Pages: [1]   Go Down
Author Topic: Building a Winch. Stepper motor or regular DC motor.  (Read 1793 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 2
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I am looking to build a winch and I need precise speed control. The winch needs to be able to lift about 40 pounds. I looked at just buying one but I need to be able to program two winches to work together. I have access to two wheelchair motors but I would have to buy a stepper motor. A stepper motor would be easier to control as a DC motor would likely need a feedback controller. Stepper motors are also more expensive. I guess my question is how difficult would it be to simultaneously and precisely control 2 DC motors? Any other suggestions/ideas would be appreciated as well.
Logged

St. Louis, Missouri
Offline Offline
Sr. Member
****
Karma: 0
Posts: 278
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

It's not clear from your description but I'm guessing you need to coordinate the 2 motors to position a load? DC motors would work if you could incorporate some sort of limit switches.
If you could give us some more specific information about the project it would help.
Logged

0
Offline Offline
Tesla Member
***
Karma: 118
Posts: 8962
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

You will probably have to use rotary encoders on the motors and use their output to input a program to control the speed of the motors via an h-bridge (if not using stepper motors).
Logged

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

East Coast USA
Offline Offline
Newbie
*
Karma: 0
Posts: 16
Hands in the air!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Like you said, position/speed feedback from the shaft would help a lot. But for simple, precise speed control of a DC motor, you can use an H-Bridge or MOSFET, taking a PWM signal from the micro controller.
Logged

Build your own sentry gun! http://psg.rudolphlabs.com

0
Offline Offline
Tesla Member
***
Karma: 118
Posts: 8962
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
But for simple, precise speed control of a DC motor, you can use an H-Bridge or MOSFET, taking a PWM signal from the micro controller.

The speed of normal motors increases and decreases with the change in load, so more than this will probably be needed.
Logged

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

Offline Offline
Newbie
*
Karma: 0
Posts: 2
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Yes i am using the two motors to position a load. My group in senior design is designing and building a window cleaner.
Logged

0
Offline Offline
Shannon Member
****
Karma: 162
Posts: 10496
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

How precise?  If you use matched motors and reduction gearing so they are not heavily loaded you will get reasonalbe control just with PWM.  For more precise you need shaft-encoders and then close the loop to make two continuous rotation servo motors.

If the winch drum is not precise then your position feedback can't come from rotation, you will need linear position sensing of some form.

If all you need is to keep a platform level while winching both ends you just need an accelerometer to measure tilt of platform?  Or use one motor smiley-wink

Stepper motors will be very slow and inefficient BTW and thermal issues may need addressing.
Logged

[ I won't respond to messages, use the forum please ]

SW Scotland
Offline Offline
Edison Member
*
Karma: 13
Posts: 1325
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

If the two motors are pulling in the same direction then you could use a single motor by feeding the rope from the winch drum over a pulley assembly at the terminal location then run the rope back to the location of the winch where it can be anchored. 
Logged

East Coast USA
Offline Offline
Newbie
*
Karma: 0
Posts: 16
Hands in the air!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
But for simple, precise speed control of a DC motor, you can use an H-Bridge or MOSFET, taking a PWM signal from the micro controller.

The speed of normal motors increases and decreases with the change in load, so more than this will probably be needed.

Good point. But if the load was always 40 lbs, the motors would always move it at the same speed, right?
Logged

Build your own sentry gun! http://psg.rudolphlabs.com

'round the world...
Offline Offline
Faraday Member
**
Karma: 41
Posts: 3113
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
But for simple, precise speed control of a DC motor, you can use an H-Bridge or MOSFET, taking a PWM signal from the micro controller.

The speed of normal motors increases and decreases with the change in load, so more than this will probably be needed.

Good point. But if the load was always 40 lbs, the motors would always move it at the same speed, right?

The window surface will also strain the window wiper in an unknown way... might not be enough to destabilize the system though.
Logged

Eu não sou o teu criado. Se respondo no fórum é para ajudar todos mediante a minha disponibilidade e disposição. Responder por mensagem pessoal iria contra o propósito do fórum e por isso evito-o.
Se realmente pretendes que eu te ajude por mensagem pessoal, então podemos chegar a um acordo e contrato onde me pagas pela ajuda que eu fornecer e poderás então definir os termos de confidencialidade do meu serviço. De forma contrária toda e qualquer ajuda que eu der tem de ser visível a todos os participantes do fórum (será boa ideia, veres o significado da palavra fórum).
Nota também que eu não me responsabilizo por parvoíces escritas neste espaço pelo que se vais seguir algo dito por mim, entende que o farás por tua conta e risco.

Dito isto, mensagens pessoais só se forem pessoais, ou seja, se já interagimos de alguma forma no passado ou se me pretendes convidar para uma churrascada com cerveja (paga por ti, obviamente).

Pages: [1]   Go Up
Jump to: