Document ID: chunk:federal_register_of_legislation:F2025C00108:reg:4:p7
Version: federal_register_of_legislation:F2025C00108
Segment Type: reg
Provision Reference: reg 4 (pt 7/25)
Character Range: 104532–107755

centre of gravity.
    18.                       'Zeroing Range' means the 0.5 second time period immediately prior to 'Time Zero'.

 1.                                  Functional requirements
     1.                            For each vehicle required to be equipped with a 'Vehicle Stability Function' as defined above, the following shall apply:
         1.                     In the case of 'Directional Control', the function must have the ability to automatically control individually the speed of the left and right wheels on each 'Axle' or an 'Axle' of each 'Axle Group' by 'Selective Braking' based on the evaluation of actual vehicle behaviour in comparison with a determination of the vehicle behaviour demanded by the driver.
         2.                     In the case of 'Roll-over Control', the function must have the ability to automatically control the wheel speeds on at least two wheels of each 'Axle' or 'Axle Group' by 'Selective Braking' or 'Automatically Commanded Braking' based on the evaluation of actual vehicle behaviour that may lead to vehicle roll-over.
     2.                            To realise the functionality defined above a 'Vehicle Stability Function' must include, in addition to 'Selective Braking' and/or 'Automatically Commanded Braking', at least the following:
         1.                     The ability to modify engine torque output, as necessary, to assist the driver in maintaining control of the vehicle or 'Combination Vehicle'.
         2.                     In the case of 'Directional Control': The determination of actual vehicle behaviour from values of yaw rate, lateral acceleration, wheel speeds, and from the driver's control inputs to the braking and steering systems and to the engine.  Only on-board generated information shall be used.  If these values are not directly measured, the 'Secretary' may request the 'Manufacturer' to provide sufficient evidence of the appropriate correlation with directly measured values under all driving conditions (e.g. including driving in a tunnel).
         3.                     In the case of 'Roll-over Control': The determination of actual vehicle behaviour from values of the vertical force on the tyre(s) (or at least lateral acceleration and wheel speeds) and from the driver's control inputs to the braking system and to the engine.  Only on-board generated information shall be used.  If these values are not directly measured, the 'Secretary' may request the 'Manufacturer' to provide sufficient evidence of the appropriate correlation with directly measured values under all driving conditions
            (e.g. including driving in a tunnel).
         4.                     In the case of a vehicle equipped to tow a trailer which uses air at positive pressure: the ability to apply the service brakes of the trailer via the respective control line(s) independently of the driver.
     3.                            When a vehicle is equipped with a means for an operator to manually disable a mandatory 'Vehicle Stability Function', the 'Vehicle Stability Function' must be automatically reinstated no later than when the vehicle reaches a speed of 40 km/h and at the initiation of each new ignition