Project 2 Adaptive Cruise Control
Objective:
Development of a MATLAB Simulink Model for Adaptive Cruise Control feature as per the requirement document following Model Based Development (MBD) related processes: SLDD creation, configuration parameter changes, Model advisor check and code generation using embedded coder tool.
Overview:
Adaptive Cruise Control Feature for passenger cars allows the host vehicle to adapt to the speed in line with the flow of traffic. Driving in heavy traffic or keeping a safe distance to the preceding vehicle calls for a high level of concentration. The Adaptive Cruise Control feature can reduce the stress on the driver by automatically controlling the vehicle speed & maintaining a predefined minimum distance to the preceding vehicle. As a consequence, the driver enjoys more comfort & can concentrate on the road little better.
A radar sensor is usually at the core of the Adaptive Cruise Control. Installed at the front of the vehicle, the system permanently monitors the road ahead. As long as the road ahead is clear, cruise control feature maintains the speed set by the driver. If the system spots a slower vehicle within its detection range, it gently reduces speed by releasing the accelerator or actively engaging the brake control system. If the vehicle ahead speeds up or changes lanes, the cruise control automatically accelerates to the driver’s desired speed.
Standard Adaptive Cruise Control can be activated from speeds of around 30 km/h (20 mph) upwards and supports the driver, primarily on cross-country journeys or on freeways. The cruise control stop & go variant is also active at speeds below 30 km/h (20 mph). It can maintain the set distance to the preceding vehicle even at very low speeds and can decelerate to a complete standstill. When the vehicle remains stopped longer, the driver needs only to reactivate the system, for example by briefly stepping on the gas pedal to return to cruise control mode. In this way, cruise control stop & go supports the driver even in heavy traffic and traffic jams.
Since Adaptive Cruise Control is a comfort and convenience system, brake interventions and vehicle acceleration only take place within defined limits. Even with Adaptive Cruise Control switched on, it remains the driver’s responsibility to monitor the speed and distance from the vehicle in front.
Model Development:
Signals and calibration data:
|
Signal / Calibration Name |
Signal Type |
Data Type |
Dimension |
Min |
Max |
Initial Value |
Units |
|
CameraInput_LeadVehicle |
Input |
Uint8 |
1 |
0 |
255 |
- |
- |
|
RadarInput_LeadVehicle |
Input |
Uint8 |
1 |
0 |
255 |
- |
- |
|
CameraInput_DriveVehicle |
Input |
Uint8 |
1 |
0 |
255 |
- |
- |
|
RadarInput_DriveVehicle |
Input |
Uint8 |
1 |
0 |
255 |
- |
- |
|
Time_Gap |
Input |
Uint8 |
1 |
0 |
255 |
- |
- |
|
Set_Speed |
Input |
Uint8 |
1 |
0 |
255 |
- |
- |
|
Set_Gap |
Input |
Uint8 |
1 |
0 |
255 |
- |
- |
|
CruiseSwitch |
Input |
Boolean |
1 |
0 |
1 |
- |
- |
|
SetSwitch |
Input |
Boolean |
1 |
0 |
1 |
- |
- |
|
Acceleration_Mode |
Output |
Uint8 |
1 |
0 |
255 |
- |
- |
|
LeadVehicle_Speed |
Output |
Uint8 |
1 |
0 |
255 |
- |
- |
|
DriveVehicle_Speed |
Output |
Uint8 |
1 |
0 |
255 |
- |
- |
|
LeadVehicle_Detected |
Output |
Uint8 |
1 |
0 |
255 |
- |
- |
Creation of Simulink Data Dictionary file (SLDD):
A Simulink Data Dictionary (SLDD) file is created that contains input, output signals and calibration parameters used in the model. SLDD file is created by clicking on Modeling, then ‘Model Properties’, then ‘External Data’ and specifying a file name for the Data Dictionary.
Fig 1: Data Dictionary file in Model Explorer
Adaptive Cruise Control Model:
Fig 2: Adaptive Cruise Control Model
Fig 3: Lead_Vehicle, Drive_Vehicle and ACC_Algorithm subsystems present inside Adaptive_Cruise Control Subsystem.
Requirement 1– Lead Vehicle:
- Lead Vehicle is a vehicle which is driving in the road ahead of our drive vehicle. The subsystem Lead_Vehicle contains two input signals (Signal Name: CameraInput_LeadVehicle & RadarInput_LeadVehicle).
- Ideally sensor fusion techniques will be deployed to process & analyze data from camera & radar. For complexity reasons, in this model such algorithms are not used.
