Our customers can choose between motor encoders / Ini switches and igus output encoders (both incremental angle sensors).
Motor encoder / INI (RL-D-RBT-xxxxx-BC):
+) proven industrial standard, double ended signal transmission (A/A-, B/B-), high resolution (500 signals / motorturn * transmission of the joint)
-) 3 cables per axis (motor, encoder, INI), reverse play of the joint is not noticed, mechanical changes in the joint are not noticed (i.e. temperature, load,..)
Output encoder (RL-D-RBT-xxxxx-BC-AE):
+) cheaper, less cables, easy to replace, we measured better repeatability values for multi axis arms in different use cases (detailed results will be shown in ~6 weeks)
-) not industrially proven, single ended signal transmission (A, B) => danger of signal loss is higher, EMC not proven
Conclusion: We recommend to use our output encoders for non critical (non industrial) applications, for industrial applications we recommend motor encoders or testing of the output encoder in the given environment.
DOWNLOAD SECTION. New data sheets for output encoders:
We control the position of our RL-D joints by using the motor encoder (of our igus stepper motors). In order to define a reference point (or ZERO position), an additional inductive initiator switch (=Ini) can be installed on the joint as an option. The spec. of the Ini switch is given below, it is the same part that igus uses for drylin products. The inductive swich needs a steel part as trigger, we install a set pin in the moving part of our PRT inner ring.
The installation finally looks like this:
This submarine robot has been developped by our german customer Habib Nasri from Leibnitz University Hannover, iPeG Institute.
It is fully submersible and it is gesture controlled. It contains 1 simple arm with 2 DOF and one more complex arm with 4 DOF, all robolink joints are equipped with our “under water angle sensors”. The 6 stepper motors are placed inside a sealed aluminum housing in the center.
We have noticed, that for some people it is not clear how our angle encoders work and how to make use of it. Here are some facts about them:
1) we use incremental encoders from AMS (AS5304A), absolute encoders are not possible in the current design,
2) in order to define the ZERO position for each DOF, we use a hall sensor, beeing placed in the middle of each angular freedom,
3) that means: each robolink system has to be “initialized”, whenever the power is switched on,
4) the resolution of the encoders are:
29 (polepairs) x 160 (signals) = 4.640 signals per 360° = 0,078° for all rotationg motions of the size RL-50,
31 (polepairs) x 160 (signals) = 4.960 signals per 360° = 0,073° for all pivoting motions of the size RL-50,
62 (polepairs) x 160 (signals) = 9.920 signals per 360° = 0,036° for all motions (rot AND piv.) of the size RL-90 (Base joint),
you can find more information in our current catalogue on page 18 or in our documentation on pages 10-12 (=> pdf download in the support&service area of the robolink homepage).
The FAQ list will be updated soon (it does currently not contain our new products).