CODEWITHSUNDEEP
arduinomicrocontrollersensors
iangolden
iangolden

Reputation: 90

Measure distance of a pulley in Arduino/Raspberry PI

I'm trying to measure the distance an object is pulled along a pulley track using arduino (or Rasp Pi) sensors. I have an object that is manually pulled, from a resting position, on a pulley system and I need to be able to track the distance it travels over one pull.

Example: The object traveled 90% (example) of the total pulley distance for 5/10 pulls.

Example: The object traveled 11.53 ft along the pulley.

See the image below for a visual diagram. I have two ideas, but I'm not an Arduino sensor expert. I'd love input on an elegant solution.

  1. Use an arduino sensor to sense how many times the pulley rotates, and then use an equation to determine the distance.

  2. Use a sensor that senses the distance pulled in cord, maybe each direction, and record that distance. I got this idea from pump sensors, no idea if a comparison exists.

Really just looking for advice on what sensors to use, how to implement them (general), and what type of metrics I could record.

Visual description

Upvotes: 0

Views: 659

Answers (2)

mactro
mactro

Reputation: 518

There are at least two ways of doing this:

  1. Use a rotary encoder, which will tell how many rotations the pulley did. There are two disadvantages: line can slip on the pulley, resulting in inaccurate measurement, and there is no way you can now at what actual position the object is. Rotary encoder will give you only position relative to the starting position (unless you only need one rotation of the pulley - then you can use absolute encoders)
  2. Use a distance sensor (ultrasonic, or IR) to measure at what height is the object. That way you will know the exact position of the object, but you may have a problem if your object is too small, has a shape or surface that will impact the measurements, or if the space is limited and a sensor can pick up walls, or other surrounding objects. Also if the objects may swing on the rope, there will probably a problem.

Software implementation for all of these solutions should be pretty simple, just decide on type of sensors - there are plenty of tutorials for all of them.

Upvotes: 2

ObliteratedJillo
ObliteratedJillo

Reputation: 5166

Both task 1 and 2 can be done easily using a digital rotary encoder at very nominal cost. It can sense direction and distance of travel quite accurately.

Upvotes: 0

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