2-DoF Motion Platform I

Mon 11 April 2016 // posts

This project consists in a 2 degrees of freedom automobile simulator, simulating car pitch and roll. The structure is built with iron and steel, the later is used on top structure and at cardan base. A Playseat is installed on top structure. Motion is created by two 12V motors, powered by a modded HP DPS 600PB PSU and controlled by a monster moto shield + Arduino. Motors feedback is given by potentiometers connected to the geared output of each motor.




Welcome DK2!



  • Motor max speed is now adjusted by a pot and displayed in a LCD.
  • Added a wooden plate to top structure, therefore, ergonomics were improved.
  • Installed a big red button to the side of the seat, able to cut the power instantly.
  • Big floor foams to further absorb vibrations



  • Tried Oculus Rift for the first time on Assetto Corsa. It's just insane!



  • Built a circuit for gear and shift light display and RPM gauge control. The new aspect compared to my last displays is that gear and shift light leds (8 total) are time multiplexed, in software, with a significant reduction in electronic components (resistors) and current consumption.


  • Built the monitor stand. Iron.




  • This is how the sim is behaving after software adjustments for rally game. Dirt 3, while not being exactly a racing simulator, it's fun to race.



  • Additional rubber bits added to bottom and top structure.
  • Automotive fuses (at 10A) added to the motors circuit. Initially I did plan to use circuit breakers but they use too much space and are far from convenient to install on my current setup, instead I got 2 fuse holders and glued them to a plastic, screwed to the wood base. Looks decent.


  • Everything is looking great!
  • Things to improve: lock stressed screws with specialized glue, use plastic/nylon screws to mount PCB, further decrease noise during motion, improve weight balance.
  • Things to add: A place to mount a display panel on front of the steering wheel. Should be as light as possible.


  • Pot connectors soldered to a perf board.
  • Electronics installed and organized on top of a wood plate (monster moto shield eventually unstacked from Arduino for better cooling, when the time comes).
  • Rubber bits glued to the bottom of the structure.


  • Cardan base rebuilt in order to fix the 3mm uneveness. This time I've used steel.
  • Sim height reduced by \~20mm.
  • Threaded rods shortened.
  • New pot holders. Taller and closer to the motor arm. This should give a bigger amplitude for the pots.>


  • Firmware for Arduino improved / rewritten. New calibration function allows for automatic detection of left and right pot limits. It saves significant time whenever pots are changed. I'll probably install a button for auto calibration...


  • Further software adjustments. The sim is already very usable (Race07 - WTCC):



  • Built two new pairs of motor arms. This time I used 6mm and 4mm thick steel plates instead of 3mm iron plates. Distance from motor shaft to rod holder is 20mm and 15mm respectively. These new arms are so much more robust.
  • Action time! I finally fired X-Sim, Race07 and after quite a few software adjustments I felt a huge kick when I did hit a wall. Nice. A few adjustments later I was experiencing g-force.



  • Pot holders installed.
  • Top structure rebuilt with steel.
  • Added additional top structure bars (2) for playseat stability
  • Threaded rods cut to final size.
  • Action time, this time with people on it! I immediately found that motor arms were way to long, giving ridiculous angle amplitude, stressing the motors A LOT. I compensated with software limits, but this wasn't a solution. The motor arms even started to bend.


  • Threaded rod holders finished.
  • Motor and rods assembled to structure.
  • Reinforcement of the motors section with additional metal.
  • Action time!




  • Motor mounts assembled to main structure - this gave me a LOT of work! (measuring, aligning, remaking holes...) But I'd say the whole structure is coming up well despite some flaws during its construction. Next step is to finish the threaded rod holders on top platform, weld the pot mounts and turn on the motors!



  • Base structure assembled.
  • The 2 bottom bars where the cardan is mounted weren't aligned. One side was 3mm lower than the other. I've compensated with a 3mm steel plate, sanded, on the other side but I still have to test this solution.
  • Motor mounts rebuilt from scratch. These new ones allow the motors to be rotated in a way so they use as less height as possible.
  • Pot levers rebuilt with a 2mm thick aluminium body. Much more robust, and much less noisy.




  • Built the pot mounts and a lever from a 0.8mm iron sheet. The lever cuts are far from perfect (used an angle grinder, power drill and a file), it's too fragile and makes noise. I'll have to rethink about the levers.



  • Drive shaft cut and sanded.
  • Some electronics assembly.
  • Motors tested (without feedback potentiometers).




  • Finally found a decent drive shaft. This shaft allows for a M12 screw mount on top side, instead of welding.



  • Initial welding tests. Not visible on the photo, but the structure is not well aligned.