The marble run is controlled wirelessly by the same weight-bearing platform which controlled the Laser Gun Game.
With the marble run however, Julian only needs to focus on well balanced standing. Having to perform multiple functions (i.e. Standing correctly, aiming and shooting) caused him difficulties previously. He likes the marble run much more!
How it works
If Julian’s weight is well distributed, through both feet, the weightbearing platform, it wirelessly releases marbles on the marble run. For each marble released points are given and the marble is allowed to travel down the tracks of the run.
When his balance is incorrect, the marbles are ejected from the run and they disappear through four small slots on either side.
On a 1m x 1m masonite board are a series of 8 tracks leading down to the bottom marble receptacle. (The main support is actually recycled from the back side of the original target made for the Laser Gun Game!)
At the top of the frame is the marble dispenser. It is a piece of PVC tubing cut at an angle. It is at an angle so that, when full, the weight of the marbles does not press down on the low torque, wooden dispenser’s servo.
Every several seconds, when Julian is standing correctly, the dispensing servo is wirelessly activated and pushes the dispenser block forwards and backwards over a hole which opens to the top track of the run. As the block moves backwards a marble falls into its holder. On the push it moves that over the hole.
There are eight tracks on the run. At the end of each track, the marble hits the wall and drops to the next track.
At the end of track 3, 4, 5, 6 are four hatches. When Julian stands correctly on the platform the hatch covers are closed and the marble continues down to the next track. When his balance is wrong, the hatches are slid opened and the marbles drop through an escape shoot. There are two such escape hatches on each side. Two servos control the four hatches.
Points are given when marbles drop onto the first track and points are removed when the marbles exit down the escape hatches. These points are displayed on a blue, four digit, seven segment digital display.
The marble run in complete view. It is 1X1 metre square. Has eight tracks from top to the bottom.
The diameter of slant cut PVC tube is large enough to hold one marble. The angle of the tube is such that it doesn't force too much pressure on the sliding block that moves the marbles into place and through the tube to the top track.
4*7 segment score counter
The counter gives Julian his points for good standing and removes points for off balance stances.
Conclusion and considerations
To avoid the mistake of creating a beautifully painted and tidy project as I did with the Laser Gun—only to realise it wasn’t right for Julian, I decided to make the marble run quickly with little care to detail. For fear of wasting time, I also forwent a lot of cool gimmicky features like a marble lift or lights etc. My main interest was proof of concept and usability. And now in retrospect, as he loves it, I wish I had created it much cooler!!!