4.23. Traction Control System Controller - TracCtlSys

• Overview

• Functions

• Ports

• Parameters

• Calibration

Id	TracCtlSys
Version	0.3.1.0
Title	Traction Control System Controller
System	Drivetrain
Document Type	Application Software Component Specification Preview

4.23.1. Overview

The Traction Control System is responsible for limiting the wheel torques when there is significant tyre slip. It It provides a per-wheel activation status and cuts torque in a per-axle basis so to avoid inducing undesired yaw moment.

4.23.2. Functions

	Title	Description
1	Wheel Slip Calculation	Calculates the longitudinal slip ratio of each wheel based on wheel speeds and vehicle speed.
2	Wheel Slip Limit Determination	Determines the maximum allowed wheel slip ratio based on vehicle speed and tire characteristics.
3	Wheel Slip Error Calculation	Calculates the error between the actual and maximum allowed wheel slip ratio for each wheel.
4	Wheel Torque Feedback Control	Closed-loop PI controllers that calculate a torque limit for each wheel to minimize slip error. Includes anti-windup and gain scheduling.
5	Traction Control Activation	Determines if traction control should activate based on wheel slip errors, vehicle speed, and driver requests. Outputs an activation status.
6	Wheel Torque Arbitration	Arbitrates between the TCS torque limits and other torque requests. Prevents large torque differences between wheels.
7	CAN Communication	Sends TCS status and debug information on the CAN bus. Receives requests and vehicle state.

4.23.3. Ports

	Id	Direction	Data Type	Dimensions	Unit	Description	Keywords
1	Ts	Incoming	single	[1]	s		Ts
2	WhlDrvTqDmd	Incoming	single	[4]	N*m	Expected signal: Wheel driving torque request (FL, FR, RL, RR) If signal si NA: mandatory	Wheel Drive Torque Demand
3	WhlLgtSlip	Incoming	single	[4]		Expected signal: Wheel longitudinal slip (FL, FR, RL, RR) If signal si NA: mandatory	Wheel Longitudinal Slip
4	VehLgtSpd	Incoming	single	[1]	m/s	Expected signal: Vehicle longitudinal speed If signal si NA: mandatory.	Vehicle Longitudinal Speed
5	TyrSlipAgFrnt	Incoming	single	[1]	deg	Expected signal: Tyre slip angle at front axle (FL, FR) If signal si NA: mandatory.	Tyre Slip Angle Front
6	TyrSlipAgRe	Incoming	single	[1]	deg	Expected signal: Tyre slip angle at rear axle (RL, RR) If signal si NA: mandatory.	Tyre Slip Angle Rear
7	WhlVertF	Incoming	single	[4]	N	Expected signal: Wheel vertical forces If signal si NA: mandatory.	Wheel Vertical Force
8	VehStStsTcs	Incoming	boolean	[1]		Expected signal: All TCS signals for TCS are valid. I.e. any source for Vehicle speed is valid; any source for Wheel long slip is valid (per wheel); any source for Wheel speed is valid; any source for Yawrate is valid. If signal si NA: [true]	Vehicle State Status Tcs
9	TcsCtlStsReqd	Incoming	Enum: CmndrvHmiBtnReq	[1]		Expected signal: Traction control active If signal si NA: true if TCS is meant to be ON.	Tcs Control Status Requested
10	GearPosnDrv	Incoming	Enum: CmnenaGearSt	[1]		Expected signal: Gear Selector feedback. If signal si NA: CmnenaGearSt.Fwrd or Rvs	Gear Position Drive
11	TcsCtlStsFb	Outgoing	Enum: CmndrvHmiBtnSts	[1]			Tcs Control Status Feedback
12	TcsOut1	Outgoing	Bus: CAN_TcsOut1_t	[-1]	inherit		Tcs Output1
13	TcsOut1_send	Outgoing	boolean	[1]
14	TcsOut2	Outgoing	Bus: CAN_TcsOut2_t	[-1]	inherit		Tcs Output2
15	TcsOut2_send	Outgoing	boolean	[1]
16	TcsAcv	Outgoing	boolean	[1]	inherit		Tcs Active
17	TcsWhlDrvTqLim	Outgoing	single	[4]	N*m		Tcs Wheel Drive Torque Limit

