Field operations¶

Practical guidance for deploying marine robots, from community field experience: checklists, power budgets, failure modes, environmental limits, and maintenance. Adapt every list to your vehicle and to the manufacturers' instructions.

flowchart LR
  P["Plan<br/>objectives, permits,<br/>power budget, abort criteria"] --> R["Prepare<br/>day before:<br/>vehicle, spares, briefing"]
  R --> S["Pre-splash<br/>power-up sequence,<br/>function tests"]
  S --> D["Deploy and monitor<br/>launch, mission,<br/>status checks"]
  D --> RC["Recover<br/>locate, secure,<br/>power down"]
  RC --> PO["Post-mission<br/>data backup, rinse,<br/>inspect, lessons"]
  PO -.-> P

Safety First

Marine robotics operations involve expensive equipment, challenging environments, and potential hazards. Always:

Have emergency recovery procedures
Never deploy alone; ensure adequate staffing
Check weather and sea state forecasts
Brief all personnel on safety protocols
Have communication backup plan

Pre-Deployment Checklist¶

Day Before Deployment¶

Vehicle Preparation: - [ ] Battery fully charged and voltage verified - [ ] All O-rings inspected (no nicks, cuts, or compression set) - [ ] O-rings lubricated with appropriate grease (silicone or Krytox) - [ ] Pressure housing leak tested (vacuum test if possible) - [ ] All sensors functional (bench test in air) - [ ] Software updated and tested in simulation - [ ] Mission plan loaded and verified - [ ] Data storage cleared (ensure sufficient space) - [ ] Backup battery charged (for recovery)

Support Equipment: - [ ] Launch/recovery equipment tested - [ ] Spare parts packed (O-rings, connectors, tools) - [ ] Communication equipment charged - [ ] Shore computer ready with monitoring software - [ ] Emergency contact numbers programmed - [ ] Weather forecast reviewed

Documentation: - [ ] Mission plan documented - [ ] Risk assessment completed - [ ] Permits/permissions verified (if required) - [ ] Insurance current - [ ] Emergency procedures reviewed with team

Shortly Before Splash¶

System Power-Up Sequence:

DVL check (per manufacturer guidance)
Many DVLs must not ping in air for more than a short time, because this can damage the transducers. Check the manual, and keep pinging disabled on deck unless the manufacturer allows it
Allow the transducers to reach water temperature if the manual recommends it
Verify bottom lock after the vehicle is in the water
IMU calibration
Power on IMU
Allow gyro bias stabilization per manufacturer guidance
Verify orientation output makes sense
GPS fix acquisition
Power on GPS
Wait for a reliable fix (cold starts can take longer)
Log initial position as deployment reference
Depth sensor zero-offset
Power on with sensor at surface (in air or just submerged)
Record zero-offset (atmospheric pressure)
Verify the reading aligns with local conditions
Acoustic modem range test
Power on modem
Perform surface range test with base station
Verify bidirectional communication
Test emergency abort command
Thruster function test
Critical: Keep vehicle restrained
Command each thruster individually
Verify all directions (forward/reverse)
Check for abnormal noise or vibration
Verify thrust allocation produces expected combined motion
Camera/lights check
Power on cameras
Verify image quality and focus
Check lights (may need submersion to verify thermal performance)

Final Checks: - [ ] All hatches properly sealed - [ ] No loose cables or items that could snag - [ ] Abort/recovery line attached (if applicable) - [ ] Team briefed on deployment and recovery procedures - [ ] Visual inspection complete (no obvious damage)

During Deployment¶

Launch phase: - Monitor system status in real-time - Verify sensor data immediately after submersion - Abort if any critical sensor failures - Log deployment time and GPS position

Mission phase: - Monitor periodically (acoustic status updates if available) - Log any anomalies or environmental changes - Be ready for emergency recovery - Track estimated mission completion time

Recovery phase: - Be ready at estimated surface time - Have visual line-of-sight before approach - Secure vehicle promptly (don't let it drift) - Power down in reverse order of power-up

Post-Deployment¶

Immediate (post-recovery): - [ ] Download data promptly, before any other work on the vehicle - [ ] Backup data to multiple locations - [ ] Rinse vehicle with fresh water (if salt water deployment) - [ ] Remove batteries and dry compartments - [ ] Inspect all seals and hatches - [ ] Log any damage or issues

Same day: - [ ] Review data quality and mission success - [ ] Document lessons learned - [ ] Note any anomalies or failures - [ ] Update maintenance log - [ ] Charge batteries for next deployment

Within week: - [ ] Full inspection of all O-rings - [ ] Sensor calibration check - [ ] Review and archive mission data - [ ] Update procedures based on lessons learned

Power Budgets¶

Calculating Mission Duration¶

Basic formula:

Mission Duration = Battery Capacity (Wh) / Average Power Draw (W) × Efficiency Factor

Efficiency factor: Use a conservative factor that accounts for discharge curves, temperature, and aging. Check your battery datasheet.

Example Power Budget - Hovering AUV¶

Note: This is a template structure. Fill with values from your component datasheets and measurements.

