1. Fig. 1 Throttle body(left) and gas pedal(right)
ECE Computer Engineering Design Project
Electronic Engine Control
Fred Han, Nicholas Li, Runqi Wang, Blake Sakaluk
2017
Overview
Electronic throttles (drive-by-wire) have distinct advantages over traditional cable driven engine throttles. In our ECE 492 project, we built an electronic throttle and transmission control system for University of Alberta’s Formula SAE club. Using the Altera DE0 nano FPGA as the control unit, we managed to achieve precise position control on a Hyundai throttle body. We’ve also integrated advanced features like wheel slip control and clutchless shifting into our system.
For colour ideas, University Visual Identity Guidelines can be found here:
To close the throttle plate by a desire amount, we had to implement a feedback control loop since reversing the polarity on the motor will only cause the throttle plate to turn all the way back to fully closed state. Using the TPS readings as a reference, our system detects when a closing throttle passes its target position and switch to open state PWM signal to maintain the throttle’s current location.
Fig. 8 RPM based throttle control
Testing
To safely test the operation of our system, we developed an Arduino based engine simulator. This simulator reads the TPS signal from our throttle body and mimics the RPM response of the WR450 engine. This simulated RPM value will be used by the DE0 for clutchless shifting. The simulator will also compute wheel speed based on the current RPM.
When integrated with our electronic throttle, we were able to produce a smooth RPM increase/decrease by pressing/releasing the accelerator pedal.
Fig. 3 DC motor driving circuit
To open the throttle plate, a 20kHz 3.3V PWM signal is generated by the DE0 and then fed into input1 of the H-bridge while input2 is kept high. A duty cycle ranging from 56% (fully close) to 34% (fully open) is used control the precise degree of opening. Indicated by Fig 4 and 5.
Fig. 1 Throttle body(left) and gas pedal(right)
Fig. 6 Throttle position control feedback loop
Conclusion
Overall, we managed to successfully implement more than 90% of purposed features. And it’s also worth mentioning that although we did not test with an actual Formula SAE car throttle body, our system can be easily configured to work with any DC motor based throttle bodies.
Fig. 4 20kHz PWM signal produced by DE0 nano
Acknowledgements
Special Thanks to
University of Alberta Formula SAE club
Dr. Elliott & Nancy Minderman
Michael Wong & Brendan Bruner
*Fig. 2 is taken from TLE-5206 datasheet
Fig. 7 Transmission shift solenoids
Fig. 2 System block diagram
Design
The throttle body shown in Fig 1 is driven by a 12V DC motor and the throttle plate position is communicated through two built-in Throttle Position Sensors (TPS). The DC motor is controlled with an Infineon TLE-5206 H-bridge, under sign/magnitude mode. Indicated by Fig 3.
Clutchless shifting involves matching the current engine RPM to the RPM of the new gear, To up shift, we’ll need a slightly lower RPM. To down shift, we’ll need to rev-match the engine to a higher RPM. Automating this matching process requires us to modify the throttle plate feedback loop such that the system now uses the current engine RPM as the reference, as shown by Fig. 8.
Fig. 5 Fully opened throttle with 34% duty cycle
Department of Electrical & Computer Engineering