As my final year project, I have made my own steering system for our college driving simulator.

The simulator is using Delta PLC's and is using potentiometers etc for pedals.

The project requires the steering to return to a center position if it is not currently at the center ( as one would observe after turning a car).

The problem i am facing is how to interface a motor with the PLC, and also if the driver holds onto the steering in a non zero position, then the Motor should not burn out due to over current.

Please suggest me some low cost solution, and please mention if some more information is required.

 

A mathematical model of where the motor needs to be based on the inputs from the various sensors would be where I would start.

The code to make it work ought to be pretty straight forward once you get the model worked out.

--
Bob

 

One problem with car steering is that it is not entirely positional. Since the system resists forces and has a good deal of compliance built in it has a force component as well. For example when you are going around a curve you don't just crank in x degrees, you apply enough force to keep the car turning and tend to modulate the position to maintain a constant force through irregularities, etc.

This means that your system has to be able to supply torque for the duration of a turn. And it is the resisting force that centers the wheel. I don't really have a solution for you, but I have put a great deal of thought into characterizing the problem. It's an interesting exercise on a long drive. The simple, almost automatic act of keeping it between the lines is actually quite complex. At least two loops to do it smoothly.

Regards
cww

 

I think you will want a DC motor to provide torque feedback (the force returning to centre) to the driver. You can drive the motor with a DC power supply (you will need one that gives you +/- control so you can go in both directions). A rotary potentiometer or an absolute encoder will give you position.

Torque will be proportional to motor current, so you will either need to measure current, or else characterise the motor and control it using an open loop.

You won't need high speed, so you can probably connect the torque motor to the steering wheel with a timing belt and toothed pulleys with a reduction in ratio. That will also reduce the size of motor and power supply that you need.

Your power supply *must* have a controllable current limit. The motor would essentially operate in "stall" continuously, so you would adjust the current limit (e.g. through an analogue signal) to control the torque.

You will need to do some math to find out what size of motor that you need. Don't over-size the motor too much, as that will make it more difficult to control. If you are concerned about over heating, then you could force air cool the motor.