Rocket Landing Control Using Gimbal and Fin Force Distribution

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Solution Overview

Problem

Conventional rocket landing control systems face challenges in maintaining continuous horizontal translational motion without increasing manufacturing or operation costs, particularly due to inactive periods caused by the balance between lift and thrust components during landing.

Innovation Solution

A rocket control system that utilizes a gimbal mechanism and attitude control fin to generate horizontal forces independently of attitude changes, using a direct force combination of lift and thrust components, controlled by a measurement device group and operation control device to distribute steering angles effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional thrusters are added to solve the inactive period problem, then continuous horizontal translational control is achieved, but body weight and manufacturing costs increase

Engineering Contradiction:
Improvecontinuous control capabilityVSAvoidbody weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent makes the existing attitude control system perform dual functions: traditional attitude control and horizontal translational control. By redistributing the control authority of existing actuators (gimbal, attitude control fins) through a new control algorithm, the system achieves continuous horizontal control without adding dedicated thrusters, thereby avoiding weight increase while maintaining reliability

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the control parameters and control law of the existing system. Instead of adding hardware, it modifies the control distribution strategy by introducing a pseudo-steering-angle command that redistributes control authority among existing actuators based on real-time flight conditions, enabling continuous horizontal control through parameter optimization rather than structural expansion

Inventive Principle:
Principle #35Parameter changes

2Reliability

If additional thrusters are added to solve the inactive period problem, then continuous horizontal translational control is achieved, but manufacturing costs and operation costs increase

Engineering Contradiction:
Improvecontinuous control capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent makes the existing attitude control system perform dual functions: traditional attitude control and horizontal translational control. By redistributing the control authority of existing actuators (gimbal, attitude control fins) through a new control algorithm, the system achieves continuous horizontal control without adding dedicated thrusters, thereby avoiding weight increase while maintaining reliability

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the control parameters and control law of the existing system. Instead of adding hardware, it modifies the control distribution strategy by introducing a pseudo-steering-angle command that redistributes control authority among existing actuators based on real-time flight conditions, enabling continuous horizontal control through parameter optimization rather than structural expansion

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If attitude change is used for horizontal path control, then control is simple, but inactive periods occur when lift and thrust horizontal components balance

Engineering Contradiction:
Improvecontrol system complexityVSAvoidcontrol continuity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces a dynamic control distribution mechanism that adapts in real-time based on flight conditions. The pseudo-steering-angle command dynamically redistributes control authority among actuators according to the current balance between lift and thrust components, ensuring continuous control effectiveness throughout the flight envelope without the inactive periods that plague static control strategies

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameters and control law of the existing system. Instead of adding hardware, it modifies the control distribution strategy by introducing a pseudo-steering-angle command that redistributes control authority among existing actuators based on real-time flight conditions, enabling continuous horizontal control through parameter optimization rather than structural expansion

Inventive Principle:
Principle #35Parameter changes

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

Enables accurate and continuous control of horizontal translational motion during landing, reducing landing point errors and maintaining control without additional thrusters, thus avoiding inactive periods and cost increases.

Implementation Method 1

the aerodynamic force proportional to this angle of attack α acts on the rocket body. This aerodynamic force includes a component perpendicular to the velocity vector V of the rocket, which is called 'lift.' The lift L increases according to an increase in the angle of attack α.

Methodology Applied
Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 2

thrust T acts on the rocket body by a jet produced by an engine. When the rocket body is inclined to have a predetermined attitude angle θ with respect to the direction of gravity, a horizontal component Th of the thrust T increases according to an increase in the attitude angle θ.

Methodology Applied
Scientific EffectThrust vectoring: Jet

Data Source

PatentEP4184277B1Rocket control system and method of controlling landing operation of rocket
Publication Date: 2025.12.03 JAPAN AEROSPACE EXPLORATION AGENCY
  • EP4184277B1 patent drawingFigure 1
  • EP4184277B1 patent drawingFigure 2
  • EP4184277B1 patent drawingFigure 3

AI summary

Provided is a method of controlling horizontal translational motion of a rocket without changing the attitude of the body and without increasing manufacturing costs and operation costs. This allows for accurate execution of rocket landing operation. A rocket control system includes a gimbal actuator that controls a steering angle of a gimbal mechanism located on a lower side of the body of the rocket with respect to the center of gravity; a fin actuator that controls a steering angle of an attitude control fin located on an upper side of the body of the rocket with respect to the center of gravity; a measurement unit that measures a physical quantity related to motion of the body of the rocket; and a control unit that controls the gimbal mechanism and the attitude control fin according to a result of measurement by the measurement unit to control horizontal translational motion of the rocket.