Steering Control Apparatus Vibration Torque Cancellation
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Solution Overview
Problem
Vibration caused by gear meshing in variable gear ratio steering (VGRS) systems leads to uncomfortable driving experiences due to manufacturing errors, which existing technologies have not adequately addressed.
Innovation Solution
A steering control apparatus that includes a variable gear ratio device, an electric power steering device, and a control circuit with a vibration torque acquisition part, correction part, and operation control part to correct assist torque based on acquired vibration torque, thereby reducing the transfer of vibration to the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable gear ratio device with gear mechanism is provided to the steering wheel shaft, then the gear ratio can be varied to improve steering performance, but vibration caused by gear meshing is directly transferred to the steering wheel causing driver discomfort
Solution Approach 1:
The patent introduces a vibration cancellation mechanism as an intermediary between the gear mechanism and the steering wheel. This mechanism includes a vibration generator that produces counter-vibration to cancel the meshing vibration, and a sensor that detects the vibration characteristics. The vibration cancellation mechanism acts as a mediator that blocks the transmission of harmful vibrations to the driver while preserving the gear ratio variability function.
Solution Approach 2:
The patent applies the principle of mechanical vibration by using a vibration generator to produce counter-vibration that cancels the meshing vibration from the gear mechanism. The vibration generator creates vibrations with opposite phase and equal amplitude to the harmful vibrations, thereby canceling them out before they reach the steering wheel and driver.
2Ease of manufacture
If standard manufacturing tolerances are used for gear components, then manufacturing costs are reduced, but vibration is generated due to manufacturing errors affecting driver comfort
Solution Approach 1:
The patent converts the harmful vibration caused by manufacturing errors into a beneficial control parameter. By using sensors to detect the vibration characteristics and a feedback control system, the harmful vibrations are measured and canceled out. This allows the use of standard manufacturing tolerances while maintaining driver comfort, as the manufacturing errors are compensated for through active vibration cancellation rather than requiring expensive precision manufacturing.
3Force
If assist torque is provided without correction, then steering assistance is maximized, but vibration torque from gear meshing is also transferred to the driver
Solution Approach 1:
The patent implements a feedback control system where sensors detect the vibration torque generated by gear meshing, and this information is fed back to the control unit. The control unit then adjusts the assist torque from the motor to cancel out the vibration torque. This feedback mechanism allows the system to provide maximum steering assistance while simultaneously canceling the harmful vibration torque before it reaches the driver.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses the uncomfortable feeling caused by gear vibration, improving the driving experience by canceling out vibration torque generated by the gear mechanism, thus enhancing the precision and reducing manufacturing costs.
Implementation Method 1
The gear mechanism is configured to transfer rotation of the input shaft to the output shaft
Implementation Method 2
the first motor is configured to drive the gear mechanism
Implementation Method 3
The power steering device includes a second motor and is configured to assist steering operation of the driver on the steering member by torque generated by driving the second motor
Data Source
AI summary
A steering control apparatus acquires vibration torque, which is generated by vibration of a gear mechanism when a steering wheel is operated at a steering angle. By setting the acquired vibration torque as a torque difference, an EPS motor current command value is corrected based on the torque difference thereby to calculate a corrected EPS motor current command value. Rattling and vibration caused in the gear mechanism are suppressed from being transferred to the steering wheel through an input shaft so that a driver is released from uncomfortable feeling.