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robolink® D FAQs – Joint construction kit for robots
Frequently Asked Questions

Single joints and components
Joint systems and electromechanical systems
robolink® DCi (with control system)

1) What types of igus® joints are available from stock?

igus® currently supplies joints with or without a motor. In addition, the joints are available with worm or strain wave gears.
Worm gear installation sizes D-20, D-30 and D-50
strain wave gear sizes S-17 and S-20

2) What are the application areas for single joints? Are transmissions an option?

Single joints can be used, for example, as driven slewing rings (horizontal orientation) or as a single axis of rotation (also vertical). The single joints are modular in design and each one has a drive worm (generally made of anodised aluminium) and worm wheels (made of iglidur® plastic) and an igus® PRT (polymer slewing ring) bearing on the output.
Transmission ratios of between 1:5 and 1:70 are available as standard. Customised transmission ratios available upon request. 

3) Which drives / drive outputs are required in order to move the joints?

igus® generally uses stepper motors to drive the joints. These are available in installation sizes NEMA11, 17, 23, and 23XL, they provide drive torques of between 0.1 (NMEA11) and 3.5Nm (NMEA23XL). As an alternative, (simple) DC motors are available to drive the joints, with a torque range of 0.1 to 1.8Nm.
It is also possible to adapt other (customer) motors, such as servo or BLDC motors. igus® can supply adapters for a range of motors. Talk to us.

4) Which angle sensors are used?

Currently, only motor encoders (of igus® stepper motors) are in use. A contactless proximity switch is available for zero point reference (Ini kit).
igus® is currently developing a new generation of drive encoders.

5) What do joints or "systems" cost?

Single joints from around €150, motorised joints from around €300

6) What is the advantage of a gearbox made of plastic?

  • Lightweight construction
  • Lubrication-free
  • Wide range of options

7) Are we able to make any predictions on how the gearbox components will wear?

This is not yet possible at the moment; for the time being, the only wearing parts are the worm wheels, igus® is currently establishing reproducible wear data under various loads. The main variables in this respect are: load, speed, temperature and duration of use

8) What is the situation regarding replacements for the wearing parts? What is available for purchase? Only the single joints or also the worm wheels, etc., separately?

All components of the joints can be obtained separately from igus®, specifically worm shafts and worm wheels. All individual parts are held in stock.
Worm shafts: RL-D-xx-WS-.... (xx = installation size -20, -30, -50)
Worm wheels: RL-D-xx-WW-.... (xx = installation sizes -20, -30, -50)

9) Do we specify "maintenance/inspection intervals" for checking the worm wheels, for example?

Wear of the worm wheels causes greater clearance in the individual axes. This may cause the end effector to move to a different position. In such a case, it may become necessary to readjust the control system. In our experience, this effect is only minor after a "running in" period. There are not (yet) any specifications with regard to inspection intervals. A broken tooth on the worm wheels would be the "worst case scenario", this can be caused, for example, by "running against a stop" (obstacle) or by human interference ("holding back").
It is relatively easy to replace the worm wheels: unscrew the articulated arm, unscrew PRT (slewing ring), remove worm wheel (plug connection), disassemble adapter (use screwdriver as lever), assemble new worm wheel in reverse sequence).


10) How can the joints be combined?

Connection adapters are necessary to combine joints. These are supplied by igus® as a number of standard options (usually in the form of sheet metal bending parts made of painted steel).
All joints provide threaded holes on the housing and output in order to make customised connections possible.
The simplest unit is a "rotary-drive unit" consisting of 2 pcs. joints mounted offset by 90° (i.e., in principle the first two axes of an articulated arm robot).

Joint systems and electromechanical systems

11) What does the term "modular system" mean?

The basic idea of the robolink® modular system is to provide our customers with individual (mechanical) components that can be used to build a robot system. Depending on the complexity of what is required, articulated arms of varying degrees of complexity can be configured and ordered. igus® makes the arms in accordance with the customer's specifications and delivers ready-to-connect units. However, it is not possible to simply press individual joints together (i.e. "like with LEGO® bricks").

12) What does the scope of delivery of an articulated arm include?

The standard scope of delivery of an igus® articulated arm consists the following: 4-5 joints, 4-5 stepper motors with angle encoders, 4-5 "Ini" switches (are only needed for referencing), connecting plates, igus® e-chain® and all necessary cables, each 5m in length as standard (the end of the cable is "open" for connecting directly to the control system electronics).

13) How are robolink® articulated arms controlled?

There are "endless" control system options. 4-5 "stepper motor controls", a "main control system" (SPS, IPC, micro controllers, or similar) and a suitable programming environment (software) are required.

14) What specific application examples are there?


15) What grippers can be used?

Generally speaking, "all possible" grippers can be combined with our articulated arms. Due to the relatively low load bearing capacity of the system, the grippers should be as light as possible. There is a wide range of lightweight pneumatic grippers on the market, such as the ones from SCHUNK, FESTO or FIPA, for example. If the use of pneumatic components is not desired, as is often the case, electric grippers are necessary. There are some very lightweight electric grippers on the market e.g. from GIMATIC, SCHUNK or SOMMER (which cost considerably more than simple, pneumatic grippers, however).

robolink® DCi (with control system)

16) What does the scope of delivery of a "complete system" include?

RL-DCi arms: in addition to the articulated arm, the control electronics system of the igus® Robot Control is built into the base of the articulated arm, a supplied "controller" (touch display) serves as an input unit ("homing", launching of programmes). A 24V power supply unit is also included, as is the software of the igus® Robot Control on a CD with an instruction manual.
The following are not included: grippers or suction units, a Windows laptop (is required for the programming software), and the ethernet cable for connecting the laptop to the robot.

17) How do I connect a robolink® DCi to my own control system?

Through digital inputs and outputs (standard = 4x DIO).


19) I'm having problems with setting up a robolink® – who can help?

  • For mechanical problems (joints, motors, noises, installation, etc.), contact  Martin Raak (igus® GmbH)
  • In case of system control difficulties (robolink® DCi), please contact us via email at:


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