- The speed profile output (Signal Name: LeadVehicle_Speed) is obtained by adding both the radar input and camera inputs (Signal Name: CameraInput_LeadVehicle & RadarInput_LeadVehicle).
- Speed data of the lead vehicle is critical in implementing the Adaptive Cruise Control algorithm.
Fig 4: Lead_Vehicle Subsystem
Requirement 2 – Drive Vehicle:
- Drive Vehicle is the vehicle driven by the user & this is the vehicle which has ACC algorithm in it.
- Like the Lead Vehicle, Drive Vehicle algorithm also has 2 input signals (Signal Name: CameraInput_DriveVehicle, RadarInput_DriveVehicle) & one signal coming as an Input to this subsystem (Signal Name: Acceleration_Mode) – three inputs into this requirement in total.
- Like the above requirement, sensor fusion techniques will also be deployed here, but for complexity reasons they are not used in this model.
- Two output signals come from this subsystem (Signal Name: DriveVehicle_Speed & LeadVehicle_Detected).
- Signal DriveVehicle_Speed is summation of three input signals mentioned above & LeadVehicle_Detected is renamed from Input Signal RadarInput_DriveVehicle by mere use of Signal Conversion block.
Fig 5: Drive_Vehicle subsystem
Requirement 3 – Adaptive Cruise Control Algorithm:
- Adaptive Cruise Control feature has 3 major modes of operation: OFF Mode, STANDBY Mode & ON Mode. This particular requirement is implemented as state machine logic in Simulink.
- The input signals to this state machine system are (Signal Name: Time_Gap, Set_Speed, Set_Gap, CruiseSwitch, SetSwitch).
- The output signals (Signal Name: DriveVehicle_Speed & LeadVehicle_Detected) from requirement-2 is fed back as an input signal into this state machine block.
- Additionally, output signal (Signal Name: LeadVehicle_Speed) from requirement-1 is given as an input signal to this state machine block as well.
- Output from this subsystem is a signal (Signal Name: Acceleration_Mode) which governs the vehicular speed of the drive vehicle which automatically adjusts its speed & velocity to match the lead vehicle.
Fig 6: State machine chart ACC_Logic in ACC_Algorithm subsystem for Requirement 3
Requirement 3a – ACC OFF MODE state logic:
- This is the default state inside state machine logic. Output signal Acceleration_Mode is at value 0 in this state.
- This state is governed by input signal CruiseSwitch.
- If CruiseSwitch is equal to 1, state ACC STANDBY mode will get activated. If CruiseSwitch is equal to 0, state ACC OFF mode will get activated, from either ACC ON mode or ACC STANDBY mode.
Requirement 3b – ACC STANDBY MODE state logic:
- This is the second activated state inside state machine logic. Output signal Acceleration_Mode is at value 1 in this state.
- This state is governed by both input signals CruiseSwitch & SetSwitch.
- If CruiseSwitch is equal to 1, state ACC STANDBY mode will get activated. If CruiseSwitch is equal to 0, state ACC OFF mode will get activated, from either ACC ON mode or ACC STANDBY mode
- If SetSwitch is equal to 1, state ACC ON mode will get activated. If SetSwitch is equal to 0, state ACC STANDBY mode will get activated.
Requirement 3c – ACC ON MODE state logic:
This state will be activated when input signal SetSwitch is equal to 1. There are 6 sub states to this state logic: They are:
- LeadVehicle_Detected_Follow (Default)
- LeadVehicle_Not_Detected
- LeadVehicle_Detected_Resume
- LeadVehicle_Not_Detected_Resume
- LeadVehicle_Speed_lessthan_Set_Speed
Requirement 3c (i) – LeadVehicle_Detected_Follow (ACC ON MODE):
- This is the default sub state inside ACC ON MODE state. Output signal Acceleration_Mode is equal to 2.
- Condition to transit from LeadVehicle_Detected_Follow to LeadVehicle_Not_Detected; Input signal condition LeadVehicle_Detected == 0.
- Condition to transit from LeadVehicle_Detected_Follow to LeadVehicle_Speed_lessthan_Set_Speed; Input Signals condition (LeadVehicle_Detected == 1) && (LeadVehicle_Speed < Set_Speed) || (Time_Gap < Set_Gap)
Requirement 3c (ii) – LeadVehicle_Not_Detected (ACC ON MODE):
- Output signal Acceleration_Mode is equal to 1.
