[DonRotolo]

GH Players know that sometimes every button on the screen is the same color, and sometimes the button positions are reversed. In both cases it would be easy to note the cahnge and react accordingly.

Here's a mind exercise to get yu started on building your own:

1. Sensors. You need a sensor that will detect "button" from "no button" on each 'string' of the guitar. Start simple with four sensors - you may need more later.

2. Position. Use the same TV each time. Put some masking tape on the screen across the 'strings' and note exactly where the 'buttons' pass. For example, the left-most button (yellow is it?) always passes this spot a split-second before I'm supposed to play that 'note'. Find those spots...

3. Timing. How much time between when you can reliably detect the 'button' on screen to when you have to press that button and strum the guitar? That's your processing speed, make sure your microprocessor has the power to keep up that speed easily.

4. Actuators: One type to press buttons, another to 'strum'. Solenoids? Are you willing to cut open the guitar and wire up directly? How about a guitar-simulator, that replicates the electronics instead?

5. Software: Simple: When 'button' 1 is 'seen', actuate button 1 on the guitar and hit 'strum'. repeat real fast for all strings at the same time.

Start out easy, but eventually you should be able to make a robot that will play any song, at any level, perfectly every time.

Don