Ocean Observing with Slocum Gliders

What is an AUV/glider? Autonomous Underwater Vehicle Remotely controlled through satellites (Iridium) Connection available when glider is at the surface Sampling devices CTD (standard) Optics Chlorophyll Turbidity Light penetration

Antenna (Iridium, Freewave, GPS & Argos) Buoyancy Pump Science Payload Bay Control Board Pitch Motor Air Bladder Rudder Altimeter CTD Fore Hull Aft Hull Cowling

How gliders “fly” Buoyancy pump in  the glider pulls in 0.5 L of water When surfacing to connect glider inflates air bladder Sink downward on an angle one dive and one climb is called a ‘yo’ Push pump out  glider inflects and floats upward on an angle

The Brains – turning glider on We have a sealed up glider and a computer, now what? GliderDOS & PICODOS Analogy: Windows vs MSDOS How do we talk to glider? Use a serial interface (like USB but much older) Freewave and/or Iridium (in tail) Terminal Software Procomm, ZOC, minicom, etc (freewave) Dockserver (freewave or iridium)

Glider Rules, do’s and don’ts Never run a glider open Never turn glider on without an internal vacuum, if not sure remove vacuum plug and re-seal Vacuum should be set to 6 in Hg on a shallow glider, 7 in Hg on a deep glider – higher is safer… You can test your freewave and comms prior to turning on! (little black button back of FW) Glider communication rate 115200 8N1 19200 8N1 (freewave modem)

Glider ‘Operating Modes’ MISSION Science sampling & data logging Surfacing interval Reasons for mission abort Swimming/Glide Profile Waypoints/navigation Glider in water or lab (2 operating ‘modes’) GLIDERDOS We can also sample, transfer data, etc Need to set up the glider to drift or else it will try to swim! Ballasting, lab work, etc

Command & Control Power on default glider behavior: (it tries to surface and take action) Max buoyancy & turns on air bladder Establish communications Sequences missions (initial.mi and lastgasp.mi) Our Goals Note any errors upon startup Wait until scroll slows and then try to break out of sequence with CTRL^C Make sure we are at a prompt Turn off air pump (only if in lab!) Check internal vacuum

Command & Control 2 Callback xx (iridium) What are sensors, how do we interface with them Masterdata Put c_air_pump 0 Get m_vacuum Lab_mode on Neuters safety timer 10 minutes (u_max_time_in_gliderdos) Loadmission lowpow.mi (lab only!!)

Common commands help Where Use Consci Zero_ocean_pressure Send Zs Dockzr Zr Exit Exit reset Run sequence

Sensors and Autoexec.mi Masterdata http://marine.rutgers.edu/~kerfoot/slocum/masterdata/ Glider encylopedia Stores all default information for missions and sensors! Sensors U_ Sci_ C_ M_ Mission defaults and constructs/definitions Great to use for piloting and data handling! AUTOEXEC.mi Gliders identity file Longterm.dat

Opening & Closing glider Take your time Be clean and thorough Glider is delicate (aluminum) never over-tighten anything. If anything is tighter than finger-snug, something may be wrong Every glider is a little different For the most part make all electrical connections Take a picture before you seal it Make a checklist (if need to) of things you un-plugged and then re-plug back in Glider may not correct missing connections!

Glider Ballasting (prep glider) Make sure well sealed glider Make sure all parts present Check vacuum again Ballast puts pump at 0 cc puts battery at 0 in Loadmission lowpow.mi (lab only!!) Before placing in tank, check vacuum again Ballast, yes again

Glider Ballasting D = M / V 1 density unit is 1 sigma BUOYANCY! D is in units of kg / m^3 or g / ml 1 density unit is 1 sigma 1 kg/m^3 .001 g / ml Typical densities = 1025 kg / m^3 or 1.025 g / ml BUOYANCY! B = Vg * Dw Sea Water equation of state (Density from conductivity and temperature, and depth)

Glider Ballasting Pump size is ~ 400 mL (+- 200 mL) We operate from neutral, 0 ml (ballast) Maximum range of 50 kg / (50 + pump) L +- 4 sigma, use +-3 for safety margin Maximum range is 6 sigma units! We need help to improve range, how do we do it? We shrink a little at depth (V decreases, D increases) so we can get a bit deeper (this is the only way its possible for a 1 km glider to get deep!) Ballasting considerations (in priority order) Lowest surface density (for entire deployment!) Coldest surface water Densest deep water

Deep Glider Example

How a deployment works MISSION Science sampling & data logging Surfacing interval Reasons for mission abort Swimming/Glide Profile Waypoints/navigation Glider in water or lab (2 operating ‘modes’) GLIDERDOS We can also sample, transfer data, etc Need to set up the glider to drift or else it will try to swim! Ballasting, lab work, etc

Missions Missions are: What is a behavior Prioritized List of Behaviors Defined by behavior arguments What is a behavior Glider is capable of a dozen or so behaviors Sampling, surfacing, diving, climbing, navigating, hovering, etc Behavior arguments Define start and end of behavior Define how deep we dive, climb, or when we surface Why does priority of behaviors matter? Aborts and shared behaviors Missions are mostly static, define your missions, verify they work and stick with them. Often a mission skeleton can be used across gliders

Missions & MAFiles MAfiles make a mission flexible and changeable Goto Yo Sample Can’t edit a file on glider, thus we use MAfiles (snippets of a mission file) Missions can also be used for sensor value setting, like put, but for many sensors: for instance lowpow.mi

Glider Data Files Uses of each type of file 2 computer, Glider and Science Each computer generates 4 filetypes of similar construct D(inkum)BD – EBD M(edium)BD – NBD S(mall)BD – TBD MLG – NLG Uses of each type of file Decoding into Matlab or ASCII

How a deployment works ‘Dockserver’ (Remote glider access and control, scripts) (Glider terminal) Iridium modem (SBD, SURFACE DIALOGS, RE-TASKING) Glider deployed Data websites ‘Ironman’ (Rutgers computing server and fileserver) (data parsed and plotted in MATLAB) (automatic file syncronization between dockserver and IMCS fileserver) Google Earth piloting and display Email monitoring, diagnostic pages, alerts and broadcasts

Piloting Surface logs, websites Google Earth Plots you should have to pilot WINSCP, SSH access KML to goto Decoding, plotting Any other questions?