The Disqualifier – Pneumatic Gauntlet 2

2 weeks ago

Post 12- 2025 : Main Project Final Report Part 2

In my sophomore year of college, I was unmistakably disqualified from a taekwondo tournament—no confusion, no gray area, just cleanly and thoroughly booted from the mat. I left the team not long after. At the time, it felt like failure. Over the years, though, that moment took on a new shape. What began as frustration eventually hardened into a sort of rebellious pride. That pride now takes form in my final project: The Disqualifier.

This is not a device meant to blend in or comply. The Disqualifier is designed, with complete sincerity, to get its wearer unmistakably removed from any official competition in unarmed combat sports. It functions as a pneumatically powered punching mechanism—a gauntlet that launches a fist forward with real force, either retracting automatically or following through with full extension depending on power level.

Figure 1: Firing sequence

This report focuses not on the motivations or narrative behind the project, but rather the process: the material choices, the system architecture, the technical hurdles, and the design decisions that shaped The Disqualifier into what it became—a pneumatic gauntlet capable of propelling a strike with mechanical force.

II. Design Evolution

The project began with a completely different concept: a shin-guard that would kick. The idea was to use a pneumatic actuator to fire the foot upward in a Muay Thai-like motion, with the user directing the kick. However, this design quickly encountered two issues—emotional disinterest and mechanical complexity. As I chronicled in my course blog posts, the spark just wasn’t there anymore.

The turning point came from revisiting my first martial art: dambe. Dambe, a striking sport practiced by the Hausa people of Nigeria, uses one arm as a weapon (“spear”) and the other as defense (“shield”). The symbolic and practical simplicity of the one-armed strike was both nostalgic and mechanically sound.

By combining this martial inspiration with the controlled aggression of professional fighting games, I pivoted to designing a gauntlet—a punch-focused, arm-mounted actuator. This direction simplified impact management, reduced weight near joints, and freed up movement for testing.

Figure 2: Dambe fighter post-match (Mafua)

III. Mechanical Design and CAD Modeling

I began with a sketch of the desired strike path and physical clearances needed. The gauntlet had to comfortably house a double-acting pneumatic cylinder, deliver consistent airflow, and brace safely against the forearm to handle the reactive force of a punch.

Figure 3: Sketch of initial design of the gauntlet

Initial CAD designs focused on the straps for the actuator. The structure had to support linear travel without deflecting under pressure. PLA printed renders just broke, even upon adding telescoping extension mount for the artificial fist was added to avoid damaging the cylinder during testing. Modularity guided the entire design. I ensured that the pneumatic hardware could be detached or replaced without tools.

IV. Pneumatics System

Figure 4: Double-acting pneumatic cylinder (Amazon)

The mechanical heart of The Disqualifier is its double-acting pneumatic cylinder. This actuator extends when compressed air enters Port A and exits Port B, and retracts when the flow is reversed. The system relies on a handheld tire inflator—chosen for portability and affordability—as the primary compressor.

Figure 5: Teflon coated valve

Tubing was selected for size compatibility (1/4″) and air pressure durability. Threaded connectors were sealed with Teflon tape to prevent leaks. During testing, push-to-connect fittings were added to reduce installation and teardown time.

I initially explored incorporating a manual valve toggle, but eventually opted for electronic control to simulate real-time actuation. This opened the door for responsive input handling—press a button, throw a punch.

V. Electrical and Control Architecture

To manage air direction, I implemented a micro-solenoid valve capable of switching airflow paths via a basic polarity shift. A standard 9V battery provided power, controlled through a mechanical pushbutton.

Figure 6: Solenoid control valve that I ended up using (Amazon)

The solenoid’s operation was straightforward in theory but prone to inconsistency. When wired directly to the battery, the system developed a slow leak. I suspect this was caused by an internal safety mechanism in the solenoid or a voltage mismatch. This failure altered the control logic—rather than a full push-button cycle with solenoid retraction, the system operated on a simpler, binary compression-fire loop.

While less elegant than the original design, the revised system still allowed for manual testing, safe actuation, and an effective demonstration of the concept.

VI. Fabrication and Assembly

Materials were chosen for simplicity and cost-efficiency. The gauntlet’s structure was assembled with nylon and leather straps, which offered enough rigidity for mechanical loads but remained lightweight. Actuator external wiring was reinforced with zip-ties and adhesive Velcro for stability during testing.

Figure 7: Parts of the assembly spread out.

Assembly involved three major stages:

Actuator Integration – Mounting the cylinder along the forearm axis with sufficient clearance for travel.
Tubing and Sealing – Connecting the compressor to the solenoid and then to the actuator using quick-fit joints.
Control Wiring – Connecting the solenoid to the battery circuit and isolating wires from moving components.

I performed several dry runs to ensure structural alignment and actuation clearance. A minor design flaw—tubing catching on internal edges—was solved with duct-tape guards around key contact points.

VII. Testing and Performance

Testing followed a simple hierarchy: ensure function, assess safety, and evaluate spectacle.

Figure 8: Compressor (Amazon)

Initial airflow tests verified the actuator extended and retracted under full pressure. The tire inflator provided sufficient PSI for short bursts of force, and the tubing held without visible stress.

Figure 9: Actuator test rig.

The solenoid’s leak issue did limit repeatable retraction, but the actuator still fired reliably when pressure was manually cycled. For the sake of performance, I adjusted the expectation to a “punch-then-reset” behavior.

Final tests focused on assembly durability—how well the gauntlet handled repeated pressure cycles, whether components stayed in place, and whether the artificial fist projected properly. The results were conclusive: it worked, and it looked the part.

VIII. Lessons Learned and Future Improvements

The Disqualifier succeeded in meeting its core objectives: function, aesthetic, and provocation. It delivered a mechanically powered punch, was built within budget, and clearly broke the rules of any combat sport.

Figure 10: Article 9 in the USATKD regulations on metallic articles ensuring disqualification (USATKD)

That said, the project revealed several areas for refinement:

Flow Control: A more sophisticated solenoid valve or microcontroller circuit could regulate airflow with greater precision. Perhaps it could even implement a more rapid fire rate.
Power System: Swapping to a rechargeable battery pack would improve reliability and reduce electrical resistance.
Impact Design: Incorporating spring buffering or energy absorption would allow for heavier punches without risking structural failure.
Wearability: Upgrading the mounting system with PLA printed stiffeners would greatly enhance comfort.

More broadly, this project reminded me of the value of iterative play—of designing with a wink and a smile. While it began as a satire of disqualification, it ended as a genuine exercise in creative engineering.