light controlled comfort umbrella
TRANSCRIPT
Table of content
• Executive Summary and Background
• Project Timeline: Goals and Tasks
• Design: State Diagram, Mechanical, and Electrical
• Light-to-Voltage: Phototransistor Circuit and Op-amps
• The Controller: PICAXE
• Voltage-to-Rotation: Motor Circuit and H-bridge
• Technological Challenges and Learning
• Conclusion, Cost, References, and NGs
Open the flap layer until 50<L<70
Design: State Diagram
• Too cold• Little sun-
light
If L < 50
• The 'Com-fort' Zone
100< L <150• Too hot
• Too much sunlight
If L > 200
Close the flap layer until 50<L<70
- Four critical values in the feedback system.. Wide?- Sensitivity vs. Oscillation (Noise)
- Hysteresis & Deadband..System with Memory
- L: Intensity of the Light under the Umbrella.. Relative !
sensitivity
Design: State Diagram
Phototransistor(Light-to-Cur-
rent)
2 Op-amps(Current-to-
Voltage & Gain)
PICAXEH-bridge (Two –way rotation)
Gear Motor
Light-to-Voltage: Phototransistor Circuit and Op-amps
• Phototransistor Circuit Demonstration
The Controller: PICAXE18M2
Note: if the H-bridge connects +VDC toR1 and GND to R2 at the same time or+VDC to R3 and GND to R4 at the same time,It shortens the battery. Hence..
Voltage-to-Rotation: H-bridge
Resistor 1 Resistor 2 Resistor 3 Resistor 4
Forward VDC VDC GND GND
Reverse GND GND VDC VDC
Halt GND GND GND GND
Final Demonstration
• http://www.youtube.com/watch?v=kHai--hbqNA&feature=g-upl
Technical Challenges and Learning
• Oscillations (H-Bridge)Single power supply -> Capacitor and Serial in-Ground• Oscillations (Phototransistor Circuit) -> Wider range• Oscillations (Noise) -> Larger Umbrella and Curtain• Speed of the rotation: Current Divider• Photodiode with reverse bias configuration -> Pho-
totransistor• Soldering -> Debug!
Reference
• http://www.johnloomis.org/ece445/topics/egginc/pt_char.html
• http://www.robotroom.com/BipolarHBridge.html• http://en.wikipedia.org/wiki/Hysteresis• http://en.wikipedia.org/wiki/Phototransistor#Other_modes_o
f_operation
Take 0 – Youtube NGs
• NG1 : http://youtu.be/2Ko6o740K6k• NG2: http://youtu.be/_-qF7b6f4oU