I'm Positive Displacement Pump

This week we looked into the mechanisms and electronics involved in our bus position monitor. One initial idea of the mechanism for this design was using a large syringe type pump and tube to adjust the height of liquid in the tube. This shows the progress of the bus on route, the top of the liquid shows the times remaining, when the tube is empty the bus has arrived. This would work but we would need to make a motor that could pull and push the head of the syringe pump.




The sketch below illustrates our solution to this problem. The mechanism would work using a positive displacement pump driven by a programmable step motor to regulate exactly how much water passes into the tube. The step motor will be attached to the center of the Mercedes symbol which rotates, allowing water to be squeezed through the pipe.

The step motor has not been fully cooperating with us at this stage, but we have faith. Ned and Pat went to the workshop and begun to make the positive displacement pump. The tubing in the photo below was a good example of how it will work, but we realised it will have to be thinner and softer for our lo-fi model.

Now all we have to figure out is how we can tell the step motor the position of the bus. Or at least how we can communicate this in the concept presentation.