Motor Selection

[YAN-1]

Hello. I am currently doing my undergraduate project in which I have to control a Kart such that one can drive it remotely. In order to accomplish that, I have to install a motor on the steering shaft to replace the steering wheel. The problem I am facing (2 months away from the deadline) is that I still can't select a suitable motor. I have conducted an experiment to determine the maximum torque needed to turn the steering wheel of the kart when it is stationary and it was found to be around 30 Nm. The motor will have to be driven from the car battery and I will control its position through a PID controller implemented by a PIC16F877 microcontroller. So given the torque needed (I think it should be multiplied by a safety factor), and the fact that the motor has to work from a 12 Volt or 24 Volt battery, and that it has to change direction of rotation rapidly without damaging itself, I have no idea which motor to select! Of course it has to be a geared motor but I've searched a lot without a result. PLEASE PLEASE can anyone recommend a motor and give me its link or its brand name? I would also appreciate your thoughts on this subject.
Thank you very much.
Nichola V. Abdo

 

[stevez]

Torque is a part of it but now you need to know how fast you want to turn the shaft with 30 N-M of torque. That will tell you how much power you need. Your situation is somewhat challenging but far from impossible. You need the torque at startup. Consider some kind of braking as well - to hold the position once you get there.

One thing to keep in mind with any gearmotor is that there is some loss or inefficiency as a result of the gears. That suggests you'd need more power from the shaft of the motor itself, than you'd expect to get after the reduction.

Another thing to consider in a gear motor is the lash or looseness of the gear train. If you brake with the motor some rotation will still be allowed because of the looseness.

Again, power is the product of torque and rotational speed.

 

[Nigel Goodwin]

Do you have car scrap yards where you are?.

Windscreen wiper motors are pretty good for this sort of thing, or electric window winder motors.

Or even better!, if you can find one in a scrap yard?, mk2 Fiat Punto's have electically assisted power steering - I suspect a motor from that would be excellent!.

You also need to create a servo around the motor, to allow absolute positioning.

 

[alec_t]

[MODNOTE]Second OP's Post moved to its own Thread[/MODNOTE]

 

[Sangoma]

Also worth looking at is an electric wheelchair motor, similar in design to a windscreen wiper motor (worm gear on the motor, so no braking needed, as you will have position control, and designed to rotate both ways, which a windscreen motor isn't) but heavier.

 

[ericgibbs]

hi,
This Thread is 8 years old.

E.