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ME 72a Capstone Design

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James Muren

Project Timeline

Sep 2024 - Dec-2024

OVERVIEW

Mechanical Engineering Capstone project in which five teams of six students competed head-to-head in a robot hockey game. Each team was tasked with strategizing, researching, designing, and manufacturing three unique robots from scratch over the course of two ten-week terms.

HighlightS

  • Led a team of 6 to design a high-torque, durable robotic drivetrain for use in a robot hockey competition.
  • Designed a custom 20:1 gearbox and transmission system in SolidWorks.
  • Defined performance parameters through extensive research and calculated desired motor specifications.
  • Created GD&T for low-tolerance manufacturing conditions on waterjet, CNC, and NC milling.
  • Planned team meetings, organized building tasks, and established effective communication between sub teams.

SKILLS

SolidWorksProject ManagementGD&TCNC3D Printing

Additional Details

Problem Statement

The conventional manufacturing processes using assembly fixtures  lack the precision required for manufacturing miniaturized ultrasound devices at high-volume production. This is required to fit inside a small catheter. Achieving the necessary +/- 15 micron accuracy for critical assembly steps, including UV adhesive dispensing, part alignment, and clamping, often relies on manual or semi-automated methods. These methods are prone to human error, time-consuming, and inconsistent, leading to increased scrap rates, higher production costs, and limitations in scaling manufacturing output. Therefore, there is a critical need for an automated solution that can consistently deliver ultra-high precision across multiple assembly stages to enable reliable and efficient manufacturing of these advanced miniaturized components.

Bill of Materials (BOM)

The following table lists the components used in the prototype, including part numbers, quantities, materials, estimated costs, and potential suppliers.

Item

Component

Part Number

Qty

Material

Cost ($)

Supplier

Notes

1

Heat Sink

637-20ABPE

1

Aluminum

25.00

McMaster-Carr

100x100x50 mm, extruded aluminum

2

Cooling Fan (12V, 40 mm)

AFB0412SHB

1

Plastic/Metal

10.00

DigiKey

Low-noise, 35 dB max, 12V DC

3

Device Housing

Custom (3D-printed)

1

PLA

15.00

University 3D Print Lab

FDM-printed, 200x150x100 mm

4

Thermal Insulation Foam

851-074

0.5 m²

Polyurethane Foam

8.00

Amazon

Cut to fit optics compartment

5

Temperature Sensor

DS18B20

1

N/A

12.00

Adafruit

±0.5°C accuracy, digital output

6

Arduino Uno

A000066

1

N/A

25.00

Arduino Store

Runs Python PID via serial interface

7

Fan Muffler

Custom (3D-printed)

1

PLA

5.00

University 3D Print Lab

Reduces fan noise

8

Fasteners (Screws, M3)

91292A112

10

Stainless Steel

3.00

McMaster-Carr

M3x10 mm, for securing components

9

Thermal Paste

AS5-3.5G

1

Silicone-based

5.00

Amazon

Improves heat transfer to sink

Motor Review

Basic PID Controller Script

PYTHON
import time class PIDController: """A PID controller for precise control in robotic systems. Attributes: kp (float): Proportional gain. ki (float): Integral gain. kd (float): Derivative gain. setpoint (float): Desired target value. prev_error (float): Previous error for derivative calculation. integral (float): Accumulated integral term. dt (float): Time step in seconds. """ def __init__(self, kp: float, ki: float, kd: float, setpoint: float = 0.0): """Initialize PID controller with gains and setpoint. Args: kp: Proportional gain for error response. ki: Integral gain for accumulated error. kd: Derivative gain for error rate of change. setpoint: Desired target value (default: 0.0). """ self.kp = kp self.ki = ki self.kd = kd self.setpoint = setpoint self.prev_error = 0.0 self.integral = 0.0 self.dt = 0.01 def compute(self, current_value: float) -> float: """Compute PID output based on current system value. Args: current_value: Current measured value of the system. Returns: float: Control signal to adjust the system. """ # Calculate error error = self.setpoint - current_value # Proportional term p_term = self.kp * error # Integral term self.integral += error * self.dt i_term = self.ki * self.integral # Derivative term derivative = (error - self.prev_error) / self.dt d_term = self.kd * derivative # Calculate total output output = p_term + i_term + d_term # Update previous error self.prev_error = error return output if __name__ == "__main__": # Initialize PID controller pid = PIDController(kp=1.0, ki=0.1, kd=0.05, setpoint=10.0) # Simulate mode (e.g., motor position) current_value = 0.0 for _ in range(100): control_signal = pid.compute(current_value) # Simulate system response: position updates based on control signal current_value += control_signal * 0.1 print(f"Current Value: {current_value:.2f}, " f"Control Signal: {control_signal:.2f}") time.sleep(pid.dt)


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