Matt Srum wanted to be a technologist since he was a kid, but he didn’t get into robotics until college when one of his professors participated in the DARPA Robotics Challenge. Hearing about the competition inspired Srum to build an RC car controlled with C++. That was over a decade ago, and his biggest challenge then was that the car had to support the weight of the laptop that controlled it.

Shortly after college, Srum joined Walmart as a Java programmer. He began working on various associate-facing applications and eventually joined the Global License Manager (GLM) project, which allows stores to keep track of state and federal licenses for liquor, fishing and more. He and his team work on and test user stories that they deliver in two-week Agile sprints.

But it wasn’t until recently that Srum decided to get back into robotics. “When Raspberry Pi came out, I thought, wow—I don’t have to put a laptop on top of the car anymore,” Srum laughed. He purchased a RC racecar advertised to go 18 miles an hour. He replaced the racecar shell with a larger, RC truck shell with added supports to house the Raspberry Pi. Even then, he needed something more precise.

Matt Srum, programmer at Walmart, hacked his race car using Raspberry Pi.

“The car used a direct current motor, and the problem with that is it can go all the way to the left, or all the way to the right. There wasn’t any precision,” Srum said. “That’s when I decided to add a servo motor.” The servo is common in advanced remote control devices. So why not just buy a more complex car?

“You don’t learn anything from buying one, and I wanted to learn,” Srum said. “My original idea was just a project to hone in on my computer vision skills. I didn’t want to just watch videos, I wanted a real world example.” He took to the internet and began reading up on Python. He found tutorials by Adrian Rosebrock and Python libraries for the motor and servo, and he modified the code to meet his specifications.

The coding ended up being the easy part; the challenge came when he began playing with current. The Raspberry Pi sends simultaneous commands to the motor control and servo control through a serial port. “Raspberry Pi can only take five volts, but the battery is twelve volts. If you send the whole current, the Raspberry Pi starts smoking,” Srum said. “I’ve never smoked one, but I did have a scare once when I connected the wrong wires. I thought I’d destroyed it.”

Srum didn’t stop at more precise controls, though. He added computer vision capabilities to allow the car to travel on a fixed path. More recently, he added a Sense Hat, which can identify altitude, speed, latitude, longitude and more. Sense Hats have even been used to conduct testing at the International Space Station.

Recently, the car traveled nearly a mile on a fixed track, and Srum has plenty of plans for what he wants the robot to do next. But he’s even more excited about getting to take his new skills back to the workplace.

“When I began at Walmart eleven years ago, we didn’t use open source. We couldn’t play with all this stuff. But in the last five years, it’s gotten really exciting,” Srum said. “We’re on the cutting edge of technology.”

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