Document ID: chunk:federal_register_of_legislation:F2025C00107:reg:4:p7
Version: federal_register_of_legislation:F2025C00107
Segment Type: reg
Provision Reference: reg 4 (pt 7/26)
Character Range: 104684–107870

when the 'Vehicle Stability Function' applies a service brake pressure at any wheel for a continuous duration of at least 0.5 second of at least 34 kPa for pneumatic brake systems and at least 172 kPa for hydraulic brake systems.
    18.                       'Yaw Rate' means the rate of change of the vehicle's heading angle measured in degrees per second of rotation about a vertical axis through the vehicle's centre of gravity.
    19.                       '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 may be used.  If these values are not directly measured, the 'Manufacturer' must supply to the 'Administrator' 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 may be used.  If these values are not directly measured, the 'Manufacturer' must supply to the 'Administrator' 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