MoTeC MDC - Manual (Page 6)

MoTeC MDC 4 Functionality
Speed Measurement
The four wheel speed sensors are either directly connected to the MDC, or via the ABS module (if fitted). If the
ABS module is removed, the sensors must be directly connected to the MDC.
The MDC wheel speed inputs can be configured as hall effect or magnetic sensors with adjustable thresholds, and
individual sensors can be enabled or disabled. The speed calibration can be adjusted for different wheel sizes and
sensor teeth. Magnetic sensor input thresholds are individually configurable for front and rear sensor pairs
according to the current front and rear speeds.
Front, rear and vehicle speeds are calculated from the wheel speeds, and all speeds are transmitted in CAN
messages for logging by the ADL (Advanced Dash Logger).
Individual wheel speeds are transmitted to the ECU over a communication bus using factory wiring. A MoTeC
EVO89 or EVO48 OEM ECU (if fitted) can be configured to log these wheel speeds or use them in engine control
strategies.
For information on configuring speed inputs, see Setup | Input in the MDC Manager section.
Speed Calculations
The method of calculating front, rear and vehicle speeds is dependent on the status of the brake input.
When the foot brake is applied, speeds are calculated as follows:
• Front Speed is the faster of the two front wheel speeds.
• Rear speed is the faster of the two rear wheel speeds.
• Vehicle speed is the faster of the calculated front speed and rear speed.
When the foot brake is not applied, speeds are calculated as follows:
• The front speed is the average of the two front wheel speeds, weighted 80% towards the slowest front
wheel speed. If one front wheel speed is less than half of the other front wheel speed, then front speed is
simply the faster of the two front wheel speeds.
• The rear speed is the average of the two rear wheel speeds, weighted 80% towards the slowest rear
wheel speed. If one rear wheel speed is less than half of the other rear wheel speed, then rear speed is
simply the faster of the two rear wheel speeds.
• The vehicle speed is the average of the front and rear speeds, weighted 80% towards the slowest speed.
If either the front or rear speed is less than half of the other speed, then vehicle speed is simply the faster
out of the front speed and rear speed.
If any wheel speed exceeds 300km/h, the sensor reading is ignored until its speed returns to below 300km/h for 2
seconds. This is to prevent erratic behaviour from noisy wiring or faulty sensors.
Handbrake Override
If the front wheel speed is 0km/h and the handbrake is active, the handbrake will then be ignored in all lock
calculations until the handbrake is released. This functionality allows the diff to be locked in preparation for takeoff
during a handbrake start.
Throttle Calibration
The throttle position sensor input can be calibrated using a table to convert voltage to throttle position. This allows
non-linear calibration of throttle position to more closely model the change in torque vs. throttle butterfly angle.
The MDC Manager configuration program allows throttle input voltages to be read directly from the MDC in order
to perform 0% and 100% calibrations.
For information on calibrating the throttle input, see Setup | Input in the MDC Manager section.
Steering Position Measurement
The steering position sensor is a rotary encoder that has an index output to indicate the 0° rotation position. The
steering wheel position will be reported as 0° until it has passed the 0° rotation position and an absolute position is
known.