Systems and methods for determining vehicle and trailer resistance related characteristics
Methods and systems determine resistance related constants for use by a vehicle towing a trailer. A system for controlling functions of the vehicle and the trailer includes sensors that provide sensor data. A processor performs a readiness check, based on the sensor data, by determining whether the sensor data exceeds predetermined thresholds. When the readiness check is passed, meaning the thresholds are not exceeded, and based on the sensor data, the processor computes values for constants that represent aerodynamic resistance and rolling resistance of the vehicle and the trailer. Based on the constants, the processor controls functions of the vehicle.
1. A system for controlling functions of a vehicle having vehicle brakes and a trailer having trailer brakes, the system comprising:
sensors of the vehicle configured to provide sensor data comprising deceleration values across a range of speeds of the vehicle and the trailer; and
a processor configured to:
perform, based on the sensor data, a readiness check by determining whether the sensor data exceeds predetermined thresholds;
compute, based on the sensor data and when the readiness check is passed, meaning the predetermined thresholds are not exceeded, values for constants that represent aerodynamic resistance and rolling resistance of the vehicle and the trailer specifically;
save the constants as a part of a profile unique to the trailer; and
control, based on the profile, functions of the vehicle and the trailer including to apply, in proportional response to application of the vehicle brakes, the trailer brakes.
2. The system of claim 1 , wherein, prior to computing the constants, the processor controls the functions of the vehicle based on generic constants predetermined and stored in memory.
3. The system of claim 1 , wherein the sensors comprise:
a speed sensor configured to provide speed signals representative of speed of the vehicle;
a brake sensor configured to provide brake signals representative of brake application of the vehicle; and
a steering angle sensor configured to provide steering signals representative of angles at which wheels of the vehicle are turned.
4. The system of claim 1 , wherein the processor is configured to correct the values based on a motoring force of the vehicle.
5. The system of claim 1 , wherein the processor is configured, prior to computing the values for the constants, to determine, from an acceleration sensor, the deceleration values during operation of the vehicle.
6. The system of claim 1 , wherein the processor is configured, with input of the sensors, to collect deceleration data across the range of speeds of the vehicle and the trailer, wherein the constants are related to both acceleration and velocity.
7. The system of claim 1 , wherein the processor is configured to compute, based on the constants, a combined weight of the vehicle and the trailer.
8. The system of claim 1 , comprising an interface configured to communicate information to and from the processor, wherein the processor is configured to determine a weight change of the vehicle and the trailer, and is configured to communicate, through the interface and after the weight change, a need to update the constants.
9. The system of claim 1 , wherein the processor is configured to access data limits from a memory and to rationalize the constants by restricting the constants to within the data limits.
10. The system of claim 1 , wherein the constants comprise a first constant and a second constant, wherein the first constant represents air density, an aerodynamic drag coefficient, a frontal area of the vehicle and the trailer, and mass of the vehicle and the trailer, and the second constant represents a rolling resistance coefficient of the vehicle and the trailer and acceleration of gravity.
11. A method for controlling functions of a vehicle having vehicle brakes and a trailer having trailer brakes, the method comprising:
providing, by sensors of the vehicle, sensor data including providing deceleration values across a range of speeds of the vehicle and the trailer;
performing, by a processor and based on the sensor data, a readiness check by determining whether the sensor data exceeds predetermined thresholds;
computing, by the processor based on the sensor data and when the readiness check is passed, meaning the predetermined thresholds are not exceeded, values for constants that represent aerodynamic resistance and rolling resistance of the vehicle and trailer specifically;
saving the constants as a part of a profile unique to the trailer; and
controlling, by the processor and based on the profile, functions of the vehicle and the trailer including applying, in proportional response to application of the vehicle brakes, the trailer brakes.
12. The method of claim 11 , comprising:
predetermining generic constants that represent the aerodynamic resistance and the rolling resistance of the vehicle and the trailer;
storing the generic constants in a memory accessible by the processor; and
controlling, prior to the computing of the constants and by the processor, the functions of the vehicle based on the generic constants.
13. The method of claim 11 , wherein the providing the sensor data comprises:
providing, by a speed sensor, speed signals representative of speed of the vehicle;
providing, by a brake sensor, brake signals representative of brake application of the vehicle; and
providing, by a steering angle sensor, steering signals representative of angles at which wheels of the vehicle are turned.
14. The method of claim 11 , comprising correcting, by the processor, the values based on a motoring force of the vehicle.
15. The method of claim 11 , comprising:
determining, by the processor with input from an acceleration sensor and prior to computing the values for the constants, the deceleration values.
16. The method of claim 11 , comprising collecting, by the processor with input of the sensors, deceleration data across the range of speeds of the vehicle and the trailer, wherein the computing the values for the constants includes factoring in both acceleration and velocity.
17. The method of claim 11 , comprising computing, by the processor and based on the constants, a combined weight of the vehicle and the trailer.
18. The method of claim 11 , comprising:
including an interface in the vehicle configured to communicate information to and from the processor;
determining, by the processor a weight change of the vehicle and the trailer; and
communicating, by the processor, through the interface and after the weight change, a need to update the constants.
19. The method of claim 11 , comprising:
accessing, by the processor from a memory, data limits; and
rationalizing, by the processor, the constants by restricting the constants to within the data limits.
20. A vehicle having vehicle brakes configured to tow a trailer having trailer brakes, the vehicle comprising:
sensors of the vehicle configured to provide sensor data comprising deceleration values across a range of speeds of the vehicle and the trailer; and
a processor configured to:
perform, based on the sensor data, a readiness check by determining whether the sensor data exceeds predetermined thresholds;
compute, based on the sensor data and when the readiness check is passed, meaning the predetermined thresholds are not exceeded, a first value for a first constant that represents an aerodynamic resistance of the vehicle and the trailer, and a second constant that represents a rolling resistance of the vehicle and the trailer;
save the first constant and the second constant as a part of a profile unique to the trailer;
compute, from the first constant and the second constant; a command value for a controlled parameter of the vehicle; and
control, based on the command value, a system of the vehicle and the trailer including apply, in proportional response to application of the vehicle brakes, the trailer brakes.