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Robotics, how to detect contact with objects?

  1. Apr 24, 2016 #1
    I have a robotic arm that needs to be able to detect whether or not it bumped into something like a wall.

    What would be the most practical way to do this without adding a large amount of sensors in different parts of the arm?
  2. jcsd
  3. Apr 24, 2016 #2


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    What types of sensors have you researched? Have you ruled out some types for any reason?

  4. Apr 24, 2016 #3


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    In order of safety & reliability. Note that many Safety Codes require a physical interruption such as a switch in a supply line. Shutting off an 'Enable' input to an IC is generally NOT considered sufficient.

    1) Often done with Bumper Strips. Think of a car bumper mounted so it moves toward the car body when something is hit. Then put a small switch behind the bumper to kill motor power in that direction.

    2) Mount the drive motor(s) in a compliant mounting (rubber?) such that the motor body rotates a small amount at high torque. Mount a switch that gets actuated when the motor body rotates. (This is how electric garage door openers shut down when the door is blocked. [They crush fewer people that way.])

    3) Sense the motor drive current and shut down on overcurrent. Not always useful, especially when high acceleration is desired.
  5. Apr 24, 2016 #4


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    How big is this arm?

    1) Bumper strips can be as simple as a bent wire.

    2) Torque sensors can be used for a more sophisticated solution. They can improve your control system as well.

    3) For high speed and acceleration you would want to actively stop the motor if there is a safety concern.

    Ultrasonic sensors can be used for object detection. For a robotic arm you will probably violate the large amount constraint.

    Is the wall any wall of any type or do you have a particular wall in question? Can you make it conductive and sense collision electrically?

  6. Apr 25, 2016 #5
    So basically it's a life size humanoid robot. I need the robot to be able to move it's arms in a complex environment without damaging them. The best solution I have found so far are capacitive proximity sensors although I'm not too sure that's the best choice. It seems like a good choice because they can sense a nearby object without actually touching it, just as long has it has some resonable mass which most objects do anyways.
  7. Apr 26, 2016 #6
    You might dig around the net for "whisker sensors", some interesting work being done with interesting solutions for this problem. Maybe it'll give you some ideas.
  8. Apr 26, 2016 #7
    Thanks for the suggestion! Well if the capacitive sensors don't work I'll probably use that idea.
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