Leading up to Year Three Competition, the Mississippi State (MSU) EcoCAR 2 team has spent large amounts of time refining its controls strategy. The controls team works with their MicroAutoBox and RapidPro to interface with the components of MSU’s vehicle.
The controls team is responsible for making sure the car runs correctly: ensuring communication between necessary components, implementing safety features, and maximizing performance to meet the team’s vehicle technical specifications.
MSU’s controls group, led by Ryan Nazaretian, has made significant progress this spring:
“This being my first semester working on controls, I have encountered a steep learning curve learning nearly every aspect of my responsibilities. From the help of other students on the team as well as help from the previous controls lead, Jonathan Moore, I have been able to complete an extraordinary amount of work efficiently to get the vehicle ready for competition.”
For the car to run smoother, the MSU controls team has implemented a custom shift map to make the vehicle run more efficiently. With its 6-speed automatic transmission, the shifting is controlled by the supervisory controller in the car rather than the transmission control module.
The shift map is dependent on the accelerator pedal position and the vehicle speed. The MSU controls team worked on finding the optimal combination of these three to cut seconds off of its 0-60 time while improving the efficiency of the vehicle. The team had been diagnosing its shifting problem for some time. It was traced back to the chain drive. MSU’s car has a silent chain drive that connects the engine and electric motor to the transmission. This allows the car to run in gas-only, electric-only, or gas and electric simultaneously. However, the technical specifications of the chain drive restrict it from exceeding 6,000 RPMs. The engine and electric motor can both exceed that number easily. While the transmission control module was asking for a higher input speed, the controls restrictions for the chain drive housing refused to allow it. To put it simply, the car was confusing itself. This was causing the vehicle to get stuck in second gear at wide open throttle. By running the car through multiple tests and analyzing the results, MSU was able to identify this problem and work out a solution.
Solving this problem has helped MSU shave valuable seconds off its 0-60 time and move towards a better car. The engineers on this project have gained valuable experience in diagnosing and devising solutions to complex problems.
Categories: Under the Hood