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Vehicle's steering system in progress

Publication date : 02/02/2021 18:56:42
Category : Ground liaison

Since March 2020, several members of the Vehicle Dynamics team have been working on the design of the vehicle's steering system (by doing "PR" and "TX" supervised projects).

After a partial functional analysis, we identified an existing steering system on which we could rely : a PGO 250 buggy steering system, including the steering column, Cardan joints, steering rack, connecting rods, and ball joints. The system has the advantage of being space-saving and, above all, of having the pinion centered on the cog. 

Once in our possession, we characterized it with 2D and 3D parameters (from the steering wheel to the front wheels). Thus, we were able to carry out 2D and then 3D analytical geometrical studies of the system. These allowed us to optimize the part's geometry (especially the connecting rods and the steering column), to adapt them to our vehicle and the other parts already chosen (uprights and wheels). Besides, the challenge was to make the steering system the most efficient according to Ackermann's geometry (or Jeantaud's Epure). 

To check the geometrical studies' accuracy, we created a 3D model of our steering system using a skeleton modeling on Catia V5. It allows us to simulate the displacement of all the parts for given angles of rotation of the steering wheel and the upper wishbones.

Then, we created a 3D model of the buggy parts and integrated them on the skeleton to ensure the system's feasibility (good adaptation, no collision, etc.)

Finally, we studied the ground loads on the wheels for several use cases. It allowed us to determine the stresses in the links and parts of the steering system. 

The last thing we have to do is to calculate the dimension of the few missing links, then move to the manufacturing process and rectify the last's steering system parts.