4.23.4. Parameters

	Id	Data Type	Dimensions	Range	Unit	Description	Keywords
1	TcsFbGainSldgKiFrnt	single	[1,3]	Min: , Max:		Tcs front integral feedback gains LUT	Tcs Feedback Gain Sliding Ki Front
2	TcsFbGainSldgKiRe	single	[1,3]	Min: , Max:		Tcs rear integral feedback gains LUT	Tcs Feedback Gain Sliding Ki Rear
3	TcsFbGainSldgKpFrnt	single	[1,3]	Min: , Max:		Tcs front proportional feedback gains LUT	Tcs Feedback Gain Sliding Kp Front
4	TcsFbGainSldgKpRe	single	[1,3]	Min: , Max:		Tcs rear proportional feedback gains LUT	Tcs Feedback Gain Sliding Kp Rear
5	TcsDrvLgtSlipLimUseLut	boolean	[1,1]	Min: , Max:		Use LUT for longitudinal slip limit	Tcs Drive Longitudinal Slip Limit Use Lut
6	TcsPropGainAdjFacFrnt	single	[1,1]	Min: , Max:		Adjustment factor for front P gain	Tcs Proportional Gain Adjust Factor Front
7	TcsPropGainAdjFacRe	single	[1,1]	Min: , Max:		Adjustment factor for rear P gain	Tcs Proportional Gain Adjust Factor Rear
8	TcsAcvnManOvrd	boolean	[1,1]	Min: , Max:		Tcs manual override: False use HMI input (if TcsEnad is true); True always on	Tcs Activation Manual Override
9	TcsEnad	boolean	[1,1]	Min: , Max:		Tcs manual enable parameter: False disabled; True enabled	Tcs Enabled
10	TcsSndCanDiag	boolean	[1,1]	Min: , Max:		Send Tcs CAN diagnostics message	Tcs Send Can Diagnosis
11	TcsAcvnLogcFrntLe	boolean	[1,1]	Min: , Max:		Enable Tcs on Front Left wheel	Tcs Activation Logic Front Left
12	TcsAcvnLogcFrntRi	boolean	[1,1]	Min: , Max:		Enable Tcs on Front Right wheel	Tcs Activation Logic Front Right
13	TcsAcvnLogcReLe	boolean	[1,1]	Min: , Max:		Enable Tcs on Rear Left wheel	Tcs Activation Logic Rear Left
14	TcsAcvnLogcReRi	boolean	[1,1]	Min: , Max:		Enable Tcs on Rear Right wheel	Tcs Activation Logic Rear Right
15	TcsFbGainSldgBrkPnt	single	[1,3]	Min: , Max:	m/s	Vehicle speed breakpoints for Tcs feedback gains	Tcs Feedback Gain Sliding Brake Point
16	TcsLgtSlipVehSpdBrkPntLim	single	[1,6]	Min: 0, Max: 500	km/h	Breakpoints for speed-based reference slip	Tcs Longitudinal Slip Vehicle Speed Brake Point Limit
17	TcsLgtSlipLutReLim	single	[1,6]	Min: -1, Max: 100		Slip for slip angle-based reference slip for rear axle	Tcs Longitudinal Slip Lut Rear Limit
18	TcsLgtSlipLutFrntLim	single	[1,6]	Min: -1, Max: 100		Slip for slip angle-based reference slip for front axle	Tcs Longitudinal Slip Lut Front Limit
19	TcsIntglGainDrpFac	single	[1,1]	Min: , Max:		Multiplier for negative integral gain	Tcs Integral Gain Drop Factor
20	TcsFfwMuNom	single	[1,1]	Min: , Max:		Nominal mu for Tcs FFW	Tcs Feedforward Mu Nominal
21	TcsIntglGainAdjFacRe	single	[1,1]	Min: , Max:		Adjustment factor for rear I gain	Tcs Integral Gain Adjust Factor Rear
22	TcsIntglGainAdjFacFrnt	single	[1,1]	Min: , Max:		Adjustment factor for front I gain	Tcs Integral Gain Adjust Factor Front
23	TcsDrvLgtSlipReLim	single	[1,1]	Min: 0, Max: 100	1	Rear axle longitudinal slip ratio limit for Tcs	Tcs Drive Longitudinal Slip Rear Limit
24	TcsDrvLgtSlipFrntLim	single	[1,1]	Min: 0, Max: 100	1	Front axle longitudinal slip ratio limit for Tcs	Tcs Drive Longitudinal Slip Front Limit
25	TcsLgtSlipVehSpdTblLim	single	[1,6]	Min: 0, Max: 100	1	Slip for speed-based reference slip	Tcs Longitudinal Slip Vehicle Speed Table Limit
26	TcsLgtSlipLimLutAg	single	[1,6]	Min: 0, Max: 90	deg	Slip angle breakpoints for speed-based reference slip	Tcs Longitudinal Slip Limit Lut Angle
27	TcsTqLimFilFrq	single	[1,1]	Min: , Max:	Hz	Cutoff frequency for Tcs torque limit filter	Tcs Torque Limit Filter Frequency
28	TcsMaxWhlTqDifTcs	single	[1,1]	Min: , Max:	N*m	Maximum Tcs torque difference between wheels on axle	Tcs Maximum Wheel Torque Difference Tcs
29	TcsAcvnWhlLgtVMin	single	[1,1]	Min: 0.1, Max: 10	m/s	Wheel longitudinal velocity for wheel slip control deactivation	Tcs Activation Wheel Longitudinal Velocity Minimum

