- #1
LeenSTL
- 5
- 0
I'm looking into implementing some parts of drive by wire on an SUV and need assistance determing the load requirement for steering effort. Braking force is widely published as roughly 150 lbs of pressure but I am unable to find a similar estimate of force needed to turn a steering wheel. I'm looking for a simple rule of thumb for sizing a 12v DC motor in a chain drive application. The motor might be a stepper motor or servo for ease of control.
My current thinking is to have a sprocket welded (or similarly attached) to the steering shaft between the steering column and the power steering unit. The motor would be able to drive the steering shaft via a chain, and when the electric motor is unpowered the vehicle would be manually steerable (assuming that the ignition key is in place and the steering column is unlocked). The chain would retain alignment in spite of any flexing due to rough road conditions, out of balance tires etc. Some older marine autopilot drives work this way; they even have a nice failsafe clutch in the middle!
I'll have to work out how many teeth to use on the motor and the shaft sprockets to give an output RPM in the desired range. How do I figure out much power I need in the DC motor to turn the steering shaft under load? I don't want it to be too small to turn or hold the load (which is why a stepper or servo might be a good motor choice).
Thanks for any assistance ... :)
My current thinking is to have a sprocket welded (or similarly attached) to the steering shaft between the steering column and the power steering unit. The motor would be able to drive the steering shaft via a chain, and when the electric motor is unpowered the vehicle would be manually steerable (assuming that the ignition key is in place and the steering column is unlocked). The chain would retain alignment in spite of any flexing due to rough road conditions, out of balance tires etc. Some older marine autopilot drives work this way; they even have a nice failsafe clutch in the middle!
I'll have to work out how many teeth to use on the motor and the shaft sprockets to give an output RPM in the desired range. How do I figure out much power I need in the DC motor to turn the steering shaft under load? I don't want it to be too small to turn or hold the load (which is why a stepper or servo might be a good motor choice).
Thanks for any assistance ... :)