Having trouble with start, stop, delay and return home with dynamic brake.

Thread Starter

RickD

Joined Mar 9, 2021
7
I am working on a project using various DC motors and having trouble figuring out a circuit that is confusing to me and probably very simple to members.
I am trying to keep this inexpensive and currently using a wiper motor. I have looked into Arduino and delay relay modules and have learned much about Dynamic breaking and reversing.
My question is, I need a circuited that can be controlled by a low or high signal from a programed relay controller to start the motor then stop at 90 deg with brake, then delay for a second before returning home with dynamic brake.
Any suggestions would be very much appreciated.
 

shortbus

Joined Sep 30, 2009
8,429
A wiper motor is a bad one to chose. How much power is needed? How are you going to define your movement limits? If power needed is relatively small a stepper motor would be a better choice. Is there some reason you don't want to use the way the wiper does it, with a crank? Another option would be a rear window wiper motor from a SUV they don't use a crank but electrically make the back and forth movement.
 

atferrari

Joined Jan 6, 2004
4,235
90º sharp seems hard to get by just braking.

You should consider something predictable. A stepper motor fits the idea.

Do you plan / have any micro involved in the control?
 

MaxHeadRoom

Joined Jul 18, 2013
22,623
I would have though it worth looking at the wiper motor & mechanism option.
Advantages are, the motor does not have to be reversed, the mechanism, could be modified for the length of stroke, the stop is usually sharp and could be further shortened by dynamic braking, disconnect the motor and short the motor leads.
It may need an added L.S. for the extended stop requirement.
 

Thread Starter

RickD

Joined Mar 9, 2021
7
90º sharp seems hard to get by just braking.

You should consider something predictable. A stepper motor fits the idea.

Do you plan / have any micro involved in the control?
Thanks for the reply,
What I was trying is a single channel relay mod for the input and using a micro switch to stop it with dynamic brake, then some sort of adjustable latch relay for delay until start again. I can use the wiper motor park for the end stop or a micro

Thanks for the reply,
What I was trying is a single channel relay mod for the input and using a micro switch to stop it with dynamic brake, then some sort of adjustable latch relay for delay until start again. I can use the wiper motor park for the end stop or a micro
My problem is how to wire in dynamic brake into the equation. Its not super imperative it stop exactly at 90 deg as long as it stops in the same spot on the return to end position, I believe the micro or Park will do that.

I would have though it worth looking at the wiper motor & mechanism option.
Advantages are, the motor does not have to be reversed, the mechanism, could be modified for the length of stroke, the stop is usually sharp and could be further shortened by dynamic braking, disconnect the motor and short the motor leads.
It may need an added L.S. for the extended stop requirement.
Yeah, I like them because the are geared and reliable.
What I was trying is a single channel relay mod for the input and using a micro switch to stop it with dynamic brake, then some sort of adjustable latch relay for delay until start again. I can use the wiper motor park for the end stop or a micro.

My problem is how to wire in dynamic brake into the equation. Its not super imperative it stop exactly at 90 deg as long as it stops in the same spot on the return to end position, I believe the micro or Park will do that.

A wiper motor is a bad one to chose. How much power is needed? How are you going to define your movement limits? If power needed is relatively small a stepper motor would be a better choice. Is there some reason you don't want to use the way the wiper does it, with a crank? Another option would be a rear window wiper motor from a SUV they don't use a crank but electrically make the back and forth movement.
The reason I am using the wiper motor is because it is geared, reliable, strong and has the park option.
I am turning a display that is 24" x 36"

What I was trying is a single channel relay mod for the input and using a micro switch to stop it with dynamic brake, then some sort of adjustable latch relay for delay until start again. I can use the wiper motor park for the end stop or a micro.

My problem is how to wire in dynamic brake into the equation. Its not super imperative it stop exactly at 90 deg as long as it stops in the same spot on the return to end position, I believe the micro or Park will do that.
 

atferrari

Joined Jan 6, 2004
4,235
Thanks for the reply,
What I was trying is a single channel relay mod for the input and using a micro switch to stop it with dynamic brake, then some sort of adjustable latch relay for delay until start again. I can use the wiper motor park for the end stop or a micro
Since I am not sure what are the most realistic/practical options, I give way to the other posters; they have all the experience, which I lack of.

Sorry for interfering here.
 
Last edited:

djsfantasi

Joined Apr 11, 2010
7,549
First, do you realize if you’ve cut power to the wiper motor at 90 degrees and you use the park option, the motor will advance to ~130 degrees and then advance to the park position?

Second, you realize that you can’t reverse polarity to reverse the motor to reverse the position. And that the motor will always advance to its end position at ~130 degrees before reversing?

A wiper motor’s action is done internally through gearing. Not by traditional control methods.

I’m experienced in the use of wiper motors, using them for DIY Halloween animatronics in public haunted houses.

If I needed specific control, I used surplus geared motors controlled by an H-Bridge and a microcontroller (ATTiny85).
 

MaxHeadRoom

Joined Jul 18, 2013
22,623
My problem is how to wire in dynamic brake into the equation. Its not super imperative it stop exactly at 90 deg as long as it stops in the same spot on the return to end position, I believe the micro or Park will do that.
Dynamic brake is to cut the power and direct the motor leads to a N.O. contacts, which close at the end of stroke., a pair of DPDT relay contacts should do it?
 

Thread Starter

RickD

Joined Mar 9, 2021
7
First, do you realize if you’ve cut power to the wiper motor at 90 degrees and you use the park option, the motor will advance to ~130 degrees and then advance to the park position?

Second, you realize that you can’t reverse polarity to reverse the motor to reverse the position. And that the motor will always advance to its end position at ~130 degrees before reversing?

A wiper motor’s action is done internally through gearing. Not by traditional control methods.

I’m experienced in the use of wiper motors, using them for DIY Halloween animatronics in public haunted houses.

If I needed specific control, I used surplus geared motors controlled by an H-Bridge and a microcontroller (ATTiny85).
Thanks for the reply,
I am using the wiper arm, where the wiper is usually connected is my display. The motor will be running in one direction, the wiper motor makes a full revolution and the wiper end stops at 90° then returns in reverse. I just need it to stop at the 90° position for adjustable time before going back to park.
 

Thread Starter

RickD

Joined Mar 9, 2021
7
Thanks for the reply,
I am using the wiper arm, where the wiper is usually connected is my display. The motor will be running in one direction, the wiper motor makes a full revolution and the wiper end stops at 90° then returns in reverse. I just need it to stop at the 90° position for adjustable time before going back to park.
 

Attachments

Thread Starter

RickD

Joined Mar 9, 2021
7
My problem is I don't know how to make this circuit with dynamic brake, without it the momentum goes past the micro switch
 

djsfantasi

Joined Apr 11, 2010
7,549
Thanks for the reply,
I am using the wiper arm, where the wiper is usually connected is my display. The motor will be running in one direction, the wiper motor makes a full revolution and the wiper end stops at 90° then returns in reverse. I just need it to stop at the 90° position for adjustable time before going back to park.
That’s what I mean by a wiper motor. The wiper arm on a car is driven by a motor that travels in one direction only. It is mechanically connected to the arm so that it travels approximately 0-130 degrees back and forth. You can’t change the motion to any lesser degree. You can stop it at 90, but it had to go to 130 before it returns to the beginning.
 
Top