Hysteresis Compensation

Waveform Builder

4 min read

The waveform-builder application and scripts were design to construct waveforms from LSA that can be played in the 867 measurement lab. The waveform is a .txt file with two columns, time (s) and current (A). The current must start with 0.

GUI

Script

The mm_waveform_builder.scripts.build_lsa_from_config allows defining a generation configuration wiki:yaml which is used for waveform generation.

The call signature for the script is

python -m mm_waveform_builder.scripts.build_lsa_from_config [-h] [-p] [-o OUTPUT] [--no-confirm] [--rms-max RMS_MAX] file [file ...]
 
positional arguments:
  file                  Configurations to build waveform from. Multiple configurations can be merged into one.
 
options:
  -h, --help            show this help message and exit
  -p, --plot            Plot waveform after generation
  -o OUTPUT, --output OUTPUT
                        Output directory.
  --no-confirm          Do not prompt before generating waveform.
  --rms-max RMS_MAX     Maximum RMS current in A.

The script takes a configuration YAML as input and outputs a directory to the --output argument value directory with 2 files:

  • waveform.txt: The generated waveform, with 2 columns
  • slices.yml: The slices of each cycle in the generated waveform. This allows simpler post-processing of measurements, if cycle-by-cycle analysis is required.

Prior to writing the generated waveform, if -p is used, the waveform will be plotted with matplotlib.

The --rms-max argument allows setting the value. By default this is 3000 for the 867 HOLEC, and the script uses the default decay time of 61.5s.N.B. The calculation is accurate, but the system response of the HOLEC seems to be nonlinear, and therefore this functionality is not entirely useful.

Script Configuration

The configuration YAML takes the following form:

parameter: MBI/IREF
pad_zero: 10.0
supercycles:
  PHYS_LHCFILL_ZERO:
    cycles:
      - SHiP_L1230_2024_V2
      - SPS_TIMING_2021_V1
      - LHC_PILOT_Q20_2024_V1
      - SPS_TIMING_2021_V1
      - SPS_TIMING_2021_V1
      - SPS_TIMING_2021_V1
      # - MD_26_L60_Q20_2022_V1
  PHYS_ZERO:
    cycles:
      - SHiP_L1230_2024_V2
      - SPS_TIMING_2021_V1
      - SPS_TIMING_2021_V1
      - SPS_TIMING_2021_V1
      - SHiP_L1230_2024_V2
      - SPS_TIMING_2021_V1
      - SPS_TIMING_2021_V1
      - SPS_TIMING_2021_V1
cycles:
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_LHCFILL_ZERO
  - supercycle: PHYS_LHCFILL_ZERO
  - supercycle: PHYS_LHCFILL_ZERO
  - supercycle: PHYS_LHCFILL_ZERO
  - supercycle: PHYS_LHCFILL_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  - supercycle: PHYS_ZERO
  • The parameter value controls which LSA parameter to retrieve the discrete function from.
  • The pad_zero controls how many seconds of 0 will be pre- and appended to the waveform. A linear ramp will connect the 0-values to the initial reference current to avoid a step. This key is optional.
  • The supercycles key allows the definition of Supercycles, which compose multiple subcycles with the cycles subkey. The defined supercycle can be used in the top-level cycles key.
  • The cycles section is the most important section of the configuration. Here you can put the supercycles to “play”, or cycles.
    • Supercycles are specified with supercycle key.
    • Cycles can be used with cycle key to directly specify an individual cycle.
    • Timing users can be used with the user key. (e.g. SFTPRO1)
    • In addition, the idle key allows to specify a “wait” time to remain at idle current, specified in milliseconds, to put an artificial “break” between cycles.

For the cycle and user keys, subkeys scaleX and scaleY are allowed, and allow the scaling of cycles in time and current values.

Sample configurations

parameter: "QF/IREF"
pad_zero: 5.0
cycles:
  - user: SFTPRO1
    scaleY: 0.5
  - cycle: SFT_PRO_MTE_L4780_2023_V2

Combining multiple configuration files

Multiple configuration files can be merged together, by specifying multiple configurations at the command line. The input_file argument accepts multiple arguments, and configurations are merged left-to-right, with right-most taking precedence.

Economy modes

By appending _DYNECO or _FULLECO to cycle names in either the Supercycle definition or cycles definition, the constructed cycle will be adapted to Dynamic Economy or Full Economy modes.

To use dynamic economy cycles, the configuration needs to be extended by adding the following section:

dyneco_params:
  reg_time_ms: 2.0  # ms
  acceleration: 40000.0
  duration_parabola_ms: 120.0
  start_delay_ms: 50.0
  load_ohms_ser: 50.0  # ohms
  load_henrys: 6.7  # H
  limit_v_pos: 26000.0
  initial_ref: 155.7363  # A
  dyneco_start_ct: 200.0
  dyneco_end_ct:
    SFT_PRO_MTE_L4780_2023_V1: 9500
    SFT_PRO_MTE_L4780_2023_V2: 9500
    SFT_PRO_MTE_L4780_2024_V1: 9500
    SFT_PRO_MTE_L4780_2024_V2: 9500

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