Hello!
I am currently working on a project in which I want to train the rotation of a wrist. I would like to use a servomotor, but adjust this resistance specifically. Can I realize this via the arduino?
Thanks!
Please explain what you mean this, and define "resistance".
Welcome to the forums. Unfortunately you have told us nothing as to your project starting with the hardware. No idea what you are getting at with adjusting servo motor resistance? Did you mean servo motor rotation? Please explain, in detail all of your project, hardware and any software code you have.
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Thank You
Ron
The development is intended to improve the wrist function. A servo motor has a certain torque. But depending on the needs of the person using the device, I want to adjust the torque. So I thought if this would be possible to realize with an arduino.
Hope I have explained it better now. Thanks.
That is a start, but it is still not clear what the servo has to do with wrist motion. Are you expecting the servo to oppose the wrist motion, or make the wrist move?
Torque can be adjusted only a few very expensive types of servos, and hobby servos rapidly burn out if forced to stall.
It's all still a rough school idea. I had thought to develop a device where you can attach a hand grip. The servo motor should then represent the torque as I said and this torque I would like to set manually for the person.
I'm not sure if this is even feasible, so I wanted to ask if it's even possible to manually set this torque via a microcontroller.
Sorry, I have no idea what that means. Explanation of force and torque.
I think I get what you're talking about. It's not going to have anything to do with Arduino though, unless you just choose to control that particular servo with one. You're definitely not going to use Arduino to change a normal servo the way you're asking. This is going to be a special type of servo motor, and whether or not that is controllable with an Arduino will depend on the servo motor you choose.
I think what you are talking about here is some form of Haptic feedback.
That is, a knob that is difficult to turn, and you want to control how difficult it is to turn this knob for different people. Is that it?
If so forget servo motors that will not work and you will burn them out. In fact most servos have worm gears in them that are impossible to turn. without damaging the gears.
Simple answer is no. A more complex answer is that the torque of a servo can be changed over a small range by controlling the voltage you apply to it. But as I said before it is not going to work because of how gears are arranged in a servo.
Now I did write and article back in 1998 that featured a large stepping motor to do this. The idea was to give a bit of a kick back when playing a game of pong. it consisted of a large four coil stepping motor (about 40 mm long) and connected to the shaft with gears was a rotary shaft encoder (called pot on the diagram) so that I could tell the position of the pot for the game of pong.
By energising some of the coils I could make the motor harder to turn. I derived the signal from a D/A converter which allowed me to apply a variable energising value, and so control how hard it was to turn.
Maybe this might be the sort of thing you need for your project, but it is highly experimental and you will have to do some work on it. Maybe you don't need the geared encoder for your application.
Edit:- The stepping motor was originally designed to run off 200V so running it off 12V is way under rating it. Hence it is easy to turn against two coils energised.
You might think about how the resistance knob on a spin bike is controlled with a stepper motor.
Or alternatively use some sort of regenerative braking with an electric motor.
Based on your post #4 my best guess is you want to measure a rotary force. I suggest a rotary dynamic brake where a voltage or current is applied to a shaft. Next on the shaft is a rotary torque sensor which will measure the force required to turn a knob on the shaft. I do not see an servo or any other motor used for doing this. There is much more to doiing this and good components are not quite inexpensive.
Ron
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