Vehicle Test Stand Acceleration Sensor Integration
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Solution Overview
Problem
Existing methods for determining vehicle longitudinal acceleration on a test bench often result in inaccuracies due to simplified vehicle modeling, leading to deviations from actual driver-perceived acceleration, and require test drives, which are time-consuming and costly.
Innovation Solution
A method that uses an acceleration sensor and a position control circuit to detect and calculate low-frequency longitudinal acceleration components, allowing for realistic simulation of vehicle acceleration by dynamically controlling actuators based on direct torque measurements, and employing high-pass filtering to prioritize high-frequency components perceived by the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If longitudinal acceleration is determined from a vehicle model based on measured rotational movement, then the determination can be made on the test bench without test drives, but the accuracy deviates from actual driver-perceived acceleration
Solution Approach 1:
An acceleration sensor is introduced as an intermediary device mounted on the vehicle to directly measure the actual acceleration experienced by the vehicle. This sensor data serves as a mediator between the vehicle model calculations and the final acceleration determination, allowing correction of model deviations while maintaining test bench efficiency.
Solution Approach 2:
The system implements feedback by continuously comparing the model-determined acceleration with the sensor-measured acceleration and using this information to correct the vehicle model parameters. This closed-loop approach allows the system to learn from discrepancies and improve accuracy over time while remaining on the test bench.
2Measurement precision
If an acceleration sensor is attached to the motor vehicle to determine longitudinal acceleration, then accuracy improves, but the movement of the vehicle relative to the roller test stand causes a difference between wheel and roller speeds that falsifies test results
Solution Approach 1:
The acceleration determination is segmented into two independent components: wheel/roller speed measurement (for drivetrain analysis) and sensor-based acceleration measurement (for drivability assessment). This segmentation allows each measurement to be optimized for its specific purpose without interfering with the other, resolving the conflict between accuracy and validity.
Solution Approach 2:
The system transitions from relying solely on rotational movement data (one dimension) to combining rotational data with direct acceleration sensing (adding a temporal dimension). This dimensional expansion allows the system to capture both the mechanical motion and the actual acceleration experience, enabling accurate drivability assessment without compromising test validity.
3Manufacturing precision
If the entire longitudinal acceleration signal is simulated by the actuator, then complete acceleration profile is achieved, but the distance covered during testing increases significantly
Solution Approach 1:
Low-frequency acceleration components are extracted and separated from the total acceleration signal. These low-frequency components are then simulated by the position control circuit, while the high-frequency components are handled by the actuator. This extraction allows the actuator to focus on the critical high-frequency drivability aspects without needing to reproduce the entire acceleration profile, significantly reducing test distance.
Solution Approach 2:
The system dynamically assigns different frequency components of acceleration to different simulation mechanisms: the actuator handles high-frequency components critical for drivability, while the position control circuit handles low-frequency components. This dynamic division allows accurate acceleration profiling with minimal travel distance by optimizing which components are physically simulated versus which are calculated.
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a vehicle test stand and a method for ascertaining a vehicle longitudinal acceleration (as) during a test of a vehicle (2) in such a vehicle test stand (1), comprising at least one actuator (6) for moving the vehicle (2) in a longitudinal direction. During the test, a rotational movement which is carried out by a wheel or a powertrain of the vehicle (2) is measured in real-time, a longitudinal acceleration (a) corresponding to the measured rotational movement is ascertained, and the at least one actuator (6) is actuated depending on the ascertained longitudinal acceleration. The vehicle (2) is connected to an acceleration sensor (7), and an acceleration signal (as,HF) of the acceleration sensor (7) is detected during the test. A low-frequency longitudinal acceleration component (aNF; a'NF) is calculated based on the ascertained longitudinal acceleration (a) and a position control loop (18) for controlling the actuator (6), and the vehicle longitudinal acceleration (as) is ascertained based on the detected acceleration signal ( as, HF) and the calculated low-frequency longitudinal acceleration component (aNF; a'NF).