Momentum - April 2019 - 10

FEATURE

STUDENT
GENERATION

LAP SIMULATION TOOL
SHOWS THE WAY

On an Alabama test track, 2018

Until now, the University of Alabama Formula SAE team assumed
that the fastest lap times would result in the highest score from the
Endurance and Efficiency Events, but that assumption is changing.
IN THE FORMULA SAE STUDENT COMPETITION, there is a dynamic
event called Endurance in which a maximum of 100 points can be
earned for fuel efficiency and 275 for performance (time). After the
Formula SAE Lincoln 2018 event, the University of Alabama team
considered whether saving fuel while maintaining a reasonable lap
performance would increase our overall score.
It was decided to create a lap simulation tool to optimize the
performance and fuel efficiency of a vehicle completing an autocross
course. Lap simulation programs typically modify the car's design
parameters to decrease lap time, but our goal is a lap simulation tool
that can increase our competition score by modifying controllable
parameters on the car. In the FSAE event, it is possible to increase the
combined score if the fuel consumption can be reduced in such a way
that the lap time score does not decrease as much as the fuel efficiency
score increases.
The simulation considers gear shift RPM, maximum throttle position,
fuel mixture, and a lift and coast procedure to achieve the highest
possible total score from the lap performance and fuel efficiency. These
parameters can be controlled through the ECU using the GPS position.
For the simulation, the Lincoln 2018 competition course was modeled
using the car's GPS device, and the simulated lap times were validated
using previous competition times and scores. The track used in the
simulation is shown in Figure 1.

10 April 2019

The controllable parameters are varied to increase
the total score by either supplying more power under
the curve or reducing power to increase fuel efficiency.
The solution identifies areas of the track where the
total score can increase from using partial power for
better fuel efficiency instead of using full power for a
greater lap performance. The solution is brute force
with different options for the input parameters to find
the highest combination score of endurance and fuel
efficiency. Historical score data from events previous to
FSAE Lincoln 2018 allowed the simulation to calculate the
overall score and guide the optimization.
At first, the simulation considered values for the
various parameters, and those parameters were applied
to an entire lap. In general, the fuel efficiency score
increases quickly as fuel usage drops, but the increase
in lap time and heavily weighted performance score
can overpower the fuel efficiency in many cases.
Interestingly, optimizing the gear shift points increased
the score, in part, by choosing shift points that result in
greater average power during the run as compared to
shifting at the max RPM in each gear. The overall score
increase was around 3 points from improved average

MOMENTUM



Momentum - April 2019

Table of Contents for the Digital Edition of Momentum - April 2019

Momentum - April 2019
Contents
A better MOMENTUM
Briefs
Reliability overhaul: a lesson in resilience
Turbulence on the track
Full circle
Lap simulation tool shows the way
Baja SAE technical inspection
VW’s MEB platform: a modularity enabler
The F-22 Raptor gets its first metallic 3D-printed part
SAE 101: WCX 2019
Moon shot as metaphor for autonomous vehicle technology
DOSSIER: Greg Sawvelle
Momentum - April 2019 - Momentum - April 2019
Momentum - April 2019 - Cover2
Momentum - April 2019 - Contents
Momentum - April 2019 - A better MOMENTUM
Momentum - April 2019 - Briefs
Momentum - April 2019 - Reliability overhaul: a lesson in resilience
Momentum - April 2019 - 5
Momentum - April 2019 - Turbulence on the track
Momentum - April 2019 - 7
Momentum - April 2019 - Full circle
Momentum - April 2019 - 9
Momentum - April 2019 - Lap simulation tool shows the way
Momentum - April 2019 - 11
Momentum - April 2019 - Baja SAE technical inspection
Momentum - April 2019 - VW’s MEB platform: a modularity enabler
Momentum - April 2019 - The F-22 Raptor gets its first metallic 3D-printed part
Momentum - April 2019 - SAE 101: WCX 2019
Momentum - April 2019 - Moon shot as metaphor for autonomous vehicle technology
Momentum - April 2019 - 17
Momentum - April 2019 - DOSSIER: Greg Sawvelle
Momentum - April 2019 - 19
Momentum - April 2019 - 20
Momentum - April 2019 - Cover3
Momentum - April 2019 - Cover4
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