Update example

petercorke · petercorke · commit c7af1e0ae3e4 · 2020-11-09T13:38:43.000+10:00
diff --git a/examples/readme.py b/examples/readme.py
@@ -5,23 +5,30 @@
 print(robot)
 T = robot.fkine(robot.qz)
 print(T)
-qt = rtb.trajectory.jtraj(robot.qz, robot.qr, 50)
-robot.plot(qt.q, movie="panda1.gif")
 
 # IK
 from spatialmath import SE3
 
-T = SE3(0.1, 0.2, 0.5) * SE3.OA([0, 1, 0], [0, 0, -1])
-q, *_ = robot.ikunc(T)
-print(q)
-print(robot.fkine(q))
+T = SE3(0.8, 0.2, 0.1) * SE3.OA([0, 1, 0], [0, 0, -1])
+q_pickup, *_ = robot.ikine(T)  # solve IK, ignore additional outputs
+print(q_pickup)# display joint angles
+print(robot.fkine(q_pickup))    # FK shows that desired end-effector pose was achieved
+
 
-# URDF model
+qt = rtb.trajectory.jtraj(robot.qz, q_pickup, 50)
+robot.plot(qt.q, movie="panda1.gif")
+
+# URDF + Swift version
+dt = 0.050  # simulation timestep in seconds
 robot = rtb.models.URDF.Panda()
 print(robot)
-env = rtb.backend.Swift()
-env.launch()
-env.add(robot)
-for qk in qt.q:
-    robot.q = qk
-    env.step()
+env = rtb.backend.Swift()   # instantiate 3D browser-based visualizer
+env.launch("chrome")        # activate it
+env.add(robot)              # add robot to the 3D scene
+env.start_recording("panda2", 1 / dt)
+for qk in qt.q:             # for each joint configuration on trajectory
+      robot.q = qk          # update the robot state
+      env.step()            # update visualization
+env.stop_recording()
+
+# ffmpeg -i panda2.webm -vf "scale=iw*.5:ih*.5" panda2.gif
