Control function for speed

Speed-controlled driving mode is supported by the shift strategy to achieve an efficient and smooth overall behavior. It ensures that the acceleration or tensile force (uphill driving) requested by cruise control is reached. Additionally, there is no loss of comfort by increased gearshift activity or pendulum shifts. In line with the driving situation (constant-speed driving, acceleration, deceleration), cruise control selects the requested tensile force and the ideal gear. When cruise control is active Integrated Chassis Management (ICM) takes over the dynamic vehicle management task. Within certain limits the driver does not have to interact and the system actuates engine and service brake. For this purpose, Integrated Chassis Management (ICM) calculates the desired acceleration and transmits it. Digital Engine Electronics (DME) and Digital Engine Electronics 2 (DME2) determine the required engine torque on the basis of the current driveline transmission. This request is implemented within physical boundaries. It additionally provides a corresponding virtual accelerator pedal value. Amongst others, Integrated Chassis Management (ICM) detects the following operating conditions:

• Control function for driving at constant speeds
• Control function for the following operation
• Sensing any set speeds
• Corner control function
• Control function on downhill gradients

These operating conditions must be supported by the gearbox with individually adapted shift strategies. This corresponds to the features of the controller and also to subjective driver choices with relation to the shift characteristics. The gear selection mechanism uses suitable shift diagrams. The difference is that the torque or load request to the gearbox comes from the Integrated Chassis Management (ICM). Gear selection achieves that the selected speed is set without any loss of comfort (no increased shift activity or pendulum shifts). Similar to driver mode, the automatic transmission supports in the following driving situations:

• Normal operation with emphasis on comfortable shift characteristics and best-possible efficiency
• Uphill driving and trailer towing with the required tensile force reserves to avoid unnecessary shifting activity
• Downhill driving with downshifts that support deceleration
• Cornering detection with reduced shift activity to support the specific ACC control characteristics