Changes between Version 19 and Version 20 of Tutorials

Timestamp:

Mar 29, 2016, 2:13:20 PM (10 years ago)

Author:

fma

Comment:

--

Tutorials

@@ -67 +67 @@
         return pool
 }}}
-
 
 As you can see, we just implemented 2 virtual methods, {{{_createLegs()}}} and {{{_createActuatorPool()}}}.
@@ -374 +373 @@
 }}}
 
-{{{GAIT_PARAMS}}} dict contain some additional gaits params:
+{{{GAIT_PARAMS}}} dict contains some additional gaits params:
 
 * {{{length}}} is the distance each leg will move for an entire cycle when the robot translate;
@@ -383 +382 @@
 
 These values must be adjusted for each robot, to avoid legs collisions.
-== Complex example ==
-
-Have a look at [[source:py4bot/examples/cronos|py4bot/examples/cronos]], which contain the code for my 4DoF hexapod
+
+== Real robot example ==
+
+Ok, a simulated robot is cool, but a real one is much more fun!
+
+Let's say that you built you own cool 3DoF hexapod, like these:
+
+* http://www.thingiverse.com/thing:1338781
+* http://www.thingiverse.com/thing:920882
+* http://www.thingiverse.com/thing:879555
+* http://www.thingiverse.com/thing:31569
+* http://www.thingiverse.com/thing:1603
+* http://www.thingiverse.com/thing:1604
+* http://www.thingiverse.com/thing:1080281
+* http://www.thingiverse.com/thing:585 (this is an octopod; I didn't yet implement gaits for such robot, but it is possible)
+
+and let's say you want to use a [http://www.dfrobot.com/wiki/index.php/Veyron_Servo_Driver_(24-Channel)_(SKU:DRI0029) Veyron servos driver] as low-level hardware driver.
+
+Let's modify our {{{Hexapod}}} class:
+
+{{{
+#!python
+
+import settings
+
+
+class Hexapod(Robot):
+    def _createLegs(self):
+        legs = {}
+        legIk = {}
+        for legIndex in settings.LEGS_INDEX:
+            legs[legIndex] = Leg3Dof(legIndex, {'coxa': Coxa(), 'femur': Femur(), 'tibia': Tibia()})
+            legIk[legIndex] = Leg3DofIk(settings.LEGS_GEOMETRY[legIndex])
+
+        return legs, legIk
+
+    def _createActuatorPool(self):
+        driver = Veyron()
+        pool = ServoPool(driver)
+
+        for leg in self._legs.values():
+
+            # Create joints servos
+            num = settings.LEGS_SERVOS_MAPPING[leg.index]['coxa']
+            servo = Servo(leg.coxa, num)
+            pool.add(servo)
+
+            num = settings.LEGS_SERVOS_MAPPING[leg.index]['femur']
+            servo = Servo(leg.femur, num)
+            pool.add(servo)
+
+            num = settings.LEGS_SERVOS_MAPPING[leg.index]['tibia']
+            servo = Servo(leg.tibia, num)
+            pool.add(servo)
+        return pool
+}}}
+
+In addition, we must add a few things in the '''{{{settings.py}}}''' module:
+
+{{{
+#!python
+
+SERVOS_CALIBRATION = {
+     0: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # coxa leg RF
+     1: {'offset': -90., 'pulse90': 1500, 'ratio': 1000/90.},  # femur leg RF
+     2: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # tibia leg RF
+     3: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # unused
+     4: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # coxa leg RM
+     5: {'offset': -90., 'pulse90': 1500, 'ratio': 1000/90.},  # femur leg RM
+     6: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # tibia leg RM
+     7: {'offset':   0., 'pulse90': 1505, 'ratio': 1000/90.},  # unused
+     8: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # coxa leg RR
+     9: {'offset': -90., 'pulse90': 1500, 'ratio': 1000/90.},  # femur leg RR
+    10: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # tibia leg RR
+    11: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # unused
+    12: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # unused
+    13: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # tibia leg LR
+    14: {'offset': -90., 'pulse90': 1500, 'ratio': 1000/90.},  # femur leg LR
+    15: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # coxa leg LR
+    16: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # unused
+    17: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # tibia leg LM
+    18: {'offset': -90., 'pulse90': 1500, 'ratio': 1000/90.},  # femur leg LM
+    19: {'offset':   0., 'pulse90': 1505, 'ratio': 1000/90.},  # coxa leg LM
+    20: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # unused
+    21: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # tibia leg LF
+    22: {'offset': -90., 'pulse90': 1500, 'ratio': 1000/90.},  # femur leg LF
+    23: {'offset':   0., 'pulse90': 1500, 'ratio': 1000/90.},  # coxa leg LF
+}
+}}}
+
+{{{SERVOS_CALIBRATION}}} dict contains:
+
+* {{{offset}}} is the angle between the servo reference and the real angle. See the [[FAQ#Howisgeometrydefined|FAQ]] for the real angles definition;
+* {{{pulse90}}} is the pulse value for the neutral position of the servo, which is usually 90°;
+* {{{ratio}}} is the pulse width per degree.
+
+Offsets may vary, depending how you mount the servos. Same, ratio sign may have to be inverted on one side, if you have a symetrical design; all angle are always computed using trigonometric direction (CCW).
+
+There is a graphical tool called '''{{{py4bot-gui-calibration.py}}}''' to help you calibrate your servos, and generate this dict.
 
 == Conclusion ==
 
 That's it for now with this tutorial. This is the first working dev. release; their are many additional things to do, and final implementation may change, according to feedback/suggestions I will get. But the core is there. Again, the goal of this framework is to provide a high level tool to build complete and powerfull applications to control you multi-legs robots.
+
+Have a look at [[source:py4bot/examples/cronos|py4bot/examples/cronos]], which contain the code for my 4DoF hexapod; it is a work in progress.