Mike Grauer's Final Project Report for Bio Inspired Robots Fall 2006 - Revision history

GICL Bot: GICL Bot: Updated link(s)

2009-03-17T23:06:58Z

GICL Bot: Updated link(s)

Mgrauer: /* Useful Links and Resources */

2006-12-19T00:40:59Z

Useful Links and Resources

Mgrauer: /* Virtual Model and Physics Based Simulation */

2006-12-19T00:36:19Z

Virtual Model and Physics Based Simulation

Mgrauer: /* Virtual Model and Physics Based Simulation */

2006-12-19T00:19:15Z

Virtual Model and Physics Based Simulation

Mgrauer: /* Virtual Model and Physics Based Simulation */

2006-12-19T00:17:18Z

Virtual Model and Physics Based Simulation

Mgrauer: /* Introduction */

2006-12-19T00:16:49Z

Introduction

Mgrauer: /* Virtual Model and Physics Based Simulation */

2006-12-19T00:16:21Z

Virtual Model and Physics Based Simulation

Mgrauer: /* Virtual Model and Physics Based Simulation */

2006-12-18T23:56:57Z

Virtual Model and Physics Based Simulation

Mgrauer: /* Robot Design and Rationale */

2006-12-18T19:23:13Z

Robot Design and Rationale

Mgrauer: /* Physical Assemblies */

2006-12-18T19:21:42Z

Physical Assemblies

@@ Line 364: / Line 364: @@
 [[Media:Goodwalker.avi]]
-[[Media:Extrusions.zip]]
+<!--GICL Bot edit:-->[[Extrusions.zip Contents|Extrusions.zip]]
@@ Line 388: / Line 388: @@
 [[Media:Adamsexample4.avi]]
-[[Media:Example.zip]]
+<!--GICL Bot edit:-->[[Example.zip Contents|Example.zip]]
 == Useful Links and Resources ==

@@ Line 392: / Line 392: @@
 == Useful Links and Resources ==
-include lego robot book
+I found the following book on building robots with Legos quite useful:
-inclue lego robot pdf from handyboard
-include the adams tutorials
+http://www.amazon.com/Building-Robots-Lego-Mindstorms-Ultimate/dp/1928994679

@@ Line 357: / Line 357: @@
 I created a virtual model of my robot in the Adams physics based simulation environment.  Rather than representing the individual Lego blocks, I created Adams geometric primitives for each of the major parts of the robot.  The proportions of the body parts to each other is roughly the same as in my Legos model.  Adams allows a user to simulate the reactions of bodies in a physical reality, with forces such as friction and gravity, motions, and various attachments of bodies to each other.  Adams is a complex software package, which I only delved a little into, and it has a substantial learning curve.  I have posted links below to resources that I found helpful in learning Adams.
-Certain abstractions were needed to represent the robot in Adams that do not map to the physical reality.  One such example is that the drive train of the physical robot is powered by a motor, which is in turn powered by a battery.  The motor turns a long axle, which turns two worm gears, the worm gears then turn two 24T Lego gears, which are fixed to two axles set perpendicularly to the long axle of the drive train.  In this way as the motor turns, the leg joints, which are attached to the two cross axles, revolve in a circle and the legs follow suit.  When construction the Adams virtual model, I set individual rotational motions on each of the four hip joints, so there really isn't anything to synchronize the virtual model's hips as there is in the physical model.  I set the rotational speed of the virtual model as 88 degrees/sec, which I arrived at by empirically observing that it takes approximately 4.1 seconds for the physical model's legs to perform one complete rotation (360 degrees / 4.1 seconds is roughly 88 degrees per second).
+Certain abstractions were needed to represent the robot in Adams that do not map to the physical reality.  One such example is that the drive train of the physical robot is powered by a motor, which is in turn powered by a battery.  The motor turns a long axle, which turns two worm gears, the worm gears then turn two 24T Lego gears, which are fixed to two axles set perpendicularly to the long axle of the drive train.  In this way as the motor turns, the leg joints, which are attached to the two cross axles, revolve in a circle and the legs follow suit.  When constructing the Adams virtual model, I set individual rotational motions on each of the four hip joints, so there really isn't anything to synchronize the virtual model's hips as there is in the physical model.  I set the rotational speed of the virtual model as 88 degrees/sec, which I arrived at by empirically observing that it takes approximately 4.1 seconds for the physical model's legs to perform one complete rotation (360 degrees / 4.1 seconds is roughly 88 degrees per second).
 Algthough there were some differences between the physical and virtual model, I feel that the virtual model I created had reasonable fidelity to the physical model, which is bourne out in the simulation video of the virtual model.  In the simulation video, the robot appears to walk with much the same lurching gait as the real model, and the head and tail both swing up and down as in the real model.  I have included a simulated video of my virtual model walking, as well as the actual file for my virtual model.
@@ Line 376: / Line 376: @@
 I have also created a video tutorial that shows creating part of a robot similar to mine.  This tutorial demonstrates creating a robot body, attaching a hip gear as a revolute joint to the body, adding a rotational motion to the hip gear, adding a leg attached to the hip on a rotational joint, adding a foot onto the leg with a fixed joint, creating a ground plane, and adding contact forces between the ground and the foot (I realize now that I forgot to add frictional force, which is just a modification of the contact force between the ground and the leg).  I also show how to set a simulation going in this tutorial.  Following the tutorial step-by-step will not arrive at robot like mine with four complete legs forward walking motion, but it will demonstrate most of the steps needed to construction such a robot.  I have also uploaded the robot model that was created during the tutorial, which can be loaded into an Adams environment.
 [[Media:Adamsexamplepart1.avi]]

