Dynamometer Control Device Synchronizing Front Rear Wheel Speeds
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Solution Overview
Problem
Chassis dynamometer systems for four-wheel drive vehicles experience oscillatory control responses due to the lack of consideration for the fixed moment of inertia, leading to speed differences between the front and rear wheels, which can occur during synchronization control.
Innovation Solution
A control device that includes a driving force estimator, torque command signal generators, and synchronization correction signals to eliminate speed differences between the front and rear wheels, with synchronization control gains defined to ensure all poles of the transfer function are negative real numbers, preventing oscillatory behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization control is performed by adjusting current command signals according to speed difference and polarity, then the speeds of front and rear wheel rollers can be made equal, but oscillatory control response occurs due to lack of consideration for fixed moment of inertia
Solution Approach 1:
The patent changes the control parameters by introducing a synchronization control gain that is adjusted based on the magnitude of the standard deviation of the speed difference. This dynamic parameter adjustment allows the system to achieve reliable synchronization while preventing oscillatory behavior by adapting the control strength to the current speed difference conditions.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the speed difference between front and rear wheel rollers, calculating the standard deviation, and using this information to adjust the synchronization control gain. This closed-loop feedback mechanism ensures both synchronization accuracy and control stability by responding to actual system conditions.
2Adaptability or versatility
If the front wheel roller and rear wheel roller are independently driven without mechanical coupling, then each wheel can be controlled separately, but a speed difference is produced between the rollers requiring synchronization control
Solution Approach 1:
The patent introduces a synchronization control mechanism as an intermediary between the independently driven front and rear wheel rollers. This mediator calculates speed differences, determines appropriate control gains based on standard deviation, and adjusts current command signals to eliminate speed differences, thereby enabling both independent control and reliable synchronization.
Solution Approach 2:
The patent applies dynamic control by adjusting the synchronization control gain based on the real-time magnitude of the standard deviation of the speed difference. This dynamic adjustment allows the system to adapt to varying operating conditions, maintaining reliable synchronization while preserving independent control capability across different driving scenarios.
Data Source
AI summary
A control device of a dynamometer system is provided with: a driving force observer which estimates a generated driving force of a vehicle; an electrical inertia control unit which uses the driving force to generate a front wheel basic torque command signal and a rear wheel basic torque command signal; a synchronization control unit which generates a synchronization control torque command signal with respect to the basic torque command signal and the basic torque command signal in such a way as to eliminate a speed difference; and torque command signal generating units which use the synchronization control torque command signal to adjust the basic torque command signal and the basic torque command signal. The synchronization control unit is defined in such a way that the poles of a denominator polynomial of a transfer function from the driving force to the speed difference are all negative real numbers.