4.23.5. Calibration

The TracCtlSys modulates the wheel torques request when significat tyre slip is detected on a per-wheel basis.

4.23.5.1. Step 1 - Enable/Disable traction control

Set TcsEnad to true to enable traction control, set it to false to disable it.
Set TcsAcvnLogcFrntLe and TcsAcvnLogcFrntRi to true to enable the traction control on the front wheels.
Set TcsAcvnLogcReLe and TcsAcvnLogcReRi to true to enable the traction control on the rear wheels.

4.23.5.2. Step 1.1 - Vehicle parameters

Verify that VehprmTyrEfcRollgRdFrnt and VehprmTyrEfcRollgRdRe represent the vehicle parameters for effective wheel rolling radius.

4.23.5.3. Step 2 - Provide the tyre longitudinal slip limits

Set TcsDrvLgtSlipLimUseLut to true to select the longitudinal tyre slip limit as a function of lateral tyre slip (see Step 2.1) via a lookup table ;
set it to false to provide a constant limit (see Step 2.2).

4.23.5.4. Step 2.1 - Provide the longitudinal tyre slip limits

TcsLgtSlipLutFrntLim array for lateral slip angle-based reference slip limits for front axle
TcsLgtSlipLutReLim array for slip angle-based reference slip limits for rear axle
TcsLgtSlipLimLutAg lateral slip angle breakpoints for speed-based reference slip

4.23.5.5. Step 2.2 - Provide longitudinal tyre slip limit as a static threshold

Set TcsDrvLgtSlipFrntLim to provide front axle longitudinal slip ratio limit for Tcs
Set TcsDrvLgtSlipRearLim to provide rear axle longitudinal slip ratio limit for Tcs

4.23.5.6. Step 2.3 - Low speed TCS limits

Specify TcsLgtSlipVehSpdTblLim as a table data to overwrite limits for very low vehicle speeds
Specify TcsLgtSlipVehSpdBrkPntLim breakpoints for TcsLgtSlipVehSpdTblLim
Make sure dimension are consistent.

4.23.5.7. Step 3 - Tune the feedback controller (PI-with gain scheduling)

Customise the tracking performance of the feedback controller:

TcsFbGainSldgKpFrnt Proportional gain for PI controller as a function of longitudinal vehicle speed
TcsFbGainSldgKpRe Proportional gain for PI controller as a function of longitudinal vehicle speed
TcsFbGainSldgKiFrnt Integral gain for PI controller as a function of longitudinal vehicle speed
TcsFbGainSldgKiRe Integral gain for PI controller as a function of longitudinal vehicle speed
TcsFbGainSldgBrkPnt vehicle speed breakpoints for TCS feedback gains

Tune, if necessary, the following parameters to scale the PI contribution (scaling factor in the range [0,1]):
TcsPropGainAdjFacFrnt
TcsPropGainAdjFacRe
TcsIntglGainAdjFacFrnt
TcsIntglGainAdjFacRe

Tune, if necessary, the cut-off frequency (in Hz) of the low-pass filter on the feedback contribution via TcsTqLimFilFrq.

4.23.5.8. Note 1

The following parameter is available for development and tuning purposes only:
Debug mode:
When TcsEnad is set to true, TcsAcvnManOvrdcan be used to override the HMI activation request if button interface is not available or not working.

4.23.5.9. Note 2

For development purposes only, if TcsEnad is true, setting TcsSndCanDiag to true allows sending the CanTcsOut1 and CanTcsOut2 debug CAN messages