Thrust Vector Control

Design requirements

Our customer interview focused on elementary school children and families, with school groups as a secondary audience. A successful exhibit needs immediate feedback, a clear connection to real rocket control, and the durability to handle repeated interaction.

The brief calls for a visual explanation supported by a short plaque, accessible controls, and no combustion or explosions. Reliability, electrical protection, heat management, and a controlled resting state are design requirements to verify as the prototype develops.

Mechanical development

Physical mockup

We used wood, cardboard, paper, PVC pipe, pins, hot glue, and a dummy fan to test the arrangement before committing to detailed hardware. The model made three issues clear: the gimbal and body rotation axes need careful alignment, travel stops need thoughtful placement, and pivot friction can mask the behavior we want to demonstrate.

Concept selection

The concepts included a bearing-mounted gimbal system, a compressed-air reaction-control approach, an exhibit-focused rocket with visual feedback, and my pinned-gimbal concept. We compared manufacturing and assembly, accuracy, durability, entertainment value, and component cost.

The team used the Analytic Hierarchy Process to weight those criteria, followed by a weighted scoring matrix. The report identifies Concept 1—the bearing-supported, servo-gimbaled fan with IMU feedback and dial input—as the preferred direction. That selection is a design decision, not evidence of final hardware performance.

See the team’s selection matrix

See the functional decomposition

Dynamics and control

The engineering work connects the rocket’s unstable dynamics, the feedback controller, and the actuator’s ability to move the fan. The models guide component choices and testing; real hardware behavior will determine the final parameters.

Bench testing and integration

I tested the servo, IMU, and EDF separately before combining their interfaces in a Teensy 4.1 sketch. Getting the BusLinker working required checking UART wiring and selecting the correct Servo-TTL jumper configuration. Once communication worked, we could test gimbal motion alongside the fan hardware.

EDF power troubleshooting

The EDF made power transients part of the integration work. We moved toward higher power draw in steps, rather than jumping straight to a larger throttle command. Sudden stops also coincided with PSU shutdowns; our working diagnosis was a voltage overshoot reaching the supply’s protection threshold. That explanation still needs transient measurements to confirm.

The revised sketch ramps the ESC command up and down for normal operation. This makes load changes more gradual, but it is not a guarantee against a supply trip. Immediate minimum-throttle commands remain separate from the normal ramped stop.

Coordinating the sensor, servo, and EDF

The main loop keeps serial commands and throttle ramping active while scheduling sensor-to-servo updates every 20 ms. The ramp changes the ESC pulse by 2 µs every 50 ms, with a 50% command limit for bench testing. These are command settings, not measured RPM, thrust, or power percentages.

void loop() {
  unsigned long now = millis();
  readSerialCommands();
  updateThrottleRamp();

  if (now - lastServoUpdate >= SERVO_UPDATE_MS) {
    lastServoUpdate = now;
    if (imuConnected) {
      updateGyroControl();
    }
  }

  if (now - lastStatusPrint >= STATUS_INTERVAL_MS) {
    lastStatusPrint = now;
    printStatus();
  }

  while (Serial2.available() > 0) {
    Serial2.read();
  }
}

The MPU6050 includes an accelerometer and gyroscope, but this version uses gyroscope rate feedback to command the servo. It does not yet estimate absolute tilt or demonstrate stable balancing. The sketch also includes arming, status output, and an IMU-fault response; it does not include a communication watchdog.

View the team’s code, CAD, and project files on GitHub ↗

Essential components

Core prototype hardware and power plan. The ordering sheet lists an Arduino Nano; the current integrated sketch uses Teensy 4.1.