Method and system for dynamic testing of a vehicle exhaust system in a rigid frame test fixture
First Claim
1. A method for generating engine attachment control boundary conditions and corresponding actuator control signals for an exhaust system laboratory test fixture comprising:
- collecting actual acceleration road load data for both a vehicle frame at each of the locations where the exhaust system attaches to the vehicle frame, and relative displacement or acceleration data for a vehicle powertrain relative to the vehicle frame;
obtaining vehicle coordinates for test fixture accelerometer locations by identifying the vehicle coordinates that define the locations and directions on the vehicle frame at which the actual acceleration road load data was collected;
performing a rigid body analysis by applying the actual acceleration road load data and the identified vehicle coordinates in a statistical multiple linear regression analysis to define a rigid body that fits the road load acceleration data at the vehicle coordinates;
verifying the fit of the defined rigid body;
determining boundary conditions on the test fixture by selecting a set of accelerometer locations and directions which best fit the defined rigid body; and
determining the actuator control signals based on the determined boundary conditions in combination with a first control model arranged to control frame motion relative to a test floor.
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Abstract
A method and system are provided for generating engine attachment control boundary conditions and corresponding control signals for an exhaust system laboratory test fixture which accurately reproduce both the dynamic behavior of a vehicle powertrain during operation, and the dynamic behavior of the vehicle frame during operation in the area where the exhaust system is attached to the vehicle frame. Road load data is collected in vertical, lateral, and longitudinal directions on the vehicle frame during vehicle operation at each of the locations where the exhaust system attaches. In addition, temperature and thermal cycling data are also collected during operation of the vehicle. The road load data is used to determine a best fit rigid body model. Accelerometer locations and directions are determined from statistical analysis and ranking to find the measures best fitting the determined rigid body. This information is then used to generate the test boundary conditions and control signals to be input to the test fixture. Thermal profiles are generated based on the collected temperature data to form input control signals to control heating of the exhaust system during testing. The generated thermal profiles allow simulation of real-world thermal stresses caused by hot exhaust gases.
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Citations
23 Claims
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1. A method for generating engine attachment control boundary conditions and corresponding actuator control signals for an exhaust system laboratory test fixture comprising:
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collecting actual acceleration road load data for both a vehicle frame at each of the locations where the exhaust system attaches to the vehicle frame, and relative displacement or acceleration data for a vehicle powertrain relative to the vehicle frame;
obtaining vehicle coordinates for test fixture accelerometer locations by identifying the vehicle coordinates that define the locations and directions on the vehicle frame at which the actual acceleration road load data was collected;
performing a rigid body analysis by applying the actual acceleration road load data and the identified vehicle coordinates in a statistical multiple linear regression analysis to define a rigid body that fits the road load acceleration data at the vehicle coordinates;
verifying the fit of the defined rigid body;
determining boundary conditions on the test fixture by selecting a set of accelerometer locations and directions which best fit the defined rigid body; and
determining the actuator control signals based on the determined boundary conditions in combination with a first control model arranged to control frame motion relative to a test floor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
collecting data representative of actual exhaust system temperature and thermal cycling produced during operation of a vehicle;
generating a set of at least one thermal profile; and
heating the exhaust system attached to the test fixture based on the generated set of thermal profiles.
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14. The method of claim 1 further comprising determining whether to operate the test fixture to simulate the effect of the vehicle powertrain being attached to the vehicle frame based on the rigid body analysis, and determining the actuator control signals based on the determined boundary conditions in combination with a second control model arranged to control powertrain motion relative to the frame if the test fixture is to be operated as though the powertrain were attached to the frame.
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15. The method of claim 14 further comprising determining to operate the test fixture as though the powertrain were not attached to the frame if the vehicle is determined to not behave like a rigid body.
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16. The method of claim 1 further comprising selecting whether to use a fabricated frame rail or a rigid body mass table as the type of test fixture.
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17. A system for generating engine attachment control boundary conditions and corresponding actuator control signals for an exhaust system laboratory test fixture, wherein the test fixture includes a set of accelerometers mounted thereon and controlled by the actuator control signals to test a vehicle exhaust system mounted to the fixture, wherein the system comprises:
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a data collection subsystem arranged to collect actual acceleration road load data for both a vehicle frame at each of the locations where the exhaust system attaches to the vehicle frame, and relative displacement or acceleration data for a vehicle powertrain relative to the vehicle frame;
control processor connected to the set of accelerometers and responsive to the collected data to obtain vehicle coordinates for a set of locations for the test fixture accelerometers by identifying the vehicle coordinates that define the locations and directions on the vehicle frame at which the actual acceleration road load data was collected, the control processor being further arranged to perform a rigid body analysis by applying the actual acceleration road load data and the identified vehicle coordinates in a statistical multiple linear regression analysis to define a rigid body that fits the road load acceleration data at the vehicle coordinates, determine boundary conditions on the test fixture by selecting a set of accelerometer locations and directions which best fit the defined rigid body, and determine the actuator control signals based on the determined boundary conditions in combination with a first control model arranged to control frame motion relative to a test floor. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification