Steering Control System Reducing Motor Current at Low Speed
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electric power steering systems, when a vehicle stops with a turned steering wheel, feedback control maintains a current in the electric motor, leading to increased power consumption, as the system struggles to balance the force for returning to a neutral position with the frictional force between the wheels and the road, potentially going against the driver's intention and causing unnecessary torque.
Innovation Solution
A turning control system with a controller that calculates and adjusts the steering operation amount and angle command values to minimize the electric motor's current by decreasing the angle operation amount when vehicle speed is low and steering torque is minimal, ensuring the system aligns with the driver's intention and reduces power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is performed to maintain the turning angle at a target turning angle, then the turning angle control precision is improved, but the electric motor current increases leading to higher power consumption
Solution Approach 1:
The patent applies dynamics by making the feedback control gain variable rather than constant. The gain is adjusted based on vehicle speed and steering angle, allowing the system to maintain high precision when needed while reducing power consumption when the vehicle is stationary or moving slowly. This dynamic adjustment resolves the contradiction between maintaining precise control and minimizing energy usage.
Solution Approach 2:
The patent changes the parameter of feedback control gain based on operating conditions (vehicle speed and steering angle). By modifying this control parameter dynamically, the system achieves both precise turning angle control when required and reduced motor current when the vehicle is stationary, thus resolving the contradiction between control precision and power consumption.
2Stability of the object's composition
If feedback control is performed to maintain the turning angle at a target turning angle when the vehicle is stopped, then the turning angle stability is improved, but the electric motor current remains large causing unnecessary power consumption
Solution Approach 1:
The patent makes the feedback control gain dynamic by adjusting it according to vehicle speed and steering angle. When the vehicle is stopped and the steering angle is small, the gain is reduced or control is suspended, allowing the turning angle to naturally return to neutral under friction forces while minimizing power consumption. This resolves the contradiction between maintaining stability and reducing energy usage during stationary periods.
Solution Approach 2:
The patent applies preliminary anti-action by anticipating the unnecessary power consumption issue before it occurs. The control system proactively reduces or suspends feedback control when vehicle speed is below a threshold and steering angle is small, preventing the motor from maintaining unnecessary current and thus avoiding the contradiction between stability and power consumption.
3Speed
If the feedback control gain is increased to improve the turning angle control response, then the control response speed is improved, but the electric motor torque increases causing excessive force
Solution Approach 1:
The patent applies dynamics by making the feedback control gain variable based on vehicle speed and steering angle. This allows the system to provide high control response speed when the vehicle is moving by increasing the gain, while reducing the gain when the vehicle is stationary to minimize motor torque. This dynamic adjustment resolves the contradiction between fast response and excessive force.
Data Source
AI summary
A turning control system includes a controller. The controller is configured to perform a decrease process of decreasing a magnitude of an angle operation amount which is reflected in an operation process with respect to the magnitude of the angle operation amount calculated in an angle operation amount calculating process when a vehicle speed is equal to or lower than a prescribed speed and a magnitude of an input torque of a steering wheel is equal to or less than a prescribed value. The controller is configured to perform a correction process of correcting an input when the decrease process is performed such that a magnitude of the input decreases when an angle command value calculating process calculates an angle command value.