Improving our Conveyor and Launcher – Friction, Elasticity and Automation

Date: August 7, 2018

Members Attending: Alexis, Eylert, Kira, Lynn, Robert

Mechanism: Fuel-Cube-Conveyor, Fuel-Cube-Shooter

Todo:

Test driving our robot we noticed a few things. One of them was the shooter launching the cubes better when they were not pressed against the cardboard. This led us to the conclusion, that the friction between the cubes and the cardboard was preventing them from flying consistently. That is why we decided to remove the cardboard and let the cubes slide on two parallel extrusions instead.

Conveyor with extrusions instead of cardboard/sheet in the back of the conveyor

The next problem we had with our conveyor was cubes not having the same height from the backside of the conveyor and sometimes even not being parallel to the conveyor. This led to them being stuck at the rail to whicht the stopper servo is attached and also the inconsistent shooting results. That is why we decided to add a guiding rail to the front of the conveyor. At the end of this rail we attached a small wheel using end rods to prevent the cubes from catching at the edge.

Additionally, we only attached it loosely to the frame, so the guide is quite springy and will adapt to cubes in different positions.

Guiding rail with wheel

Since this led to the cubes sometimes catching at the extrusions in the back when being pushed into the conveyor by omnom we decided to attach omni wheels to them.

Bottom of the conveyor with omni wheels attached to the extrusions in the back

This solved most of our issues with the conveyor. It is working quite reliably now.

Now to our shooter. We knew that shooting results is very dependent on the distance of the two wheels. One milimetre changes the grip and torque needed etc. We usually adjusted this distance over two lap brackets and the rail connecting the two sides of the conveyor/shooter over the top.

The solution: Loosening the screws in the lap corners. Thus the distance between the wheels is not defined anymore. Instead we put in medical tubing to make the shooter springy and for consistent grip on the cubes.

Robot from the top. the black medical tubing contributes to the elasticity of the shooter

A nice side effect of this is, that we can now detect cubes being shot using a touch sensor. Since the wheels move apart when a cube is launched, the touch sensor (seen in the bottom left of the picture) is released.

 

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