Simulate ocean waves with for a glider on the surface and generate MEMs sensor responses

A Python3 script which needs Pandas and NumPy installed.

To run the script:
./simWaves.py exp.00.yml
which generates multipe files:

• exp.00.log which is a copy of the log output
• exp.00.csv which is the motion of a water parcel summed for all waves
• exp.00.*.info.csv are the individual wave trains
• exp.00.*.ellipse.csv are the observations for the individual wave trains

The main csv has the following columns:

• t time in seconds starting at 0
• [x, y, z] are the water parcel's position in meters in the true north earth coordinates, x is eastward, y northward, and z vertically
• v[x,y,z] are the instantaneous linear velocities in m/sec
• a[x,y,z] are the instantaneous linear accelerations in m/sec^2
• omega[x,y,z] are the instantaneous angular velocities in radians/sec
• alpha[x,y,z] are the instantaneous angular accelerations in radians/sec^2

The info csv file columns are:

• period wave's period in seconds
• amp wave amplitude in m, this is half the peak to trough height
• hdg wave's direction from true north in degrees
• lambda wavelength in m
• spd wave phase speed in m/sec
• a and b are ellipse semi major and minor axis parameters in m

The ellipse csv has the following columns:

• t time in seconds starting at 0
• w[x, z] are the water parcel's position in meters in the wave's coordinate system, x is along the direction of motion
• wv[x,z] are the instantaneous linear velocities in m/sec in the wave's coordinate system
• wa[x,z] are the instantaneous linear accelerations in m/sec^2 in the wave's coordinate system
• wOmega is the instantaneous angular velocity in the wave's y direction in radians/sec
• wAlpha is the instantaneous angular acceleration in the wave's y direction in radians/sec^2
• [x, y, z] are the water parcel's position in meters in the true north earth coordinates, x is eastward, y northward, and z vertically
• v[x,y,z] are the instantaneous linear velocities in m/sec
• a[x,y,z] are the instantaneous linear accelerations in m/sec^2
• omega[x,y,z] are the instantaneous angular velocities in radians/sec
• alpha[x,y,z] are the instantaneous angular accelerations in radians/sec^2

Items still to be done include:

• add a wave to glider transfer function
• add sensor noise terms to linear and gyro simulated observations
• update README.md with better information

Algorithm:

The YAML file specifies all the parameters needed for a simulation

For each wave specified, a wave train is generated which is a set of amplitudes and periods such that the cumulative period time exceeds the simulation duration.

For each wave in the train, a depth dependent wavelength and phase speed are calculated, along with the particle orbit ellipse semi minor and major axis parameters.

A set of times to sample at is generated.

For each wave train the following is done:

• A random initial phase is calculated so the wave trains don't all start at zero.
• In the wave's coordinate system, positions, velocities, accelerations, angular velocity, and angular acceleration are calculated.
• The above positions, velocities, and accelerations are rotated into the earth's true north coordinate system.

The individual wave trains are summed in the earth's coordinate system.

To be added

• add glider response to the wave accelerations/velocities.
• estimate sensor response, i.e. time averaged accelerations instead of instantaneous.
• add noise to the sensor readings