Abstract:
The present invention is related to a method of controlling a device having a calibration process. The calibration process has a partial calibration routine and a calibration routine. A detector within the control system is capable of receiving one or more input signals and determining whether a partial calibration or calibration should occur. The first step in the process involves starting the control method where the detector receives input signals or generates it own data within the detector. The detector also determines whether a partial calibration routine or a calibration routine will take place based upon the value of the input signals received. A partial calibration routine will be performed if the input signals to the detector do not favor a calibration.

Description:
This application is a National Stage of International Application No. PCT/US2006/020682, filed May 30, 2006. This application claims priority to U.S. Patent Application No. 60/685,917 filed on May 31, 2005. The disclosures of the above applications are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a control strategy for self calibrating actuators under specific conditions, wherein the control strategy further provides a partial calibration feature that will maintain adequate actuator performance. 
     BACKGROUND OF THE INVENTION 
     It is common practice in the automotive industry to use electric actuators to control various vehicular functions. These control actuators are often faced with operating in harsh environments that are subject to change. As a result the operation of these actuators can become misaligned or sometimes blocked. Thus periodic calibration or confirmation of the actuator function is often necessary to ensure that the actuator has a proper range of operation. An example of a type of system where calibration or confirmation is desirable is in a turbocharger. The actuator in a turbocharger is used to control the turbocharger unit and the boost pressure that the unit provides to the engine. If the actuator becomes misaligned then the valves in the turbocharger may not open properly and cause an incorrect pressure differential across the turbine. The misadjustment or misalignment of the valves can result in poor engine performance, failure to meet emissions legislation, or damage to the turbocharger and related vehicle components. 
     It is desirable to configure or program the actuator to calibrate itself when predetermined time periods or conditions exist. Doing so will prevent an intrusive event that may affect the engine performance, vehicle emissions, or potential system damage. 
     SUMMARY OF THE INVENTION 
     The present invention is related to a method of controlling a device having a calibration process. The calibration process has a partial calibration routine and a calibration routine. A detector within the control system is capable of receiving one or more input signals and determining whether a partial calibration or calibration should occur. The first step in the process involves starting the control method where the detector receives input signals or generates its own data within the detector. Next the detector determines if a calibration is required based on the values. The detector also determines whether a partial calibration routine or a calibration routine will take place based upon the value of the input signals received. A partial calibration routine will be performed if the input signals to the detector do not favor doing more than a partial calibration. If a partial calibration routine occurs, then the device is commanded to move to a first function or limitation of its operating range so that the device learns the characteristic of the limitation. Next the device operates using the learned characteristic and a previously stored value of a second characteristic representing the second limitation or function of the operating range of the device. If it is determined that a calibration routine will take place then the device will learn the first characteristic as described above, and a second characteristic located at a second function or limitation of the operating range of the device. After a calibration routine the device will then operate using the learned values of the first characteristic and second characteristic obtained during the calibration routine. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a schematic diagram of a control strategy method for operating a device; and 
         FIG. 2  is a schematic diagram of the actuator control method operating in a device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     Referring to  FIG. 1 , the control strategy  10  is shown wherein a device is programmed with the control strategy  10 . The control strategy  10  begins with a step  12  that includes start command where the method of controlling the calibration/verification sequence is initiated. Throughout the specification, claims and drawings, reference will be made to calibrating or learning the limitations of a device. However, it is within the scope of this invention to also include in the definition of calibration as a verification sequence. Calibration as used herein is defined as learning the limitations or functions of a device as well as verifying the limitations or functions of the device. Thus, if a device has already been calibrated so that the approximate values of its functions have been determined, a verification routine will be necessary during the life of the device to determine or verify that it is operating properly and that the values for the functions on the device are still correct. 
     After the step  12  the device will proceed to a step  14  and determine if the calibration or verification of the device&#39;s parameters is required. This determination is based on various inputs, shown in  FIG. 1  as input  1 , input  2  and input  3 , which are indicative of various conditions that exist. The type and number of inputs used will vary depending upon the particular application of the method described herein. However, using this method in automotive engine systems will almost certainly include such inputs that generally convey information pertaining to the vehicle&#39;s electric system, engine speed and vehicle speed. If it is determined that no calibration or verification is required or possible then the control strategy  10  will repeat the step  12  and continue to monitor the inputs at step  14  until it is determined that the calibration or verification is required. 
     Once it has been determined at step  14  that a calibration or verification will take place the device will advance to a step  16 . At step  16  the device will determine which type of calibration or verification to perform. The device may command a partial calibration, which is just one portion of a calibration routine, by learning or verifying the value of a first function at a step  18 . At a step  20  the device will operate using the value of the first function and a previously stored value for a second function. The previously stored value can be a pre-programmed value, an end of line value, or a value obtained from the last calibration routine. The partial calibration will then be completed at a finish step  22  where the device will continue to operate using the learned position obtained at step  18  and the previously stored value for function  2  supplied at step  20  for operation of the device. 
     If at step  16  the device determines that the calibration routine is needed then the device will learn the position of a first function at step  24 . The device will learn the position of a second function at a step  26 . At a step  28  the device will verify the operation of the operating range of the device by moving between the learned position of the first function and the learned position of the second function. The device will then finish the calibration routine at a step  30  and operate using the learned positions obtained at steps  24  and  26 . 
