuration. When the sensors detect a change in the magnetic field a count is detected and can be used for measurement or speed control.
  • Motion control systems – Motion control is a technology that encompasses, and is a part of several industries. A motion-control system is any that involves moving and controlling parts.
  • Multi turn rotary encoders – A multi-turn rotary encoder measures rotation within 360 degrees along with the number of full rotations.
  • Natural frequencies – Natural frequency is the frequency at which a system tends to oscillate in the absence of any driving or damping force.
  • Optical encoders – Optical encoders use a light source that sends light through a grating to detectors so that angular and or motion feedback can be sent to a control
  • Photoelectric scanning principle – The photoelectric scanning principle uses the distance, absence, or presence of light by using a transmitter that sends light through a substance or pattern to a receiver.
  • Position encoders – Position encoders measure the mechanical displacement or position of an automated system.
  • Positional rotation servo motor – These motors rotate about 180 degrees in each direction and are the most commonly used servo motor.
  • Precision – Precision is the closeness or (tolerance) of agreement among repeated measurements of the same characteristic, by the same method, under the same condition.
  • Resolver – A resolver is a type of rotary electrical transformer used for measuring degrees of rotation. Unlike encoders that are typically digital, revolvers are analog. Still curious about the difference between resolvers and encoders? Watch the quick video here.
  • Repeatability – This is the capability of a system to return to an identified position within the specified tolerance.
  • Resolution – This is the smallest unit of motion that an encoder or motor is capable of measuring or controlling. [WATCH] The differences between accuracy, repeatability and resolution, explained.
  • Rotary encoders – A rotary encoder measures motion and speed of rotation around 360 degrees. This is also known as a “shaft encoder.”
  • Sealed encoders – A sealed encoder provides certified protection for the sensitive components of the encoder against contaminants like dust or liquid.
  • Shaft encoders – A shaft encoder measures motion and speed of rotation around 360 degrees. This is also known as a “rotary encoder.”
  • Servo motor – A servo motor controls linear or rotary motion with a high level of precision, both in terms of speed and accuracy. A servo motor is a closed-loop mechanism that uses position feedback, like an encoder, for control.
  • Single turn rotary encoders – A single-turn rotary encoder measures rotation within 360 degrees and does not track the number of full rotations. In a quick video, learn the key factors to consider when choosing a rotary encoder.
  • Touch probe – Touch probes are used for probing (part setup, zero location setup, and CMM type location and measurement of part geometry), component/fixture/work piece setup, inspection and 3D or 2D digitizing/surfacing.
  • Touch trigger probe – A touch trigger probe generates an electronic signal when the probe touches an object.