steering Mechanism

[ukesh]

I want to implement an steering mechanism for my battle bot. I'm thinking of using rack and pinion arrangement for it rather than a servo steering mechanism. For the rack and pinion arrangement, a motor is needed for attaching it to the pinion. I've seen in small rc cars, But i exactly dont know what type of a motor is it? If it is normal dc motor, how to use it to give just few rotations like 5 or 6 rotations?

[waltr]

I would use a DC gear motor and a feed-back encoder.

[ukesh]

I guess using a feed back system requires a microprocessor. But i will be controlling my bot with an 6 Ch RC transmitter. further total voltage in my bot should not exceed 36V. With my current configuration total voltage is about 35V. So adding a microprocessor and a feedback system is out of option i think

[Soeren]

Hi,

I guess using a feed back system requires a microprocessor.

No, it could be made with an op-amp if needs be.

But i will be controlling my bot with an 6 Ch RC transmitter. further total voltage in my bot should not exceed 36V. With my current configuration total voltage is about 35V. So adding a microprocessor and a feedback system is out of option i think

What on earth are you arriving at 35V?  Do you add up the voltage of several sub-units or what?
Adding more circuits does NOT add to the supply voltage!

[ukesh]

What on earth are you arriving at 35V?  Do you add up the voltage of several sub-units or what?
Adding more circuits does NOT add to the supply voltage!

Well for driving my main motor(for forward and reverse)  I'm going to use an 18V battery. Then for the weapon system i will be using an relay which handles a 12V supply and the receiver is powered by an 4.8V battery. So totally 34.8V

[Razor Concepts]

Like soeren said, having those different circuits at different voltages does not mean you add the voltages together.

[ukesh]

Like soeren said, having those different circuits at different voltages does not mean you add the voltages together.

It is mentioned that the total voltage in the bot must not exceed 36V. So, what I'm doing is wrong? If so, what is the correct procedure?

[SmAsH]

I think by "the total voltage" they mean the highest voltage?
Generally you don't add voltages up like that unless they are somehow connected eg. series.

[ukesh]

I think by "the total voltage" they mean the highest voltage?

okay, I will get that clarified.
And about the steering, its better if i keep it simple. all i want is to make a motor to rotate for a few times (like 6 or 5 times) I think its possible. I've seen in cheap RC cars. But i dont know how to make that setup.

[SmAsH]

You could try to get a motor with an arm attached to the steering... Like on small rc cars.

[ukesh]

ya i tried searching for an arm, but all stores just have arms for servos. Guess I'll have to make one for myself
Even if found an arm, how do i setup the motor to get just a few rotations? I somewhere read that gearing is on option, But I'm not sure about that.

[madchimp]

To use a motor for steering you would be best off using a gear motor of some sort and you will need some sort of feed back even if it is only limit switches. One option would be to use a threaded rod attached to the motor and have a nut on the threaded rod attached to the steering linkage so when you run the motor one direction it turns one way and when you run the motor the other direction it turns the other way. With the threaded rod idea you might be able to do ok without a gear motor and use a plain motor since the threaded rod will act somewhat like a gear reduction setup but I would still highly recommend at least limit switches. You can use limit switches without a micro controller so if you are just trying to stay away from a micro controller you can still use limit switches. Another limitation that you will have with this setup and just about any other without feed back would be that a normal steering servo will center when you let go of the steering where as using a motor with no feed back or just limit switches will just stop where ever it happens to be.