Homing Disk

This idea modifies an existing product; The 'Aerobie Pro Ring’ from Superflight Inc. <link>

B: "Daddy, I want a Frisbee that steers itself."
C: "Yeah, me too!"
Me: "That's a WIBNI."

For those who haven't had the pleasure: The Aerobie Pro Ring can be described as a Frisbee with a far superior aerodynamic design. Good throwers can easily play the length of a football field (either one), but accuracy over long distances can be problematic, even for the best. Just a few degrees off throwing and... You get the picture.

Another source of inaccuracy is the disc itself. It can get 'out of tune' (not perfectly shaped) causing it to bank to one side or the other. This can be remedied by bending the disk up to correct a right bank, or down to correct a left bank (assuming clockwise rotation). When releasing the disk from this bending, it returns to what appears to be exactly the same shape. The difference between 'out of tune' and 'in tune' is imperceptible until it is thrown. It is this very slight bending that is the inspiration for this idea.

Note: 'A' refers to the thrower, and 'B' refers to the recipient.

An imaginary line is created between two players wearing radio transmitters operating at different frequencies. The Homing Disk (an Aerobie until just now) has two small directional antennas just beneath the rubber exterior on the outer edge. These are situated 180 degrees apart. Each antenna feeds a receiver tuned in to one of the frequencies.

The receivers poll for signal strength and signal the processor when the strongest signal is detected. When the disk is rotating, the strongest signal will be confirmed when the antenna is just past facing the transmitter. The processor functions as a stopwatch; It clocks the time between notification of the strongest signal received on frequency A and frequency B, then the time between B and A.

If the time between notification A and B is zero, the disk is on the imaginary line between the players. If the time between A and B is not zero, and the time between A and B is greater than the time between B and A, the disk is right of the line from player A to player B. If the time between A and B is not zero, and the time between A and B is less than the time between B and A, the disk is left of the line from player A to player B.

The disk 'knows' where it is with respect to the imaginary line. So what's it gonna do when it's off the line? Dynamic in-flight tuning obviously. As described above; A minuscule change to the shape of this disk alters the aerodynamic properties significantly. An imperceptible bend up or down will affect a turn left or right, respectively. Built into, and spaced evenly around the flexible core (polycarbonate backbone) of the disk are small PZT stack actuators and electrostrictors divvied across two separate circuits - one configuration to bend the core up, the other down. The processor determines which circuit to apply a voltage to, and how much voltage based on how far off the imaginary line the disk is. It steers towards the line.

With a half-decent throw, the Homing Disk will hit its mark. Great for playing with not-so-accurate throwers, or playing on the beach when you don't want to get wet. If you enjoy running for the catch, then run - it will follow. For manual control, be sure to purchase the R/C option.

- The thrower is known as player 'A' by having the greater signal strength of the two frequencies at the time the disk is thrown (centrifugal force detected).
- All the electronics built into the disk (batteries included) are balanced throughout the core.
- Lefties playing with righties: Didn't Mommy say that was bad? Perhaps not, but I'm not going to think about it 'till tomorrow. Good night.