- Condition to transit from LeadVehicle_Not_Detected to LeadVehicle_Detected_Follow; Input signals condition [(LeadVehicle_Detected==1) && (DriveVehicle_Speed == Set_Speed) && (LeadVehicle_Speed >= Set_Speed) && (Time_Gap >= Set_Gap)]
- Condition to transit from LeadVehicle_Not_Detected to LeadVehicle_Speed_lessthan_Set_Speed; Input signals condition [(LeadVehicle_Detected == 1) && (LeadVehicle_Speed < Set_Speed) || (Time_Gap < Set_Gap)]
Requirement 3c (iii) – LeadVehicle_Detected_Resume (ACC ON MODE):
- Output signal Acceleration_Mode is equal to 3.
- Condition to transit from LeadVehicle_Detected_Resume to LeadVehicle_Detected_Follow; Input signals condition [(DriveVehicle_Speed == Set_Speed) && (LeadVehicle_Speed >= Set_Speed) && (Time_Gap >= Set_Gap)]
- Condition to transit from LeadVehicle_Detected_Resume to LeadVehicle_Not_Detected_Resume; Input signal condition LeadVehicle_Detected==0.
- Condition to transit from LeadVehicle_Detected_Resume to LeadVehicle_Speed_equal_Set_Speed; Input Signal condition [(DriveVehicle_Speed < Set_Speed) && (LeadVehicle_Speed > DriveVehicle_Speed) && (Time_Gap >= Set_Gap)]
Requirement 3c (iv) - LeadVehicle_Not_Detected_Resume (ACC ON MODE):
- Output signal Acceleration_Mode is equal to 1.
Requirement 3c (v) - LeadVehicle_Speed_lessthan_Set_Speed (ACC ON MODE):
- Output signal Acceleration_Mode is equal to 4.
- Condition to transit from LeadVehicle_Speed_lessthan_Set_Speed to LeadVehicle_Not_Detected; Input signal condition [(LeadVehicle_Detected == 0) && (DriveVehicle_Speed == Set_Speed)]
- Condition to transit from LeadVehicle_Speed_lessthan_Set_Speed to LeadVehicle_Speed_equal_Set_Speed; Input signals condition [((LeadVehicle_Speed*1.25>=DriveVehicle_Speed) && (LeadVehicle_Speed * 0.75<=DriveVehicle_Speed)) && (DriveVehicle_Speed < Set_Speed) && ((Time_Gap<=1.25*Set_Gap) && (Time_Gap >=0.75*Set_Gap))]
Requirement 3c (vi) - LeadVehicle_Speed_equal_Set_Speed (ACC ON MODE):
- Output signal Acceleration_Mode is equal to 5.
- Condition to transit from LeadVehicle_Speed_equal_Set_Speed to LeadVehicle_Not_Detected_Resume; Input signal conditions is [(LeadVehicle_Detected == 0) || (DriveVehicle_Speed <= Set_Speed)]
- Condition to transit from LeadVehicle_Speed_equal_Set_Speed to LeadVehicle_Detected_Resume; Input signal conditions [(DriveVehicle_Speed < Set_Speed) && (LeadVehicle_Speed > DriveVehicle_Speed) || (Time_Gap >= Set_Gap)]
- Condition to transit from LeadVehicle_Speed_equal_Set_Speed to LeadVehicle_Speed_lessthan_Set_Speed; Input signals conditions [(LeadVehicle_Speed<Set_Speed) && (LeadVehicle_Speed<DriveVehicle_Speed) || (Time_Gap == 0.75*Set_Gap)]
Fig 7: ACC_Logic chart in ACC_Algorithm subsystem
Requirement Tagging of Simulink Model:
The requirements ‘Requirement 1’ , ‘Requirement 2’ , and ‘Requirement 3’ as provided in the Requirements Word document are tagged to their corresponding subsystem in the Simulink Model.
The steps involved in tagging a requirement in the Simulink model is to first highlight the requirement statement in the Word document, then right click on the subsystem in the model that has to be tagged, then select ‘Requirements’ and then ‘Link to Selection in Word’.
Fig 8: Highlighting the requirement to be tagged in the requirement Word document.
Fig 9: Tagging ‘Lead_Vehicle’ subsystem to its requirement in Word document
MAAB Guidelines Check in Model Advisor:
A check is performed using ‘Model Advisor’ tool in Simulink to see whether the developed model meets the modeling standards for MAAB.
Fig 10: Model Advisor Report for MAAB guidelines check.
Generation of C – Code from model:
Using the embedded coder tool in MATLAB, C code is generated for the model.
Fig 10: C code generation using embedded coder in MATLAB.
C-Code:
/*
* File: ACC_MBD.c
*
* Code generated for Simulink model 'ACC_MBD'.
