Steering Assist Torque Compensation for Cardan Joint Fluctuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The fluctuation of torque applied to the steering shaft due to universal joints causes discomfort to the driver, as it varies with the steering angle, which is not aligned with the driver's intended steering torque.
Innovation Solution
A turning control device that applies assist motor torque closer to the steered wheels, using a control device to adjust the assist motor torque based on steering angle and detection values to stabilize the steering torque, incorporating a compensating torque control process to maintain consistent torque levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the assist motor torque is applied closer to the steered wheels than the universal joints, then the steering assist effectiveness is improved, but the torque applied to the steering shaft fluctuates in accordance with the steering angle causing driver discomfort
Solution Approach 1:
The control device continuously monitors the steering angle and uses this feedback to dynamically adjust the assist motor torque. By detecting the steering angle and calculating the required compensation torque based on the relationship between steering angle and torque ratio, the system maintains stable steering shaft torque while providing effective assist closer to the steered wheels.
Solution Approach 2:
The system changes the torque parameter of the assist motor dynamically based on the steering angle. The control device calculates a compensation torque that varies with steering angle to counteract the fluctuation caused by the universal joint geometry, thereby maintaining constant steering shaft torque across different steering positions.
2Stability of the object's composition
If the torque at the position closer to the steered wheels is controlled to not fluctuate with steering angle, then the steering torque stability is improved, but the torque applied to the steering shaft fluctuates due to universal joint geometry
Solution Approach 1:
The control device acts as an intermediary between the assist motor and the steering system. It processes the relationship between steering angle and torque ratio, calculating a compensation torque that mediates the effect of universal joint geometry on steering shaft torque, thereby stabilizing the overall steering torque.
Solution Approach 2:
The system applies preliminary compensatory torque to counteract the expected fluctuation caused by universal joint geometry. By calculating the anticipated torque variation based on steering angle and applying an equal and opposite compensation, the system prevents steering shaft torque fluctuation before it occurs.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A turning control device for controlling, as a controlled object, a turning apparatus (10) including a steering wheel (12), an input shaft (14), an intermediate shaft (18), an output shaft (22), a first Cardan joint (16), a second Cardan joint (20), steered wheels (36), and an assist motor (42) includes a control device (50). The control device (50) configured to execute: a torque acquisition process of acquiring a detection value of a torque applied to a position closer to the steered wheels (36) than the second Cardan joint (20); a steering angle variable acquisition process of acquiring a value of a steering angle variable indicative of a steering angle as an angle of the steering wheel (12); and an assist control process including a fluctuation torque control process of fluctuating the torque of the assist motor (42) in accordance with the steering angle with the value of the steering angle variable being taken as an input.