Note: Traction Control is not available on the G4X Atom, Monsoon, and Storm.
Traction Control is designed to provide controlled tyre slip which can greatly improve vehicle safety and drive-ability. In a lot of cases Traction Control will also allow the vehicle to accelerate faster by preventing excess wheel spinning.
Traction Control is a Motorsport only feature and is not recommended for use on public roads or as a replacement for OEM traction or stability control systems.
Note: Traction Control requires Torque management to be turned on and configured.
WARNING: Incorrect setup or use of Traction Control could result in an accident or cause harm to the vehicle and/or its occupants. It is essential that Traction Control is configured and tested in a safe controlled environment.
Operation
Traction Control uses the Slip runtime value as its primary source to determine tyre slip. It is essential that the vehicle has wheel speed sensors fitted, wired and calibrated to allow the ECU to determine when there is a difference in speed between the driven and non-driven wheels. ABS modules can also often be used to get precision wheel speeds over a CAN bus. Gear detection should also be correctly configured if per gear Traction Control setting is required.
Traction Control provides lockouts to allow it to be disabled under low speed, RPM and throttle conditions. There is also the ability to use a driver pushed button to manually disable and re-enable Traction Control.
Once operating, Traction Control constantly monitors Slip. When Slip exceeds the value in the Slip Threshold Table, Traction Control limits engine torque by means of fuel or ignition event cuts and ignition retard. Closed loop PID control is used to maintain Slip at the desired value.
Two Slip Threshold Tables can be configured to allow different amounts of tyre slip. These can be used for a wet/dry or road/track setup.
If a Traction Light is required a GP Output can be configured to look at the status of the disable input (light on when traction disabled) or the Traction status to turn the output on when traction control kicks in. If a flashing light is desired a GP PWM with a low frequency can be used to do this.
Traction Control settings are detailed individually below.
Settings:
This setting is used to turn Traction Control, Off, On or disable it. When it is set to disabled the tables and input settings remain but but no traction control is performed.
Used to select the input that is used to disable Traction Control (disabled when the input is active).
Used to specify how fast the torque is reintroduced once slip is no longer greater than the Target Slip.
Traction Control will be disabled when the Engine Speed is below this value.
Traction Control will be disabled when the Throttle Position is below this value.
Traction Control will be disabled when the Driven Wheel Speed is below this value.
Note: If Speed Lockout is set too low, Traction Control will activate during launches or possibly even in the pits during tight turns.
Selects the number of Slip Threshold Tables used and whether or not an overlay table is present. When two tables are selected the Table 2 Activation setting will become visible.
Used to select the input that switches between Slip Threshold Table 1 and Slip Threshold Table 2.
Proportional Gain, Derivative Gain
The gains used in the closed loop slip target PD algorithm. It is essential that these gains are set correctly for Traction Control to perform well. If these gains are incorrectly set the most likely effect will be a cycling of torque reduction, power, torque reduction etc. These gains require careful tuning and some knowledge of PD control to set correctly. Use logging of Slip and a repeatable situation to help tune these gains.
Refer HERE for more information on PID control.
Slip Threshold Table, Slip Threshold Table 2
Used to set the maximum Slip that can occur before before Traction Control will activate. After Traction Control is active torque is controlled via the Torque Management function target the specified Slip, the PID values are used to constantly generate torque reduction values which are fed into Torque Management to try and maintain the target slip. This means the values in these tables are both a threshold and a target.
Typical Slip Threshold values would range from 3% (almost no slip) to 10% (significant slip, enough to cause the vehicle to slide). Typically lower Slip Thresholds are used at higher speeds (i.e. in higher gears).
Used to add an extra dimension of control to the Slip Threshold Tables. The value in this table is applied to the active Slip Threshold Table value as a percentage multiplier.
Example: value of 50% in the Slip Threshold Table and a value of 3% in the overlay table comes out as 50 * (1 + 3/100) = 51.5% Slip allowed