Boat windscreen wipers

Hello all, I have just spent the afternoon wining in a new port side wiper motor and added a second (starboard) wiper, after much swearing and some customising I have two working wipers, neither cover as much screen as they could and they are out of sync, they are like comedy wipers and I just cannot live with that so I need to engineer a solution.

I am thinking two stepper motors moved to the center of the screens to give me 170deg sweep, in sync, with variable speed and park.

Its a 12v DC system and I would rather pull as little current as possible

I had a google about and mostly I found people making projects with wiper motors not the other way around

Has anyone done this themselves? Can anyone recommend some motors (12v or less) it would be nice to keep the diameter under 5cm or have an offset shaft (like a wiper motor)

Thanks in advance for any advice or suggestions

Dano

Or would a servo be a better option?

Anyone any idea what sort of torque I will need?

Drop the idea of using stepper motors. Use geared DC motors. The angle of sweep should be created mechanically. Take a look inte a new brand new car for ideas.

The demand for torque is up to You to calculate, measure, judge.....

Dan0:
Hello all, I have just spent the afternoon wining in a new port side wiper motor and added a second (starboard) wiper, after much swearing and some customising I have two working wipers, neither cover as much screen as they could and they are out of sync, they are like comedy wipers and I just cannot live with that so I need to engineer a solution.

Do the wipers have a self-parking feature - if so it should be possible to use that to keep them in sync.

If not, a simple solution might be to buy a couple of used rear-window wipers from a car-breaker - they will probably have a self-parking feature.

Windscreen wipers need a huge amount of torque to move the blade over dry glass.

...R

Thanks for your reply Railroader although its completely opposite of what I am trying to achieve, I already have geared DC motors ie windscreen wiper motors, I want to go digital and have complete control

Edited google says 40Nm starting torque

Robin2:
Do the wipers have a self-parking feature - if so it should be possible to use that to keep them in sync.

If not, a simple solution might be to buy a couple of used rear-window wipers from a car-breaker - they will probably have a self-parking feature.

Windscreen wipers need a huge amount of torque to move the blade over dry glass.

...R

They do have a park but I didnt test that yet, thats only for when you turn them off though, one negative is switched and the other negative is used for the park, I imagine it has a limit switch inside. When they are running they will still be out of sync I think. I dont need used wiper motors I have two brand new chrome motors, they were £50 each, they will be donated to the boat next door. I am looking for a digital solution, probably automatic, certainly variable, hopefully low current.

Put encoders on your DC motors. Boom, digital. Wire to an Arduino. Add motor drivers that the Arduino can control. Pololu has a good selection of motor drivers and instructional pages on their use. Encoders could be limit switches and/or encoders on the motors.

Many wiper motors use a pulse to start a stroke. A very long "pulse" will make the wipers run until the "pulse" ends.
Use the motors You already have! They are up to the task.

Ah thanks Railroader and groungfungus now we are talking

I've been dealing with wiper motors, in my car, as motors for hobbies in more than one respect. They are very powerful and if Your motors are intact, then use them!
Can You do some research to find out about the old controll unit, cabeling etc. that would be a good help.

These are the units, I assumed it was some kind of reciprocating mechanism rather than an electronic control

I should have taken the old one apart but as it was overheating I binned it

That's surely a good wiper motor. The text says "110 degrees". Thinking between the thumb and the poiting finger, guessing, 110 degrees looks quite standard. That's hard to change. I guess the wiper arm is mechanicaly connected to the axle.
Can You find wiper motors having a larger stroke?
What was the stroke of the original motors?

Dan0:
…and they are out of sync, they are like comedy wipers and I just cannot live with that so I need to engineer a solution.

I don’t know what kind of boat you have, but I can’t imagine why the wipers would have to be in sync. For me, having them in sync would make the boat behave like a car. I definitely don’t want to have a car feeling in my boat. I don’t think boats have the wipers in sync, if they ever have many of them.

That said, if I anyhow would like them to be in sync, I’d search for a DC motor driver capable of providing the amps that the wipers need. Then I’d search for a position feedback system. A rotary encoder or just start and end switches. When I’m capable of controlling the RPM of the motors and I can read the position of the blades or just the pulse when the blades reach one end, I’d write a PID system to control the speed of each motor.
Here’s one circuit of a wiper motor. If you have anything similar, you can use the parking mechanism as a position feedback system.


The pin 31b is 12 V (HIGH) most of the time, but when the blade is in rest position, it goes to 0 V (LOW). Just have your Arduino control the speed of each motor so that the LOW pulse happens at the same time on both motors.

[EDIT]
Well, the motor driver is a bit overkill. If you just have relays for the motors, have your Arduino read the signal from 31b from each motor. When 31b goes low on either motor, stop that motor until 31b goes low on the other motor. Let both run again until either 31b goes low again.

The chance is very small that opening the motor and changing the mechanics is possible.
You can take a look.

110 also. Ideally they could be positioned in the middle of the screen and sweep ~170deg

Looking on the net the park control may be on a cam

Do the 2 wipers interfere with each other or not?

How was the old system working, how was it done?

Johan_Ha:
I don't know what kind of boat you have, but I can't imagine why the wipers would have to be in sync. For me, having them in sync would make the boat behave like a car. I definitely don't want to have a car feeling in my boat. I don't think boats have the wipers in sync, if they ever have many of them.

That said, if I anyhow would like them to be in sync, I'd search for a DC motor driver capable of providing the amps that the wipers need. Then I'd search for a position feedback system. A rotary encoder or just start and end switches. When I'm capable of controlling the RPM of the motors and I can read the position of the blades or just the pulse when the blades reach one end, I'd write a PID system to control the speed of each motor.
Here's one circuit of a wiper motor. If you have anything similar, you can use the parking mechanism as a position feedback system.


The pin 31b is 12 V (HIGH) most of the time, but when the blade is in rest position, it goes to 0 V (LOW). Just have your Arduino control the speed of each motor so that the LOW pulse happens at the same time on both motors.

Thats the diagram Ive just been looking at and was thinking along the same lines as you (apart from the sync part, they have to be in sync! I dont have OCD but its driving me nuts)

Railroader:
Do the 2 wipers interfere with each other or not?

How was the old system working, how was it done?

No they are on different screens, there was only one before with a hole for the second. If I could post a vid here I would show you