Rawlings Spinball Sports LED Speed Display
A Basic Electronics Upgrade Wasn't So SimpleBy Tom Hart
Two years ago, sporting goods giant Rawlings came to Spinball Sports, a small pitching machine manufacturer, and asked if we could build machines for them; an offer we just couldn't refuse. However, there was a catch – we had to modify our current machine design to add LED speed displays. We already had big plans to produce fully automated machines over the next couple of years, so a basic seven segment LED display didn't sound so bad, even if we only had four months to make it happen. Still, we had no idea how to do it.
We played around with the idea of adding an off-the-shelf panel mount LED voltmeter to the control panel, and somehow scaling the motor voltage to match the wheel speed. However, the displays we could find were too big, too dim to use outdoors, and way too expensive. How hard could it be to design our own?
It turns out, it's not that bad. Everything we needed to know is online and it's all free! There are dozens if not hundreds of terrific online sources – tutorials, videos, and of course kits, covering everything from Ohm's law to advanced robotics. "However, we definitely got the most benefit from watching dozens of short video tutorials on PIC microcontrollers and basic electronics. But the key is you have to actually build something.
Did you know you can get a microcontroller for under a buck? A tiny little computer for next to nothing. And you can use it to control the LEDs in a 7-segment display, like say, in a pitching machine's speed control. It took months of tutorials, building, testing and re-testing, but we met our deadline, and now Rawlings sells the only two wheel pitching machine with LED speed displays. And that was just the beginning. We took what we learned from the basic display and took it one step further – an LED based control panel for a three wheel machine.
Two wheel pitching machines are fairly easy to set up. Pitch speed is the average of the two wheel speeds. Spin amount is determined by the difference in wheel speeds. The greater the difference, the greater the spin, and the greater the curve, with the ball always curving away from the faster wheel. Unless you're an expert in vector addition, it gets much more complicated when you add a third wheel. A third wheel would offer better ball contact, velocity and control. A batter would also be able to see the ball the entire time allowing for improved pitch timing. If only there were a cheap, easy way to have the machine do the math for you... Hey – that microcontroller!
And so, a single basic microcontroller handles everything on the control panel of our 3 wheel machine, the iPitch®. It receives user input from three rocker switches and sends outputs to LED indicators to show pitch speed, spin direction, and spin amount. Then it calculates the wheel speeds required to throw the selected pitch and sends it to the motor drives. Not bad for a buck.
What's next? Well you can't have an iPitch® without an iPad. We still use a microcontroller to handle the machine's basic functions, but the original control panel has been replaced by an iPad Mini. The iPad communicates with the microcontroller over Wi-Fi allowing the machine operator to control the machine from anywhere on the field. We briefly considered industrial type touchscreens which would have been cheaper, but the iPad provides the best quality dynamic user interface, plus it's really cool.
So in two years, we went from basic 7-segment displays to a fully automated machine. And we didn't even have to go to a single class. Whatever you want to build, you can do it. You can start small, but just start.
Tom Hart is a former college baseball player and Boeing mechanical engineer. He founded pitching machine manufacturer Spinball Sports, located in Mount Vernon, IL, along with fellow ballplayer / Boeing engineer Terry Payne in 2004.