PREFACE

Just like for the smart bike concept where we had laid out a series of functional (should) conditions, here is the manifesto that needs to be followed for the folding helmet design in order of priority.The Manifesto is a series of should conditions that define the guiding principles to enable functionality and/or operations of a product or service.Our design and engineering teams will follow these “abilities” to the detail to ensure that the required conditions needed for the helmet are adhered to.

TABLE OF CONTENTS

• Guiding Principles
• Version Control
• Product Variations
• Summary

GUIDING PRINCIPLES

1. Fit – The helmet should fit the user’s head comfortably and securely.
2. Foldability – The helmet should be designed to fold in a way that is easy to use and transport.
3. Adaptability – The helmet should be able to adapt to different head sizes and shapes.
4. Safety – The helmet should be designed with safety as a top priority and meet or exceed all relevant safety standards.
5. Protectability – The helmet should provide adequate protection to the user in the event of a crash or impact.
6. Sensorability – The helmet should be able to incorporate sensors for measuring and monitoring various metrics, such as head impact forces or biometric data.
7. Motorability – The helmet should be able to open and close automatically using servo motors.

1. FIT – Since we are custom creating helmets based on the 5 standard sizes and then varying it based on scanned head profile, the key criteria is fit. In the infamous trial of OJ Simpson the most talked about statement was “If it does not fit, you must acquit”. In our case, we must commit to building the helmet sized to the head and this is the most important criteria:

• For the Armadillo, based on the front and back curvatures of slat 5/6 and slat 1 we will define the appropriate sliver that will also account for slat thickness. As the slat shell thickens we would need to move the pivot point towards the forehead so that the overall helmet corresponds to the correct shape.
• For the Hercules, it is the inner slat 4L and 4R (Symmetrical) that will define the fitness
• For the Athena, albeit it looks like the Armadillo, the governing criteria for fitness will be the innermost front and back slats. Since the head is not symmetrical in the direction of movement for this the design of slat 1 will not be symmetrical and will account for the difference in the front and the back as the inner slats move into it.

A criterion that we will utilize for the design is:

‘Follow the “2V1” rule to make sure the helmet fits right: Two fingers above the eyebrows: The helmet should cover the top of the forehead and should rest about two fingers’ width above the eyebrows. Straps form a V under the ears. The side straps should fit snugly around the ears in a “V”shape.’

SolidWorks will be utilized to manage the CADding of the helmet and will consist of the following Assemblies:

1. Headform – imported standard IGES file or Point cloud from scanning. This will be converted to an entity.
2. Baseplate – Consisting of 42 control points on a plane that define the headform profile plane. This cut profile should exactly match the headform at the region of the cut.
3. Skullcap – The inner control points of the baseplate will be extruded in this assembly to meet up with the head shape. The skull cap should exactly fit the shape of the head.
4. Slice – Following our Outcome Based Modeling principle of Sliver-Slice-Slat to create the representation of the unslated slice. The apex will be a triangular vertex. This should represent the closed form of the final assembly albeit without the design elements.
5. Wireframe – This will be a variant of the skullcap but with the inner dimensions of the final helmet and will be used to conduct optimization studies (reduce the delta between the skullcap and the wireframe). The slice will be used as the basis to slit and rotate about the pivot point and then the skullcap will be used as a basis to expand into the wireframe. This surface will be a TBD item for later on to build an AI/ML model to optimize the design.
6. Slat Assemblies – These will be carved from the Slice and design elements apex, overlaps, dovetails/grooves/rails, stubs and brims and other nuances like scalloping and the provisioning for a bulge to account for counter sink bolts. This will be the basis to export to STLs for 3D printing.
7. Shell Geometries – This will be the full geometry for each slat which will be needed for CAE Simulations. Infill will only be 0.8 mm (4 – 2×1.6) so will ask Markforged this question.
8. Nuts and Bolts – We will use the M6 size for the nuts and bolts and the CAD files of these would be included in this assembly to enable complete and exploded views of the helmet.

The design phases will step thru these 8 assembly steps with each one being validated by the prior.

2. FOLDABILITY – This is our differentiator. In the multiple different folding patterns with the Armadillo, Hercules, Athena and more to come the goal is to achieve maximum compactness of the folded helmet. This helps shipping and handling, less space in warehousing, and in general usability.

