Arbitration Modules for EPS Controller Signal Consistency
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Solution Overview
Problem
In electrical power steering (EPS) systems with two controllers, differences in sensor readings and latency lead to inefficiencies due to non-trivial differences in calculated motor control commands, resulting in imbalanced assist torque generation.
Innovation Solution
A motor control system with arbitration modules that share and arbitrate input signals between controllers to generate consistent control outputs, using methods like averaging and low-pass filtering to minimize lag and ensure consistent signals, thereby maintaining balanced assist torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two independent controllers are used to calculate redundant motor control commands, then reliability is improved, but differences in sensor readings and latency lead to non-trivial differences in calculated commands, resulting in inefficiencies
Solution Approach 1:
The patent merges the control paths of two independent controllers by introducing arbitration modules that combine input signals from both controllers. The arbitration modules process signals from both controllers and generate unified arbitrated input signals, ensuring both controllers receive consistent inputs and produce consistent outputs, thereby maintaining reliability while improving efficiency.
Solution Approach 2:
The patent implements feedback mechanisms where controllers exchange their calculated commands with each other. Each controller receives the other's command as feedback, allowing them to adjust their outputs to match. This feedback loop ensures both controllers produce identical commands, eliminating inefficiencies while preserving the reliability benefits of redundant controllers.
2Measurement precision
If closed-loop control is performed with two controllers, then control precision is improved, but the two controllers end up with different values on integrator states, leading to large control commands and inefficiencies
Solution Approach 1:
The arbitration modules merge the control paths by combining input signals from both controllers before they enter the closed-loop control process. This ensures both controllers operate on identical input data, maintaining control precision while preventing divergent integrator states that would lead to large control commands and inefficiencies.
Solution Approach 2:
The patent creates equipotential conditions for both controllers by ensuring they receive identical arbitrated input signals. This equalizes their operating conditions, preventing one controller from developing different integrator states than the other, thereby maintaining efficiency while preserving control precision.
3Measurement precision
If high-speed communication protocols are used to synchronize controllers, then consistency between controllers is improved, but system complexity and cost increase
Solution Approach 1:
The arbitration modules serve as intermediaries between the two controllers, processing and combining their signals locally. This eliminates the need for high-speed communication protocols between controllers, as the arbitration modules handle signal synchronization using simpler, slower communication methods while still achieving consistent outputs from both controllers.
Solution Approach 2:
The patent replaces expensive, complex high-speed communication infrastructure with simpler, cheaper arbitration modules that perform signal combining and synchronization functions. This reduces system complexity and cost while maintaining the necessary consistency between controllers through software-based arbitration rather than hardware-based high-speed communication.
Data Source
AI summary
Technical solutions are described for a motor control system, such as one used in a steering system, the motor control system including multiple controllers. In an example, the motor control system includes a first arbitration module associated with a first controller, and a second arbitration module associated with a second controller. The first arbitration module generates a first arbitrated input signal based on a first input signal directed to the first controller, and a second input signal directed to the second controller. The second arbitration module generates a second arbitrated input signal based on the first input signal and the second input signal. The first controller generates a first control output using the first arbitrated input signal, and the second controller generates a second control output using the second arbitrated input signal.