ACCESSIBLE TRANSPORTATION INTERFACE

Key Concepts

The effectiveness of an assistive button-pushing device depends on several interconnected factors:

1. Mechanical Design Considerations:
   • Leverage principles provide mechanical advantage for force amplification
   • Material selection impacts durability and user comfort
   • Mounting solutions must accommodate diverse environments
   • Portability requires balancing size, weight, and functionality
2. Programming for Adaptability:
   • Different buttons require different actuation profiles
   • User input methods must match client capabilities
   • Feedback systems improve user confidence and device reliability
   • Power management extends battery life for real-world use
3. Human-Centered Design Principles:
   • Solutions must consider client's full journey, not just technical function
   • Social acceptability impacts adoption and consistent use
   • Device visibility has implications for user identity and preferences
   • Setup and maintenance requirements affect long-term usability

Activity: "Design Requirement Specification"

1. Working from client interview data and exploration findings, develop a comprehensive design requirements document that includes:
   • Required force output range and adjustability
   • Size and weight constraints
   • Battery life specifications
   • User interface requirements
   • Environmental considerations (weather, vibration, public use)
   • Accessibility considerations for the device itself
2. Create a design evaluation matrix with weighted criteria based on client priorities

Extension Activity: "Multi-Environment Prototype Development"

1. Design Development:
   • Create CAD models of button-pusher components optimized for 3D printing
   • Design and prototype multiple attachment methods for different surfaces
   • Develop mounting solutions that accommodate various user positions
2. Implementation:
   • Program smart servo with multiple actuation profiles selectable by user
   • Incorporate visual feedback via Neopixel to indicate mode and status
   • Implement power-saving features for extended battery life
   • Create quick-connect system for changing end effectors
3. Field Testing Protocol:
   • Develop testing protocol for evaluating device in simulated transit environments
   • Create documentation for tracking performance metrics across different scenarios
   • Design user feedback forms to capture qualitative experience data

# Advanced button pusher with multiple modes and feedback
import time
import board
import pwmio
import servo
import neopixel
from digitalio import DigitalInOut, Direction, Pull

# Setup servo
pwm = pwmio.PWMOut(board.A2, duty_cycle=2 ** 15, frequency=50)
my_servo = servo.Servo(pwm)

# Setup mode switch
mode_switch = DigitalInOut(board.D2)
mode_switch.direction = Direction.INPUT
mode_switch.pull = Pull.UP

# Setup activation button
activate_button = DigitalInOut(board.D3)
activate_button.direction = Direction.INPUT
activate_button.pull = Pull.UP

# Setup Neopixel for feedback
pixel = neopixel.NeoPixel(board.NEOPIXEL, 1, brightness=0.2)

# Define operation modes
GENTLE = 0
MEDIUM = 1
FIRM = 2
current_mode = GENTLE

# Mode colors
MODE_COLORS = [
    (0, 100, 0),    # Green for gentle
    (100, 100, 0),  # Yellow for medium
    (100, 0, 0)     # Red for firm
]

# Button pressing functions
def press_button(mode):
    if mode == GENTLE:
        pixel.fill((0, 255, 0))  # Bright green during operation
        for angle in range(0, 30, 2):
            my_servo.angle = angle
            time.sleep(0.03)
        time.sleep(0.5)
        for angle in range(30, 0, -2):
            my_servo.angle = angle
            time.sleep(0.03)
    elif mode == MEDIUM:
        pixel.fill((255, 255, 0))  # Bright yellow during operation
        for angle in range(0, 45, 3):
            my_servo.angle = angle
            time.sleep(0.02)
        time.sleep(0.7)
        for angle in range(45, 0, -3):
            my_servo.angle = angle
            time.sleep(0.02)
    else:  # FIRM
        pixel.fill((255, 0, 0))  # Bright red during operation
        my_servo.angle = 0
        time.sleep(0.2)
        my_servo.angle = 60
        time.sleep(0.8)
        my_servo.angle = 0
    
    # Return to mode indicator color
    pixel.fill(MODE_COLORS[current_mode])

# Main loop
last_mode_switch_state = True
pixel.fill(MODE_COLORS[current_mode])  # Initial mode indicator

while True:
    # Check for mode change
    if mode_switch.value != last_mode_switch_state and not mode_switch.value:
        current_mode = (current_mode + 1) % 3
        pixel.fill(MODE_COLORS[current_mode])
        print(f"Mode changed to: {['GENTLE', 'MEDIUM', 'FIRM'][current_mode]}")
        time.sleep(0.2)  # Debounce
    
    last_mode_switch_state = mode_switch.value
    
    # Check for activation
    if not activate_button.value:
        press_button(current_mode)
        time.sleep(0.3)  # Prevent multiple activations

Assessment Criteria

Students will present their final designs to a panel simulating the PLTW Capstone presentation format. Assessment will focus on:

1. Solution Effectiveness:
   • Demonstrated ability to activate various button types
   • Adaptability to different environments
   • Ease of use for the target client
   • Portability and setup considerations
2. Engineering Quality:
   • Design optimization for 3D printing
   • Code efficiency and elegance
   • Mechanical reliability and durability
   • Power management and battery life
3. Human-Centered Design Application:
   • Evidence of empathy-based design decisions
   • Consideration of client's full experience
   • Aesthetics and social acceptability
   • Attention to secondary user needs (caregivers, maintenance)
4. Documentation and Presentation:
   • Clear communication of design rationale
   • Complete technical documentation
   • Evidence-based evaluation of solution effectiveness
   • Professional presentation style and materials

Assessment Rubric