Maker Pro
Maker Pro

Idea for a consumer product

Hunt2871

May 26, 2022
2
Joined
May 26, 2022
Messages
2
I have an idea for a consumer product and would like some advice on how to control thing. It will consist of a 12V dc gear reduction motor with 2 shafts which will turn around 3 RPM most of the time but would be nice if it were possible to occasionally step that up to about 50 RPM or so. The motor will turn two shafts in the same direction and torque will be insignificant. A simple high torque dual shaft dc gear motor is more than sufficient for what I need. The tricky part is in how I would like to control it. At a minimum I would like for the motor to rotate from a fixed position to 180 degrees in one direction and then reverse direction and rotate 180 degrees in the opposite direction...and I would like for it to do this with input (on, off) from a remote switch. That is the bare minimum but it would be nice if I could also rotate the shaft in either direction from 0 degrees to maybe 375 or so but no further, at the push of a button on a remote. It would also be nice if the shaft could be rotated manually to anywhere in that same range remotely and finally it would be nice to be able do the latter at a higher rate of speed than the set 3-5 RPM which the motor would be turning normally.

To picture what I have in mind imagine a camera mounted on a shaft and you want to pan it on a level plane 180 degrees and when it reaches 180 degrees it would automatically reverse direction and pan on the same level plane 180 degrees in the opposite direction with input from an on/off remote.

Secondly the camera would pan on a level plane from 0 degrees to about 375 degrees in one direction until stopped by the remote switch but stop automatically at 375 degrees and when the user used the remote to start it again it would reverse direction and travel until stopped by the user or at 0 degrees. In other words upon input from the remote it would travel in one direction until the user stopped it or it reached 375 degrees and then it would stop automatically. When the user started it again after it stopped automatically it would travel in the opposite direction but if the user stopped it the user could decide which direction it needed to travel.

Finally I would like to all of this with time instead of some sort of limit switch or other means of measuring the distance traveled. If it is a 5 RPM motor than it should travel, with no load and under ideal conditions, 5 complete 360 rotations every 60 seconds....so it would seem that in 6 seconds it would have turned 180 degrees.


Any ideas how to do this effectively? Would a stepper motor be easier to control?
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
13,720
Joined
Nov 17, 2011
Messages
13,720
To rotate a motor by a specific amount of degrees you have several options:
  1. Using a servo motor where an encoder gives feedback of the position to a controller which in turn advances or backs up the motor. Can be as simple as a RC-servo using a potentiometer but not very accurate or can be as complex as a DC motor with a high resolution optical encoder).
  2. Using a stepper motor where the number of steps defines the angle, assuming no steps are lost. No feedback is required, as the number of steps and the angle directly correspond to each other. Only some method of defining the "0" position is required, e.g. a simple optical fork optocoupler.
The second option is imho easier for the application you have in mind. The controller can be a simple one, e.g. using the Arduino platform using the microcontroller board plus a stepper driver module and a remote control module.
When I state "Arduino platform" this is simply because it is easyly and widely available, so are the add on modules for driving the stepper and the remote control receiver and the software libraries to control both.
 

John Canon

Jun 1, 2022
91
Joined
Jun 1, 2022
Messages
91
I install PTZ security cameras and they have a similar function. From a joystick or a control interface the user can manually or pre-program side-to-side motion, up and down motion, and lens zoom. Most PTZs also have a function that will rotate the picture 180 degrees when the lens passes the azimuth. The speed is also adjustable. It is amazing what stepper motors can do.
 
Top