Backdrivable Marine Steering Actuator with Force Sensor

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Solution Overview

Problem

Existing steering apparatuses for marine vessels lack efficient and reliable actuation mechanisms that can steer the vessel effectively, particularly in scenarios where electrical power is unavailable or when resisting unintended steering movements.

Innovation Solution

A steering apparatus comprising a backdrivable linear actuator with an electric motor, a threaded shaft, and a force sensor, which allows for precise control and resistance to unwanted steering movements, even without continuous electrical power. The actuator is coupled to a steering device, such as a rudder, and includes a force sensor to measure forces applied by a helm or steering cable, enabling power-assisted steering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a non-backdrivable actuator is used to prevent unintended steering movements, then steering stability is improved, but the ability to steer without electrical power is lost

Engineering Contradiction:

Improvesteering stabilityVSAvoidsteering capability without power

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The actuator is designed to be backdrivable, allowing the steering mechanism to be manually overridden when electrical power is unavailable. This dynamic characteristic enables the system to adapt between powered and unpowered operating modes, resolving the contradiction between maintaining steering stability through non-backdrivability and preserving steering capability without power.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If a backdrivable actuator is used to allow manual steering without power, then adaptability is improved, but resistance to unintended movements deteriorates

Engineering Contradiction:

Improvesteering capability without powerVSAvoidsteering stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A force sensor is integrated into the actuator to detect forces applied to the steering mechanism. This feedback enables the control system to distinguish between intentional steering inputs and unintended movements, allowing the system to maintain stability while preserving manual override capability. The feedback mechanism resolves the contradiction by providing information to differentiate between desirable and undesirable backdriving.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If an electric motor is used for actuation, then ease of operation is improved, but reliability in power-free scenarios deteriorates

Engineering Contradiction:

Improvesteering controlVSAvoidsteering functionality without power

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The electric motor is designed with backdrivability, allowing it to be easily overridden by manual force when needed. This dynamic characteristic enables the system to switch between electrically-assisted operation (improving ease of operation) and manual operation (maintaining reliability without power), resolving the contradiction between these two requirements.

Inventive Principle:

Principle #15Dynamics

4Measurement precision

If a force sensor is added to detect applied forces, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveforce detectionVSAvoidactuator structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The force sensor serves multiple functions: it detects intentional steering inputs, identifies unintended movements, and provides feedback for control adjustments. By consolidating these multiple functions into a single component, the increase in device complexity is justified by the significant improvement in measurement precision and the ability to resolve the contradiction between backdrivability and steering stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides efficient and reliable steering of marine vessels by utilizing a backdrivable linear actuator that can resist unintended movements and maintain steering control even without continuous electrical power, enhancing the vessel's maneuverability and stability.

Implementation Method 1

The motor is an electric motor

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

a threaded shaft coupled to the output shaft of the motor and threadedly coupled to the actuator ram such that rotation of the output shaft of the motor causes actuation of the actuator

Methodology Applied

Scientific EffectMechanical threading: Screw