The Disqualifier: 5 Specifications and 5 Constraints

As mentioned in previous posts, my project is a pneumatically powered chin guard that propels the leg into a Muay Thai styled kick. The aesthetic followed will be cyberpunk and the device will be composed of a variety of martial arts equipment and pneumatic instruments. Throughout this class we have been taught the importance of the balance between aesthetics within our design aspirations and real world limitations of what we can produce. As such, here are 5 specifications and 5 constraints of my final project for this class: the Disqualifier.

Specifications: 

Figure 1: Anthropometric data on the segment I am designing for (Anthropometric)

• Kick-Initiation Force: The first specification I would like this device to meet is the force required for a kick’s initiation. This from calculations is roughly 300-500N of force. However, this production of the force introduces other concerns.
• Stroke Length of 150mm: From my other studies, particularly those from my Biomechanics classes pertaining anthropometric analysis and charts, the best and commercially available option for my pneumatic cylinder’s stroke (the length that it can actuate from the cylinder) is 150mm.
• Light Weight Frame (Sub 2kg): Given that the motion needs to still feel fluid as part of the design, the device cannot be too cumbersome or heavy for ease of use.
• Controlled Actuation Timing: Perhaps the easiest specification to meet. The device must be able to fire at will, allowing for timed and predicted response from the cylinder.
• Secure Mounting Interface: The shin guard and all other components must remain safely affixed to the leg at all times while in motion. Further it should do so without restricting movements.

Contraints: 

Figure 2: Demonstration of motion intended (Ultimate)

• Financial Cap: I want to keep the spending on this project to what I would spend on a textbook for the class. As such, I want to keep the total project price to below 200 USD.
• Ergonomic Air Supply: The supplier of compressed air for the pneumatic cylinder to be able to fire should be light enough to be worn on the body.
• Impact Durability: Solenoids and wiring should be impact resistant, or even proof. Being able to endure sudden strikes while maintaining functionality.
• User Safety: In all honesty, this feature is more of a “perk” if I get the device working… of course I am joking. The actuator must not overextend or misfire in a way that could injure the user.
• Disqualification Risk in Competition: The design must acknowledge that this device is illegal in sanctioned martial arts and should be so in design. There should be multiple instances of parts and assembly that can get someone kicked out of a Taekwondo or Muay Thai tournament.

Figure 3: Deformation/density gradient developed in another class using FEBio analyzing the forces of contact on the tibia bone when exposed to the kicking motion described.

Considering these design factors, the idea of a shin-guard is feeling less and less attainable the more I think about the design. For example, impact durability for the human leg is already questionable in these forms. Further the user safety balancing (particularly on the ankle and the ACL) with the sufficient forces required for propulsion feels somewhat untenable. I will continue to iterate on my designs.

References:

Anthropometric-detailed-data-Tables.pdf. (n.d.-a). https://multisite.eos.ncsu.edu/www-ergocenter-ncsu-edu/wp-content/uploads/sites/18/2016/06/Anthropometric-Detailed-Data-Tables.pdf

Ultimate Guide to muay thai kick – techniques and execution. Rajadamnern. (2025, February 4). https://rajadamnern.com/blog/muay-thai-kick/