Vehicle testing device and vehicle speed deviation calculation method for vehicle testing device

A vehicle testing method for performing vehicle tests by operating a vehicle on a chassis dynamometer, the vehicle speed testing method comprising:

• controlling a speed of the vehicle on the chassis dynamometer by performing changeovers between an accelerator operation to accelerate the vehicle and a brake operation to decelerate the vehicle;
• and
• calculating at least one of a first changeover vehicle speed deviation for changeover from the accelerator operation to the brake operation and a second changeover vehicle speed deviation for changeover from the brake operation to the accelerator operation in a vehicle speed following control to drive the vehicle along a standard mode of a vehicle drive pattern defined by time and a vehicle speed within a range of a deviation of a predetermined speed and a deviation of a predetermined time from the standard mode, in a vehicle testing apparatus for performing vehicle tests by operating a vehicle on the chassis dynamometer, wherein
• the first changeover vehicle speed deviation is calculated by calculating a first inclination of the standard mode by approximate differentiation of the vehicle speed at a judgment standard point of a current time instant on the standard mode of the vehicle drive pattern, multiplying the first inclination of the standard mode by a first changeover time deviation preset value which is a preset value of a time deviation for changeover from the accelerator operation to the brake operation, and calculating the first changeover vehicle speed deviation from the judgment standard point to an accelerator-to-brake changeover judgment point for changeover from the accelerator operation to the brake operation at the current time instant by addition of a product determined by multiplication of the first inclination and the first changeover time deviation preset value and a first changeover vehicle speed deviation preset value which is a preset value of the vehicle speed deviation for the changeover from the accelerator operation to the brake operation, and
• the second changeover vehicle speed deviation is calculated by calculating a second inclination of the standard mode by approximate differentiation of the vehicle speed at a judgment standard point of the current time instant on the standard mode of the vehicle drive pattern, multiplying the second inclination of the standard mode by a second changeover time deviation preset value which is a preset value of the time deviation for changeover from the brake operation to the accelerator operation, and calculating the second changeover vehicle speed deviation from the judgment standard point to a brake-to-accelerator changeover judgment point for changeover from the brake operation to the accelerator operation at the current time instant by addition of a product determined by multiplication of the second inclination and the second changeover time deviation preset value and a second changeover vehicle speed deviation preset value which is a preset value of the vehicle speed deviation for the changeover from the brake operation to the accelerator operation.

A vehicle testing apparatus comprising:

• a chassis dynamometer on which a test vehicle is to be operated;
• and
• a controller configured to:
• perform a vehicle speed following control to drive the test vehicle along a standard mode defining a target vehicle speed varying with time according to a predetermined drive pattern within a range of a predetermined allowable speed deviation and a predetermined allowable time deviation from the target vehicle speed of the standard mode, and thereby to perform a vehicle test of the test vehicle on the chassis dynamometer,
• cause a changeover between an accelerator operation to accelerate the test vehicle and a brake operation to decelerate the test vehicle, to drive the test vehicle along the target vehicle speed of the standard mode in the vehicle speed following control, by comparing an actual vehicle speed deviation from the target vehicle speed with a changeover vehicle speed deviation, and
• calculate the changeover vehicle speed deviation by calculating an inclination of the target vehicle speed of the standard mode, multiplying the inclination by a preset time parameter, adding a preset vehicle speed parameter to a product resulting from multiplication between the inclination and the preset time parameter and setting the changeover vehicle speed deviation equal to a sum resulting from addition of the preset vehicle speed parameter and the product, wherein
• the inclination is a rate of change of the target vehicle speed of the standard mode with respect to time at a current operating point determined by a current time instant and a value of the target vehicle speed at the current time point,
• the preset time parameter is a parameter representing a preset value of a changeover time deviation which is smaller than the predetermined allowable time deviation, and
• the preset vehicle speed parameter is a parameter representing a preset value of a changeover vehicle speed deviation which is smaller than the predetermined allowable speed deviation.