Butterfly Rolling Manipulation - Revision history

Lynch: /* Processing */

2010-06-19T22:04:20Z

Processing

2010-06-19T22:04:02Z

Processing

2010-03-19T08:26:05Z

Next Steps

2010-03-19T08:23:51Z

Next Steps

2010-03-19T08:21:18Z

Results

2010-03-19T08:17:04Z

Processing

2010-03-19T08:16:36Z

Processing

2010-03-19T08:13:37Z

Processing

2010-03-19T08:13:14Z

Processing

2010-03-19T08:12:38Z

Processing

@@ Line 156: / Line 156: @@
 Below is a plot of the planned motion of the butterfly manipulator.
-[[Image:Buttefly_Screenshot.jpg|800px|thumb|The planned motion of the butterfly manipulator.|center]]
+[[Image:Butterfly_Trajectory.jpg|800px|thumb|The planned motion of the butterfly manipulator.|center]]
 =Results=

@@ Line 153: / Line 153: @@
 Based on the graphs created in processing, the PD control was effective in controlling the motor. Minor discrepancies occurred consistently at the beginning of each run, and small oscillations can be observed at the end, but the actual position was very close to the reference trajectory throughout most of the motion.
+Below is a plot of the planned motion of the butterfly manipulator.
+[[Image:Buttefly_Screenshot.jpg|800px|thumb|The planned motion of the butterfly manipulator.|center]]
 =Results=

@@ Line 167: / Line 167: @@
 - Eliminate backlash via gearless motor
+- Get more robust H-bridges - The L298N is a less than ideal H-bridge for the Pittman 8224 motor, however it was the closest thing available. In order to increase the amount of current that the H-bridge was capable of supplying to the motor, two H-bridges were connected in series as shown in the circuit diagram.
-- Get more robust H-bridges
 - Sense position of the disc using copper foil tape and resistive wire

@@ Line 166: / Line 166: @@
 - Eliminate backlash via gearless motor
+- Get more robust H-bridges
 - Sense position of the disc using copper foil tape and resistive wire
+- Implement more sophisticated controller including feedback from the disk
-- Implement PID control on motor position, along with control of PID using sensing of disc
 - Test other butterfly shapes with lower or higher curvature
 - Test other disc shapes with different center of masses and weights
-- Replace H-Bridges with nicer ones that can take higher amperage
-- Optically isolate circuit from noise

@@ Line 156: / Line 156: @@
 =Results=
-As seen by this [http://www.youtube.com/watch?v=lgmugtaGoTo&feature=related youtube video], we were able to perform the trick.  However, there are a few failure modes, namely:
+As seen by this [http://www.youtube.com/watch?v=lgmugtaGoTo&feature=related youtube video], the butterfly motion was successfully executed. However, a few failure modes exist. Namely:
 )  Sliding off the side due to loss of traction.  This can be seen [http://www.youtube.com/watch?v=lgmugtaGoTo&feature=related#t=00m37s here] <br>
 )  Losing contact with the surface of the butterfly.  This can be seen [http://www.youtube.com/watch?v=lgmugtaGoTo&feature=related#t=00m49s here]. <br>
 These might be lowered in frequency with finer tuning of the gains or adjustment of the coefficient of friction on either the disc and/or the acrylic butterfly.  The future addition of sensing of the disc location could also help counteract many problems causing failure modes.
-Rolling of a disc or ball around a butterfly-like shape has never been done in full gravity.  The reliability of the manipulation is around 75% after many hours of tuning.  This is very impressive given the time frame of three to four weeks to complete the project.
 =Next Steps=

@@ Line 152: / Line 152: @@
 [[Image:Processing_Screenshot.jpg|800px|thumb|A screen shot of the Processing window|center]]
-Based on the graphs created in processing, the PD control was effective in controlling the motor. Minor discrepancies occurred consistently at the beginning of each run, and small oscillations could be observed at the end, but the actual position was very close to the reference trajectory throughout most of the motion.
+Based on the graphs created in processing, the PD control was effective in controlling the motor. Minor discrepancies occurred consistently at the beginning of each run, and small oscillations can be observed at the end, but the actual position was very close to the reference trajectory throughout most of the motion.
 =Results=

@@ Line 150: / Line 150: @@
 Processing is also used to reset the hand. By pushing the "reset" button in the processing GUI, processing activates an interrupt which tells the hand to reset using the light sensor and run the main code again.
-[[Image:Processing_Screenshot.jpg|600px|thumb|A screen shot of the Processing window|center]]
+[[Image:Processing_Screenshot.jpg|800px|thumb|A screen shot of the Processing window|center]]
 Based on the graphs created in processing, the PD control was very effective in controlling the motor. Minor offsets occurred consistently at the beginning and end of each run due to backlash from the motor and inertia of the system mass, but the actual position was very close to the reference trajectory a majority of the time.