     The control method described in  FIG. 1  has many applications for various devices. For example, the control method can be used in conjunction with any type of air pump where the span air flow pressure must be learned or calibrated. Additionally, some devices draw a certain amount of current and the range of current that can be drawn to a device may need to be learned during operation of the device. Also, other factors such as angular revolution, linear movement or torque determination may be desirable functions that can be monitored using the control system described in  FIG. 1 .  FIG. 1  uses the terms calibration and verification, and these terms have different meanings. For example, calibration implies that the device is learning the position of an operational limitation, whereas verification means that the device is verifying the position or the value of an operational range as opposed to learning the value. While calibration and verification take on two meanings, the terms will be used interchangeably throughout this specification. However, it is within the scope of this invention for the control strategy  10  to be used either in conjunction with calibration or it can also be appreciated the invention is not limited in the number of functions that can be included in the calibration. The example described a device or system with 2 functions but it can be any number of functions. 
       FIG. 2  depicts an embodiment of the invention where the control strategy  110  is incorporated in a system having two controllers, an engine control unit (ECU)  111  and actuator control unit (ACU)  116 . At a step  112 , the engine is turned on or off. At a step  114 , the engine control unit (ECU) detects engine activity and transmits information regarding the engine activity to the ACU  116  in the form of an input signal. The input signal also contains engine speed, electrical system information and other factors. 
     The ACU  116  receives the information from the ECU  111 . The ACU  116  then determines at a step  120  whether or not conditions allow for the actuator to perform a partial calibration routine. If at step  120  it is determined that a calibration routine is not possible due to the engine conditions or other factors, then at step  122  the ACU  116  performs a partial calibration with the actuator  122 . A partial calibration is where the ACU  116  commands the actuator to drive to a second function. The ACU  116  then records the value of the second function, replacing learned values from previous partial calibrations or preprogrammed values. At step  124 , the actuator then operates using previously stored data regarding a first function and the information acquired during the partial calibration  122 . At step  120 , the ACU  116  will continue to monitor and determine when conditions will allow for a calibration routine step  126  to be performed. For example, when the engine is sitting at idle or is cruising at ideal cruising speeds, the ACU  116  performs the step  126  of calibration with the actuator. During step  126 , a calibration routine of the actuator is driven to all the functions within the range of the actuator. The ACU  116  then records the values of all the actuator&#39;s functions, replacing the learned values from previous calibration routines. Then at step  128  the ACU  116  operates using the data acquired during the calibration. 
     In the preferred embodiment the ECU  111  is configured to transmit information  114  to the ACU  116 , and the ACU  116  is configured to receive information  118  from the ECU  111 . The control strategy  110  can be implemented in applications where there is a single controller, such as a configuration where the ECU directly controls the actuated device. It is also within the scope of the present invention for the ACU  116  to be integrated into the device or for the ACU  116  to be a separate unit. Additionally, it is possible to implement the control strategy  110  of the present invention into a situation where there are two or more controllers. Such an embodiment would allow for the coordination for multiple controller units making or allowing the control strategy to operate based on multiple variables. For example, multiple controllers could input signals to the ECU so that the ECU could command the actuator to perform various learn sequences based upon signal values from various engine system components. One example of such an alternate embodiment would be where the ACU receives a signal from the ECU that is representative of engine conditions, while another variable inputted to the ECU could be a value inputted from a controller that monitors electrical consumption of the vehicle&#39;s cabin compartment. 
     It is possible for the conditions to direct the ACU  116  to perform step  126  when electrical disturbances in the vehicle may affect the performance of an actuator, which would then require the actuator to perform a calibration process. Electrical disturbances include high voltage, low voltage, or intermittent voltage; where an intermittent voltage could be caused by manufacturing defects, mechanical stress, or corrosion. However, before the ACU  116  performs a calibration with the actuator it must be determined if the ACU  116  has received information from the ECU  111 . If the ACU  116  has received information from the ECU  111  then the ACU  116  can determine if conditions allow for a calibration at step  120 . The reason the ACU  116  must receive information from the ECU  118  before the ACU  116  can determine if conditions allow for a calibration routine is to ensure that the ACU  116  does not perform a calibration routine with the actuator during certain engine operating conditions. Therefore, after the steps  122 ,  123  of performing a partial calibration routine are complete, the ACU  116  disregards other factors that direct the ACU  116  to command the actuator to perform the step  120  of a second self calibration process until the ECU transmits a second input signal to the ACU  116 , to allow the ACU  116  to command the actuator to run the second self calibration process. Under certain engine operating conditions a calibration process is performed it can cause poor engine performance, failure to meet emissions legislation, or damage to vehicle components. Also prior to engine start-up or at engine shut down the signals transmitted by the ECU can cause the ACU to command a calibration process. A specific example includes calibration or verification that must occur prior to an engine reaching a specific RPM during starting. 
     If the ACU  116  has not received information from the ECU, but the conditions have directed the ACU  116  to perform a calibration; the ACU  116  will perform a partial calibration with the actuator at step  122 . A partial calibration will not cause undesirable effects while being performed. After the partial calibration has been performed the actuator operates using previously stored data and the information acquired during the partial calibration at step  124 . The control strategy  110  must then reset in order to determine if the conditions allow for a calibration at step  120 . 
     The devices that the present control strategies  10 ,  110  can be used with are devices or actuators such as, but not limited to vehicle engine actuators including turbochargers, exhaust gas recirculation valves, throttle valves, shift actuators, transfer case shift mechanisms, clutches and transmission shift mechanisms, variable cam timing mechanisms, tuning actuators, fuel injectors, etc. The control strategies  10 ,  110  of the present invention are used to learn or calibrate the functions of these devices and other devices having similar functions. Functions include but is not limited to mechanical stops, current or voltage fluctuation, air flow capacity, torque range angular movement, fuel metering, fuel quantity, force, linear travel, rotary movement, etc. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.