• For the Armadillo and the Hercules (sans the Vanguard), the helmet should extend exactly 180 degrees when open and appropriately close to a slice shape without any discrepancies. This means that the individual slats should account for overlap, the brim in the bottom (half in case of the Armadillo and half/full in case of the Hercules) and ensure that the open and close mechanism is clean and locks in place at the end of the movement. The Armadillo will have 5 slats spanning the 180 degrees with an additional 6th if Vanguard is not present. The Hercules will have 7 slats.
• For the Athena, it will have 7 slats with the top central slat and 3 slats in front and 3 slats at the back that open to a total of 200 degrees (50 degrees for the central slat and 20 and 30 degrees respectively the front and back slats. It will also provisions for addition of a bicarbonate transparent visor slat in the front.

We have invested in multiple different mechanism types – from horizontal stoppers to vertical rails to grooves (outside/inside) to dovetails and each of these will be utilized based on need for the different types of helmets.

3. ADAPTABILITY – Utilizing parametric modeling and our concept for Outcome Based Design, the helmet will be fully customizable to the Standard Head shapes based on the NIOSH Anthropometric data and scanned head profile.

Immutable parameters (Global variables) for the design process

1. Head-Helmet Gap – this is the wriggle room between the head and the helmet to include padding and other bulge outs like the hooks for chin straps. It will be set to 16 mm on the horizontal (XY axis) and updated based on design considerations for fit.
2. Helmet Type – Hercules/Armadillo/Athena (1/2/3)
3. Shell Thickness – this will be fixed throughout the design process. It is typically set to 4mm for thick shells, 3.2 mm for medium shells and 2mm for thin shells.
4. Number of Slats – This will be prescribed to 5 or 6 for the Armadillo and 4 for the Hercules and Athena.
5. Movement Type – Ledge-cutout, Groove (default) /Rail (reduce weight) /Stopper (old).
6. Rail height – For rail movement the height of the rails.
7. Tolerance gap – this is the minimum gap between the slats to enable movement. It will be set to 0.36mm. Along with the shell thickness, the number of slats and the type of movements (add rail height for railed movement) this will determine the dimensions of the sliver/brim.
8. Apex Radius – This will define the bluntness of the apex, the basis for the pivot point.
9. Pivot hole Radius– Default M6 bolt radius + tolerance.

Our guidelines to achieve quick design is to follow our philosophy of Outcome Based Design utilizing Sliver-Slice-Slat, wherein we will evolve the design based on the baseplate crossection to create;

• Sliver – a 2D representation of the outline of the helmet.
• Slice – an extruded 3D version of the constituents of the entire helmet but in one piece.
• Slat – Carved our segments from the slice to represent each slice.

This must be followed for all our “hoodie” based helmet types – the Armadillo, the Hercules and the Athena.

Exploiting Symmetries – To reduce the design effort the following mirroring capabilities will be employed to the full design;

• For the Armadillo, since the design is symmetrical for the left and right, only one half of the helmet shall be modeled.
• For the Hercules, since the design in symmetrical for left and right, the initial definition process will be modeled in half, but the creating of the slice and its slatting and inclusion of design elements will be done for the whole helmet.
• For the Athena, like the Armadillo, the right side of the helmet will be completely modeled and then mirrored to the left.

We will also utilize generative design to optimize the design for fit so that the clearance between the skull cap and the helmet is conformant to the requirements. This will be based on the delta between the skullcap and the wireframe.

Each slat will be correctly tagged on the inside with the slat number, front or back, left or right so that printing, post processing and assemblies proceed without issues.

For dovetailed slats, the ledge will always be on the baseplate to reduce the need for having supports.

4. SAFETY – The prime directive of the helmet is to protect the noggin and we are ensuring that this will happen for all different use cases.

All helmets will have a chin strap not only to secure the helmet in place but also to prevent the movement of the slats once it is placed on the head. This is a very important criteria. Rather than having a locking mechanism, the strapping will be the basis for preventing the natural movement of the folding slats.

For the innermost slat the apex region (for all helmets) will need to be buldged out to account for the counter sink of the bolt at the pivot point. This will prevent grazing of the skin at the bolt region.

