uniax: added force control as seperate module

Change-Id: I8b14fc90f5885834e342f6bc5e5dd0ea711b27ea

secop_psi/uniax.py

@@ -0,0 +1,129 @@
+#  -*- coding: utf-8 -*-
+# *****************************************************************************
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any later
+# version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+# details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+# Module authors:
+#   M. Zolliker <markus.zolliker@psi.ch>
+#
+# *****************************************************************************
+"""use transducer and motor to adjust force"""
+
+import time
+from secop.core import Drivable, Parameter, FloatRange, Done, Attached, Command
+
+
+class Uniax(Drivable):
+    motor = Attached()
+    transducer = Attached()
+    step = Parameter('maximum motor step', FloatRange(unit='deg'), default=5, readonly=False)
+    fine_step = Parameter('motor step for fine adjustment', FloatRange(unit='deg'), default=1, readonly=False)
+    tolerance = Parameter('force tolerance', FloatRange(), readonly=False, default=1)
+    filter_interval = Parameter('filter time', FloatRange(0, 60, unit='s'), readonly=False, default=1)
+    span = Parameter('difference between max and min', FloatRange(), needscfg=False)
+    pollinterval = 0.1
+    fast_pollfactor = 1
+
+    _target = None
+    _mot_target = None
+    _direction = 0
+    _last_era = 0
+    _cnt = 0
+    _sum = 0
+    _min = None
+    _max = None
+    _last_min = None
+    _last_max = None
+
+    def read_value(self):
+        force = self._transducer
+        mot = self._motor
+        era = int(time.time() / self.filter_interval)
+        newera = era != self._last_era
+        value = force.read_value()
+        if newera:
+            self._last_era = era
+            if self._min is None:
+                self._min = self._max = self._last_max = self._last_min = value
+            if self._cnt > 0:
+                self.value = self._sum / self._cnt
+                self._sum = self._cnt = 0
+                self.span = self._max - self._min
+                self._last_min = self._min
+                self._last_max = self._max
+                self._min = self._max = value
+        self._min = min(self._min, value)
+        self._max = max(self._max, value)
+        self._sum += value
+        self._cnt += 1
+        high_value = max(self._max, self._last_max)
+        low_value = min(self._min, self._last_min)
+        if self._target is None:
+            if mot.isBusy():
+                self.status = self.Status.IDLE, 'stopping'
+            else:
+                self.status = self.Status.IDLE, ''
+            return Done
+        step = 0
+        if self._direction > 0:
+            if high_value < self._target:
+                step = self.step
+        else:
+            if low_value > self._target:
+                step = -self.step
+        if not step:
+            if self._direction * (self._target - value) < self.tolerance:
+                self.stop()
+                self.status = self.Status.IDLE, 'target reached'
+                return Done
+            if newera:
+                step = self.fine_step * self._direction
+        if step and not mot.isBusy():
+            mot_target = mot.value + step
+            self._mot_target = mot.write_target(mot_target)
+        return Done
+
+    def write_target(self, target):
+        self._target = target
+        if target - self.value > 0:
+            self._direction = 1
+        else:
+            self._direction = -1
+        if self._motor.status[0] == self.Status.ERROR:
+            self._motor.reset()
+        self.status = self.Status.BUSY, 'changed target'
+        self._mot_target = self._motor.target
+        self.read_value()
+        return target
+
+    @Command()
+    def stop(self):
+        self._target = None
+        self._motor.stop()
+        self.status = self.Status.IDLE, 'stopped'
+
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