Mechanical Stepper Motor Actuator for Guided Munitions

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Solution Overview

Problem

Current actuation technologies for gun-fired projectiles and mortars face limitations such as limited control authority, high power requirements, large volume occupation, high cost, survivability issues at high-g firing accelerations, and complexity in integration, which hinder their effectiveness and practicality for guided munitions.

Innovation Solution

The development of mechanical stepper motor actuators with varying step sizes and integrated locking mechanisms, powered by pressurized gas or detonation charges, which provide high force and torque while occupying minimal volume and requiring low electrical power, enabling precise control and survivability in harsh environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If electric motors are used for actuation in guided weaponry, then control authority and actuation capability are achieved, but volume occupation and power requirements increase significantly

Engineering Contradiction:

Improvecontrol authorityVSAvoidactuator volume

Core Design Contradiction:

ForceVSVolume of moving object

Solution Approach 1:

The patent replaces electric motors with a mechanical actuation system using shape memory alloys (SMAs). The SMA elements directly convert thermal energy to mechanical work through phase transformation, eliminating the need for electric motors, batteries, and power electronics. This substitution dramatically reduces actuator volume while maintaining control authority through the high-strain capability of SMA materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes phase transformation in shape memory alloys to achieve large strains (order of magnitude improvement). By changing the thermal state of the SMA material (heating/cooling cycles), the system achieves significant mechanical deformation without requiring large-volume electric motors. The parameter change from solid-phase to austenite-phase enables high-strain actuation in a compact form factor.

Inventive Principle:

Principle #35Parameter changes

2Power

If electric motors and batteries are used for actuation, then actuation capability is achieved, but the volume required for electrical and electronics gear increases

Engineering Contradiction:

Improveactuation capabilityVSAvoidelectrical and electronics volume

Core Design Contradiction:

PowerVSVolume of moving object

Solution Approach 1:

The patent replaces the entire electrical actuation system (motors, batteries, power electronics) with a thermal-mechanical system using shape memory alloys. The SMA elements are activated by thermal energy from resistive heating elements or external heat sources, eliminating the need for heavy battery systems and complex power electronics while maintaining actuation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs periodic heating and cooling cycles to activate and deactivate the shape memory alloy elements. This periodic thermal action enables repeated actuation cycles without requiring continuous power input, reducing the volume and power requirements for the electrical system while maintaining actuation capability throughout the projectile's flight.

Inventive Principle:

Principle #19Periodic action

3Manufacturing precision

If smart materials with high strain capability are used, then actuation effectiveness improves, but electrical energy requirements and volume of electrical gear increase

Engineering Contradiction:

Improvestrain capabilityVSAvoidelectrical energy requirements

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent utilizes phase transformation in shape memory alloys to achieve high strain capability. The material transitions between martensite and austenite phases, enabling large reversible deformations (10% or more strain). This phase-change mechanism provides high actuation effectiveness while requiring only thermal energy for activation, significantly reducing electrical energy requirements compared to conventional electric motors.

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

These actuators offer high control authority, dynamic response, and reliability, reducing volume and power requirements, enhancing the precision and cost-effectiveness of guided munitions while withstanding high-g forces and harsh conditions.

Implementation Method 1

Methodology Applied

Scientific EffectDetonation: Detonation

Implementation Method 2

Transform Chemical Energy to Mechanical Energy

Methodology Applied

Scientific EffectChemical energy conversion: Combustion

Data Source

PatentUS10132393B2Mechanical stepper motors for guided munitions and industrial machinery

Publication Date: 2018.11.20 OMNITEK PARTNERS LLC

AI summary

A projectile including: a body having an internal space; and a mechanical stepper motor disposed in the body, the mechanical stepper motor including: a shuttle having one of a plurality of pockets and movable pins offset from each other with a first spacing; a body portion having the other of the plurality of pockets and movable pins offset from each other with a second spacing, where the first spacing is different from the second spacing; and actuation means for engaging at least one of the movable pins into a corresponding pocket to step one of the shuttle and body portion a predetermined linear and/or rotary displacement; wherein the mechanical stepper motor outputs the predetermined linear and/or rotary displacement to an actuated device operatively connected to the shuttle.