• For simple bump caps with thin shell and stoppers or rails the goal is to prevent head bumps in crawl spaces and low ceilings. This could also extend to light weight protection for joggers from concussion if they were to stumble and fall.
• Industrial Helmets will be made of a thicker shell with a flexible TPU infill and a lanyard system that conforms to regulations of having an air gap and support system to distribute the load.
• Construction Hats will be similar to industrial helmets but will not have the air gap or the lanyard system.
• Military grade helmets will have the thickest shell (4mm) and we will utilize Markforged Digital Forge technologies to analyze and print them. The shell will be made of Onyx material and the infill will be Kevlar/Carbon Fiber/Fiber glass based on cost considerations.
• Certain types of helmets will be made for recreational use – bicycling, running, e-commuting etc and will have different profiles, aerodynamics and other considerations that will be tested for the appropriate safety guidelines.

This condition will be validated using engineering simulation that would enable virtual testing of the helmet for different impact scenarios mandated by governing bodies.

CAE Analysis of the helmet will be performed in two stages

1. Slat Analysis – Here the most impactful slat will be chosen to purport a rigorous impact load analysis.
   • For the 5 slat Armadillo, this will be Slat 4 (Closer to the forehead)
   • For the Hercules, this will be Slat 1 (the topmost slat that runs from front to back).
2. Full Helmet Analysis – In this the helmet overlaps, the potential of pivot point rotation and the ability to withstand impact will be the key considerations.

The helmet slats will be modeled as a two wall shell with infill (which same of different material) having a particular density (25%) to account for the lattice nature of the physical object. The infill region will also be a CAD model that will be utilized for the simulation.

The CAE Simulation results will also serve as synthetic data for developing a “learned” inference engine to enable AI/ML for real time monitoring of the structural conformity of the helmet.

5.  PROTECTABILITY – The helmet slats maybe reinforced with Fiberglass, Carbon Fiber or Kevlar to provide impact and ballistics protection in addition to the nascent properties of the domed shell structure and the scaly overlap. These will be printed using Markforged Digital Forge continuous fiber filament infusion.

In addition to the slats, the Armadillo and the Hercules may also have a Vanguard slat to protect the back of the head and neck region and will be appropriately profiled using a toroidal ellipsoid to define the surface that varies in different directions to account for continuing the head slat shape and then conforming to the neck profile. It will also have considerations to house batteries and PCBs that will drive the sensors detailed in item 6.

6.  SENSORABILITY – This will correspond to our CONNECT-DETECT-PROTECT theme and consist of Arduino sensor from their Nicla family (Sense ME, Vision and Voice) for multiple different use cases for the military (wellbeing), first responders (smart directions and instructions), industrial (detection), residential (fall detection) and recreational (safety and environmental protection). Details of these are in a separate whitepaper and this will be our second differentiator in the helmet market. Data from sensors will be real time processed using edge servers and summaries will be transported to our big data platform for situational, temporal and conditional analysis based on the use type.

7. MOTORABILITY – A long stretch goal is to be able to open and close the helmets using small servo motors. An example of this is at: https://www.youtube.com/watch?v=JB-ZJZBsHCU

VERSION CONTROL

Each helmet variant will be cataloged in our Product Development Management repository and consist of;

Metadata

• Project Name – Armadillo/Hercules/Athena
• Project Type – Folding Helmet
• Version Number
• Date Created
• Key Designer
• Key Engineer

CAD Geometry

• Solidworks CAD File
• STL Files
• CAD Digital Assets

CAE Analysis

• Ansys LS-DYNA CAE Files
• Ansys LS-DYNA Results
• Ansys LS-DYNA Summary

PRODUCT VARIATIONS

Here are the different product variants:

1. The Armadillo
2. The Hercules
3. The Athena

SUMMARY

We will be investing quite a bit in small batch manufacturing and marketing and I would like the above conditions are completely understood by our design and engineering teams so that we reduce the churn in progressing the solution.

By following these guiding principles, the design and engineering teams can ensure that the foldable helmet meets the necessary functional requirements while also providing a high level of usability and safety for the user.

NITIN UCHIL Founder, CEO & Technical Evangelist
nitin.uchil@numorpho.com