2.5. Thorlabs Benchtop DC Servo

Summary:	ThorlabsBDCServo
Type:	Actuator
License:	licensed under LGPL
Platforms:	Windows
Devices:	Thorlabs 30 mm XY Stage with Integrated Controller, Brushed DC Servo Motors
Author:	J. Krauter, TRUMPF SE + Co. KG, Ditzingen

2.5.1. Overview

ThorlabsBDCServo is an acutator plugin to control the following integrated devices from Thorlabs:

Benchtop DC Servo (M30XY)

It requires the new Kinesis driver package from Thorlabs and implements the interface Thorlabs.MotionControl.Benchtop.DCServo.

Please install the Kinesis driver package in advance with the same bit-version (32/64bit) than itom.

This plugin has been tested with the Benchtop DC Servo M30XY.

2.5.2. Initialization

The following parameters are mandatory or optional for initializing an instance of this plugin:

serialNo: str, optional
Serial number of the device to be loaded, if empty, the first device that can be opened will be opened

default: “”

connectToKinesisSimulator: int, optional
If 1, a connection to the running Kinesis Simulator is established before starting to search for devices.

Value range: [0, 1], Default: 0

2.5.3. Parameters

These parameters are available and can be used to configure the ThorlabsBPDCServo instance. Many of them are directly initialized by the parameters of the constructor. During the runtime of an instance, the value of these parameters is obtained by the method getParam, writeable parameters can be changed using setParam.

acceleration: Sequence[float]

Acceleration values for each axis in mm/s^2.

2 values required, Value range: [0, 5], Default: [5, 5]

async: int

asychronous (1) or synchronous (0) mode

Value range: [0, 1], Default: 0

backlash: Sequence[float]

Backlash distance setting in mm (used to control hysteresis).

2 values required, Value range: [0, 5], Default: [0, 0]

channel: Sequence[int], read-only

Channel number of each axis.

deviceName: str, read-only

Description of the device

enabled: Sequence[int]

If 1, the axis is enabled and power is applied to the motor. 0: disabled, the motor can be turned by hand.

Allowed number of values: 0 - 2, Value range: [0, 1], Default: [1, 1]

firmwareVersion: int, read-only

Firmware version of the device

homed: Sequence[int], read-only

If 0, the axis is not homed. 1: homed.

Allowed number of values: 0 - 2, Value range: [0, 1], Default: [1, 1]

maximumTravelPosition: Sequence[float], read-only

Maximum travel position for each axis in mm.

2 values required, Value range: [15, 15], Default: [15, 15]

minimumTravelPosition: Sequence[float], read-only

Minimum travel position for each axis in mm.

2 values required, Value range: [-15, -15], Default: [-15, -15]

name: str, read-only

name of plugin

numaxis: int, read-only

number of axes (channels)

Value range: [0, 100], Default: 2

serialNumber: str, read-only

Serial number of the device

timeout: float

Timeout for positioning in seconds.

Value range: [0, 200], Default: 5

velocity: Sequence[float]

Velocity values for each axis in mm/s.

2 values required, Value range: [0, 2.6], Default: [2.6, 2.6]

2.5.4. Exemplary usage from Python

In the following examples, it is shown how to use this Plugin in itom. The example shows a typical measurement routine. First the homing run is performed, then the stage moves to a start position and from there a certain range is rastered in both axes.

from itom import actuator
import numpy as np

# init a actuator
mot = actuator("ThorlabsBDCServo")

# set some parameter
mot.setParam("velocity", [2.6, 2.6])
mot.setParam("acceleration", [5.0,5.0])
mot.setParam("backlash", [0,0])

# home both axes of stage
mot.calib(0, 1)

# move to a arbitrary start position of -5.0 mm, 2.0 mm
startPos = (-5.0, 2.0)
mot.setPosAbs(0, startPos[0], 1, startPos[1])

# measurement parameter
numX = 10
numY = 10

rangeX = 1.0  # mm
rangeY = 1.0  # mm

stepX = rangeX / numX  # mm
stepY = rangeY / numY  # mm

# save start position of routine
measureStartPos = mot.getPos(0, 1)

# create vectors of absolute position
xVec = np.arange(measureStartPos[0], measureStartPos[0] + rangeX + stepX, stepY)
yVec = np.arange(measureStartPos[1], measureStartPos[1] + rangeY + stepY, stepY)

# move by using absolute positions
for absX in xVec:
    mot.setPosAbs(0, absX)
    for absY in yVec:
        mot.setPosAbs(1, absY)
        print("x: {}, y: {}".format(mot.getPos(0), mot.getPos(1)))

# do the some by using relative movement
mot.setPosAbs(0, startPos[0], 1, startPos[1])
measureStartPos = mot.getPos(0, 1)

for idxX in range(numX):
    mot.setPosRel(0, stepX)
    mot.setPosAbs(1, measureStartPos[1])
    for idxY in range(numY):
        mot.setPosRel(1, stepY)
        print("x: {}, y: {}".format(mot.getPos(0), mot.getPos(1)))

2.5.5. Compilation

To compile this plugin, install the Thorlabs KINESIS driver package in the same bit-version than itom (32/64bit). It has been implemented using KINESIS version 1.14.32. Then set the CMake variable THORLABS_KINESIS_DIRECTORY to the base directory of Kinesis (e.g. C:/Program Files/Thorlabs/Kinesis). The required libraries from Kinesis will automatically be copied to the lib folder of itom. Do not use Kinesis 1.6.0 or below for compiling this plugin.

Kinesis 1.7.0 requires the Microsoft C++ Redistributable 2012.