80 % weight saving: polymer bearings in six-wheel robots for Mars exploration

This six-wheeled robot - a Mars Rover - was built by a group of students at the Technical University of Łódź. The robot consists of more than 2,000 parts and is designed to move over extremely difficult areas that need to be explored. The robot is remote-controlled and can operate for more than 2 hours at a distance of 1.5 km from the control station.
The robot design provides for low weight, high reliability and maintenance-free and smooth operation. There are no shock absorbers or springs in the rocker arm suspension used in the robot. This makes it possible to overcome large obstacles, but also means that the suspension is highly susceptible to vibrations, especially at high speeds. This can lead to damage to the measuring device and other components of the robot. To prevent this effect, the introduction of a controlled resistance on the shaft was planned.

The robot uses iglidur ® plain bearings of the W300 series, which connect the body with the rocker arm suspension.
The use of the plastic bearings in this application contributed to several goals that were not possible to achieve with normal bearings. A key parameter that influenced the improvement in the quality of the system's operation was the ability to introduce a controlled resistance to movement through the correct placement of a hole for sleeves and shaft. The movement resistance helped to reduce vibrations on the suspension while travelling. Another consequence of using iglidur® W300 bearings was a reduction in the space required for the bearing (bearing on a 30 mm shaft) to 34 mm compared to at least 42 mm for a ball bearing. This also enabled a weight reduction of more than 80 %.