1st Sea Test 2017 Testing the Xsens MTi3

Last Sunday, the 6th of August, marked 2017’s first sea test. It’s high time the Black Python tasted the saltwater once again! This time around, we got our hands on some new kit to try out. Armed with a ROS driver from ETH Zurich, Sunday was our first chance to put our new toy through its paces, with a morning test at Southampton Sailing Club.

2017 water test cover The estuary by the sailing club, complete with great weather

Xsens has generously sponsored us with one of their MTi-3 motion tracker modules and a developer board. This is a major upgrade for the Black Python’s electronic compass, replacing the Pololu MinIMU-9 we have been using.

Xsens logo Snazzy Xsens logo

The Xsens device not only has more accurate sensors, it also does onboard processing to calculate its orientation, integrating magnetic field readings, acceleration and gyroscope data. Our own code to calculate the heading from the MinIMU’s sensors was not entirely reliable, so if we can benefit from Xsens’ clever algorithms, it’s a definite win.

2017 water test setup Setting up the Black Python

2017 water test calibration Tony and Sophia with the good old calibration dance

2017 water test accel We wanted to show the accelerometer testing screen here. You can just about make it out. We should probably shop this to brighten the screen.

The good news was that the Xsens appeared to be performing nicely: we could watch the heading updating smoothly as we turned the boat round. But it wasn’t without challenges; due to a configuration issue which we’re still working out, the boat thought that whichever way it was pointing when we started ROS was east.

Struck by some mysterious issues with the GPS, we decided not to try autonomous sailing on this test. But the boat wasn’t staying dry! We sent it into the water under remote control, with the Xsens on board to collect accelerometer data as it bobbed on the waves. With that data, we plan to see if we can pick up the pattern of the waves to decide when the boat should tack.

After the test, and the tidy-up, the team enjoyed a well-earned Sunday roast at a nearby pub.