Sensor placement
2/22/12
sensors
Inflator Kite Test
2/21/12
We tested the inflator on a kite in the shop on Friday. The overall performance of the pump, pressure release valve, and radio link exceed our requirements. The firmware crashed after several hours of operation, however, so we will need to fix this bug and ensure that any future errors do not result in a deflated or exploded kite. The test showed that the inflation rate is 1.4 psi/hour and deflation rate is 5.6 psi/hour with a 40 sqm kite in the pressure range of interest. This is fast enough to handle small leaks, temperature-related pressure changes, and minor inflation adjustments for performance optimization.
KAICam App Update
2/3/12
Jamie has made several changes to the KAICam Android application, in support of the cruise with MBARI this week. To make the screen space on larger tablets more usable, the layout is now dynamically adjusted to maximize the preview image size.
To help in situations in which the network topology changes frequently, the app now automatically find other instances of itself that inhabit the same network. This way, the remote viewing client can connect to a camera server without being specially configured with the camera’s IP address in advance.
Other improvements include better networking efficiency and stability, and the continuous logging of GPS and air pressure (for altitude) where available.
The two images are screenshots of the app running on […more]
Electronic Kite Inflator
1/6/12
The electronic kite inflator, which we sometimes refer to as the kite Inflation Management System (IMS), is now ready for additional field testing. The device is designed to monitor and regulate the pressure of inflated kites. A Zigbee radio link is used to transmit pressure and status to the ground and to receive pressure setpoint commands. The inflator is integrated into the web-based logger interface, which allows us to monitor and control the kite pressure from any smartphone.
The latest version of the inflator uses a smaller and more robust PCB, and has a pressure release valve. Previously, the device could only inflate the kite, and had no way to release air if necessary. With the new release valve, the […more]
Kite Inflation Maintenance System
11/15/11
Jamie has augmented our kite inflation controller, which monitors a kite’s inflation levels and maintains a designated psi by inflating the kite further, in case of a leak or temperature change, for example. The new electronics add precise pressure measurement, a radio link to the ground, and remote pressure control. In the photos, the system is inflating a kite section to 8 psi. Our smaller kites take higher inflation pressures, up to 9 psi, whereas the larger kites take lower pressures, 2-3 psi. This system is splashproof, but not waterproof, which is sufficient now that our launch and retrieval procedures largely keep the kite out of the water.
The graph shows the pressure as the small kite section is inflated […more]
Image Panorama Tests
7/18/11
To generate useful ground imagery from cameras mounted on our kites, we will likely record a succession of images that can then be “stitched” together into a panorama. As an early test, we combined 32 low (VGA) resolution images from the pan/tilt webcam in the boat shop to produce the images here.
Creating coverage of the ground from a kite will be a similar process, so this is a promising result. The projection of the 3D world into a 2D image inherently results in apparent distortion, and the distortion becomes more noticeable as the width of the panorama increases. These images demonstrate two different projections into 2D space, which cause different type of distortion in each case. If the kite […more]
Comparing Three Wind Sensors
5/6/11
We have been concerned about the accuracy of the wind sensor that we have been using on the Kitefoiler, an Airmar PB200 ultrasonic anemometer. Today we took this sensor to Crown Beach, along with our old standby, a Maretron WS100 (also ultrasonic), and a handheld mechanical anemometer. In summary, the new Airmar sensor was found to report wind speeds that were 23% higher than the other two sensors, which tended to be in good agreement with each other.
We will do further testing to determine if the wind direction relative to the sensor makes a difference, if the sensor is dirty, and if it is broken or operating outside of its specified accuracy range. The graph shows the measured correspondence […more]