Lego Sherlock Holmes figure focuses a light beam on a Lego criminal with a small magnifying glass.

Vehicle Dynamics Sensor

The OpenLog Artemis and Lidar.

Sparkfun ( has introduced a new data logger called the OpenLog Artemis, which I’ve installed on a LEGO vehicle to measure the vehicle’s motion. A key feature of the OpenLog Artemis is that you don’t have to write any code to control it—just power it on and it will record data onto an SD card. It’s compatible with a variety of sensors with plug-and-play operation, again with no need to write code. So I added a lidar distance sensor, the VL53L1X, seen in the above photo alongside the OpenLog Artemis. I mounted both devices on the chassis of a 42065 Technic RC Tracked Racer. As seen in the videos below, I also have a NeoPixel array on the chassis, because I like to look at the color show.

One measurement set is in the video above to determine how fast the RC Tracked Racer can spin. The graph below reveals that the rotation rate is 200 degrees per second. The OpenLog Artemis has an embedded magnetometer, also plotted, which shows a sinusoidal variation as the vehicle’s heading is spinning.

Graph of rotation and bearing.

The next test is on collision, with the vehicle repeatedly driven into a hard object, as in the video above. The lidar indicates the distance to the object, which goes to zero as the vehicle collides, as in the green line in the graph below. The impacts show up on the OpenLog Artemis’s acceleration sensor, with spikes to 2g of deceleration. The deceleration may be more than 2g, but the scale of the sensor maxes out at 2g.

Graph of distance and acceleration.