In part one of the RACECAR software install, we set the stage. In this article, we install the RACECAR packages. Looky here:
One of the packages that is installed is for Ackerman Steering. This is the type of steering geometry that is used in most automobiles. Angled steering arms allow the wheel angles to change at a different rate. In the old horse buggy days, parallel steering arms were used on which when the wheels turned, both turned at the same angle. As you know, the wheel closest to a turn follows a smaller radius circle than the outside wheel. In other words, the outside wheel travels further than the inner wheel, so it is intuitive that the angle of the outer wheel should be different than the inner one. Angled steering arms provide a mechanical solution to the problem. The R/C car used in the Jetson RACECAR has this type of steering mechanism connected to the steering servo.
This is a straightforward installation which installs the ROS racecar package, along with packages for nodes controlling the VESC (Vedder Electronic Speed Controller) and an Ackerman Steering node. There is also a Stereolabs ZED camera package installed, and support for some other sensors.
All of these packages come straight from the MIT RACECAR repository. The install script is in the JetsonHacks account on Github.
$ git clone https://github.com/jetsonhacks/installRACECAR.git
$ cd installRACECAR
Most of the needed software is now installed on the Jetson RACECAR. The one remaining issue before we can get the vehicle rolling is the VESC, which needs firmware installation and configuration. This is done using a software tool called ‘bldc-tool’, and is the subject of the next article. Stay tuned!