Safe and accurate robot positioning

Robots are called upon to perform increasingly demanding tasks, including high-accuracy machining operations on aircraft fuselages and other large components, or positioning tasks as cobots in direct collaboration with humans. In these applications, exact motion control of the robot arm is the critical factor.

The KCI 120 Dplus dual encoder from HEIDENHAIN provides motor feedback and position measurement in a single device. By measuring the position downstream from the gearbox, the KCI 120 Dplus compensates for design-related errors in dynamic, highly manoeuvrable robots. Articulated robots with a serial architecture, for example, may contain up to six axes, each of which affects final accuracy. Each axis is driven by a servomotor through a gear system that is susceptible to zero-position error, reversal error, and joint elasticity.

Applied forces and dynamic effects from the machining task may further limit positioning accuracy.

In order for the two-fold functionality of the KCI 120 Dplus to be used in as many applications as possible, three versions of the dual encoder are now available. The central scanning unit and two separate disk/hub assemblies are thus suited for various hollow-shaft diameters and installation dimensions. That way the KCI 120 Dplus from HEIDENHAIN, which can be integrated very easily, always offers the same functionality no matter how compact its dimensions are.

Servo encoders for compact robot motors

The KCI 1319 and KBI 1335 rotary encoders developed by HEIDENHAIN for robot motors are inductive encoders that consist of a scanning unit and a screw-fastened circular scale or alternatively a disk/hub assembly for seating onto a motor shaft. Benefits include:

Very compact design and low weight

Immunity to contamination and magnetic fields

Easy installation with wide tolerances

Safe and secure physical mounting

Safe data transfer via EnDat 2.2 with functional safety

Overload protection with an external temperature sensor is possible.

Solutions for large hollow shafts

The KCI 120 and KBI 136 compact rotary encoders, for large hollow shafts with diameters of 30 mm or 40 mm, are two of the inductive rotary encoders that HEIDENHAIN designed specifically for robotics applications. They offer the same benefits as the smaller 1300 series but are designed for significantly more sturdy and powerful robot motors.

Robot motors with very large shaft diameters

Designers can significantly improve the absolute position accuracy of their robots by employing an additional high-accuracy encoder at each robot axis. Installed downstream from the gearbox, these secondary encoders measure the actual position of every robot joint.

AMO offers the WMRA angle encoder as a secondary encoder. Modularly designed with a scale drum, measuring ring and separate scanning unit, it is ideal for large shaft diameters and difficult installation spaces.

Rotary encoders for stepper and BLDC motors

The new R35i and R35iL encoders from RENCO are incremental rotary encoders without integral bearings. Featuring resolutions of up to 40 000 measuring steps per revolution, they are the ideal feedback systems for stepper motors in closed loop operation and for exact position measurement in a wide range of applications.

For extremely limited installation space, RENCO offers the R35iL. It is one of the smallest rotary encoders currently on the market, with a profile of just 8.6 mm.