Monster Servo from a wiper Motor

Lynxmotion
1

I am trying to use a wiper Motor (from a car) as a servo.

The motor I want to use is on the Monster Guts website. Search for 12VDC Wiper Motor.

Sorry, I’m new here and I am not yet allowed to post URLs.

I want to use the lynxmotion Single H-Bridge - HS-5745 Servo Amp to control the motor since I want to control it from my SSC-32 card.

I will be running the Motor on 5VDC because that will give me the speed I want.

It will be used in a Halloween project as an armlifter for a plastic full sized skeleton purchased from Bucky’s Boneyard. You’ll have to google that if you are unfamiliar.

I am concerned that the Single H-Bridge - HS-5745 Servo Amp will burn up if I try to drive that motor with it because of the current needed to drive that motor. Is that the case?

If so, is there any way to use the positioning elements of that board and replace the H-brigde circuit part with a 4PDT relay? or maybe a LMD18200T chip from National Semiconductor?

I will be mounting an external POT that turns in sync with the armature of the wiper motor and will be using a pulley system to lift the arms.

Any wisdom you can share would be greatly appreciated. Also any alternate ideas would be great!

2

Some previous discussion below on making large servos. Bottom has some reversing relay setups. You can use the analog input on the ssc-32 to read a pot position, but you will need to make a program to handle the control actions.

lynxmotion.net/phpbb/viewtop … 99&start=0
geocities.com/zoomkat/switch.htm

3

is this the one?!

img228.imageshack.us/img228/3189/42167063ar6.th.jpg
**
Product Information**

    • 12 VDC has high and low speeds
* High Speed @ 12V: 53 r.p.m.
* Low Speed @ 12V: 38 r.p.m.
* High Speed @ 5V: 21 r.p.m.
* Low Speed @ 5V: 15 r.p.m.
* Working Torque - 3.98 foot pounds (5.4 N m)
* Static Torque - 13.27 foot pounds (18 N m)*
4

That is exactly the one.

I already have software that sends control information to the SSC-32. I am using Brookshire Software’s VSA.

I need to simply be able to plug this monster into the SSC-32 and have it act like a normal servo, except that it has enough torque to lift a dining room table.

OK, a little exaggeration there, but you get my point.

I have read through the other threads and none really seem to have an answer in them as to what to buy that will work with the SSC-32 and have enough current capacity to work with this motor.

The motor can draw as much as 10 amps under a heavy load.

I don’t think my intended load is that heavy, but I would like to have that much capacity just in case.

Basically, I want something JUST like the Single H-Bridge - HS-5745 Servo Amp, except able to handle more current. Would that be a HB-25 Motor Controller?

5

lol.
well i di like the sound of monster servos and SSC! good mix if it wrks. would be cool to use PS2 contoller to get this thing moving! you have made me want to take my tools to the wifes car and start ripping the servos from that! lol!

a few years ago i was thinking of buying some monster servos for a massive Hexapod idea i had in mind but money wasnt an option. would be cool to see someone do this!!!?

ill try and find out some info on if it will work.

6

I doubt you will be able to just place an order for what you want. As far as I know your desired gizmo does not currently exist. That being said, I’ve done some tinkering to make my own large motor servo, and there is still work to be done. If you really want your large motor servo, then you will probably have to build it yourself.

7

there was actually a project underway for something this but it just hasn’t gotten much attention lately. :frowning:

I also remember some time back there was some openservo stuff going on with adapting their controller design to support bigger motors, basically beef up the h-bridge, but I stopped following stuff over there (too many forums too little time) so it might be worth searching their site. maybe one of our regulars here still watches their efforts and can give some more direct info.

Like zoomkat suggested though if this exists as a purchase-able product off the shelf anywhere it isn’t common knowledge.

8

So, would this work…

Keep in mind that I don’t need to be super precise. I just need basic control of when the motor comes on in a certian direction, and when it goes off. It’s OK if it does not land in exactly the same position every time. For my purposes, close enough is close enough.

I would start with the HS-5745 Servo amp.

This amp does plug directly into the SSc-32 and would drive a large motor like a servo, just not quite as large as I had hoped.

I take the output that was supposed to go to the motor. Instead of sending it to the motor, I send that output to a relay.

This is hard without being able to post pictures. Let’s call the two output leads from the HS-5745 lead ‘A’ and Lead ‘B’ since the polarity will be constantly changing.

I will actually have 2 5VDC relays.

First, there is Relay 1

Output Lead ‘A’ from the HS-5745 goes to the anode of a diode. The cathode of the diode goes directly to the + post of the DC relay 1 coil.

Output Lead ‘B’ from the HS-5745 goes directly to the - post of the DC relay 1 coil.

This means that Relay 1 will ONLY close when the output of Lead ‘A’ and ‘B’ from the HS-5745 is roughly 5VDC with lead ‘A’ being positive and Lead ‘B’ being the negative. This relay will not be activated if the polarity is reversed.

Then, there is Relay 2.

Output Lead ‘A’ from the HS-5745 goes directly to the - post of the DC relay 1 coil.

Output Lead ‘B’ from the HS-5745 goes to the anode of a diode. The cathode of the diode goes directly to the + post of the DC relay 1 coil.

This means that Relay 2 will ONLY close when the output of Lead ‘A’ and ‘B’ from the HS-5745 is roughly 5VDC with lead ‘B’ being positive and Lead ‘A’ being the negative. This relay will not be activated if the polarity is reversed.

Now, all I have to do is make sure that the relay contacts are rated for 10 amps or better. Then if Relay 1 is activated, it will complete a circuit which will send 5VDC at 10 amps (or more) to the motor with the +5VDC side going to the + terminal on the motor, and the -5VDC side going to the - terminal on the motor.

When Relay 2 is activated, relay 1 will be deactivated, and Relay 2 will complete a circuit which will send 5VDC at 10 amps (or more) to the motor with the +5VDC side going to the - terminal on the motor, and the -5VDC side going to the + terminal on the motor.

If the SSC-32 is not sending any signal to the channel that the HS-5745 is connected to, then there would be no output from the HS-5745 and both relays would be off resulting in no motion of the ‘servo’.

All I need to do is make sure that the 5Kohm pot is connected and attached to something that moves along with the servo arm.

Am I missing something here?

Will the servo overshoot it’s desired direction and start swinging back and forth trying to reach the correct position, or will I be OK?

9

One potential issue is that the output to the motor is probably pulsed, and relays may behave differently under pulsed conditions. I’ll put that on my list to check down the road. You might be able to do the same thing as the HS-5745 using the parts from an HS-422 servo, which would include the pot.

lynxmotion.com/images/html/smodh2.htm

10

I’d be curious how this turns out too. I want to control a wiper motor with that same servo controller, and had planed on hooking two Solid State Relays to the motor outputs. I hadn’t planned on the pulsed motor feed being a problem, but might have to install a capacitor to dampen out the pulses. I’ll order my relays and try it in a couple of weeks, so I’ll let you know how it works.

11

Solid state relays might work pretty well, but one would have to purchase four for each motor to be controlled, and that could be $$$.

12

I know this is an old thread, but I did this back in around 2012 to drive my Dalek head and eye. Uses an absolute encoder to sense position and PWM motor control from and Arduino. Power is via an L298N module wired in parallel. Some rewiring of the motor is needed to make it run both ways.

hackaday.io/project/19973-big-g … per-motors

I’m working on a more elegant design if anyone is interested.