Porsche Traction Management (PTM)
Porsche Traction Management (PTM)
General
The intelligent all-wheel control Porsche Traction Management (PTM) for active control of longitudinal and lateral dynamics is used as standard for the first time in the 911 Turbo high-performance sports car. PTM enables optimum use of the high power output of the new 911 Turbo. The system provides increased driving stability, traction or more agile handling, depending on the driving situation. As a result, the vehicle is very agile on narrow country roads, offers exceptional traction and provides a high level of driving safety in the high-speed range, even in the case of extreme driving maneuvers.
Porsche Traction Management is made up of the following systems:
- Full-time all-wheel drive with electronically controlled center differential lock for torque distribution between the front and rear axles
- Automatic Brake Differential (ABD) for traction improvement
- Anti-Slip Regulation (ASR) for slip control during acceleration and improved driving stability
NOTE: The PTM control unit is located under the shelf behind the rear seats on the DME control unit.
PTM can optionally be supplemented by a mechanical rear differential lock.
PTM Control
The intelligent all-wheel control used in the new 911 Turbo actively controls drive torque distribution between the front and rear axles depending on the current driving situation and driver wishes. The PTM control unit evaluates different input variables such as the wheel speeds of all four wheels, lateral acceleration, longitudinal acceleration and steering angle. The aim of this torque distribution is to provide the driver with excellent driving dynamics and traction as well as maximum driving safety at all times. Several function sequences are checked in parallel in the control unit of the PTM, and are then evaluated and combined in order to define a control strategy. This strategy determines the required locking torque of the longitudinal clutch for the respective driving situation.
The PTM incorporates the following basic functions:
Basic Torque Distribution
The engine torque is distributed steplessly between the front and rear axles depending on the driving situation.
Derivative Action Control
If a driveaway situation is detected and rear wheel slip assumed on the basis of various input variables such as accelerator pedal position and change duration, the PTM clutch is already closed to such an extent that wheel spin is prevented as far as possible. This means that the maximum possible drive power is applied to all four wheels when driving away, therefore ensuring the best possible acceleration.
Slip Controller
If excessively high slip is detected between the two axles on the basis of the wheel speeds, additional torque and therefore increased drive power is supplied to the front axle through greater intervention of the multi-plate clutch.
Understeer Correction
If the comparison between steering angle and yaw speed indicates vehicle understeer, less torque is supplied to the front axle and more torque to the rear axle in order to ensure dynamic vehicle stabilization.
Oversteer Correction
If the comparison between steering angle and yaw speed indicates vehicle oversteer, more torque is supplied to the front axle and less torque to the rear axle in order to ensure dynamic vehicle stabilization.