Speed Measurement
Compute speed from rotor angular position
- Library:
Motor Control Blockset / Sensor Decoders
Description
The Speed Measurement block calculates the angular speed from the angular position of the rotor by calculating the change in the angular position with respect to time.
Ports
Input
θ — Angular position of rotor
scalar
Angular position of the rotor specified in either radians, degrees, or per-unit.
Data Types: single | double | fixed point
Output
⍵ — Angular speed of rotor
scalar
Angular speed that the block computes based on the angular position input.
Data Types: single | double | fixed point
Parameters
Position unit — Unit of angular position
Radians (default) | Degrees | Per unit
Unit of the angular position θ.
Speed calculation criteria — Method of speed calculation
Maximum application speed (default) | Speed resolution | Time interval for speed calculation
The speed calculation method used in the block. The selected method determines the range of the rotor speed that the block can measure.
These parameters change values according to the Speed calculation criteria parameter:
| Parameter name | Maximum application speed | Speed Resolution | Time interval for speed calculation |
|---|---|---|---|
Delays for speed calculation (number of samples) |
| 28 | 28 |
Maximum measurable speed (RPM) |
| 10344.8276 | 10713.2857 |
Measurable speed resolution (RPM) |
| 4.9892e-06 | 4.9892e-06 |
Block sample time (S) — Sample time after which block executes again
100e-6 (default) | scalar
The fixed time interval (in seconds) between every two consecutive instances of block execution.
These parameters change values according to the Block sample time (S) parameter value:
Delays for speed calculation (number of samples)
Maximum measurable speed (RPM)
Measurable speed resolution (RPM)
Maximum application speed (RPM) — Maximum measurable rotor speed
1000 (default) | scalar
The maximum rotor speed (in rotations per minute) that the block can measure.
These parameters change values according to the Maximum application speed (RPM) parameter value:
Delays for speed calculation (number of samples)
Maximum measurable speed (RPM)
Measurable speed resolution (RPM)
Dependencies
To enable this parameter, set Speed calculation criteria to
Maximum application speed.
Speed Resolution (RPM) — Minimum detectable value of change in angular position
5e-6 (default) | scalar
The minimum value of the θ input that the block can
detect.
These parameters change values according to the Speed Resolution (RPM) parameter value:
Delays for speed calculation (number of samples)
Maximum measurable speed (RPM)
Measurable speed resolution (RPM)
Delays for speed calculation (number of samples) — Number of angular position samples measured
299 or 28 (default) | scalar
The number of samples of the angular position input that the block measures to compute the average position value.
These parameters change values according to the Delays for speed calculation (number of samples) parameter value:
Maximum measurable speed (RPM)
Measurable speed resolution (RPM)
Dependencies
To enable this parameter, set Speed calculation criteria to
Time interval for speed calculation.
Speed unit — Unit of angular speed output
RPM (default) | Degrees/Sec | Radians/Sec | Per unit based on maximum measurable speed | Per unit based on dialog
Unit of the angular speed output.
Speed data type — Data type of angular speed output
single (default) | double | fixed point
The data type of the angular speed output ⍵.
Note
The Speed Measurement block may occasionally display the warning message
'Wrap on overflow detected.'