Component	Power (W)	Duty Cycle	Avg Power (W)	Notes
Onboard Computer	TBD	TBD	TBD	Datasheet + measured load
DVL	TBD	TBD	TBD	Datasheet
IMU	TBD	TBD	TBD	Datasheet
Depth Sensor	TBD	TBD	TBD	Datasheet
Sonar	TBD	TBD	TBD	Datasheet
Cameras/Lights	TBD	TBD	TBD	Datasheet
Thrusters	TBD	TBD	TBD	Measured under mission profile
Acoustic Modem	TBD	TBD	TBD	Datasheet
Miscellaneous	TBD	TBD	TBD	Converters, comms, auxiliaries
Total			TBD

Margin: Reserve capacity for contingencies and recovery. Document your policy in the mission plan.

Power Optimization Strategies¶

High-power consumers: 1. Thrusters - Often the largest consumer during transit - Minimize aggressive maneuvering - Use efficient paths - Consider buoyancy gliding if applicable

Lights - Necessary for imaging but power-hungry
Only enable when imaging
Use minimum brightness needed
Consider strobes vs continuous
Computers - Always-on baseload
Use efficient processors where feasible
Disable unused cores/features
Optimize software (avoid busy-wait loops)

Low-power mode: - Disable cameras/lights during transit - Reduce sonar ping rate - Lower computer CPU frequency - Can extend mission duration depending on your hardware

Environmental Operating Limits¶

Sea State Limits¶

Surface vehicles (ASV/USV):

Define go/no-go criteria based on vehicle design, operator experience, and local marine forecasts. Document limits in your SOPs and update them based on field experience.

Limitations to consider: - GPS accuracy degrades (antenna motion) - Acoustic modem performance drops (surface bubbles) - Solar panels less effective (shadowing from waves) - Hull slamming can damage equipment

UUV deployment: - Launch/recovery most critical phase - Launch/recovery often has stricter limits than submerged operation - Once submerged, UUV largely unaffected by surface conditions - Deep thermoclines caused by storms can affect acoustics

Current Limits¶

Vehicle capability: - Strong currents can prevent waypoint following and increase power consumption - Define abort criteria based on your vehicle's measured performance

Impact: - Increased power consumption (fighting current) - Poor station-keeping - Mission duration reduced - Path deviations increase

Mitigation: - Plan missions with/across current (not against) - Increase speed margins in planning - Use current profiles if available - Have abort criteria (if drift exceeds X meters)

Temperature Effects¶

Battery performance: - Capacity drops in cold conditions - Very cold environments can cause permanent damage - Use manufacturer derating curves when available

Electronics: - Temperature ratings vary by component - Pressure housings can help stabilize temperature - Sensors may need time to stabilize

Acoustic propagation: - Thermoclines bend sound (can create shadow zones) - Warm surface, cold deep = sound bends down - Affects acoustic modem range and USBL accuracy

Depth Limitations¶

Design implications: - Verify depth ratings for every pressure-bearing component - Pressure housing cost increases with depth - DVL range and acoustic performance can limit operations

Failure Modes and Recovery¶

Critical Sensor Failures¶

DVL Failure¶

Symptoms: - No bottom lock - Erratic velocity readings - Beam status errors

Immediate actions: 1. Switch to IMU-only dead reckoning (short term) 2. Surface for GPS fix if possible 3. Reduce mission to lower speed (dead reckoning degrades with speed) 4. Abort if position accuracy critical

Prevention: - Pre-mission warm-up - Check beam status before critical maneuvers - Plan missions within bottom-lock range

IMU Failure¶

Symptoms: - Orientation divergence - Attitude solution errors - High residuals in EKF

Immediate actions: 1. If hovering ROV: Surface immediately (no attitude = no control) 2. If torpedo AUV: May continue with degraded performance 3. Check magnetometer (often fails separately from gyros) 4. Attempt recalibration if possible

Prevention: - Pre-flight calibration - Avoid magnetic interference sources - Temperature stabilization time

GPS Failure (Surface Vehicle)¶

Symptoms: - No fix or stale fix - Large position jumps

Immediate actions: 1. Continue with dead reckoning (DVL + IMU if available) 2. Check antenna connection 3. Check for obstructions (debris on antenna) 4. Try rebooting GPS receiver

Recovery: - Most failures are cable/connector issues - Salt buildup can block antenna - Requires return to shore for repair

Acoustic Modem Failure¶

Symptoms: - No responses to commands - Corrupted messages - Complete silence

Immediate actions: 1. Vehicle continues autonomous mission (if programmed) 2. Wait for scheduled surface (can't command abort) 3. Monitor expected surface location for recovery

Prevention: - Always program autonomous abort conditions - Don't rely solely on acoustic for critical commands - Have time-based or location-based automatic surface

Mechanical Failures¶

Thruster Failure¶

Single thruster: - Thrust allocation can often compensate - Reduced performance but mission may continue - Monitor power draw on remaining thrusters

