Goniometer control for Marco Braun Probehead (AXYs) added

src/tools/goniometer.py

@@ -0,0 +1,125 @@
+__author__ = 'Markus Rosenstihl <markus.rosenstihl@physik.tu-darmstadt.de>'
+
+import re
+import serial
+import time
+import logging
+import os
+logfile = os.path.expanduser("~/.goniometer.log")
+logging.basicConfig(filename=logfile,level=logging.INFO)
+logger = logging.getLogger()
+logger.name = "goniometer"
+
+class goniometer:
+    """
+    This class is meant to control the goniometer probe head from Marco Braun (AXYs)
+    """
+    def __init__(self, dev="/dev/ttyUSB0",
+                 baudrate=38400,
+                 timeout=1,
+                 return_to_origin=True,
+                 loglevel=2,
+                 logangle=False):
+        """
+        Upon creating an instance the goniometer will be initialised and the current angle defined as being 0.
+        The goniometer log can be found in `~/.goniometer.log`.
+
+        :param return_to_origin: Set to true if you want the stepper to return to the beginning when
+        the class instance is deleted (for example with "del" ). Default: True
+        :type return_to_origin: bool
+        :param loglevel: This sets the log level 0=DEBUG,1=INFO,2=WARNING. Default: 2
+        :type loglevel: int
+        :param logangle: Should a history of the angles be kept? The log can be accessed in the `_angle_history`
+          variable. Default: False
+        :type logangle: bool
+        """
+        self.serial = serial.Serial(port=dev, baudrate=baudrate, timeout=timeout)
+        logger.setLevel([logging.DEBUG,logging.INFO,logging.WARNING][loglevel])
+        self.serial.readlines() # empty serial buffer
+        self.current_angle = 0.0
+        self._angle_history = []
+        self.initialise()
+        self.return_to_origin = return_to_origin
+        self.logangel = logangle
+
+    def __del__(self):
+        if self.return_to_origin:
+            logging.info("Return to origin")
+            self._send("g1")
+            self._wait()
+        self.serial.close()
+
+    def _send(self, string_to_send):
+        formatted_string = "%s>\r\n"%string_to_send
+        logging.debug("send: %s"%(repr(formatted_string)))
+        self.serial.write(formatted_string)
+
+    def _recv(self):
+        retstr = self.serial.readline().strip().replace("\x00","")
+        search_result = re.search("<(\d+)>", retstr)
+        if search_result != None:
+            angle = float(search_result.group(1))/36.0
+            self.current_angle = angle
+            if self.logangle:
+                self._angle_history.append(angle)
+            logging.debug("%.2f"%angle)
+            return angle
+        else:
+            return None
+
+    def _wait(self):
+        logging.debug("Wait until rotation finnished (current: %.2f)"%(self.current_angle))
+        time.sleep(4)
+        while True:
+            retstr =  self._recv()
+            if not retstr:
+                logging.debug("Rotation finnished (current: %.2f)"%(self.current_angle))
+                break
+
+    def initialise(self):
+        logging.info("Initialize goniometer")
+        self._send("R000")
+        self.current_angle = 0.0
+
+    def stop(self):
+        """
+        Stops the current movement, not possible while doing :func:`step` and :func:`angle`
+        """
+        logging.info("Stop goniometer")
+        self._send("S456")
+
+    def step(self, sample_rotation_degree=1.0):
+        """
+        How many degrees should we step further. Negative values are not allowed, the stepper would return to 0.
+        A ValueError exception is raised in this case.
+        :param sample_rotation_degree: How many degrees to rotate. Default: 1
+        :type sample_rotation_degree: float
+        """
+        if sample_rotation_degree <= 0:
+            raise ValueError,"This does not what you expect, would move to the start position whatever the value"
+        logging.info("Step goniometer: %.2f"%sample_rotation_degree)
+        direction = "g" if (sample_rotation_degree < 0) else "G"
+        sample_rotation_degree = -1*sample_rotation_degree if sample_rotation_degree < 0 else sample_rotation_degree
+        steps = int(sample_rotation_degree%360)
+        self._send("%s%i"%(direction, steps ))
+        self._wait()
+
+    def angle(self, angle_degree):
+        """
+        To what angle, in degrees, should we rotate. Mod 360 is calculated for `angle_degree`.
+        If angle is smaller than current angle an exception will be raised.
+        (From  the underlying :func:`step` function)
+
+        TODO: rotate either back or over to the wanted position.
+
+        :param angle_degree: position in degree
+        :type angle_degree: float
+        """
+        angle_degree %= 360
+        delta_degree = angle_degree - self.current_angle
+        logging.info("Rotate tp %.2f (from %.2f, i.e. delta=%.2f)"%(angle_degree, self.current_angle, delta_degree))
+        self.step(sample_rotation_degree=delta_degree)
+
+
+
+