Jun
11
Filed Under (Chile, gliders, Iquique, MOOMZ, OSU, power, seagliders, SG157) by shearmar on 11-06-2009
Energy usage plot for sg157 since the beginning of the deployment.

Energy usage plot for sg157 since the beginning of the deployment.

We’ve been experimenting with some power saving strategies on sg157 this week. In the plot of energy consumption, you can see that the blue 10V battery is draining a lot faster than the red 24V battery. The 10V battery powers the onboard computer and the scientific sensors. The 24V battery mainly powers the buoyancy pump. So, our energy consumption for science is rapidly outpacing our energy consumption for flying.

How to fix that? Shut off the science sensors! So we tried that starting MondayJun 08 by uploading a one-line science file:

// Science for OSU sg157 and/or sg158 with PAR sensor
/depth  time    sample  gcint
1000    600     0000    600

This file determines that from the surface to 1000 m the sampling interval is 600 seconds (10 minutes), none of the sensors are turned on (0000), and the guidance and control interval (time between steering) is also 600 seconds. This had an immediate affect:

10V battery energy usage by sensor, major consumers are optics and TT8 (computer)

10V battery energy usage by sensor, major consumers are optics and TT8 (computer)

Notice the major drop near dive 540. This is great, it extended our mission duration from end of August to end of October! Nevermind the fact we are no longer collecting data … and this had an added complication of suddenly erratic flying by the glider. With the glider checking in only every 10 minutes to steer and make flying decisions, sg157 would fly past 1000 m, go to deep and rocket up to the surface in what I’m assuming is an emergency manuever.

Anatoli did some experimentning, and now we are flying with shorter gcints and the CT sensor on, consuming only slightly more power than everything off, and having no more erratic dives.

Apr
19
Filed Under (Chile, energy, gliders, power, seagliders, SG157) by shearmar on 19-04-2009

I’m trying a drastic change in the science file to see if I can make any impact on the energy consumption. Right now the power remaining should get us to end of July, and this may work well for the timing of a MOOMZ cruise, but if the cruise gets delayed further having sg157 last as long as possible will be a priority. Here’s the new science:
// Science for OSU sg157 and/or sg158 with PAR sensor
/depth time sample gcint
50 4 1111 60
150 4 1111 120
250 52 1110 180
600 104 1110 300
1000 104 1100 360

Apr
13
Filed Under (Chile, energy, gliders, MOOMZ, power) by shearmar on 13-04-2009

The change to the science file didn’t result in any substantial energy savings. See the blue line on the plot below

Ideally the blue and red curves, should parallel one another. We’ll have to try something more severe in terms of sampling the lower portion of the water column to save energy.