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Control Challenges for High-Speed Autonomous Racing: Analysis and Simulated Experiments
- Rohan Kumar Manna - Purdue University, Electrical & Computer Engineering, USA ,
- Daniel J. Gonzalez - United States Military Academy at West Point, Department of Electrical Engineering and Computer Science, USA ,
- Vishnu Chellapandi - Purdue University, Electrical & Computer Engineering, USA ,
- Manuel Mar - Purdue Polytechnic Institute, USA ,
- Shyam S. Kannan - Purdue Polytechnic Institute, USA ,
- Shakti Wadekar - Purdue University, Electrical & Computer Engineering, USA ,
- Eric J. Dietz - Purdue Polytechnic Institute, USA ,
- Christopher M. Korpela - United States Military Academy at West Point, Department of Electrical Engineering and Computer Science, USA ,
- Aly El Gamal - Purdue University, Electrical & Computer Engineering, USA
Journal Article
12-05-01-0009
ISSN: 2574-0741, e-ISSN: 2574-075X
Sector:
Topic:
Citation:
Manna, R., Gonzalez, D., Chellapandi, V., Mar, M. et al., "Control Challenges for High-Speed Autonomous Racing: Analysis and Simulated Experiments," SAE Intl. J CAV 5(1):101-114, 2022, https://doi.org/10.4271/12-05-01-0009.
Language:
English
Abstract:
We present our approach to several control challenges in high-speed autonomous
racing for the Indy Autonomous Challenge (IAC). The IAC involves autonomous
head-to-head racing at speeds approaching 200 mph. The autonomy system must
maintain traction and stability when operating at such high speeds while also
maneuvering aggressively around other competitor vehicles. One key challenge
arises from limited actuator update frequency. We propose two lateral control
methods to follow the desired trajectory: a cross-track error method and a pure
pursuit lookahead angle method. Analysis shows that, when linearized,
cross-track error and pure pursuit angle are related by a first-order system. To
analyze the effect of actuator update frequency on closed-loop performance, we
emulate the discrete rate as a time delay. Control parameters and gains for both
controllers can be solved by using loop-shaping techniques to guarantee
closed-loop bandwidth and phase margin. The bandwidth is limited by the time
delay associated with the loop frequency. The results depict that the steering
actuator update frequency should be as high as possible to maximize vehicle
stability and indicate that increasing the steering actuator update frequency
allows for a higher closed-loop control bandwidth and increased tracking
performance. (For example, a 50 Hz control bandwidth can be achieved by a 1 kHz
actuator update frequency.) Our acceleration and longitudinal control strategy
maximizes acceleration performance while respecting traction and engine
revolutions per minute (RPM) limits by applying throttle and shifting gears
based on the engine torque-speed profile to achieve the desired wheel traction
forces. We demonstrate our control strategies in simulation at various control
loop frequencies. A higher control loop frequency allows for higher-bandwidth
lateral controllers exhibiting a faster response to changes in the desired
trajectory. From a rolling start in an initial acceleration test at a constant
control loop frequency, our longitudinal control and shifting strategy
outperforms the IAC default automatic transmission.