The team of Jan Kedzierski (Ph.D.) from Wroclaw University of technology now presents their NEW generation of the autonomous robot FLASH. It is (again) equipped with 2 pcs. 5 DOF robolink wire driven joint arms. They developpped their own drive technology for this robot based on DC/BLDC motors as an open source project. It will be published soon, I will link to their project then.
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:
we do several lifetime and performance tests with our robolink D joints. Until July, main topics were material and geometry optimisations for the gear and bearing components. Nowadays, we do lifetime tests for different joint types at different loads and speeds. The attached film shows or test unit with currently 9 test places, it will be enlarged in the next weeks up to 12 oor 14 test places.
Some numbers and facts that we found out until now:
# general efficiency factor for our current material combination (iglidur J with aluminum HC) is betweeen 0,28 and 0,35 (over all sizes).
# output torque at tooth-break: 19 Nm (size -20) and 30 Nm (size -30), measured at room temperature for first movement. Today we measure this “breaking torque” at continuous operation. Main influences are the rotation speed, and together with this, the temperature in the gear. We see a huge loss of “breaking torque” in operation. For size -20 we find a safe number at high speed rotation of 2,5 Nm (>100.000 cycles) and 3,5 Nm at low speed rotation.
we see good potential for improvement in the material combination and geometry optimisation.
The Basic idea of our NEW RL-D Joints is, that every Joint can be composed out of several components (Joint kit). Main differentiations are:
# Rotary sliding bearing igus PRT-01 (aluminum table with iglidur J sliding elements) or PRT-02-AL (aluminum ring with compact plastic ring made of iglidur J4) or PRT-02-LC (outer aluminum ring replaced by moulded outer ring => low cost solution).
# worm shaft made of hard anodized aluminum, or as injection moulded plastic part (iglidur RN33), additional materials as an Option.
# axial bearings of the worm shaft as roller bearings or thrust washer made of iglidur J.
# worm wheel currently made of iglidur J, additional materials will be offered in the future.
We have pre defined 3 general Solutions. Standard will make use of PRT-02-AL, hard anodized aluminum worm shaft with roller bearings. For the “high-end” solution, PRT-02-AL will be replaced by PRT-01, the low cost solution will contain PRT-02-LC, worm shaft made of iglidur RN33 and thrust washers as axial bearings => see Pictures. STEP data of all Solutions for 3 sizes attached.
Annotation: RL-D-50-xxx is currently only possible as high-end solution. PRT-02-AL or -LC are not yet available at igus.
RL-D-xx-101 (symmetric Version with 2 PRT (used in our trade Show robots)
RL-D-xx-102 (asymmetric Version with 1 PRT (used as first axis or for horizontal applications)
At this year’s COMPAMED, we will show a 4 DOF robolink Joint arm, mounted on a common wheel chair. igus does not offer this as a complete solution for end users, but we want to demonstrate the possibility to use our Joints and actuators for such interactive purposes. This Joint arm may perform pre programmed movements as well as individual movements controled by common Joysticks. The gripper is an igus 3 jaws gripper. Please visit us at the COMPAMED in Düsseldorf (12.11.-14.11.14) at hall 8b / A20.