DEMONSTRATOR

For the visu­al­i­sa­tion of Traction‑X, a demon­stra­tor was devel­oped in a bach­e­lor the­sis.
This was man­u­fac­tured with the help of addi­tive man­u­fac­tur­ing. To make the visu­al­i­sa­tion even more real­is­tic, the demon­stra­tor was dri­ven by a DC-motor and a stepper-motor.

Many peo­ple are famil­iar with the state­ment: You can print any­thing! The­o­ret­i­cal­ly, this is true, but it is not prac­ti­cal and does not make sense. It is also impor­tant to com­bine the many dif­fer­ent processes.

Stan­dard alu­mini­um pro­files for the frame and plas­tic parts from three print­ing process­es were cho­sen as com­po­nents.
Besides the FLM (Fused Lay­er Mod­el­ling) process, the SLS (selec­tive laser sin­ter­ing) and LS (laser sin­ter­ing) process­es were also used. When it comes to mate­ri­als, it is also impor­tant to see which mate­r­i­al makes the most sense. Com­po­nents with a sim­ple shape and low demands on strength and accu­ra­cy were print­ed from PETG (Poly­eth­yl­ene tereph­tha­late gly­col) fil­a­ment using the FLM process. These are the black com­po­nents on the demonstrator.

The rim parts were pro­duced from PA 12 (polyamide 12) by laser sin­ter­ing, then paint­ed in silver.

The plain bear­ing, the ring gear and the motor pin­ion were also pro­duced by laser sin­ter­ing. As high wear resis­tance and good slid­ing behav­iour are required, the mate­r­i­al Iglidur I3 from the com­pa­ny Igus (https://www.igus.de/product/719?artNr=I3-PL-10000) was used here.

The dri­ve shaft is the sup­port­ing part of the demon­stra­tor. It con­nects the wheel to the frame. In order to avoid dam­age due to unex­pect­ed stress­es caused by trans­port or improp­er con­tact with the demon­stra­tor, for exam­ple, this was made of AlSi10Mg.

A Rasp­ber­ry Pi is used to con­trol the two motors.
The DC motor dri­ves the out­er rim, i.e. the tyre, via two gear stages.
The spe­cial fea­ture here is that the gear stage locat­ed in the rim has dou­ble heli­cal gear­ing.
Why this choice?
A heli­cal gear has a smoother run­ning behav­iour and less noise com­pared to a degree gear, but axi­al forces are gen­er­at­ed.
There­fore, either a heli­cal or axi­al ball bear­ing must be installed to coun­ter­act the axi­al forces or, alter­na­tive­ly, a dou­ble heli­cal gear­ing can be used, which does not gen­er­ate any axi­al forces.

A step­per motor was used to sim­u­late com­pres­sion and rebound.
The damper unit con­sists of two units.
The upper damper unit con­sists of the upper damper con­nec­tion, the step­per motor and the trape­zoidal spin­dle. The low­er damper unit con­sists of the low­er damper con­nec­tion and the trape­zoidal nut.

The trape­zoidal spin­dle and the trape­zoidal nut con­vert the rota­tion­al move­ment of the step­per motor into an axi­al movement.