Motor Control and Position
What is the best way to control a simple 12VDC motor that I might get from Radio Shack?· I know special considerations must be taken to prevent voltage spikes to the microcontroller, but do I need to buy some type of motor control, or is it easy enough to build a circuit to handle it?
Also, I'm using the motor to control a linear actuator (the motor will turn a threaded screw) which I will need to know the position of.· I don't need it to an extremely high amount of accuracy.· What would be the best way to do this?· I was thinking of·reading the voltage accross a linear potentiometer, but a tachometer might do the job as well.· What would be the most cost-effective solutiton?
Thanks,
Joey
Also, I'm using the motor to control a linear actuator (the motor will turn a threaded screw) which I will need to know the position of.· I don't need it to an extremely high amount of accuracy.· What would be the best way to do this?· I was thinking of·reading the voltage accross a linear potentiometer, but a tachometer might do the job as well.· What would be the most cost-effective solutiton?
Thanks,
Joey
Comments
Do you need continuous rotation? Ie. ability to rotate 360 degrees+?
To use a DC motor, you will need a motor controller - and you need to power it seperatly from the stamp/javalin or you will upset the processor! Have a look at http://www.parallax.com/html_pages/products/motorcontrol/motor_control.asp
If you only need 180 degree's I would recommend using a servo instead, as it solves these issues for you. If you want 360 degree rotation and a position, use a stepper motor & control board - however that seems to be quite expensive. Otherwise use the tachmeter you suggest. Finally if you use a continuos rotation servo you get speed control & 360 degrees - but you'll have to work out a method of counting rotation!
James
Also where can I find tachometers that are compatible with the motor controllers on Parallax? Or a motor with a tachometer built in would be good also if it's cheaper than attaching a tachometer to a $5 motor from RadioShack.
Thanks,
Joey
I guess your in USA, if so have a look at www.hobbyengineering.com - or in the UK try www.activerobots.com / www.techsupplies.co.uk
You could put a sensor of some type on a fly-wheel attached to the motor? Something on a fly-wheel perhaps, attached to the motor?
James
Thanks everyone for the help,
Joey
Terry
Thanks Terry,
Joey
Otherwise, reading the resistance of a a pot that is connected to vary over the range of movement available is probably the simplest way I can think of.
Post Edited (Antz) : 9/2/2004 1:56:44 AM GMT
Bean
Thanks everyone,
Joey
Oh wait, I guess that depends on the speed of what is driving the stepper motor...
I think I remember seeing stepper controller chips that handle the stepping and you just tell it how many steps you want to move.
I'll see if I can find something on the web.
Bean