Patent Application
20080119999
The present disclosure relates to transmission control systems and more particularly to methods and systems for controlling a transmission based on altitude data from a telematics system.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Vehicle manufacturers are now incorporating the use of a GPS receiver in their vehicles as part of an onboard communication between the vehicle and a central communication receiving location. The onboard communication system automatically locates the vehicle and provides the vehicle driver with assistance in a variety of circumstances. This type of information is typically provided to the driver for road side assistance or map direction purposes.
Telematics systems, such as ONSTAR® provided by General Motors, incorporate a GPS receiver that uses a satellite to provide real time information to the system. For instance, the GPS receiver determines the current longitude, latitude, and altitude of the vehicle. It would be advantageous for other control systems within the vehicle to make use of the data determined by the telematics systems.
Accordingly, a control system for controlling a transmission of a vehicle including a telematics system is provided. The system includes: a grade module that determines a current grade based on an altitude signal received from the telematics system; a force balance module that computes a vehicle mass based on a force balance equation and the current grade; and a transmission control module that controls the transmission based on the vehicle mass.
In other features, a method of controlling a transmission is provided. The method includes: receiving an altitude signal generated by a telematics signal; computing at least one of a vehicle mass and an aerodynamic drag factor based on the altitude signal; and controlling the transmission based on the at least on of vehicle mass and aerodynamic drag factor.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
Referring now to
An accelerator pedal 22 enables a driver of the vehicle 10 to adjust the position of the throttle 14 to achieve a desired speed. An accelerator pedal position sensor 24 generates a pedal signal indicating a position of the accelerator pedal 22. A control module 26 receives the pedal signal and adjusts the position of the throttle 14 accordingly. The control module 26 adjusts fuel delivery to the engine 12 based on the airflow. Similarly, a brake pedal 28 allows the driver to enable a brake system 40. The brake system 40 applies a braking torque to counter the drive torque. A brake pedal sensor 30 senses the position of the brake pedal 28 and generates a brake pedal signal accordingly. The control module 26 receives the signal and controls the brake system 40 of the vehicle 10. A vehicle speed sensor 42 generates a vehicle speed signal by sensing a rotational speed of at least one of a wheel (not shown) and a driveshaft 44. The control module 26 computes a vehicle speed from the vehicle speed signal and based on the position of the vehicle speed sensor 42.
The vehicle 10 is shown to include a telematics system 46. The telematics system is operable to facilitate communication between one or more satellites and the vehicle 10. An exemplary telematics system 46 may include General Motors' ONSTAR® system. The telematics system 46 includes a GPS receiver operable to determine a current altitude of the vehicle 10 and generate an altitude signal. The control module 26 receives the altitude signal and controls one or more vehicle components based on the altitude. In various embodiments, the control module 26 receives the altitude signal, computes at least one of vehicle mass, grade, and an aerodynamic drag factor, and controls the transmission based on the computed values. The more precise computed values allows the control module 26 to better control particular transmission functions such as powertrain braking, tow/haul, and neutral idle control.
Referring now to
With reference to
F
TE
−F
AERO
−F
ROLLING
−F
ACCEL
−F
GRADE
−F
BRAKES=0. (1)
The actual grade (GACTUAL) can be computed based on a change in altitude (ACHANGE) and a distance traveled (DTRAVELED) and provided:
G
ACTUAL
=A
CHANGE
/D
TRAVELED. (2)
Based on the force balance equation (1) and the actual grade (GACTUAL), vehicle mass (M) can be determined as follows. For vehicle mass computations, the brake system 40 of
F
AERO
=AD
FACTOR
*V
2. (3)
ADFACTOR can initially be set to a predetermined value. Thereafter ADFACTOR can be computed, as will be discussed in more detail below. FGRADE and FROLLING are functions of vehicle mass (M) as shown as:
F
GRADE
=M*(G*Sin(GACTUAL)); and (4)
F
ROLLING
=R*M. (5)
Where G represents a predetermined gravity constant and R represents a predetermined friction constant. FTE is computed based on an estimated engine torque 66, gear ratio 68, tire size 70, and torque converter status 72. Substituting in the above equations provides:
F
TE
−F
AERO
−R*M−M*(G*Sin(GACTUAL)=M*A. (6)
Solving for M provides:
M=(FTE−FAERO)/(A+R+Sin(GACTUAL)*G). (7)
This equation provides for a more accurate mass computation. A more accurate mass computation can enhance powertrain braking functionality and allow tow/haul mode to be automatically entered without requiring driver initiation.
Based on the force balance equation (1), the aerodynamic drag factor (ADFACTOR) can be determined as follows. When the brake system 40 of
F
TE
−F
AERO
−F
ROLLING
−F
ACCEL
−F
GRADE=0. (8)
F
TE
−F
AERO
−F
ROLLING−(M*A)−FGRADE=0. (9)
M can initially be set to a predetermined value. Thereafter, M can be computed as discussed above. Solving for FAERO yields:
F
AERO
=F
TE
−F
ROLLING−(M*A)−FGRADE. (10)
FTE, FROLLING, and FGRADE can be computed as described above. Provided equation (3) above ADFACTOR can be calculated as follows:
AD
FACTOR
=F
AERO
/V
2. (11)
Thus, the ADFACTOR can be filtered and further refined as the mass calculation is updated to reflect the actual mass. The ADFACTOR is then used to compensate for changing aerodynamics of the vehicle 10 and trailer 48.
Referring now to
The grade module 50 receives as input distance traveled 56 and the altitude signal 58 received from the telematics system 46 of
The transmission control module 54 controls the transmission 18 of
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present disclosure can be implemented in a variety of forms. Therefore, while this disclosure has been described in connection with particular examples thereof, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and the following claims.
