Monday, 4 November 2013

Voxel Project (Part 2)

Control System

In the original VoxCAD simulator there are four materials; soft, hard and two which inflate to 20% their original value but out of phase with each other. For the single cube project we want to be able to control each cube edge independently so that we can explore what dynamics a cube can accomplish. This does however somewhat complicate the control system, we now need to be able to control 12 edges via a PC and to be able to set the extension value (or rate of expansion) for each edge.

The cube itself is designed with hydraulic syringes so we need some mechanism to apply and reduce pressure to the system. The obvious choice is again to use syringes connected to some form of motor control. There are many comercial systems available, mostly used in the medical profession, but these are large and expensive machines used for delivering exact millilitre dosses and not practical for our requirement.

On the hobby scale there are a few examples of syringe pumps, these mostly use a threaded bar and guide-rail system to pull the syringe plunger back and forth. YouTube syringe pump example

The quick prototype I have below is designed on an oil rig system of rotating wheel and pulley bar. It does take a lot of torque to move the syringe forward and the original Lego Mindstorm motor does not have the power required (although this is not what it was designed for). We have some high torque servos which should hopefully have the power to move the mechanism. The design does have the advantage that there are limited components and these are joined by simple dowel joints. The required parts could be easily manufactured in bulk using the 3D-printer.

More designes to come :)

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