tab2 calc controller + schema

tab2 is derived from tabsup

bliss/controllers/motors/tab2.py

+"""
+2 legs table
+
+* 2 legs : back & front
+* 2 degrees of freedom : rotation and translation
+
+Configuration parameters:
+
+* <back> : alias for real back leg axis
+* <front> : alias for real front leg axis
+* <ttrans> : Y-axis translation calculated axis alias
+* <trot> : Z-axis rotation calculated axis alias  (in degrees)
+* <d1> : distance from front leg to sample
+* [<d2> : distance from sample to back leg]
+
+See sphinx documentation for a nice schema.
+
+tests ??
+
+"""
+
+from bliss.controllers.motor import CalcController
+import math
+
+
+class tabsup(CalcController):
+    def __init__(self, *args, **kwargs):
+        CalcController.__init__(self, *args, **kwargs)
+
+        self.d1 = self.config.get("d1", float)
+        try:
+            self.d2 = self.config.get("d2", float)
+        except KeyError:
+            self.d2 = self.d1
+
+    def calc_from_real(self, positions_dict):
+        tyf = float(positions_dict["front"])
+        tyb = float(positions_dict["back"])
+
+        return {"ttrans": (self.d1 * tyb + self.d2 * tyf) / (self.d1 + self.d2),
+                "trot": math.degrees(math.atan((tyf - tyb) / (self.d1 + self.d2)))}
+
+    def calc_to_real(self, positions_dict):
+        ttrans = positions_dict["ttrans"]
+        trot = positions_dict["trot"]
+
+        return {"back": ttrans + self.d2*math.tan(math.radians(trot)),
+                "front": ttrans - self.d1*math.tan(math.radians(trot))}