*
* Model version : 1.20
* Simulink Coder version : 9.5 (R2021a) 14-Nov-2020
* C/C++ source code generated on : Sun Oct 17 00:24:01 2021
*
* Target selection: ert.tlc
* Embedded hardware selection: Intel->x86-64 (Windows64)
* Code generation objectives:
* 1. Execution efficiency
* 2. RAM efficiency
* Validation result: Not run
*/
#include "ACC_MBD.h"
/* Named constants for Chart: '<S2>/ACC_Logic' */
#define IN_ACC_OFF_MODE ((uint8_T)1U)
#define IN_ACC_ON_MODE ((uint8_T)2U)
#define IN_ACC_STANDBY_MODE ((uint8_T)3U)
#define IN_LeadVehicle_Detected_Follow ((uint8_T)1U)
#define IN_LeadVehicle_Detected_Resume ((uint8_T)2U)
#define IN_LeadVehicle_Not_Detected ((uint8_T)3U)
#define IN_LeadVehicle_Not_Detected_Res ((uint8_T)4U)
#define IN_LeadVehicle_Speed_equal_Set_ ((uint8_T)5U)
#define IN_LeadVehicle_Speed_lessthan_S ((uint8_T)6U)
#define IN_NO_ACTIVE_CHILD ((uint8_T)0U)
/* Block signals and states (default storage) */
DW rtDW;
/* External outputs (root outports fed by signals with default storage) */
ExtY rtY;
/* Real-time model */
static RT_MODEL rtM_;
RT_MODEL *const rtM = &rtM_;
/* Model step function */
void ACC_MBD_step(void)
{
/* local block i/o variables */
uint8_T LeadVehicle_Speed;
uint8_T DriveVehicle_Speed;
uint8_T LeadVehicle_Detected;
uint8_T rtb_Acceleration_Mode;
/* Sum: '<S4>/Add' incorporates:
* Inport: '<Root>/CameraInput_LeadVehicle'
* Inport: '<Root>/RadarInput_LeadVehicle'
*/
LeadVehicle_Speed = (uint8_T)((uint32_T)CameraInput_LeadVehicle +
RadarInput_LeadVehicle);
/* UnitDelay: '<S1>/Unit Delay' */
Acceleration_Mode = rtDW.UnitDelay_DSTATE;
/* Sum: '<S3>/Add' incorporates:
* Inport: '<Root>/CameraInput_DriveVehicle'
* Inport: '<Root>/RadarInput_DriveVehicle'
*/
DriveVehicle_Speed = (uint8_T)((uint32_T)(uint8_T)((uint32_T)
CameraInput_DriveVehicle + RadarInput_DriveVehicle) + Acceleration_Mode);
/* SignalConversion: '<S3>/Signal Conversion' */
LeadVehicle_Detected = Acceleration_Mode;
/* Chart: '<S2>/ACC_Logic' incorporates:
* Inport: '<Root>/CruiseSwitch'
* Inport: '<Root>/SetSwitch'
* Inport: '<Root>/Set_Gap'
* Inport: '<Root>/Set_Speed'
* Inport: '<Root>/Time_Gap'
*/
if (rtDW.is_active_c3_ACC_MBD == 0U) {
rtDW.is_active_c3_ACC_MBD = 1U;
rtDW.is_c3_ACC_MBD = IN_ACC_OFF_MODE;
rtb_Acceleration_Mode = 0U;
} else {
switch (rtDW.is_c3_ACC_MBD) {
case IN_ACC_OFF_MODE:
rtb_Acceleration_Mode = 0U;
if (CruiseSwitch) {
rtDW.is_c3_ACC_MBD = IN_ACC_STANDBY_MODE;
rtb_Acceleration_Mode = 1U;
}
break;
case IN_ACC_ON_MODE:
if (!SetSwitch) {
rtDW.is_ACC_ON_MODE = IN_NO_ACTIVE_CHILD;
rtDW.is_c3_ACC_MBD = IN_ACC_STANDBY_MODE;
rtb_Acceleration_Mode = 1U;
} else if (!CruiseSwitch) {
rtDW.is_ACC_ON_MODE = IN_NO_ACTIVE_CHILD;
rtDW.is_c3_ACC_MBD = IN_ACC_OFF_MODE;
rtb_Acceleration_Mode = 0U;
} else {
switch (rtDW.is_ACC_ON_MODE) {
case IN_LeadVehicle_Detected_Follow:
rtb_Acceleration_Mode = 2U;
if (LeadVehicle_Detected == 0) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Not_Detected;
rtb_Acceleration_Mode = 1U;
} else if (((LeadVehicle_Detected == 1) && (LeadVehicle_Speed <
Set_Speed)) || (Time_Gap < Set_Gap)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Speed_lessthan_S;
rtb_Acceleration_Mode = 4U;
}
break;
case IN_LeadVehicle_Detected_Resume:
rtb_Acceleration_Mode = 3U;
