The green flag is back out, and the Jetson RACECAR project is starting again! The Jetson RACECAR is a ROS based, 1/10 scale, R/C car platform autonomous vehicle. The Jetson RACECAR is based on the MIT RACECAR project, an open source hardware and software project.
Here’s a quick look at some of the changes that we’re making to the previous work. Looky here:
Autonomous vehicles are a very interesting area to study. Current research vehicles tend to be rather expensive. The idea here is to build a scale model with many of the same features and sensor types so that any particular problem area can be broken down into the component parts. The idea here is play. We want to be able to play with the parts that interest us.
With that idea in mind, that means we should be able to look into any given component as deeply as desired, while maintaining full control of vehicle. As an example, the stock Electronic Speed Ccontroller (ESC) on the TRAXXAS performs admirably, but is difficult to control at slow speeds. After all, it’s intended use is off road racing, there’s not much need for going at a snails pace!
However, under robotic control we should be able to control the vehicle at any speed we choose. For that reason, the VESC controller is the choice because it both can be controlled at slow speeds, and is open source. In theory, that means if you’re interested in control theory, you can look ‘at the bottom of the hardware stack’.
The selection of sensors is also a major choice point. For example, the MIT RACECAR uses a Hokuyo UST-10LX laser range finder. MIT races in the tunnels underneath the campus, so the LIDAR is a great mapping aid. On the other hand, it’s not very well suited towards outdoor racing. Cameras seem to be the choice for the great outdoors. The Hokuyo is a little on the pricey side, a major strike against it for some folks.
When working with consumer products, there are frequent changes to products. Sometimes the products are discontinued, are changed significantly, or are difficult to acquire. If they are difficult to get a hold of because of popularity, that’s a good thing. If it’s because of lack of demand, that can be bad.
In this particular project, there have been several parts that have changed or been replaced. The TRAXXAS car itself is difficult to acquire. The SparkFun IMU has been superseded. The original battery to drive the electronics has been superseded. The VESC (an open-source, brushless motor controller) which originally had quite a long lead time, is now more easily available. The VESC also is now offered in a version with considerably friendlier device package.
It’s Go Time
In the video, we go over some of the hardware selections. Some platforms made from laser cut 1/4″ ABS mount on the TRAXXAS car chassis to support the Jetson Dev Kit, sensors and electronics.
This means that for actual control of the vehicle, we’ll be able to use the MIT RACECAR ROS software without change. We’ll worry about sensor selection further on down the line.
As noted in the video, this is the second prototype. There is a third prototype which uses updated parts, and some of the lessons learned from this particular build.
As a note, this doesn’t mean there aren’t other equally interesting component choices. You can read the Daniel Tobias’ Cherry Autonomous Racecar article to see an alternate and absolutely amazing implementation.
Looking forward to getting this going again!