Powersteering to ECO-car

Hi!

In short: We want to have electrical steering to our ECO-car - what part can you recomend for it?

So we started up a team last year and said that we were going to compeet in Shell Eco Marathon, down in Amsterdam. We bouilt the car in 3 months and have now accived 650 km in 1 liter petrol.
Now we are going to bould a new car, much lighter and that have more thought in to it. One of my things to do is to bould the cars steering - and we are now going to bould it with electrical powersteering. The ide behind it is that it is lighter.

The car has three wheels - one in the back and two in the front. The steering is in the front wheels.

The specs/mosts is...

  • Electrical
  • 12v
  • Stepper motors
  • One motor on each front wheel
  • light weight

The problem that I see at the moment is if we can do this with Arudino, I have just seen stepper drivers that can do 2A and I think (yeah, I think - but you may know better) that thats too low?

Here you can see more photos... Higtech

Thanks so far! :slight_smile:

For steering a real vehicle you need power-assist, not fly-by-wire, so that when something
goes wrong electrically you can still steer! That's quite specialist I think - the mechanical
side of things that is.

If you use Brushed DC motors, like from a cordless drill, you can apply positive or negative DC to give positive for negative torque. This will allow the motor to help you turn the wheels. If the power is out, you can still turn, you just don't get any help. Limiting the current of the motor will keep them from pulling too hard. The torque of a DC motor is proportional to the current. Your car is awesome!

The tricky part is measuring the torque on the steering wheel in order to estimate
the amount of "help" the assist motor needs to provide - possibly an application for
a strain guage or a specialist torque-measuring load cell.

And once you provide assist the torque at the steering wheel depends on the driver
and the assist motor, in other words there is already negative feedback in the system,
care is needed to avoid oscillation in the control loop.