Multiple thrusters: - Abort mission - Activate emergency surface procedure - Jettison weights if equipped

Common causes: - Seaweed/debris entanglement - Electrical short - Bearing failure (noise, vibration)

Leak Detection¶

Symptoms: - Water in pressure housing - Conductivity sensor alarm - Unexplained power loss

Immediate actions: 1. Emergency surface immediately 2. All thrusters full up 3. Drop weights if equipped 4. Activate recovery beacon

Prevention: - Careful O-ring maintenance - Vacuum test before deployment - Don't over-torque hatches

Software/Control Failures¶

Controller Instability¶

Symptoms: - Oscillation in position or attitude - Growing amplitude oscillations - Erratic thruster commands

Immediate actions: 1. Switch to backup controller (if available) 2. Reduce controller gains 3. Emergency surface if unsafe

Common causes: - Incorrect tuning for actual vehicle - Sensor noise not filtered - Actuator saturation causing integrator windup

EKF Divergence¶

Symptoms: - Position estimate jumps - High innovation values - Covariance growing unbounded

Immediate actions: 1. Reset EKF if possible 2. Disable faulty sensor input 3. Switch to primary sensor only (e.g., DVL-only navigation)

Prevention: - Proper covariance tuning - Sensor timeout detection - Outlier rejection

Data Management¶

Mission Data Collection¶

Essential logging: - All sensor raw data (for post-processing) - State estimates (position, velocity, attitude) - Control commands (thruster outputs) - System status (CPU, power, temperatures) - Timestamps (synchronized across all sensors)

Data rates: - Sensor rates vary widely by hardware and configuration - Estimate storage based on your configured rates and payloads

Post-Mission Processing¶

Quality checks: 1. Sensor health: Any dropouts or errors? 2. Position accuracy: Compare GPS fixes (if available) 3. Control performance: Did vehicle follow commands? 4. Power consumption: Match predictions?

Data products: - Processed navigation (final position estimates) - Georeferenced sensor data (imagery, sonar) - Mission performance metrics - Lessons learned documentation

Standard Operating Procedures (SOP) Template¶

Mission Planning SOP¶

Define mission objectives (survey area, inspection target, etc.)
Plan waypoints with environmental considerations
Calculate power budget and mission duration
Check environmental forecast (sea state, current, temperature)
Identify abort criteria (sensor failures, position error limits, time limits)
Review emergency procedures with team
Obtain required permissions (if applicable)

Deployment SOP¶

Pre-deployment checklist (see above)
Team brief (roles, communication protocol, abort signals)
Power-up sequence (sensors first, thrusters armed last)
Function tests (all sensors, thrusters, modem)
Launch (controlled, documented)
Monitor (periodic status checks)

Recovery SOP¶

Estimate surface location (last known position + drift)
Visual acquisition (binoculars, spotter)
Secure vehicle (recovery line/hook)
Power down (reverse of power-up sequence)
Immediate post-recovery (data download, rinse, inspect)

Lessons Learned (Community Contributed)¶

Share Your Experience

Have operational experience to share? Add it to this page with a pull request, or post it on ROS Discourse.

From the community:

"Always test acoustics first"¶

Contributor: Field roboticist

"After loading vehicle on boat and transiting to site, first thing we do is acoustic range test before launching vehicle. Saves hours of debugging if modem isn't working. Can't tell you how many times we caught a bad cable or wrong configuration before splashing."

"GPS cold start takes longer than you think"¶

Contributor: ASV operator

"Budget extra time for GPS to get a solid fix after power-on. Don't rush this. A poor GPS fix at start can corrupt navigation."

"DVL needs warm-up"¶

Contributor: Research engineer

"Once the vehicle is in the water, we power the DVL early and wait for readings to stabilize before we start the mission. We never let it ping on deck."

"Fresh water rinse saves equipment"¶

Contributor: Marine technician

"After every salt water deployment: thorough fresh water rinse. We've saved thousands in corrosion damage with this simple step. Pay attention to connectors - they corrode first."

"Document everything"¶

Contributor: Ocean engineer

"Maintain a detailed log book. Date, time, location, sea state, what worked, what didn't. Future you will thank past you when troubleshooting recurring issues."

"Spare O-rings are mission-critical"¶

Contributor: ROV pilot

"Keep a complete set of spare O-rings at deployment site. Murphy's law: you'll nick an O-ring during assembly. Having spares means mission continues; not having them means mission aborted."

Maintenance Schedule¶

After Each Deployment¶

Fresh water rinse
Visual inspection
Data download and backup
Battery recharge
O-ring inspection

Weekly (Active Use)¶

Thruster bearing check
Connector inspection
Software updates review
Battery health check

Monthly¶

Full system test
O-ring replacement (preventive)
Sensor calibration verification
Vacuum leak test

Annually¶

Complete overhaul
Pressure housing hydro test
All O-rings replaced
Battery capacity test
Professional calibration of critical sensors (DVL, INS)

For deployment-specific guidance, see vehicle manufacturer's documentation. This page provides general best practices from community experience.