Practicum 5C

The goal of this practicum is to deploy your robot in Phake lake to obtain temperature measurements at prescribed 3D locations.

This is a complete practicum manual so that you can familiarize yourself with what will happen at the lake, but internet will not be available at the lake for you to reference this website.  Printed versions of instructions will be available there.

By the end of this practicum session, you and your partner will deliver a Submission Sheet (found on Sakai), including:

1.    A plot of depth vs. time when the P control system is used to track desired depths of 0.2m and 0.4m in the lake.

2.    A table of 3D positions and corresponding temperature measurements.

Have fun deploying your robot!

Packing List

You should arrive at your practicum with the following equipment:

• • • Robot with umbilical and PCB

    • Your robot constants (pressure calibration slope and offset, resistance of resistor you added in P4A, Kp value for critical damping)

    • Water bottle with water

    • USB stick or computer so you can take your data back to a place with internet

    • Warm clothes and a warm hat

    • Shoes suitable for muddy ground

Start Time

Your practicum will start at a different time, depending on your assigned time: 

• • • Students in the first group will arrive at the Bernard Field Station gate at the exact time the practicum section should start.

    • Students in the second group will arrive at the Bernard Field Station gate at a time 1 hour later than the time the practicum section should start.

Check-in

To get to the lake, you will meet a proctor at the gate on the North side of Foothill (see map below). Be sure to cross Foothill Blvd. at the streetlight where it is safe. At the gate, be sure to do the following:

• • • Sign in with the BFS clipboard.

    •  Get a headlamp from the E79 room if your section starts later than 2:45pm.

    • A proctor will wait at the gate for 10 minutes. If you are later than this you will not be able to enter the facility

Upon arriving at the lake, you will participate in a short safety orientation presentation. YOUR SAFETY IS VERY IMPORTANT. The following safety rules will be presented:

o   Only go in the boat if you are comfortable. We won’t force you to go, and you shouldn’t feel pressured. There is no grade reduction for not going in the boat. The boats maybe a little leaky, but they should be okay.

o   If you are not a strong swimmer, please let an instructor know before getting into a boat.

o   Do not enter a boat while carrying anything in your hands.  Have a friend or a proctor hold your equipment and then pass it to you once you're settled.

o   When entering the boat, have an instructor hold the boat steady. Walk along the center line of the boat with your weight low and hands free to hold the boat’s rim.

o   Never stand up in a boat.

o   Always wear a life jacket in the boat.

If someone falls out of a boat (this has never happened before!), follow these instructions:

o  DO NOT CLIMB BACK ON THE BOAT! This may cause others to fall in the water.

o People on the boat should encourage the person to swim to shore. Tell them to face shore and kick their feet.

o People who fall out of the boat should swim to shore.

o If a whistle is available, blow the whistle to call for help.

In addition to your own safety, it is important that we care for the safety of the environment.

o  Make sure that all trash, especially wires, is disposed of trash bags at the lab site.

o  Bicycles are allowed on the paved road, but they must be locked up at the conservancy and not taken down the gravel roads.

o  Bathrooms are located at the conservancy.

Explore the VI

Before going out on your deployment, take a minute to explore the VI you’ve been building throughout the semester. 

Open the block diagram of P5C.vi. 

First try to figure out how the calibration values that you input on the front panel are being used in the block diagram. Can you identify where the block diagram is calculating the depth and the temperature? 

Then try to find where the P-Control is in the block diagram. Can you understand what it’s doing? Does it look similar to what you’ve been seeing in tutorial? 

Prepare for Deployment 

After the robot is built, show an instructor or proctor and so they can assign you a desired position and add you to the boat queue. Write down your assigned position number.

Wait until a row boat is ready. Be sure to enjoy the great outdoors (even if it is cold at night).

Fill Out a Course Evaluation Form 

Complete your course evaluation form. You should receive these in an email link.

At your assigned row boat, work with a proctor or instructor to complete the following steps. 

YOU WILL HAVE ONLY 20 MINUTES IN THE BOAT.

Have a proctor/instructor row you to your desired location.

Write down your time of deployment. 

Run your VI with the robot motor off. Place the robot in the water so it floats at the surface. This will provide a measurement of the water’s surface temperature.

Set Kp so your robot is critically damped. Have your robot track a desired depth of 0.2 m by typing 0.2 into the desired depth entry field. Make sure the robot moves to the desired depth (watch the robot and the depth chart on your VI). Let the robot hover at 0.2 m for a few seconds so that temperature can be recorded at that depth. Then, repeat for depth of 0.4 m.

NOTE 1: If your robot seems to move in the wrong direction, it is likely because you have your robot wires swapped on the PCB (relative to the assumption in the VI). To address this issue, simply click on the Reverse button on the VI.

NOTE 2: If your robot’s depth measurement doesn’t match the robot’s actual depth measurement, this is likely because your calibration is no longer valid in the current system. E.g. elevation or barometric pressure have shifted your offset.  Adjust your pressure sensor calibration intercept value in the VI to correct this. 

NOTE 3: Diving too deep will compress the foam blocks and make the robot sink!

NOTE 4: Make sure your robot is neutrally buoyant.

NOTE 5: If your robot is not settling at 0.2m, try increasing the depth to between 0.2m and 1m

Remove your robot from the water. Confirm you have logged data in your output file. You need to have temperatures from three depths: surface, 0.2 m, and 0.4 m. Make sure you have also recorded the current GPS location (with all sig figs) and the time of deployment before you return. 

Construct a plot of depth versus time. Overlay on this plot the desired depth versus time. This will be added to your submission sheet.

REMINDER:  The VI timer starts when you click run, but the time doesn’t start recording to the output file until you’ve chosen the name and directory for the output file. Because of this, the time column in the output file generated from the VI will have a near 0 number in the first row, then it will jump a couple of seconds in the next row and begin recording time normally from there. When you are looking at your data, delete the first row (with the near 0 time), then make a new column where you calculate the difference between the first recorded time after the jump and the current time in each row in order to get the elapsed time starting from 0. 

Find the average temperature at the surface, 0.2m depth and 0.4m depth from your measured data. Take a second to do a sanity check of these values, confirming that they are temperatures you might see underwater at these depths.

There is no internet at the lake, so be sure to save your data and submission form on a USB stick or a computer and take it back to a place where you have internet if you are unable to submit with your phone.

1.    E79 Practicum Manual 5A