1: Final project proposal

Idea 1: Foosball goalie

I’d like to integrate the areas of the class into constructing an automatic foosball goalie.

There are two design possibilities:

  1. A system that is placed onto the foosball table itself, with its own bar and goalie.
  2. A system that controls the existing goalie rod by attaching to the handle.

I think #1 would be more feasible and reliable, though less integrated.  It has the benefit that it could play in a self-contained setting (e.g. on a tabletop).

There are two critical problems or design thresholds I see:

  1. Actuator speed: can I move the goalie quickly enough to do anything useful?  This will require exploration of high-speed servos or other gearing schemes.
  2. Sensor speed and accuracy: can I reliably determine the ball’s location and trajectory?

For the actuator, I’m basing my thinking off of inkjet printer heads.  I imagine a belt-driven system that can achieve quick horizontal motion.

For the sensor, I’m debating between an IR sensor bank on/around the goalie figure and ultrasonic sensor(s) aiming towards the middle of the field from the outside edges.  I will need to research the timing and accuracy of these possibilies.

Idea 2: Bicycle power meter

A more recent idea is tracking power output on a bicycle (wattage).  Several commercial solutions exist, but they are cost-prohibitive for the tinkering hobbyist.  Can I make a workable solution from a cost-effective kit of parts?


  1. Force sensor at the pedal.  This would measure the force exerted by each foot.  Do resistive strain gauges have enough dynamic range?  Could I mount it in a pedal or in the shoe/pedal interface?
  2. Accelerometer at the pedal, crank, or shoe.  The crank position is key for determining the work of each pedal push.  Will cheap solid-state accelerometers work for this?
  3. Wireless transmitter with sensors.  The sensors rotate and move in complex ways, making wired connections to a base station impractical or impossible.  They will have to interface to the user display with a wireless link.
  4. User display.  This would analyze the sensor input and produce (and record) measurements.  UI and connection to a computer for analysis are key.