if ((DriveVehicle_Speed == Set_Speed) && (LeadVehicle_Speed >=
Set_Speed) && (Time_Gap >= Set_Gap)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Detected_Follow;
rtb_Acceleration_Mode = 2U;
} else if (LeadVehicle_Detected == 0) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Not_Detected_Res;
rtb_Acceleration_Mode = 1U;
} else if ((DriveVehicle_Speed < Set_Speed) && (LeadVehicle_Speed >
DriveVehicle_Speed) && (Time_Gap >= Set_Gap)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Speed_equal_Set_;
rtb_Acceleration_Mode = 5U;
}
break;
case IN_LeadVehicle_Not_Detected:
rtb_Acceleration_Mode = 1U;
/* */
if ((LeadVehicle_Detected == 1) && (DriveVehicle_Speed == Set_Speed) &&
(LeadVehicle_Speed >= Set_Speed) && (Time_Gap >= Set_Gap)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Detected_Follow;
rtb_Acceleration_Mode = 2U;
} else if (((LeadVehicle_Detected == 1) && (LeadVehicle_Speed <
Set_Speed)) || (Time_Gap < Set_Gap)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Speed_lessthan_S;
rtb_Acceleration_Mode = 4U;
}
break;
case IN_LeadVehicle_Not_Detected_Res:
rtb_Acceleration_Mode = 1U;
break;
case IN_LeadVehicle_Speed_equal_Set_:
rtb_Acceleration_Mode = 5U;
if (((DriveVehicle_Speed < Set_Speed) && (LeadVehicle_Speed >
DriveVehicle_Speed)) || (Time_Gap >= Set_Gap)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Detected_Resume;
rtb_Acceleration_Mode = 3U;
} else if ((LeadVehicle_Detected == 0) || (DriveVehicle_Speed <=
Set_Speed)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Not_Detected_Res;
rtb_Acceleration_Mode = 1U;
/* */
} else if (((LeadVehicle_Speed < Set_Speed) && (LeadVehicle_Speed <
DriveVehicle_Speed)) || (0.75 * (real_T)Set_Gap ==
Time_Gap)) {
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Speed_lessthan_S;
rtb_Acceleration_Mode = 4U;
}
break;
default:
/* case IN_LeadVehicle_Speed_lessthan_Set_Speed: */
rtb_Acceleration_Mode = 4U;
if ((LeadVehicle_Detected == 0) && (DriveVehicle_Speed == Set_Speed))
{
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Not_Detected;
rtb_Acceleration_Mode = 1U;
} else if (((real_T)LeadVehicle_Speed * 1.25 >= DriveVehicle_Speed) &&
((real_T)LeadVehicle_Speed * 0.75 <= DriveVehicle_Speed) &&
(DriveVehicle_Speed < Set_Speed) && ((Time_Gap <= 1.25 *
(real_T)Set_Gap) && (Time_Gap >= 0.75 * (real_T)Set_Gap)))
{
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Speed_equal_Set_;
rtb_Acceleration_Mode = 5U;
}
break;
}
}
break;
default:
/* case IN_ACC_STANDBY_MODE: */
rtb_Acceleration_Mode = 1U;
if (!CruiseSwitch) {
rtDW.is_c3_ACC_MBD = IN_ACC_OFF_MODE;
rtb_Acceleration_Mode = 0U;
} else if (SetSwitch) {
rtDW.is_c3_ACC_MBD = IN_ACC_ON_MODE;
rtDW.is_ACC_ON_MODE = IN_LeadVehicle_Detected_Follow;
rtb_Acceleration_Mode = 2U;
}
break;
}
}
/* End of Chart: '<S2>/ACC_Logic' */
/* Outport: '<Root>/Acceleration_Mode' */
rtY.Acceleration_Mode_f = rtb_Acceleration_Mode;
/* Update for UnitDelay: '<S1>/Unit Delay' */
rtDW.UnitDelay_DSTATE = rtb_Acceleration_Mode;
}
/* Model initialize function */
void ACC_MBD_initialize(void)
{
/* (no initialization code required) */
}
/*
* File trailer for generated code.
*
* [EOF]
*/
Simulink model file, data dictionary, model advisor report, and auto generated C-code attached for reference.