Adaptive Autopilot Control for Vessel Tracking Stability
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Solution Overview
Problem
Conventional autopilot systems for vessels and mobile structures are inherently unstable due to phase lag issues in cross track error feedback loops, leading to sluggish and unpredictable tracking, especially with noisy GPS data and variable vehicle responses, and require extensive configuration for each vehicle type, limiting their adaptability and accuracy.
Innovation Solution
An adaptive autopilot system utilizing high-quality turn rate signals and GPS data to generate high-bandwidth cross track errors, combined with sensors like orientation, position, and sonar systems, to provide robust directional control through an adaptive controller that adjusts steering demands based on real-time sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional autopilot systems use cross track error feedback loops, then directional control is provided, but phase lag issues cause instability and sluggish tracking
Solution Approach 1:
The patent implements a feedback mechanism where the adaptive controller continuously receives cross track error signals and adjusts steering demands based on real-time vehicle response. The system monitors actual tracking performance and dynamically modifies control parameters to compensate for phase lag, creating a self-correcting control loop that maintains stability despite varying vehicle characteristics and environmental conditions.
Solution Approach 2:
The adaptive controller dynamically adjusts control parameters in real-time based on measured vehicle response characteristics. The system modifies steering demands adaptively rather than using fixed control gains, allowing the control loop to respond to changing vehicle dynamics, sea conditions, and sensor noise levels, thereby maintaining stability across varying operating conditions.
2Loss of information
If conventional autopilot systems use noisy GPS data, then position information is obtained, but measurement accuracy deteriorates leading to unpredictable tracking
Solution Approach 1:
The adaptive controller acts as an intermediary between the noisy GPS position data and the steering control system. It processes cross track error signals through adaptive filtering and interpretation, separating genuine positional deviations from noise-induced variations. The system uses multiple sensor inputs and adaptive algorithms to filter out measurement noise while preserving accurate position information for control decisions.
Solution Approach 2:
The system dynamically changes processing parameters based on measured signal quality and vehicle response. When GPS noise levels are high, the adaptive controller adjusts filtering parameters, integration time constants, and steering demand modification factors to optimize tracking accuracy. This parameter adaptation allows the system to maintain measurement precision despite varying GPS data quality and environmental conditions.
3Manufacturing precision
If conventional autopilot systems are configured for specific vehicle types, then control parameters are optimized, but adaptability to different vehicles is reduced
Solution Approach 1:
The adaptive controller performs self-characterization by automatically measuring the vehicle's response to steering inputs during operation. It identifies vehicle-specific parameters such as turn rate characteristics, inertia, and response delays through real-time monitoring and adaptive identification algorithms. This self-service approach eliminates the need for manual configuration for each vehicle type while achieving optimal control parameter tuning specific to each vessel's characteristics.
Solution Approach 2:
The adaptive control system is designed to universally accommodate different vehicle types through a single unified controller architecture. By using adaptive parameter adjustment and real-time vehicle characterization, the system achieves multi-functionality across various vessel classes without requiring vehicle-specific hardware configurations or extensive manual tuning, thereby maintaining manufacturing precision while maximizing adaptability.
4Speed
If conventional autopilot systems use variable vehicle response data, then real-time control is provided, but control consistency deteriorates leading to oscillations
Solution Approach 1:
The adaptive controller dynamically adjusts control parameters in real-time to compensate for variable vehicle responses. It continuously monitors actual tracking performance and modifies steering demands adaptively, maintaining consistent tracking behavior despite variations in vehicle inertia, sea state, or sensor characteristics. This dynamic adaptation prevents oscillations by adjusting control aggressiveness to match current operating conditions.
Solution Approach 2:
The system implements continuous feedback monitoring of tracking errors and vehicle response characteristics. When oscillations are detected or variability increases, the adaptive controller adjusts feedback gains and integration parameters to dampen oscillatory behavior. This real-time feedback adjustment maintains control consistency by adapting to variable vehicle responses while preserving fast response capabilities when conditions are stable.
Data Source
AI summary
Autopilot systems and related techniques are provided to improve the ability of mobile structures to maintain a desired reference path (e.g., to keep a desired track and/or to follow a desired contour). In various embodiments, a high quality turn rate signal and GPS based signals are used to generate high bandwidth cross track/contour errors and other associated signals. An adaptive controller uses the generated cross track/contour signals to provide robust track keeping and/or contour following in the directional control of a mobile structure. Techniques are also provided for systems and methods to provide directional control for mobile structures.