Method and apparatus for controlling an engine test apparatus using lead-lag control

• US 5,521,824 A
• Filed: 11/03/1994
• Issued: 05/28/1996
• Est. Priority Date: 12/07/1992
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Larson, William R., Eagan, Thomas E., Nigus, Durwin D.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US08/335,417
• Time in Patent Office: 572 Days
• Field of Search: 364/431.03, 364/431.04, 364/431.05, 364/424.03, 364/511, 364/551.01, 364/551.02, 364/571.01, 73/116, 73/117.2, 73/117.3, 73/862, 73/862.08, 73/862.18, 324/378, 324/383, 123/146.5
• US Class Current: 701/101
• CPC Class Codes: G01M 15/044 by monitoring power, e.g. by operating the engine with one of the ignitions interrupted; by using acceleration tests

Abstract

A system (102) and method for controlling the operation of an engine test apparatus (104) during a test cycle is provided. The system (102) includes an operator interface (106) for producing a control mode signal and a plurality of setpoints. The system (102) also includes a test controller (108) for receiving the control mode signal and the plurality of setpoints and responsively operating the engine test apparatus. The test controller (108) senses operating characteristics of the engine test apparatus (104). The test controller (108) also selectively operates engine test apparatus parameters in accordance with the control mode signal.

Claims

1. A system for controlling the operation of an engine test apparatus during a test cycle, the engine test apparatus including an engine and a throttle actuator for responsively controlling fuel flow to the engine, wherein the system controllably actuates the throttle actuator using a desired one of throttle position, torque and engine speed feedback modes, comprising:

operator interface means for producing a control mode signal indicative of the desired feedback mode and a setpoint corresponding to the desired one of throttle position, torque and engine speed feedback modes;

feedback select means for receiving said control mode signal, responsively sensing an operating characteristic of the engine test apparatus corresponding to the desired feedback mode and responsively producing a respective operating characteristic signal; and

test control means for receiving said control mode signal, said setpoint, and said respective operating characteristic signal and responsively operating the engine test apparatus, and wherein said test control means operates the throttle actuator using closed loop control based on the setpoint and the sensed operating characteristic;

wherein said test control means includes a lead-lag amplifier for providing lead-lag compensation for dynamic aspects of the engine'"'"'s response in response to torque or engine speed feedback being desired said lead-lag compensation having a transfer function of;

space="preserve" listing-type="equation">k·

(s+a).sup.2 /(s+b).sup.2,

where k, a and b are constants.

2. A system, as set forth in claim 1, wherein the engine test apparatus further includes a dynamometer and a dynamometer power supply to controllably provide electric current to said dynamometer in response to a current command from said test control means.

3. A system, as set forth in claim 2, wherein the system controllably actuates the dynamometer power supply using a desired one of the torque, engine speed, and dynamometer power supply current feedback modes.

4. A system, as set forth in claim 3, said control mode signal having one of a first, second or third value, wherein said first value being indicative of controlling the throttle actuator using engine speed feedback and controlling the dynamometer power supply using torque feedback being desired, said second value being indicative of controlling the throttle actuator using torque feedback and controlling the dynamometer power supply using engine speed feedback being desired, and said third value being indicating of controlling the throttle actuator using throttle position feedback.

5. A system for controlling the operation of an engine test apparatus during a test cycle, the engine test apparatus including an engine, a throttle actuator for responsively controlling fuel flow to the engine, a dynamometer and, a dynamometer power supply adapted to controllably provide electric current to the dynamometer in response to a current command, wherein the system controllably actuates the throttle actuator using a desired one of throttle position, torque and engine speed feedback modes and controllably actuates the dynamometer power supply using a desired one of torque, engine speed, and dynamometer power supply current feedback modes, comprising:

operator interface means for producing a control mode signal having one of a first, second, third, fourth, fifth values said first value being indicative of engine speed and torque feedback modes being desired for the throttle actuator and the dynamometer power supply, respectively, said second value being indicative of torque and engine speed feedback modes being desired for the throttle actuator and the dynamometer power supply, respectively, said third value being indicative of throttle position and torque feedback modes being desired for the throttle actuator and the dynamometer power supply, respectively, said fourth value being indicative of throttle position and engine speed feedback modes being desired for the throttle actuator and the dynamometer power supply, respectively, and said fifth value being indicative of throttle position and dynamometer power supply current feedback modes being desired for the throttle actuator and the dynamometer power supply, respectively, said operator interface means being adapted for producing setpoints corresponding to said desired feedback modes;

feedback select means for receiving said control mode signal, responsively sensing operating characteristics of the engine test apparatus corresponding to the desired feedback modes and responsively producing a respective operating characteristic signals; and

test control means for receiving said control mode signal, said setpoints, and said respective operating characteristic signals and responsively operating the engine test apparatus, wherein said test control means operates the throttle actuator using closed loop control based on the respective setpoint and the dynamometer power supply using closed loop control based on the respective setpoint, and wherein said test control means includes a lead-lag amplifier in the throttle actuator closed loop control to compensate for dynamic aspects of the engine'"'"'s response in response to torque or engine speed feedback being desired said lead-lag compensation having a transfer function of;

space="preserve" listing-type="equation">k·

(s+a).sup.2 /(s+b).sup.2,

where k, a and b are constants.

6. A method for controlling the operation of an engine test apparatus during a test cycle, the engine test apparatus including an engine and a throttle actuator for responsively control fuel flow to the engine, the system being adapted to controllable actuate the throttle actuator using a desired one of throttle position, torque, and engine speed feedback modes, comprising:

producing a control mode signal indicative of a desired feedback mode and a respective setpoint;

receiving said control mode signal, responsively sensing an operating characteristic of the engine test apparatus corresponding to the desired feedback mode and responsively producing a respective operating characteristic signal;

receiving said control mode signal, said respective operating characteristic signal, and said setpoint and responsively operating the throttle actuator using closed loop control based on the setpoint; and

compensating for dynamic aspects of the engine'"'"'s response using lead-lag phase compensation in response to the desired one of throttle position, torque, and engine speed feedback modes being one of torque and engine speed feedback modes, said lead-lag compensation having a transfer function of;

space="preserve" listing-type="equation">k·

(s+a).sup.2 /(s+b).sup.2,

where k, a and b are constants.