Renesas Micon Rally Car

Firstly, the Renesas Micon Car is a line following robot car. The Rally part refers to the competitions with these cars for students and enthusiasts around the world to learn about microcontrollers, motor control, programming and mechatronics. Renesas says: "We are very grateful to hear the voice of a number of young leaders of the next generation through participation in Micon Car Rally competitions to learn craftsmanship, enrich emotional development, and experience significant personal growth. As a social enterprise, Renesas Electronics takes seriously the importance and necessity to strive to foster the development of future engineers and will continue to support activities to increase creativity and broaden possibilities for young people through the Micon Car Rally in the future." In 2012, I was proud to be the organizer and technical support for the first Renesas Micom* competition in the USA, with student participants from Southern California universities taking part. The project was a load of work and a wonderful experience for all.

*this car is referred to as Micom and Micon depending on the source

First, cut out the arm parts with side cutters. After cutting down one pair of angle pieces, attach them to the uncut pair from the bag of hardware marked "**other parts" use 2 M3 locking nuts and 2 of the black screws from the Universal Plate L set to screw together 2 pairs of arms. These should be loose enough to allow easy movement. This will be crucial later when the car is following the track and there are up or down ramps, undulations in the track material, and seams. Any of those things can cause your sensors to lose contact with the track and make the car go completely off track.

Renesas Micom Car Rally Kit on the track

Renesas provides a functional C++ program for the Rally Car on their website. This program will get the car around a track somewhat effectively. It is a basic program that can handle an easy track at slow speeds, but the car will not stay on track under some common conditions that will be encountered. It is up to the builder to add code that deals better with 90 degree turns, lane changes, and some situations where the MCU will use a false interpretation of the sensor readings during a maneuver. Renesas helps by going through some examples that will cause the car to fail and hints at what will need to be added to fix it.

Now that the kit is built and running it is time to get it going around the track and modifying it to make it follow the track faster and more reliably. Renesas provides a functional C++ program for the Rally Car on their website. This program will get the car around a track somewhat effectively. It is a basic program that can handle an easy track at slow speeds, but the car will not stay on track under some common conditions that will be encountered. It is up to the builder to add code that deals better with 90 degree turns, lane changes, and some situations where the MCU will use a false interpretation of the sensor readings during a maneuver. Renesas helps by going through some examples that will cause the car to fail and hints at what will need to be added to fix it.

Today I'll go over the 90 degree corners that are a required part of the course for Renesas Rally Cars. They are indicated by a pair of lines perpendicular to the path of the cars. These lines are 20mm wide, separated by 30mm, and located 500-1000mm before the turn. The car senses these and goes into a sub-program that looks for a sharp turn, initiated when all of the sensors detect the line on one side of the sensor bar.

This sub-program also slows the car down while waiting for the anticipated turn, turns the steering servo, applies differential steering to the drive motors, and waits for the sensor inputs that indicate a successful turn before continuing with the normal line following program (case 11).

Benefits of the LM350 add on set

After getting the issues sorted out, the effect on the car after adding the set was incredible. The straight line speed and acceleration is a giant step forward for the car. The extra volt to the servo makes the car steer faster and more accurately. The newfound power to the motors gives more authority to the differential steering. In fact, the code needs to be adjusted to compensate for the increased speed entering corners and "cranks", otherwise the car shoots off the track. One feature I have not covered is that the motor speed is adjustable with a set of dip switches on the MCU board. After a little development with the stock power supply it’s easy to start turning the speed up to 100%. With the LM350 set though, the dip switches need to be set to reduce power again, until the code is adjusted to work with the increased speed. In my case, the speed had to be reduced to 65% even after doing some adjustments to the code.

I am looking forward to making this car even faster with modifications like a faster servo, Lipo battery, and writing new code to take advantage of the new parts!

Below is my line following car from 2008 BSU classes. This one used the Basic Stamp board and IR sensors. It was mounted to a standard R/C touring car and could make it around a full size racetrack! Years later this would come in handy for the Renesas MCU Rally Car.

Flyers, the DEVCON 2012 visitors guide and the track I designed and had made by a local sign company.