Final Project — Responsive Kinetic Flower

4. Final Development of Design

The final design is an interactive kinetic flower developed as a circular modular object. The structure combines a central mechanism with a set of 3D printed petals distributed around the base, creating a composition that relates digital fabrication with organic movement and visual expression.

The design is organized around a circular base that contains the electronic and mechanical components. On the upper surface, multiple petals are arranged radially, generating a flower-like pattern. This layout was chosen to create a balanced visual composition and to reinforce the organic character of the project.

At the center of the system, a mechanical actuation mechanism controls the movement of the main petal or flower element. The objective of this mechanism is to allow the piece to open and close in response to interaction, connecting the physical form of the object with sensor-based behavior.

The project integrates several Fab Academy processes, including 2D and 3D design, additive fabrication, electronics, embedded programming, and system integration. The result is not only a decorative object, but an interactive system that responds to its environment through movement.

A. Overall Dimensions

The following section presents the general dimensions of the product, which define its overall scale and spatial configuration. These measurements were determined to ensure proper integration of the mechanical components, electronic system, and structural elements, while maintaining a compact and stable design.

B. Component Structure and Function

After defining the overall dimensions of the product, the system can be understood through its individual components. Each element was designed to fulfill a specific function within the structure, contributing to the integration of the mechanical, electronic, and aesthetic aspects of the project.

C.Fabrication – 3D Printing

After completing the 3D modeling phase, the components of the system were fabricated using FDM 3D printing. This process was selected due to its accessibility, speed, and suitability for producing complex geometries such as the petal supports and mechanical components.

Printing Strategy

The system was divided into multiple parts for fabrication: base structure, petal supports, petals, central mechanism, and gear. Each component was optimized individually to ensure print quality, reduce material usage, and avoid unnecessary supports.

• The base and structural components were printed flat to ensure stability and dimensional accuracy.
• The petals were printed in a vertical orientation to maintain their intended geometry and avoid deformation during printing.
• The gear and central mechanism were printed with higher precision settings to ensure proper fit and smooth motion.

Printing Parameters

The following parameters were used during the printing process:

• Material: PLA
• Layer height: 0.12 mm - 0.28 mm
• Infill: 15–20%
• Supports: not required in most of the parts (geometry optimized to avoid overhangs)
• Wall detection: thin walls enabled

Each print batch included multiple components arranged on the build plate to optimize time and material usage. On average, each batch required approximately 2 -4 hours of printing time.

D. Post-processing

After printing, the petals will be subject to a heat-forming process to achieve a more organic and curved shape. This step is critical, as the final geometry of the petals is not fully defined in the digital model but is achieved physically.

Minor cleaning and finishing operations were performed to remove imperfections and ensure proper assembly between components.

E. Assembly Considerations

During fabrication, tolerances were considered to ensure that all components fit correctly without excessive friction. Test fittings were performed to verify the alignment between the base, central mechanism, and gear system.

This phase marks the transition from digital design to physical validation, allowing the evaluation of structural stability, mechanical performance, and integration with the electronic system.

5. Electronics Development

The electronic system of the final project is based on the work developed in the previus weeks, where I tested the interaction between a PIR sensor, a servo motor, an LED indicator, and the XIAO ESP32-C3 microcontroller. This previous exercise was important because it allowed me to validate the basic logic that will later be integrated into the kinetic flower.

The objective of the electronic system is to allow the flower to react to the presence of a person. When the PIR sensor detects movement, the microcontroller processes the signal and activates the servo motor. The servo is mechanically connected to the central mechanism, which controls the opening and closing movement of the petals.

A. Electronic Components

• Microcontroller: Seeed Studio XIAO ESP32-C3
• Input device: PIR motion sensor
• Output device: servo motor
• Visual indicator: LED
• Manual control: switch

B. System Logic

The interaction logic follows a simple input-control-output structure:

• The switch enables or disables the system.
• When the system is enabled, the LED turns on as a visual indicator.
• The PIR sensor detects the presence or movement of a person.
• The XIAO ESP32-C3 reads the sensor signal and processes the condition.
• If motion is detected, the servo motor moves between defined angles.
• This servo movement activates the central mechanism that opens or closes the petals.

C. Connection Diagram

The following circuit configuration was tested during Week 10 and will be used as the base for the final project electronics:

• PIR sensor: connected to digital pin D4.
• Servo motor: signal connected to digital pin D3.
• Switch: connected to digital pin D5.
• LED: connected to digital pin D6 through a current-limiting resistor.
• Power: Battery power system.

In the final project, this same logic will be adapted to the physical structure of the flower. The PIR sensor will be placed in the center of the petals using a dedicated 3D-printed support, while the servo will be integrated into the lower central mechanism.

D. Code Used as Reference

#define PIR_PIN D4
#define SWITCH_PIN D5
#define LED_PIN D6

#include <ESP32Servo.h>

Servo myServo;

void setup() {
  Serial.begin(115200);

  pinMode(PIR_PIN, INPUT);
  pinMode(SWITCH_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);

  myServo.attach(D3);
}

void loop() {
  int encendido = digitalRead(SWITCH_PIN);

  Serial.print("button: ");
  Serial.println(encendido);

  delay(200);

  if (encendido == 1) {
    digitalWrite(LED_PIN, HIGH);

    int estado = digitalRead(PIR_PIN);

    Serial.print("pir: ");
    Serial.println(estado);

    if (estado == 1) {
      delay(200);
      myServo.write(0);
      delay(1000);
      myServo.write(180);
      delay(1000);
    } else {
      myServo.write(0);
    }
  } else {
    digitalWrite(LED_PIN, LOW);
    myServo.write(0);
  }
}

Code Explanation

The code begins by defining the pins used for the PIR sensor, switch, and LED. The servo motor is controlled using the ESP32Servo library, which allows the XIAO ESP32-C3 to generate the PWM signal required to move the servo to specific angles.

