Coordinated Wheel Controller for Independent Torque Control
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Solution Overview
Problem
Conventional systems face challenges in simultaneously controlling wheel slip and vehicle acceleration effectively, especially in traction control situations due to the complex and nonlinear interaction of brake torque and engine torque on vehicle dynamics.
Innovation Solution
A real-time system with a coordinated wheel controller subsystem that generates torque signals to control total and asymmetric dynamics of the axle, using feedback and feed-forward control modes to manage wheel slip and vehicle acceleration independently for each wheel, while also distributing drive and brake torque targets to achieve stable and accelerated vehicle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional ABS/TCS systems control wheel slip using brake torque and engine torque, then wheel slip can be reduced for stability, but vehicle acceleration control becomes complicated and difficult to optimize simultaneously
Solution Approach 1:
The patent segments the control task into two independent controllers: a total controller that manages the sum of torques for vehicle acceleration, and an asymmetric controller that manages the difference of torques for wheel slip control. This segmentation decouples the previously coupled control problem, allowing each controller to optimize its function independently without interfering with the other.
Solution Approach 2:
The patent introduces intermediate variables (total torque T and asymmetric torque difference ΔT) as mediators between the actuators (brake torques and engine torque) and the control objectives. These intermediate variables simplify the control architecture by providing a clear mathematical relationship: T_BL + T_BR = T and T_BR - T_BL = ΔT, making the control system more manageable and less complex.
2Speed
If engine torque is used for traction control to maximize acceleration, then vehicle acceleration improves, but wheel slip control becomes more difficult due to nonlinear interactions
Solution Approach 1:
By segmenting the control functions, the patent allows the asymmetric controller to focus exclusively on wheel slip control while the total controller handles acceleration. This separation makes wheel slip control less difficult because it no longer needs to simultaneously manage the nonlinear engine torque interactions - that task is handled by the total controller through direct torque specification.
Solution Approach 2:
The patent changes the control parameters from individual wheel torques to aggregated total torque and asymmetric torque difference. This parameter transformation simplifies the control equations and makes the system more responsive, allowing faster adaptation to changing wheel slip conditions without being constrained by the nonlinear characteristics of engine torque delivery.
3Stability of the object's composition
If brake torque is increased to control wheel slip, then wheel stability improves, but vehicle acceleration capability is reduced
Solution Approach 1:
The segmentation of control functions allows the total controller to compensate for any acceleration loss caused by brake intervention. When the asymmetric controller applies brake torque to control wheel slip, the total controller simultaneously adjusts the total torque command to maintain the desired vehicle acceleration, effectively decoupling wheel stability control from acceleration capability.
Solution Approach 2:
The patent merges the control of total torque and asymmetric torque difference into a unified distributed control system that coordinates brake and engine actuators. This merging allows the system to achieve both wheel slip control and acceleration control simultaneously by optimally distributing the required torques across available actuators based on real-time conditions.
Data Source
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AI summary
The present disclosure relates to a system for real time control of a wheel slip of each slipping wheel of a pair of wheels associated with an axle of a motor vehicle, simultaneously and independently with real time explicit control of said motor vehicle's acceleration provided by each non-slipping wheel associated with the axle. The system makes use of a total controller and an asymmetric controller associated with the axle of the vehicle for generating two torque signals used to control the total and asymmetric dynamics respectively of the axle, and a distributor for distributing the two said torque signals into available actuators' targets. The two said controllers each contain feedback and feed forward control elements, is operable to sense wheel slippage condition of each wheel on the axle, and augments the feedback and feed forward control based on the sensed wheel slippage conditions.