Multi-Unit Vehicle Control Allocation to Prevent Counteracting Forces
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Solution Overview
Problem
Existing control allocation methods for multi-unit vehicle combinations with distributed actuators result in inefficient energy consumption due to actuators working against each other, leading to counteracting forces and moments, especially when electric motors and service brakes are used across multiple vehicle units.
Innovation Solution
A method that defines a reference control input considering actuator capabilities to ensure that contributions to longitudinal forces do not counteract each other, minimizing energy waste by evenly distributing forces among vehicle units and optimizing actuator usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If control allocation is performed without considering actuator capabilities, then the control problem can be solved mathematically, but energy efficiency deteriorates due to counteracting forces
Solution Approach 1:
The patent transforms the control allocation problem by changing the parameter representation from direct force distribution to a reference control input framework that incorporates actuator capabilities. By defining uref based on actuator efficiency characteristics and capability constraints, the system achieves both mathematical solvability and energy optimality simultaneously.
Solution Approach 2:
The patent implements feedback by continuously monitoring actuator capabilities and efficiency characteristics, then adjusting the reference control input uref accordingly. This feedback loop ensures that the control allocation adapts to current system states, preventing counteracting forces and optimizing energy usage while maintaining solution validity.
2Adaptability or versatility
If actuators are distributed across multiple vehicle units, then system versatility and propulsion capability improve, but control complexity increases due to underdetermined systems
Solution Approach 1:
The patent segments the control problem into two distinct parts: a reference control input uref that encodes actuator capabilities and efficiency, and a control allocation solver that finds the optimal distribution. This segmentation reduces complexity by pre-processing capability constraints into uref, allowing the allocation problem to focus solely on finding valid force distributions.
Solution Approach 2:
The patent performs preliminary action by pre-calculating and storing actuator capabilities, efficiency characteristics, and generating the reference control input uref before the actual control allocation is needed. This pre-processing eliminates the need to repeatedly handle complex capability constraints during real-time allocation, significantly reducing computational complexity.
3Productivity
If conventional control allocation methods are used, then mathematical solutions can be found, but energy consumption increases due to lack of actuator capability consideration
Solution Approach 1:
The patent changes the parameter framework by introducing efficiency matrices and capability constraints as explicit parameters in the reference control input uref. This transformation allows the control allocation to directly incorporate energy efficiency considerations into the mathematical solution process, ensuring that solved controls are inherently energy-optimized.
Solution Approach 2:
The patent uses feedback from actuator efficiency characteristics and capability measurements to continuously adjust uref. This feedback mechanism ensures that the control allocation consistently selects energy-efficient actuator combinations and operating points, reducing overall energy consumption while maintaining solution availability.
Data Source
AI summary
A method of control allocation in a multi-unit vehicle combination is provided. The units include actuators configured to generate propulsion and/or braking forces. The method includes receiving a virtual control input for the vehicle combination as a whole, solving a control allocation problem to find a true control input for the actuators, including attempting to minimize a difference between the true control input and a reference control input. The method includes controlling the actuators based on the true control input. In particular, the method includes generating the reference control input such that a) capabilities of the actuators are taken into account, and b) such that a longitudinal force contribution of one vehicle unit does not counteract the contribution of another vehicle unit.