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Developing a Simulator for Adaptive Cruise Control Systems Using LEGO Mindstorm Robotics

Description

Safety is an important property of today’s complex systems such as automotive embedded systems. Modern Systems have achieved greater capabilities through growing reliance on increasingly capable software. Many systems rely on software to achieve their functions. Software can create hazards through erroneous control of the system or by misleading the system operators into taking inappropriate actions [1]. Adaptive Cruise Control (ACC) is an automotive safety feature that allows a vehicle's cruise control system to adapt the vehicle's speed to the traffic environment [2]. ACC uses a long range radar sensor which is attached to the front of the vehicle and detects a target vehicle up to 150 meters in front. The ACC system is able to automatically adjust the driving speed as well as the distance to the vehicle ahead in accordance with the pre-settings. ACC keeps the vehicle at a constant pre-set speed and at a certain distance to the preceding vehicle. The distance to the vehicle ahead is monitored by radar. The system can automatically accelerate and decelerate, which, particularly for long stretches of motorway, ensures speed on limited routes for comfort, depending on traffic (see in figure 1).

Adaptive Cruise Control

 

Types of Adaptive Cruise Control with Stop & Go System:

There is an extension system to ACC called adaptive cruise control systems with Stop & Go [3]. ACC stop and Go is an enhanced version of adaptive cruise control systems with a low level of deceleration. With traditional cruise control, a driver may pre-set a speed for the vehicle to maintain, allowing him/her to remove his/her foot from the accelerator pedal. ACC with Stop and Go function brings the car to a full stop and resume motion when following a target vehicle.

The Main Goal of the Project:

In this work, we want to develop an open source simulation of ACC and its extension ACC Stop & Go by using two LEGO Mindstorm robots. This simulation should be written in ANSI C programing language. The ACC simulation will be used in research on safety analysis.

 

ACC Algorithms & Equations:

We used the following equations to calculate the time gap between two lego-mindstorms and the target speed.

1) Acceleration of Current speed

currentspeed += calPID(sqrt(fabs( (currentspeed * currentspeed) + 2 * fabs((deltaX + safetyTimeGap) - timeGap)))-currentspeed); where is the CAlPID is the PID function and 2 is the acceleration ratio

2) Deceleration value of current speed:

currentspeed -= calPID(sqrt(fabs( (currentspeed * currentspeed) + 2.7 * fabs(deltaX + safetyTimeGap - timeGap)))-currentspeed); where 2.7 is the deceleration ratio.

3) Time gap

timeGap = (frontdistance/currentspeed);

4) DeltaTimegap which the time of starting deceleration the robot when there is a vehicle in the front.

deltaX = 0.5+sqrt(timeGap); where 0.5 sec is the constant time before enter int the DelteTimegap and desired Timegap (safety distance)

 

 

Video Demos:

  1. A first scenario (ACC with known front speed). This scenario is depend on the front speed of the vehicle and calculate the time gap between them. Time gap = (front speed/ (current speed *Wheel rotation per sec)

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Download and Installation Guide

Upon call-up of the ACC Simulator, you have to register yourself. Please fill in the registration mask completely (* = mandatory field). Following registration, you will receive an e-mail containing the link for download the ACC Simulator:

  • Adaptive Cruise Control System with STOP and GO function Simulink Model

  • Adaptive Cruise Control System Simulator in C langauge.
  • Adaptive Cruise Control System with Stop & Go Simulink Model
  • Adaptive Cruise Control System with Stop & Go Simulator in C Language.

To download ACC Simulator, please provide us the information below:

Promela Model of ACC simulator

To extract the Promela model of the ACC simulator by using Modex , we remove the LDE code and unnecessary code such as display and handling buttons on robots.   You can download the promela model from our sourceForge repository.

STPA Safety Analysis of ACC Simulator

TBA

Test Cases & Test Script

TBA

Publication

References

  1. N. Leveson. Engineering a Safer World: Systems Thinking Applied to Safety. Engineering Systems. University Press Group Limited, 2011.
  2. Adaptive Cruise Control System Overview, 5th Meeting of the U.S. Software System Safety Working Group
  3. Dr. Paul Venhovens, Dr. Karl Naab, Bartono Adiprasito , Stop and Go Cruise Control, Seoul 2000 FISITA World Automotive Congress, 2000

ACC Simulator Team

Dennis Maseluk

Asim Abdulkhaleq, M.Sc.

Prof. Dr. Stefan Wagner

If you have any qesution or problem, please contact Asim Abdulkhaleq