Simultaneous ramping of magnetic field in all 3 axes

[astafan8]

Sweep AMI 3D magnet to (x,y,z) in time T or at vector ramp rate R, ramping all 3 axes together (in parallel), making a linear/vector trajectory from current field to the setpoint in 3D magnetic field space.

For working with ramp duration, see:

i3d.ramp_simultaneously(setpoint=FieldVector(0.5, 1.0, 0.01), duration=2)
# See the docstring of this method for details

For working with the new vector ramp rate, see:

i3d.ramp_mode("simultaneous")
i3d.vector_ramp_rate(0.05)  # requires all axes to have same units!!!
i3d.cartesian(x,y,z)  # or any other parameter call that initiates a ramp

Note that actually simultaneous ramping is already supported with the current driver, one just needs to set the block_during_ramp parameter to False, so that the driver does not wait for one axis to finish ramping before starting ramping next one, and then manually/explicitly wait until the ramping is done. However, the benefit of the new simultaneous ramp mode and the ramp_simultaneously method is that it automatically calculates and adjusts the ramp rates of the axes.

ToDos:

• ensure that if the requested field change is 0 for one/two/all-three axes, so ramping "simply works" (e.g. the instrument attempts to ramp, find that it's already in the right place, and stops ramping)
• handle the case when the requested field change for a given axis results in a ramp rate that is less than minimal ramp rate - i hope that the instrument will just use whatever the minimum ramp rate is
• example notebook
• test on instruments

[codecov]

Codecov Report

Merging #3233 (0cab6e4) into master (6913e75) will decrease coverage by 0.11%.
The diff coverage is 45.04%.

@@            Coverage Diff             @@
##           master    #3233      +/-   ##
==========================================
- Coverage   66.23%   66.12%   -0.12%     
==========================================
  Files         220      220              
  Lines       29272    29356      +84     
==========================================
+ Hits        19388    19411      +23     
- Misses       9884     9945      +61     

[dbwz8]

Did a quick look. Didn't see anything obviously wrong.