In the setup() function, the PIR sensor and switch are configured as digital inputs, while the LED is configured as a digital output. The servo motor is attached to pin D3, and serial communication is initialized to monitor the sensor and switch values during testing.

In the loop() function, the system first reads the state of the switch. If the switch is activated, the LED turns on, indicating that the system is enabled. Then, the PIR sensor is read. If motion is detected, the servo moves between 0° and 180°, generating the mechanical action required for the flower movement.

If no motion is detected, the servo remains in its initial position. If the switch is deactivated, the LED turns off and the servo returns to 0°, keeping the system at rest.

E. Custom PCB Design and Fabrication

To move from a temporary prototype to a stable system, a custom PCB was designed. This allowed the electronic components to be organized in a compact and reliable way, reducing wiring complexity and improving integration with the mechanical structure.

• Schematic design defining all electrical connections.
• PCB layout with organized routing and connection points.
• Generation of toolpaths for CNC milling.
• Manufacturing of the board using a milling machine.
• Soldering of components and connectors.

F. PCB Validation

Before integration, the board was validated to ensure correct operation:

• Continuity tests using a multimeter.
• Voltage and signal verification.
• Oscilloscope measurements to observe signal behavior.
• Functional tests controlling the servo and reading the PIR sensor.

G. Electronic System Validation

The electronic system was designed to be embedded within the structure:

• The PIR sensor is positioned at the center of the petals using a custom support, ensuring a clear detection area.
• The servo motor is mounted in the lower base and mechanically connected to the central mechanism.
• The PCB is placed inside the base, organizing connections and reducing exposed wiring.

This integration transforms the system from a test setup into a functional interactive object, where electronics and mechanics operate together.

For a more detailed explanation of the process, you can visit the corresponding assignment pages.

Considerations and Challenges

• Ensuring stable power supply for the servo motor.
• Avoiding noise or false triggering from the PIR sensor.
• Maintaining reliable connections after moving from breadboard to PCB.
• Aligning the servo movement with the mechanical system.

6. System Integration, Testing and Final Prototype

This stage focused on transforming the project from a collection of independent subsystems into a fully integrated interactive object. The mechanical structure, embedded electronics, interaction system, power distribution, and enclosure design were progressively assembled and tested together as a single kinetic system.

Unlike previous development stages where components were tested separately, this phase revealed new challenges related to internal space organization, cable routing, structural alignment, movement tolerances, and accessibility during assembly.

A. Integration and Iterative Development

Several redesign iterations were necessary to improve the relationship between the mechanical and electronic subsystems. Small dimensional variations, cable positioning, and component distribution directly affected the reliability of the flower opening mechanism.

The integration process included:

• Internal redistribution of electronic components
• Servo support redesign
• Mechanical spacing adjustments
• Cable routing optimization
• Battery positioning improvements
• Structural reinforcement and alignment corrections

Initial integrated internal layout.

Servo integration and PCB positioning.

Connection between the servo system and the opening mechanism.

Switch and LED mounting features integrated into the enclosure wall.

Alignment and assembly refinement process.

B. System Testing and Validation

Multiple integration tests were performed to validate the complete interaction behavior of the prototype under real operating conditions.

The first tests were conducted with the enclosure open to observe the movement of the mechanism, verify servo response, evaluate sensor behavior, and identify possible interference between moving and static components.

Additional tests were later performed with the enclosure assembled in order to validate the complete interaction sequence and the stability of the integrated system.

The testing process allowed continuous refinement of:

• Servo calibration and movement limits
• PIR sensor response timing
• Mechanical reliability of the opening sequence
• Internal cable organization
• Structural stability and alignment
• Battery integration and accessibility

C. Final Integrated Prototype

The final prototype successfully integrates digital fabrication, embedded electronics, programming, interaction design, mechanical actuation, and portable power into a single autonomous kinetic object.

The system detects user presence through a PIR sensor and responds by activating the flower opening mechanism using a servo-controlled movement sequence.

This stage validated the complete integration of all developed subsystems into a cohesive interactive prototype capable of autonomous operation.

For a more detailed explanation of the process, you can visit the corresponding assignment pages.

7. Failures and Lessons Learned

The difficulties encountered during the process were not simply failures, but important design decisions that had to be reconsidered throughout the development of the project.

• The cable-based system did not provide enough control or stability for the movement.
• Thin printed parts failed structurally under repeated mechanical stress.
• The first versions of the mechanism were unnecessarily complex and difficult to assemble.
• System integration introduced new challenges related to internal space, cable routing, and component accessibility.
• Mechanical tolerances and small dimensional variations significantly affected the quality and reliability of the movement.
• Battery integration required redesigning the internal organization of the prototype.
• Interaction behavior changed under real operating conditions compared to isolated subsystem testing.
• Assembly logic became as important as functionality itself during the final integration stage.

What proved most effective throughout the process was:

• Simplifying the mechanism whenever possible.
• Rapid prototyping, especially by testing ideas first in cardboard.
• Using real references to better understand natural movement.
• Designing motion through geometry rather than relying on flexible elements.
• Iterative testing and continuous refinement during system integration.
• Considering electronics, mechanics, structure, and packaging simultaneously instead of independently.
• Improving internal organization to facilitate assembly, maintenance, and reliability.

9. Next Steps

The next phase of the project is no longer conceptual, but focused on execution and integration.

• Refine the petal design
• Build a stable final version
• Validate the complete behavior of the system