4 votes

How to detect when a stepper motor has stalled?

I found that the FFT of the current waveform of the stepper often shows the natural frequency harmonics of the motor+driver system AND that during a stall extra frequency harmonics appear!!! all you ...
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3 votes

How to limit large acceleration and jerk from PID controller?

As a general remark, a PID controller can be designed to take into account only constraints occurring at the commanded variable - the end-effector velocity in your case - through the so-called ...
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3 votes
Accepted

Force-torque sensor reading when a robot is stationary

The answer is $\vec{G}$! and also any $\vec{\tau}$ torque caused by it, if the axis connecting the geometrical center of the sensor (assuming it measures torques relative to its geometrical center) to ...
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  • 6,322
3 votes

How to detect when a stepper motor has stalled?

You need to quantify : "I measured the current through (one of the 4 wires of) my stepper motor, and it's always within a few percent of 0.5 A". A 'few percent' may be all you need to detect a little ...
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  • 31
2 votes

Appropriate control scheme for gripper end-effector

I believe the term you're looking for is compliant control. In a compliant control system, there is a position reference and a force reference, and essentially each is allowed to actuate the joint ...
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  • 14.5k
2 votes
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Appropriate control scheme for gripper end-effector

If you have a simple controller (e.g. force control or position control) the factor which decides what kind of controller is it is the reference signal which has to correspond to the feedback signal. ...
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  • 6,322
2 votes

How to detect writing on a chalkboard?

Since you are going to have a mechanism that can draw within a square why not put a light sensor on it and use the same mechanism scan for the opponent's move? At the start of the game, scan all the ...
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2 votes
Accepted

What is the Name of the part I'm describing

It sounds like you're describing a linear actuator with a pressure sensor (or strain gauge) attached to the end. To bridge that system across bluetooth, you may want to check out one of several ...
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  • 10.8k
1 vote

Sensing torque of stepper motor

Sensing the torque in a stepper motor is not a straightforward task. A method named Field Oriented Control is used to control the torque in a Stepper motor and several companies supply stepper motors ...
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  • 477
1 vote

Which sensors can be used to feel breeze blowing by the robot?

Microphone chips have been used as a transducer for this due to their low cost. (This being high density pressure measurements)
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  • 4,205
1 vote
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Why is the contact force of the rigid-body robot model ks*xr?

Edited: You should have put the subscript $c$ on variable $F$, because they define $F_c$ as the contact force the system is trying to maintain. Since achieving and servoing around that desired ...
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  • 4,326
1 vote
Accepted

FPGAs and stepper motors for precision control

This project is very nice and I was totally obvious to it thanks for spotting it ! In general the difference between FPGAs and classical ASIC integrated circuit is that FPGAs can be re-programmed by ...
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  • 1,327
1 vote

Can a robot or mechanical part be programmed to exert a specific force

Yes you can. People built robots doing exactly that for several hundred years.
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1 vote

Detect physical touch/hit

One option could be to use the MPU6050 IMU, or some other accelerometer. These sensors are cheap, so they will come in under your budget. With acceleration measurements, you can detect impulses ...
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  • 916
1 vote
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6DOF robot arm: Velocity of end effector vs. joint velocities

In the end, end effector speed is going to be determined by joint speed + kinematics, so I would choose whichever format you want that makes life easier on you. Regarding singularities, there's no ...
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  • 14.5k

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