How to Lock a motor

[simeon1770]

How do you lock a motor?

[Jeff 801]

what do you mean by lock a motor do you mean dynamic braking or something else

[simeon1770]

i mean to make the motor stop moving, when my arm it reaches a certain height it falls pretty fast and i want to know how to lock it at my leisure, so when it starts falling i can lock it and stop it from falling

[meatmanek]

There are a few solutions.

My preferred solution is to use a positional feedback sensor of some sort (potentiometer, encoder, etc) mounted to the arm, so the controller knows where the arm is, and then use a PID loop. This is the most complex in terms of programming, but if there's an easy way to mount your sensor it can be the easiest mechanically.

The next solution would be to use a worm drive, or a motor that has worm drive built in. The Denso and Keyang window motors are all worm drive, and cannot be back-driven.

The third solution, if you don't want to mess with tricky PID tuning or replacing a motor entirely in an arm, is a brake system.
Here is a picture of another team's brake mechanism:
http://www.chiefdelphi.com/forums/attachment.php?attachmentid=5139&d=1172112278

You may want to read this thread:
http://www.chiefdelphi.com/forums/showthread.php?t=54669&highlight=brake
EDIT: Never mind, you've already posted on that thread.

[WaterFreak]

we used a clutch plate mechanism with a servo to release the clutch when we want the elevator to go down.

if you need some pics, let me know.

[bear24rw]

Turning the brake on, on the speed controller will help too

[Daniel_LaFleur]

Each of these solutions has things that you need to consider.

There are a few solutions.

My preferred solution is to use a positional feedback sensor of some sort (potentiometer, encoder, etc) mounted to the arm, so the controller knows where the arm is, and then use a PID loop. This is the most complex in terms of programming, but if there's an easy way to mount your sensor it can be the easiest mechanically.


Some motors do not like to be run this way (specifically the banebots) as their cooling is attached to their drive shaft. Choose your motors wisely when doing this.


The next solution would be to use a worm drive, or a motor that has worm drive built in. The Denso and Keyang window motors are all worm drive, and cannot be back-driven.


This is probably the best solution, however these motors tend to be less efficient and less powerful, so you may need to 'assist' them (depending on your application)


The third solution, if you don't want to mess with tricky PID tuning or replacing a motor entirely in an arm, is a brake system.
Here is a picture of another team's brake mechanism:
http://www.chiefdelphi.com/forums/attachment.php?attachmentid=5139&d=1172112278


This is a great way of doing things, but you must make sure that the brake can be released with weight on it and that the brake is released when you want to move the motor again (or else it will quickly stall)


You may want to read this thread:
http://www.chiefdelphi.com/forums/showthread.php?t=54669&highlight=brake
EDIT: Never mind, you've already posted on that thread.


Each of the above will work as long as you take the proper considerations into the design.