Here you'll find setup for:
·Wheel speed inputs for each corner, both Digital Input and CAN Bus based.
·Driven and Driving wheel speed, used for the associated runtimes parameters and calculation of the %Slip runtime parameter.
·Acceleration source, used for the associated runtime parameter.
For information on wiring a wheel speed sensor, see the Wheel Speed Wiring topic.
To receive a wheel speed over CAN setup the user CAN to receive the speed as a CAN DI Frequency and select that DI Frequency as the Source DI.
XX Wheel Speed Settings
Each of the four wheel speeds have these settings available:
Select a source for the wheel speed.
Calibration & Alternative Calibration
The Calibration number is the number of pulses received over a 100m distance. A calibration number of 0 uses the frequency as the speed. This calibration value can also be used to correct wheel speeds received over CAN.
For Pin settings such as pull-up resistors and active edge see the Pin Settings topic. The Alternative Calibration setting is only visible when the 'Wheel Speed Alternative Calibration' is set to something other than None, when the alternative calibration input is active the alternative Calibration value is used instead of the normal Calibration value.
Method 1: Drive the vehicle at a known speed and adjust the calibration number until the Vehicle Speed Runtime Value displays correct.
Method 2: Wheel Speed Sensors Only.
·Calibration Number = (Number of Sensor Teeth / Wheel Diameter) * 31.83. Note that wheel diameter is in meters (m) or
·Calibration Number = (Number of Sensor Teeth / Wheel Diameter) * 1253.19. Note that wheel diameter is in inches (in).
Speed Source Settings:
Wheel Speed Alternative Calibration
This setting allows two different wheel speed calibration values to be sued for each wheel. When the input selected in this setting is active the Alternative Calibration is used instead of the the standard calibration, the alternative calibration settings are found below each standard calibration setting but are only visible when this setting is set to something other than None.
Driving/Driven Wheel Speed Source
The Driving Wheels are any wheels connected directly to the drive train, on a rear wheel drive car, this is the rear wheels.
Selects how the driving/driven wheel speed runtime parameter is calculated.
Options include:
·LF Wheel Speed
·RF Wheel Speed
·LR Wheel Speed
·RR Wheel Speed
·Average Front Speed
·Average Rear Speed
·Min Front Speed
·Max Front Speed
·Min Rear Speed
·Max Rear Speed
·Average Four Wheels
·GP Speed 1
·GP Speed 2
·GP Speed 3
·GP Speed 4
Driving Wheel Speed Correction
A percentage correction applied to the driving wheel speed. This setting is useful for making slight corrections due to different tire profiles. If using a Digital Input for the Driving Wheel speed source you can also adjust the Digital Inputs calibration number to make corrections.
Used to help smooth slip due to erratic wheel speeds. This setting controls the corner frequency of a second order low pass filter (Selecting a lower corner frequency reduces noise but adds delay). Also see % Slip Calculation.
Selects if the Acceleration parameter is calculated from the Driving Wheel Speed or Driven Wheel Speed parameter. Acceleration is the rate of change of speed displayed in units of km/h/s.
Example Speed Source Setups
Example One
Front wheel drive vehicle with four wheel speeds into ECU via Digital Inputs
1.Setup the four Functions DI Sources:
LF Wheel Speed Source DI - Digital Input 1
RF Wheel Speed Source DI - Digital Input 2
LR Wheel Speed Source DI - Digital Input 3
RR Wheel Speed Source DI - Digital Input 4
2.Setup the Speed Sources:
Driving Wheel Speed Source - Average Front Speed
Driven Wheel Speed Source - Average Rear Speed
Example Two
Rear wheel drive vehicle with four wheel speeds into ECU via CAN
1.Setup the CAN bus for the wheel speeds if not already configured. Typically on built in vehicle modes CAN DI Freq 1-4 are LF, RF, LR, RR wheel speed respectively.
2.Setup the Speed Source DIs:
LF Wheel Speed Source DI - CAN DI 1 Frequency
RF Wheel Speed Source DI - CAN DI 2 Frequency
LR Wheel Speed Source DI - CAN DI 3 Frequency
RR Wheel Speed Source DI - CAN DI 4 Frequency
Driving Wheel Speed Source - Average Rear Speed
Driven Wheel Speed Source - Average Front Speed
Note: Non zero Calibration values can be used to correct for non standard wheel sizes. Calibration values have the same effect on CAN values as DI values.
Example Three
Front wheel drive vehicle with one vehicle speed input into ECU via a Digital Input
1.Setup the Digital Input:
LF Wheel Speed or RF Wheel Speed DI Source - Digital Input 1
2.Setup the Speed Sources:
Driving Wheel Speed Source - LF Wheel Speed or RF Wheel Speed (This must match the setting selected for the Digital Input)
Driven Wheel Speed Source - OFF (No % Slip calculation available)
Example Four
Rear wheel drive vehicle with one vehicle speed into from the transmission or dashboard via a Digital Input
1. Under Digital Inputs > GP input Setup a GP Speed:
Label it "Transmission".
Source - Select a DI
Calibrate as above
2. Setup Speed sources:
Driving Wheel Speed Source - GP Speed 1
Driven Wheel Speed Source - OFF (No % Slip calculation available)
Example Five
Four wheel drive vehicle with four wheel speeds into ECU via Digital Inputs
3.Setup the four Functions DI Sources:
LF Wheel Speed - Digital Input 1
RF Wheel Speed - Digital Input 2
LR Wheel Speed - Digital Input 3
RR Wheel Speed - Digital Input 4
4.Setup the Speed Sources:
Driving Wheel Speed Source - Average Four Wheels
Driven Wheel Speed Source - OFF (No % Slip calculation available)