You may have heard about the solar car’s telemetry system or seen Infinium’s large wireless router. Electrical Engineer Ryan Mazur is here to explain what the telemetry system is and why it’s so important. As a driver of the car in the 2010 American Solar Car Challenge, a member of Race Crew for the World Solar Challenge 2011, and the current leader of the micro-electrical subdivision, Ryan knows more than most about the integral part the telemetry system plays on race day.
The telemetry system is a wireless link between the solar car, Chase, and Lead (more on chase and lead), that allows information exchange between these three vehicles. It is one of the most important tools that UMsolar uses to ensure that the solar car is driven as safely, efficiently, and fast as possible.
All the information that is moving inside of the solar car is sent to Chase over a WiFi link. This includes information about the solar array, the battery, and the motor. Strategists inside of Chase use this information to make critical race decisions about how fast to drive. The information is also sent to the Lead vehicle. Here the electrical engineers look mostly at battery and array numbers. They constantly monitor what is happening electrically and make sure everything is running safe and normal.
Some of the information that’s exchanged through telemetry:
Telemetry can tell us how much power the array is generating. This is critical for strategy. By comparing this to solar measurements made from Chase, we can detect if part of the array is not working.
We can see how much power the motor is using at any given time. If the car is braking regeneratively, we can see how much energy is being put back into the battery. The numbers coming off the motor also tell us the solar car’s speed.
We can see what the operating conditions of the battery pack are. Numbers like maximum cell voltage, minimum cell voltage, pack current, and temperature of the battery cells are relayed over telemetry.
While it is important that the solar car be able to send information to Chase and Lead, the solar car must also receive information. The strategists can send a suggested speed to the solar car. This shows up on the driver’s display and the driver can set the cruise control accordingly.
There is also a text-based messaging system. Short text messages and text alerts can appear on the driver’s display. This is useful for letting the driver know about railroad tracks or debris that is ahead. It can also be used to keep the driver aware and raise his spirits during a stretch of driving that can last up to six hours. Occasionally, the engineers in Lead will send a random joke or message to the solar car. The main caravan has also been known to play “20 questions” with the driver. Questions are sent to the display and the driver can respond with Yes or No buttons that are on the steering wheel.
There’s much more to the telemetry system, but this is the basics of the system’s setup. It is a critical component of the overall micro-electrical system, and it provides real-time performance information and diagnostics. If you have any questions about the telemetry system, post a comment!