Electronics and Software Development

K2 Test – Jan 15 – Tow test

1/15/13

Today we performed a series of tests as part of our effort to improve our measurement of the kiteboat’s performance versus true wind angle (TWA), which is the angle between the wind direction and the heading of the boat. This information is ultimately used to produce polar plots, which are a standard method of showing the expected speed of a boat at different TWA. We are approaching this goal from several directions, which include adding a real-time update of the boat TWA to the boat mobile device displays and updating the KAIView software, as well as checking that the wind sensor readings are accurate. Today we towed K2 to calibrate the compass for this purpose. We additionally towed the boat […more]

Electronics Update

9/7/12

Jamie made a new inflator after the last one broke during a test a few weeks ago. The new inflator, like the old one, measures temperature, pressure and altitude, and it inflates through an intake tube.

Jamie also discovered that the junction box had a leak, possibly due to loose cable gland.

Kite Inflator Specification

8/20/12

Kite Inflator Specification

[This document is a work in progress.]

The kite inflator is a device that monitors and sets the inflation pressure of the kite. It will also serve as a general purpose data logger and transmitter for sensors such as an altimeter, temperature sensor, and GPS.

Physical, Environmental, Performance

1. max size: ?
2. max weight: ?
3. kite attachment method: ?
4. splashproof, but not submersible
5. external power switch and on/off display
6. normal use constitutes the motor valve operating for 25% of the time
7. must run for 12 hours of normal use on a full charge
8. reliable radio range of 100m on the water
9. […more]

Logger Update

3/30/12

All of the electronic interconnects that glue together the various components inside the logger box are now consolidated on a single printed circuit board. This should simplify ongoing maintenance and make it much simpler to produce additional loggers.

As an experiment, a diode and bleed resistor have been added to the battery charging port, which may help prevent galvanic corrosion at its terminals, which will almost certainly be exposed to some seawater.

Kite Inflator Update

3/30/12

We learned a number of lessons since the development of the first kite inflator PCB, including the need for a pressure release valve. The latest revision is much smaller overall, provides better electronic isolation of the pump motor, and more convenient positioning of connectors.

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.

Bridle System Algorithm

2/8/12

Dudu has been working on the bridle system algorithm for the last 3 weeks, and he finally got it working.

It has the same tools as the current software with many improvements. The algorithm finds the perfect path from the bar through all the bifurcating points along the “tree” to finally end on each kite attachment point. Attached are some screen grabs of one bridle model, and below is the XML file that contains bridle data and the C++ code that is the “engine” of the bridle system.

This was designed to be flexible and allow the use on many types of objects other than conventional kites. Dudu is now working now on the UI (User Interface) to facilitate the flexible design and […more]