I want that when a servo motor is moved by me it will resist my movements with varying levels of force. How can I do this?
Edit:I am thinking about this demonstration.
If you are talking about a hobby servo, I don't think that you can control the force and position at the same time.
This may be a XY problem. You are asking us to help you with your solution to a problem when we don't know anything about the problem. If we know what you want to accomplish, maybe we can help with a solution. Is this for something like a force feedback system?
I don't think you can do that with regular hobby servos. They are designed to move to a position and if necessary they use their full force to do so.
You could try using a simple geared DC motor (with a suitable motor driver) and varying the power fed to it using analogWrite().
A continuous rotation servo allows its speed and direction to be controlled (rather than its position) so it is like a very low geared DC motor. You could try using one but my concern is that it is too-low-geared and would present too much resistance even without power. Also, if you force it around with your hand you may strip the gears.
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I am thinking about this demonstration .
Looks interesting.
Garfielder:
I am thinking about this demonstration .
At the start of the video he says that all the servos have force sensors attached. I reckon that means that the servos are being controlled by the force sensor in much the same way that you might control them with a potentiometer. Perhaps the system responds to the sensor with the most force?
And just to be clear - the guy's finger is not moving the servo. It is providing a force input to the controller and the controller is moving the servo.
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Do you mean that a motor that resists your pressure is simply a motor that moves more slowly, as long as the pressure is within it's torque?
Garfielder:
Do you mean that a motor that resists your pressure is simply a motor that moves more slowly, as long as the pressure is within it's torque?
I presume you read Reply #5 before you wrote that question. And in that context I don't know what you had in mind when writing the question so I don't know how to answer it. Can you explain further?
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Robin2:
I presume you read Reply #5 before you wrote that question. And in that context I don't know what you had in mind when writing the question so I don't know how to answer it. Can you explain further?...R
The guy says that in the second setup it's harder for him to push the motor's shaft. You said in #5 that the arduino moves the motor, not the guy so I want to be sure I got it right - if I want to give the illusion that the motor is easily moved I will move it faster for a given pressure on the force cell, and move it slower for a hard-to-move feeling?
Servos tend to burn out if the motor is applying force, but stalled (shaft not rotating). The same is true for almost all brushed DC motors. Plan on this being a short project, with a limited number of demonstrations.
Garfielder:
The guy says that in the second setup it's harder for him to push the motor's shaft.
I didn't watch the complete video so I don't know what the second part is or what's different
You said in #5 that the arduino moves the motor, not the guy so I want to be sure I got it right - if I want to give the illusion that the motor is easily moved I will move it faster for a given pressure on the force cell, and move it slower for a hard-to-move feeling?
To change the behaviour you need to change the value of the force that is needed to make the system move. The speed of the servos is determined by the drivers within the servos.
Plus what @jremington said.
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I have worked on devices that use motor assist to move large heavy things. The assist unit is a handle that has piezo transducers in it. The more pressure on the transducer, the more of a motor assist is provided. The handle with the transducers was able to feel force in a X/Y/Z which controlled 3 motors.