Week 8 Input Device

Our group's vision is to design and create a water clock which uses water levels to tell time. Our design will consist of 3 acrylic columns, to indicate the hour, minute, and seconds of time. The column will be filled to the appropriate level based on the current timing

The initial BOM for the water clock looks like

Qty.	Description	Purpose
1	Pump	Circulate water to top resevoir
6	DC Solenoid Valves	Control column water inflow and outflow
	Tubes	Circulate water from botton to top resevoir
3	Distributed Controller Boards (based on Neil's Step Response board)	Control water level of each column
1	Master Controller Board	Keep time and send command to column
3	Sensors	Feedback on water level

Cost

The main cost is from the valves and pump. The pump is roughly $80 and the valves are about $25 each. If we go with capacitance sensors, it would be practically free. If we need IR or ultrasound sonar, this would add the cost of three such sensors.

Here are picture of the group testing various sensors: capacitance and sonar:

We saw a lot of noise and instability with the capacity sensors, even with the verison using a shield. The utlrasound sensor had a beam that was lobe shape, so from time to time, it would bounce off the walls and result in noise.

Material Sources

The sensors are sourced from either IDC or Sparkfun. The valves and pumps are purchased from McMaster and Amazon.

Issues

- Sensing with sensor is creating a lot of noise and the measurement is not consistent (adding water sometimes increases time constant, sometimes decreases it)
- Ultrasound sensor is bouncing off the walls of the column
- Uncertain if valve will release water in time
- Will valves react quickly enough for seconds column?

Schedule/ Tasks

- Test sensor
- Test valves
- Create controller boards
- Integrate

Final Group Proejct: Water Clock

12/12/2012