Background

My final VEX season challenged teams to hit flags, flip caps, and park on platforms. Scoring worked like this:

• High flags: 2 points when toggled

• Low flags: 1 point when toggled

• Balls had to hit flags to score them (no direct robot contact allowed)

• Flags were staggered at 18", 32", and 46" heights

Analysis

Most designs followed the same cycle during matches:

1. Launch at high flag

2. Drive forward

3. Launch at middle flag

4. Drive into low flag

5. Repeat

The drive time between shots seemed unnecessary. We started wondering - what if we could hit both top flags without moving?

Robot Design

The Double Shot Design We built three key systems:

1. High-speed dual flywheel (4 motors)

2. Pneumatic angle adjuster

3. Ball indexer with millisecond timing

We manually tuned a timing sequence by using spacers to adjust the height of the pneumatic cylinders:

1. First ball launches at 46" flag

2. Hood pneumatically actuates down (~50ms)

3. Second ball feeds in (~30ms)

4. Second shot hits 32" flag

Other teams eventually built motorized versions, but using pneumatics gave us two advantages:

1. Faster actuation (50ms vs 200+ms for motors)

2. More consistent angles (pneumatic cylinders hold position better)

One VEX forum member called our cycle time "among the fastest in the world." We were under 100ms between shots.

Results & Failure Analysis

The robot performed well:

• 3x Tournament finalist

• State Championship quarter-finals

• Design Award & Create Award

• US Open qualification

But we hit two limitations:

1. Our chassis motors would sometimes go out

2. Scoring was Inconsistent towards the end of fast-paced matches as pressure changes during matches affected hood timing

For future designs, I'd:

1. Redesign the chassis to be more robust

2. Add sensor feedback for hood position rather than tuning manually

3. Conduct more failure mode testing