Robotic Arm for Solid-Propellant Charge Finishing

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Solution Overview

Problem

The manual scraping of propellant veils from the inner wall of propellant charges is hazardous due to pyrotechnic risks, and existing automated methods are inefficient in controlling force and speed, leading to potential damage.

Innovation Solution

A robotic arm equipped with a grinding tool, force sensor, and control unit regulates force and speed thresholds to safely remove propellant veils by controlling the robotic arm's movements, using a user interface and image sensors for precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual scraping is used to remove propellant veils, then operators can directly control the removal process, but pyrotechnic risks increase due to operator exposure

Engineering Contradiction:
Improvedirect control of veil removalVSAvoidpyrotechnic risk
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A robotic arm equipped with a grinding tool and force sensor acts as an intermediary between the operator and the propellant charge. The operator controls the robotic arm through a user interface, and the force sensor provides feedback about contact force, allowing indirect control that eliminates direct operator exposure to pyrotechnic hazards while maintaining control capability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The manual mechanical scraping operation is replaced with an automated robotic system that uses a grinding tool. This substitution removes the operator from the hazardous environment while maintaining the veil removal function through automated control with force feedback

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If automated robotic arm is used for veil removal, then pyrotechnic risks are reduced, but control precision over force and speed decreases

Engineering Contradiction:
Improvepyrotechnic riskVSAvoidforce and speed control
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

A force sensor is integrated into the robotic arm to provide real-time feedback about the contact force between the grinding tool and the propellant charge wall. The control unit processes this feedback and automatically adjusts the robotic arm's movements to maintain force below a predetermined threshold, achieving precise force control that prevents damage while ensuring safe operation

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The robotic arm system dynamically adjusts its operation parameters based on real-time conditions. The control unit regulates both the force applied (through force sensor feedback) and the speed of movement (maintaining below a predetermined speed threshold), allowing the system to adapt its mechanical behavior to prevent damage to the propellant charge

Inventive Principle:
Principle #15Dynamics

3Productivity

If high force is applied during veil removal, then veil detachment is more effective, but damage to the propellant charge increases

Engineering Contradiction:
Improveveil removal effectivenessVSAvoidpropellant charge integrity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The control unit enforces a predetermined force threshold parameter that limits the maximum force the grinding tool can apply to the propellant charge wall. This parameter change ensures that veil removal is performed with sufficient effectiveness while preventing excessive force that could damage the propellant charge structure

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

The method ensures safe and controlled removal of propellant veils, minimizing damage to the propellant charge and reducing pyrotechnic risks by limiting applied force and speed, thus enhancing operational safety.

Implementation Method 1

a force sensor measures the force applied by the trimming tool

Methodology Applied
Scientific EffectForce sensing: Force

Implementation Method 2

a step of removing film by grinding the wall of the central channel of the propellant charge with a grinding tool

Methodology Applied
Scientific EffectGrinding: Abrasion

Data Source

PatentEP3946838B1Device and method for finishing a solid-propellant charge
Publication Date: 2025.12.17 ARIANEGRP SAS
  • EP3946838B1 patent drawingFigure 1
  • EP3946838B1 patent drawingFigure 2~3

AI summary

The invention relates to a method for removing webs (2) formed on a wall (12) of a central canal (11) of a solid-propellant charge (1), characterized in that the method comprises a step (110) of removing webs (2) by shaving the wall (12) of the central canal (11) of the solid-propellant charge (1) using a levelling tool (32) installed on an articulated robot arm (31), during which step: - the movements of the robot arm (31) are controlled by a user interface (33) which comprises control means (33a) configured to be used by user; - a load cell (34) measures the force applied by the levelling tool (32); - a control unit (35) connected to the load cell (34) regulates the movements of the robot arm (31) in keeping the force applied by the levelling tool (32) below a first predetermined load threshold, the control unit (35) also regulating the movements of the robot arm (31) in maintaining a speed of travel of the levelling tool (32) which is below a predetermined speed threshold value.