Cruise Control Karen Lie Engr 315

Outline Introduction to Cruise Control CC Modeling CC Simulation Introduction to Adaptive Control ACC Modeling ACC Simulation

Cruise Control System Input: buttons on the steering wheel, brake, clutch, gas pedal and feedback signal Processor Sensor Output: the throttle position

Modeling Newton’s Second Law: Laplace Transform:

Transfer Function

Design Specification Rise time < 5 sec Overshoot < 10% Steady-State Error < 2%

Open-Looped System

Closed-Loop w/ PI Control Kp = 100 Kp = 800 and Ki = 40

weight of the car PI Control: Kp = 800 and Ki = 40 m = 500 kg

Adaptive Cruise Control So-called Active Cruise Control (ACC) Traffic flow characteristics Collision-avoidance system Not to be considered as a safety feature by automakers

Background First laser-based system – Toyota’s Progress, a compact luxury sedan, in 1998 First radar-based system – Nissan’s Cima 41LV-2, a luxury sedan First American ACC model – Lexus’ LS 430, in 2000

Function Preset and maintain the car speed Measure the distance to the preceding car and the relative speed Adjust the car speed accordingly Maximum deceleration = 3.5m/s^2

Adaptive Cruise Control Change gear automatically Function properly in poor weather condition Cannot pick up non-moving objects Effective in the speed between 30km-180km/h

Two types of ACC Radar-Based System – Three overlapping radar-beams (76-77kHz) -- Detects moving object up to 120 m – work in poor weather conditions Laser-Based System (lidar) – less expensive and easier to package – light beams are narrower than water droplet and snowflakes

Radar-based Adaptive Cruise Control

Modeling in Highway Merging ACC Controller Desired Range By R. Sengupta and Q. Xu

Highway Merge-In Scenario 1. At 0 sec, the preceding vehicle is traveling 12.5 m/s 2. The follower vehicle w/ACC is 150 m behind the preceding vehicle and is traveling at 25 m/s 3. At 10 sec, the third vehicle cut in in between the two vehicles

Simulation in Highway Merging By R. Sengupta and Q. Xu

Acceleration Dotted Line = Desired Acceleration Solid Line = Actual Acceleration By R. Sengupta and Q. Xu

Implementation

Distance Source Distance Source ACC Response CC Response (for comparison)

Question