Second water test

It was cold wet and raining, but oh so much fun!

 

We just completed the second water Saturday. We used the sip-n-puff straw to control the vessel. It had full handeling. The remote stop worked, albeit at a shorter distance than expected. At this point that is not a big deal because we didn't do any of the optomization on the reciver antennae. It was just tossed inside the box. 

The motor controler box temperature was read at about 10 degrees fahrenheit above ambiant. This was fine, under the cool / cold day of our test. We have to read a lot of datasheets to find the most heat senitive component in our box. That should define our upper operational range. 

Remote safty

Stanley ordered and installed our gearing system and motor direction sensor. This system will work and hold up to the rugged conditions described described in our requirements. Specifically it has to hold up to the sun rain and bird shit. 

Brian, with his pervious marine craft experience, began water proofing work on the kayak. It will be done, once we get the new rubber cover Marian mentioned.

Igor is constructing a display panel for Bryan. It will have everything that Bryan requested, and also hold up to the conditions mentioned. We expect to finish this in the next few weeks.

I've installed a remote safety mechanism. There are two water resistant transmitters that can shut off the kayak. The device will work even submerged in water. Also the transmitter floats. I did this by repurposing a remote relay mechanism, to drive a 70A relay on the input power side. Of course this could create a possibility where the motor is in use and  power is shut off, the still spinning motor would act as a generator creating a voltage spike going into the motor controller. This is called back EMF. The robotech controller board for the IGVC bot was damaged by back EMF, when they tested their remote stop. To prevent voltage spikes two 14V zener diodes were placed on the output nodes. This will clamp the output voltage to about 14V. 

During our first water test a MOSFET overheated and failed, destroying the circuit board we've inherited from the previous team. After talking to Slivovsky, our team ordered replacement boards and began work on reconstructing the motor control circuitry. We finished enough for the software to begin programing. 

Cailin and Austin, finished most the code for the kayak this afternoon. We now have direction control, forward and reverse control via the sip-n-puff. We are ready for water testing again. 

We should give Austin special mention. He was invaluable in all aspects of the kayak project. We are not done, but a good number of hurdles have been completed.

Hardware: This is where it gets real

The Sip-n-puff is a straw like device that a user can sip or puff into to controll the kayak. The SP controller takes these inputs and outputs a joystick like command to the main board dubed REV 2 Board. There are two main motors attached to the REV2 board: Main motor(forward and backward motor), and the direction motor(this turns the main motor left or right). 

Sesnor is mechanically connected to the main motor direction via bevel gears. The sensor its self is the IP67 pot listed in the decision matrix listed in the earlier post. 

 

The feed back board was just ordered from the Portland Dorkbot. The Feedback board takes in sensor data and returns the direction back tot he main board, it also display useful information back to the user via the display board. notice that the senor goes into infinite resistance towards the edges of its range. To keep the input line from floating a 1M ohm pull-up resistor was added to the input line. We calculated this effect on the sensor, the graph on the right displays the deviation from the datasheet in percents. We max out at 0.5% deviation from the datasheet, well within acceptable range. 

 

Main Body

“At Length did cross an Albatross”

Requirements:

• Four directions of control (forwards, backwards, left, and right).
• A display for motor position, command confirmation, and safety indicators
• Kayak must be able to withstand high pressure hose for cleaning
• Approximate 4 hour run time on single charge
• User’s Manual and Engineering Documentation for maintenance

Overview, Team Albatross

Because the Albatross tend to fly in the fair wind, and because they navigate the waters just off shore they were regarded as a good omens to the ancient mariner. 

The project began some time ago. There were two previous teams, a hardware team that settled and built the trimaran set up, two previous CPE teams that built the onboard computer and the motor controller, a separate ME team that built the launcher. The previous team had done a fine job of creating this kayak. Our Objectives are to give greater fidelity to the direction sense, increase water proofing, and set up a user display.