Misc Kai Concepts Tests

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.

Kite Inflator Testing

2/3/12

A few weeks ago we did some testing of the kite inflation system with a new motor, electronics, and firmware. Everything has been looking good and we are looking forward to testing it on a boat or lifting kite soon.

In the attached plot, the green line indicates the target pressure, which is changed remotely using the web interface to cause the system to inflate and deflate the kite. The red line shows the measured air pressure. The measurement is somewhat noisier than the actual air pressure because the sensor is attached to the same tube as the in intake and outlet. The improved firmware filters this noise enough to keep the actual pressure within the kite quite stable.

Chopper Test Flight

10/13/11

Dudu flew a few of the Makani team out to their test site last night, primarily to locate the field and also to test the video equipment in the helicopter and check out a gyroscope camera mount. The gyroscope was noticeably helpful and the test yielded beautiful footage that could easily be motion stabilized for stable aerial views of a kiteboat or a wing test. In the attached video, Andrea started with a shot of the airport that was filmed before the gyroscope was attached to the camera and as you will see, it is very shaky. The gyroscope takes ten minutes to get up to speed, and does not change direction very easily, but with a little forethought and practice, any […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]