Vehicle Motion Control Using Chassis-Aware Torque and Steering
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Solution Overview
Problem
The coordination of multiple electric motors and steering in electric vehicles to achieve concurrent drivability and passenger comfort, while maintaining desired vehicle acceleration and direction changes, is challenging due to the interconnection and conflict between rapid acceleration and direction changes causing increased chassis motion.
Innovation Solution
A controller is employed to predict the effects of command signals using a prediction model, which comprises two models: one for vehicle motion and one for chassis motion, to optimize steering angles and motor forces, minimizing chassis motion while achieving desired drivability and comfort by penalizing lift, pitch, and roll.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple electric motors are used to achieve rapid acceleration and direction changes, then vehicle drivability is improved, but chassis motion (roll, pitch, lift) increases reducing passenger comfort
Solution Approach 1:
The controller continuously monitors vehicle state (acceleration, yaw rate, chassis motion) and adjusts motor forces in real-time based on feedback from sensors. The cost function incorporates chassis motion penalties that are dynamically optimized based on current vehicle state, creating a closed-loop feedback system that reduces chassis motion while maintaining drivability.
Solution Approach 2:
The system dynamically changes motor forces and steering angles as control parameters to optimize the trade-off between drivability and comfort. The cost function weights for chassis motion penalties are adjusted based on driving conditions, allowing the system to prioritize comfort when appropriate while maintaining rapid response when needed.
2Object-affected harmful factors
If active suspensions are used to reduce chassis motion and improve comfort, then passenger comfort is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical active suspension system with an electrical control system that uses multiple electric motors to influence chassis motion. Instead of mechanically actuating suspension components, the system uses motor forces and steering control to achieve the same comfort objective, reducing mechanical complexity while maintaining effectiveness.
Solution Approach 2:
The electric motors serve dual functions: providing propulsion for vehicle movement and simultaneously controlling chassis motion for passenger comfort. This multi-functionality eliminates the need for separate active suspension actuators, reducing overall system complexity and cost.
3Device complexity
If semi-active suspensions are used to reduce cost compared to active suspensions, then device complexity is reduced, but control capability over chassis motion is limited
Solution Approach 1:
The system replaces the semi-active suspension mechanism with an electrical control approach using multiple motors. This substitution provides full active control capability without the mechanical complexity of semi-active suspension components, achieving both simplicity and high control capability simultaneously.
Data Source
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AI summary
A controller and a method for controlling motion of a vehicle is provided. The method comprises acquiring motion information including a current state of the vehicle and a desired state of the vehicle, determining a combination of a steering angle of the wheels and motor forces for moving the vehicle from the current state into the desired state by using a first model of the motion of the vehicle and a second model of the motion of the chassis of the vehicle, determining a cost function of the motion of the vehicle, optimizing the cost function of the motion of the vehicle to compute a command signal for controlling the steering wheel and the plurality of electric motors, and controlling the steering angle of the wheels and the motor forces based on the command signal.