Active Suspension Groundhook Blending for End-of-Travel Control
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Solution Overview
Problem
Conventional suspension systems face challenges in maintaining user comfort while effectively handling a wide range of road conditions, often leading to undesirable events like reaching the end of suspension travel, especially when encountering large road disturbances.
Innovation Solution
A vehicle control system that dynamically blends vehicle body isolation and road tracking controls using a blend ratio to adjust active suspension forces, incorporating current information to adapt to various road conditions and prevent end-of-travel events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional passive suspension systems are used, then the system structure is simple, but the system cannot adapt to varying road conditions and reaches end of suspension travel easily
Solution Approach 1:
The patent implements dynamic suspension control by continuously adjusting the blend ratio between skyhook and groundhook control strategies based on real-time road conditions. The system transitions from static to dynamic operation, allowing the suspension to adapt its characteristics dynamically rather than being fixed, thereby resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The system changes control parameters (blend ratio, force commands) based on detected road conditions. By varying these parameters dynamically, the suspension achieves adaptability to different road surfaces while maintaining a relatively simple hardware structure, thus resolving the contradiction between adaptability and device complexity.
2Ease of operation
If skyhook control is used for vehicle body isolation, then occupant comfort is improved, but the suspension reaches end of travel on large road disturbances
Solution Approach 1:
The system dynamically adjusts the blend ratio between skyhook and groundhook control based on real-time conditions. When road disturbances are small, skyhook control dominates for comfort; when disturbances are large, groundhook control increases to prevent end-of-travel events. This dynamic adjustment resolves the contradiction between comfort and reliability.
Solution Approach 2:
The system uses feedback from suspension position sensors to detect approaching end-of-travel conditions and adjusts the control strategy accordingly. By incorporating feedback about suspension state, the system can switch from pure skyhook control to a blended approach that maintains comfort while preventing mechanical limits from being reached, thus resolving the contradiction between comfort and reliability.
3Reliability
If groundhook control is used for road tracking, then end of travel events are prevented, but occupant comfort deteriorates
Solution Approach 1:
The system dynamically adjusts the blend ratio to favor groundhook control only when necessary (large road disturbances or approaching end of travel), while maintaining skyhook control for comfort during normal conditions. This dynamic balancing resolves the contradiction by applying groundhook control selectively rather than continuously.
Solution Approach 2:
The system changes the blend ratio parameter dynamically based on road conditions and suspension state. By adjusting this parameter, the system optimizes the trade-off between ground tracking (reliability) and vehicle body isolation (comfort), resolving the contradiction through parameter optimization rather than fixed control strategy.
4Adaptability or versatility
If semi-active suspension with adjustable damping is used, then trade-off between comfort and handling is achieved, but the system cannot handle large road disturbances effectively
Solution Approach 1:
The patent transitions from semi-active damping adjustment to fully active force application. The active suspension system can generate sufficient force to handle large road disturbances by applying active forces through actuators, not just adjusting passive damping. This dynamic force application resolves the contradiction between adaptability and reliability for large disturbances.
Data Source
AI summary
A vehicle may include a vehicle body, a plurality of wheels, an active suspension system operatively coupled to the plurality of wheels and the vehicle body, and at least one processor configured to control the active suspension system. The at least one processor may be configured to determine a first force command based on a vehicle body parameter, determine a second force command based on the vehicle body parameter and a suspension parameter, determine a blend ratio based on the first force command, determine a third force command based at least partly on the blend ratio, the first force command, and the second force command, and command the at least one actuator to apply force between at least one of the plurality of wheels and the vehicle body based at least partly on the third force command.