Discover, Connect & Collaborate at TECHINNOVATION 2021

Robot Joint Angular Sensor: Best Performance, Low Price

Technology Overview

Developers of mechatronic systems are aware that potential quality of the output is only as good as the quality of the encoders integrated into it.

Does your product require high-precision angular control? Is it tedious to achieve micron-precise alignment of your disk targets to reduce a significant sinusoidal angular error? There is a solution that frees your resources for other priorities! Novel technology solution for high-precision kit encoders provides installation time and cost saving. New encoders can be easily mounted by inexperienced technicians.

These smart self-calibrating inductive sensors are designed to operate even with large axial misalignments. Developed within Cambridge technology consultancy cluster, the bearingless sensors are more economical and accurate than the best optical encoders.

After switching the power supply on and off, the output of encoders remains the same. Such sensors can therefore be used to control movements of machine parts with uncompromising precision.

Inductive encoders consist of two circuit boards, each with a set of printed coils. One PCB is attached to the rotating shaft. The symmetrical design of the coils and circumferential scanning makes the sensor insensitive to small misalignments between the axis of rotation and the centers of the coils. The axial misalignment tolerance of 200 microns is significantly improved over the one micron that optical and magnetic encoders are subject to.

The technology owner is looking for collaboration with industrial partners for modifying geometry of the sensors to fit specific mechatronic systems including application in robotic joints of collaborative (“cobot”) and service robots.

Technology Features, Specifications and Advantages

Overall specifications :

  • Resolution: 19 bits
  • Reproducibility: 18 bits (even immediately after power-up)
  • Accuracy: 16 bit (achieved with bearingless installation)
  • Nominal air gap: 1.5mm ±0.5mm
  • Extended air gap tolerance: up to ±1mm, reducing resolution and accuracy by 2 bits
  • Radial misalignment: up to 200 microns
  • Temperature specification: extended option to -40 to+125 degrees
  • Group delay: 80 µs
  • Rotation speed: up to 24,000 rpm
  • Output interface update rate: up to 25kHz (an internal update rate of 50kHz)
  • Output interfaces: SPI, SSI, BISS, UART
  • Zero angle and direction of rotation: set via two wires pulled to either ground or power supply level
  • Input power supply voltage: 4.5V to 35V
  • Protection against any possible wiring errors (including reverse polarity)
  • Pre-engineered options for 56mm, 36mm, 26mm through-hole kit encoders.

Extra features :

  • Sensor rotation is not required for self-calibration
  • Easy integration with a range of products and platforms due to its open-frame design with a low profile of 12mm
  • Optional electronic multiturn counter
  • Can be used in harsh environments and withstands mechanical shocks
  • No brittle parts
  • Insensitive to the magnetic field
  • Contamination-resistant: insensitive to dirt, dust, oil, moisture, condensate, shavings, etc.
  • Bearingless installation - eliminating the need for precision ball bearings which are a source of unreliability and maintenance cost
  • Available through licence as a reference design using readily available components
  • Bespoke sensor geometries with NRE costs billed to the customer.

Potential Applications

This proprietary technology offer addresses a critical problem faced by many industrial automation companies, who require simplified installation of encoders in a cost-effective manner. The output of the encoder determines the quality of any mechatronic system. Because suggested technology relaxes mounting tolerances, even inexperienced technicians can reliably install such encoders in various mechatronic systems, including industrial robots. The low cost of ownership of technology solution enables a wider range of innovators to participate in the industrial automation revolution.

These smart kit encoders can be used in generic mechatronic systems that require high-precision motion control. They offer compact installation height and large mounting tolerances. The novel technology is ideal for integrating encoders into robotic joints in articulated robotic arms. With such high precision encoders, the robot controller can compensate for joint backlash and other types of errors. With near-perfect repeatability of angle measurements, robotic arms can place “end-effector” tools precisely as specified.

The flexible platform technology allows to design through-hole encoders with usable hole sizes as small as 10 mm. For high precision large rotary tables, hole sizes can be increased up to 400 mm. The robust performance of these sensors makes them ideal for use in the defence system rotary tables.

A modification of the technology can be used for high precision motor encoders with UVW and absolute angle output. Such encoders are upgraded to a 125 kHz internal update rate. If required, their absolute output can be converted to incremental ABZ output to keep compatibility with legacy equipment.

Customer Benefit

Technology provider offers cost-effective engineering support so you can quickly and easily integrate novel high-precision encoders into your mechatronic systems. That means less time spent on design and more time spent on commercialising your system!

Advantages :

  • A high-quality mechatronic system with reduced manufacturing costs and a lower incidence of yield problems
  • Low sensor cost but with best technical specification of the installed encoder
  • Bearingless installation is more compact, which translates into less volume for the sensor in the mechatronic system.
  • No need for recalibration after any environmental change
  • Complete and fast self-calibration of the sensor after power-up
  • Significantly increased sensor accuracy and unsurpassed reproducibility of the angular position
  • Low latency for the faster control loop to achieve smooth operation
  • Stable operation under high acceleration or deceleration
  • Extended sensor life in bearingless installations
  • Increased customer satisfaction due to reduced risk of system operation failure.

The technology offers lower cost of ownership and greatly improved system-level specification due to the reliable and repeatable integration process:

  • Simplified kit encoder installation procedure
  • Unskilled technicians can easily install sensors into a mechatronic system
  • Significantly relaxed mechanical tolerances on sensor installation
  • Improved yield as no parts needs to be scrapped because they have failed the strict critical clearance specification
  • No calibration run for increased accuracy necessary
  • Optional rapid full functional test after installation, taking less than 3 minutes
  • Especially beneficial in high volume production of low margin mechatronic systems.
Contact Person

Victor Zhitomirsky


Alterix Ltd

Technology Category

  • Electronics
  • Sensors & Instrumentation
  • Manufacturing
  • Assembly / Automation / Robotics

Technology Readiness Level


encoder robotic joint cobot rotary sensor mechatronics angular control