This invention relates to engine and vehicle control through feedback of driving performance.
Automotive vehicles are ultimately controlled by a human operator that makes decisions about the vehicle including speed, direction, and operating parameters such as transmission gear, accessory operation, refueling, maintenance, and the like. While many operators develop a general feel for how a vehicle is performing, the vehicle generally provides little if any quantitative information to the driver indicating how efficiently the vehicle is operating.
An example of the need for vehicle efficiency feedback occurs with on-highway heavy trucks. Vehicle operators have direct or indirect control over a wide range of vehicle parameters including engine fuel, service (wheel) brakes, engine retarders such as engine brakes and Jake brakes, transmission retarders, transmission gear, idling time, use of engine driven accessories such as air conditioning, and the like. Each of these parameters affects the efficiency of operation and, hence, the cost of operation. Truck owner/operators and fleet owners are highly concerned with operational costs and are therefore in need of quantitative measures of vehicle operating efficiency.
One problem with previous measures of vehicle operating efficiency is a failure to provide meaningful cost-related information relevant to vehicle control. Measures, such as instantaneous miles per gallon of fuel consumed (MPG), tend to relay inaccurate cost indicators to a vehicle driver or automatic controller. For example, MPG decreases during vehicle acceleration and increases during vehicle braking. This often does not reflect optimum driving requirements. Acceleration adds energy to the vehicle and braking removes energy from the vehicle. Braking, in particular, should be avoided if possible to prevent loss of vehicle energy through heat.
It is an object of the present invention to provide quantitative measures of vehicle operating efficiency. These measures may be used for a variety of purposes including display to the vehicle operator, storage in memory for future analysis, and input to engine controllers.
In carrying out the objects and features of the present invention, a method is provided for controlling an automotive vehicle. At least one vehicle parameter is sampled. At least one measure of driving efficiency is determined based on the sampled vehicle parameter. An estimate of operating cost is found based on the at least one measure of driving efficiency.
In an embodiment of the present invention, at least one driving efficiency limit is set. An increase in the maximum allowed vehicle velocity is permitted if the measure of driving efficiency exceeds the driving efficiency limit.
In embodiments of the present invention, measures of driving efficiency may include measures of normalized cost, measures of shifting and idling cost, and measures of change in vehicle kinetic energy such as, for example, may be caused by vehicle braking.
A method for gauging vehicle efficiency is also provided by the present invention. Vehicle velocity is repetitively sampled. If the sampled vehicle velocity is less than a previously sampled vehicle velocity and if braking is applied, the sampled braking velocity cost is determined based on the difference between the square of the sampled vehicle velocity and the square of the previously sampled vehicle velocity. A measure of driving efficiency is then determined based on the sampled braking velocity cost. These measures may include instantaneous braking velocity cost per mile and average braking velocity cost per mile.
In another method for gauging driving efficiency provided by the present invention, an engine revolution idle cost is determined. The engine speed is repetitively sampled. At least one sampled shifting and idling cost is determined as the product of a sampled engine speed and the engine revolution idle cost. A measure of driving efficiency is found based on the sampled shifting and idling cost. These measures may include instantaneous shifting and idling cost per mile and average shifting and idling cost per mile.
A driving efficiency gauge is also provided. A display presents at least one measure of driving efficiency to the vehicle operator. A memory holds a sequence of at least one measure of driving efficiency. Control logic in communication with the electronic control module controlling an internal combustion engine receives samples of at least one vehicle operating parameter from the electronic control module. The sequence of driving efficiency measures is determined based on the vehicle operating parameter samples. At least one of the efficiency measures is displayed and the sequence of efficiency measures is stored in the memory.
The above objects and other objects, features, and advantages of the present invention will be readily appreciated by one of ordinary skill in the art from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.