Actuation validation algorithm

• US 5,115,396 A
• Filed: 07/13/1990
• Issued: 05/19/1992
• Est. Priority Date: 07/13/1990
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Keegan, Kevin R.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): AUCHTERLONIE, THOMAS
• Application Number:
  US07/552,171
• Time in Patent Office: 676 Days
• Field of Search: 364/431.01, 364/431.07, 364/431.11, 364/424.03, 364/571.02, 364/571.03, 364/571.04, 364/571.05, 364/474.15, 364/148, 364/153, 364/154 , 364/431.04, 364/151, 123/361, 123/399
• US Class Current: 701/102
• CPC Class Codes: F02D 11/107 Safety-related aspects
• CPC Class Codes: G05B 19/4062 Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference

Abstract

An adaptive actuation verification method monitors the difference between a desired position and an actual position of a movable device, to ensure that the actual position of the device is approaching the desired position in an acceptable manner. A range of acceptable approaches is calculated based on the response capability of the movable device. The range is updated on-line to account for any changes in the response capability. An actuation fault is assumed when the device does not approach the desired position within the calculated range.

Claims

1. A method of detecting a fault condition in a control system which controls the position of a movable body from a present actual position to a commanded position, the method comprising the steps of:

measuring the present actual position of said movable body;

generating the commanded position of said movable body;

calculating the rate of change in the commanded position of said movable body;

establishing an error limit by (a) setting the error limit to a reset value which is a predetermined function of the calculated rate of change in the commanded position of said movable body when the reset value is greater than the error limit value and (b) decaying the error limit value by means of a predetermined decay rate when the reset value is less than the error limit value;

calculating the error in said position, said error comprising the difference between said commanded position and said actual position;

comparing said position error to said error limit;

indicating a fault condition when said position error exceeds said error limit.

2. The method of claim 1, wherein the step of decaying said error limit value further comprises the step of calculating said predetermined decay rate as a functional of normal response time of said control system to a change in said commanded position.

3. The method of claim 1, wherein the step of decaying said error limit value further comprises the steps of:

measuring operating conditions of said system that affect the response time of said system to a change in said commanded position;

calculating said decay rate as a function of said operating conditions.

4. The method of claim 3, wherein the step of measuring said operating conditions and the step of calculating said decay rate further comprises:

measuring system voltage and system temperature;

calculating said decay rate as a function inversely proportional to system temperature and directly proportional to system voltage.

5. An apparatus for detecting a fault condition in a commanded throttle angle tracking system in an internal combustion engine, comprising:

a throttle blade seated in the bore of the air inlet of said engine, said blade being rotatable with respect to said bore to control the amount of air allowed into said engine;

rotational actuating means connected to said blade to rotate said blade with respect to said bore;

blade angle commanding means for commanding a blade angle of said blade with respect to said bore, corresponding to a desired amount of air to be allowed into said engine;

means for determining the rate of change of said blade angle command from said blade angle commanding means;

actuator control means for controlling said actuating means to rotate said blade to an angle corresponding to said commanded blade angle from said blade angle commanding means;

blade angle measuring means connected to said blade to measure the angular displacement of said blade with respect to said bore;

blade angle error computing means for computing the blade angle displacement error, said error comprising the difference between said commanded blade angle and said measured blade angle;

error limit determining means for determining limit an error value of said blade angle error, comprising (a) means for resetting said error limit to a reset value that is a function of said rate of change of said commanded throttle angle when said reset value is greater than said error limit value, and (b) means for decaying said error limit value when said reset value is less than said error limit value, said decaying means having a rate of decay proportional to a normal response time of the system to changes in said commanded throttle angle;

comparing means for comparing said blade angle error to said error limit;

fault signaling means for indicating a fault condition when said blade angle error exceeds said error limit.

6. The fault detecting apparatus of claim 5, wherein the means for decaying said error limit value further comprises:

means for sensing those operating conditions of said system that affect the response time of said system to changes in said commanded throttle angle;

means for calculating said decay rate as a function of said sensed operating conditions.

7. The fault detecting apparatus of claim 5, wherein the means for decaying said error limit value further comprises:

means for measuring the temperature of said actuating means;

means for measuring the voltage applied to said actuating means;

means for calculating said decay rate as a function inversely proportional to the temperature of said actuating means, and directly proportional to the voltage applied to said actuating means.

8. A method of detecting a fault condition in a control system which controls the position of a movable body from a present actual position to a commanded position in both a forward and reverse direction of motion, the method comprising the steps of:

measuring the present actual position of the movable body;

generating the commanded position of the movable body;

calculating the rate of change in the commanded position of the movable body;

establishing a first and second error limit value by (a) setting both the first and second error limit values to one common reset value that is a predetermined function of the rate of change of said commanded position when the reset value exceeds the first or second error limit values, (b) decaying the first error limit value according to a first decay rate and the second error limit value according to a second decay rate when the reset value is less than both the first and second error limit values, the first decay rate being related to a first normal response time of the system to changes in the commanded position of the movable body in the forward direction of motion, and the second decay rate being related to a second normal response time of the system to changes in the commanded position of the movable body in the reverse direction of motion;

calculating the error in said position, said error comprising the difference between said commanded position and said actual position;

indicating the existence of a fault when the position error exceeds the magnitude of the first error limit value when the movable body is moving in the forward direction of motion; and

indicating the existence of a fault when the current position error exceeds the magnitude of the second error limit value when the movable body is moving in the reverse direction of motion.

9. An apparatus for detecting a fault condition in a commanded throttle angle tracking system in an internal combustion engine, comprising:

a throttle blade seated in the bore of the air inlet of said engine, said blade being rotatable with respect to said bore to control the amount of air allowed into the engine;

rotational actuating means connected to said blade to rotate said blade with respect to said bore;

blade angle commanding means for commanding a blade angle of said blade with respect to said bore, corresponding to a desired amount of air to be allowed into said engine;

means for determining the rate of change of said blade angle command from said blade angle commanding means;

actuator control means for controlling said actuating means to rotate said blade to an angle corresponding to said commanded blade angle from said blade angle commanding means;

blade angle measuring connected to said blade to measure the angular displacement of said blade with respect to said bore;

blade angle error computing means for computing the blade angle displacement error, said error comprising the difference between said commanded blade angle and said measured blade angle;

means for establishing continuously varying first and second error limit values, comprising means for resetting both the first and the second limit value to a common reset value that is a predetermined function of the rate of change of the commanded throttle angle when said reset value exceeds the first or the second error limit value, (b) means for decaying the first error limit value according to a first decay rate and the second error limit value according to a second decay rate when the reset value is less than both the first and second error limit values, the first decay rate being related to a first normal response time of the system to changes in the commanded throttle angle requiring motion of the throttle blade in an opening direction with respect to the bore, and the second decay rate being related to a second normal response time of the system to changes in the commanded throttle angle requiring motion of the throttle blade in a closing direction with respect to the bore;

means for comparing said-throttle angle error to said first error limit value when said blade is moving in the opening direction;

means for comparing said throttle angle error to said second error limit value when said blade is moving in the closing direction;

means for signaling a fault when said throttle angle error exceeds said first error limit value when said blade is moving in said opening direction; and

means for signaling a fault when said throttle angle error exceeds said second error limit value when said blade is moving in said closing direction.