← Older revision		Revision as of 00:19, 19 December 2006
Line 375:		Line 375:


−	I have also created a video tutorial that shows creating part of a robot similar to mine. This tutorial demonstrates creating a robot body, attaching a hip gear as a revolute joint to the body, adding a rotational motion to the hip gear, adding a leg attached to the hip on a rotational joint, adding a foot onto the leg with a fixed joint, creating a ground plane, and adding contact forces between the ground and the foot (I realize now that I forgot to add frictional force, which is just a modification of the contact force between the ground and the leg). I also show how to set a simulation going in this tutorial. Following the tutorial step-by-step will ~~now~~ arrive at robot like mine with four complete legs forward walking motion, but it will demonstrate most of the steps needed to construction such a robot. I have also uploaded the robot model that was created during the tutorial, which can be loaded into an Adams environment.	+	I have also created a video tutorial that shows creating part of a robot similar to mine. This tutorial demonstrates creating a robot body, attaching a hip gear as a revolute joint to the body, adding a rotational motion to the hip gear, adding a leg attached to the hip on a rotational joint, adding a foot onto the leg with a fixed joint, creating a ground plane, and adding contact forces between the ground and the foot (I realize now that I forgot to add frictional force, which is just a modification of the contact force between the ground and the leg). I also show how to set a simulation going in this tutorial. Following the tutorial step-by-step will not arrive at robot like mine with four complete legs forward walking motion, but it will demonstrate most of the steps needed to construction such a robot. I have also uploaded the robot model that was created during the tutorial, which can be loaded into an Adams environment.
		+
		+	[[Media:Adamsexamplepart1.avi]]
		+
		+	[[Media:Adamsexamplepart2.avi]]
		+
		+	[[Media:Adamsexample3.avi]]
		+
		+	[[Media:Adamsexample4.avi]]
		+
		+	[[Media:Example.zip]]

	== Useful Links and Resources ==		== Useful Links and Resources ==

← Older revision		Revision as of 00:17, 19 December 2006
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−	[[Media:~~Example~~.~~ogg~~]]	+	[[Media:Goodwalker.avi]]

	[[Media:Extrusions.zip]]		[[Media:Extrusions.zip]]

← Older revision		Revision as of 00:16, 19 December 2006
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	[[Image:Full robot.JPG\|center\|thumb\|450px]]		[[Image:Full robot.JPG\|center\|thumb\|450px]]
−
−
−	~~Here is a video of my simulated virtual robot walking, note the similarity in gait to the physical robot.~~
−
−	~~[[Media:Goodwalker.avi]]~~

	== Robot Design and Rationale ==		== Robot Design and Rationale ==

@@ Line 366: / Line 366: @@
 Algthough there were some differences between the physical and virtual model, I feel that the virtual model I created had reasonable fidelity to the physical model, which is bourne out in the simulation video of the virtual model.  In the simulation video, the robot appears to walk with much the same lurching gait as the real model, and the head and tail both swing up and down as in the real model.  I have included a simulated video of my virtual model walking, as well as the actual file for my virtual model.
-One aspect of virtual simulation I have explored is tolerance and parametric testing on the virtual model.  When building a physical prototype, it can be far too expensive in time and materials to perform full testing of a parametric space, so in building a suitable virtual model many more tests can be run in a repeatable and efficient manner.  For instance, I only had access to one motor for my robot, so I couldn't tell the top speed supported by my robot's gait.  Through using the virtual model, I was able to keep increasing the rotational speed until the legs collapsed from underneath the center of gravity of the robot, which occurs around
+One aspect of virtual simulation I have explored is tolerance and parametric testing on the virtual model.  When building a physical prototype, it can be far too expensive in time and materials to perform full testing of a parametric space, so in building a suitable virtual model many more tests can be run in a repeatable and efficient manner.  For instance, I only had access to one motor for my robot, so I couldn't tell the top speed supported by my robot's gait.  Through using the virtual model, I was able to keep increasing the rotational speed until the legs collapsed from underneath the center of gravity of the robot, which occurs around 300 degress per second.  I have included a simulated video of my virtual model collapsing below.
-similarties and diffs of model to reality, how helps

← Older revision		Revision as of 23:56, 18 December 2006
Line 359:		Line 359:

	== Virtual Model and Physics Based Simulation ==		== Virtual Model and Physics Based Simulation ==
		+
		+	I created a virtual model of my robot in the Adams physics based simulation environment. Rather than representing the individual Lego blocks, I created Adams geometric primitives for each of the major parts of the robot. The proportions of the body parts to each other is roughly the same as in my Legos model. Adams allows a user to simulate the reactions of bodies in a physical reality, with forces such as friction and gravity, motions, and various attachments of bodies to each other. Adams is a complex software package, which I only delved a little into, and it has a substantial learning curve. I have posted links below to resources that I found helpful in learning Adams.
		+
		+	Certain abstractions were needed to represent the robot in Adams that do not map to the physical reality. One such example is that the drive train of the physical robot is powered by a motor, which is in turn powered by a battery. The motor turns a long axle, which turns two worm gears, the worm gears then turn two 24T Lego gears, which are fixed to two axles set perpendicularly to the long axle of the drive train. In this way as the motor turns, the leg joints, which are attached to the two cross axles, revolve in a circle and the legs follow suit. When construction the Adams virtual model, I set individual rotational motions on each of the four hip joints, so there really isn't anything to synchronize the virtual model's hips as there is in the physical model. I set the rotational speed of the virtual model as 88 degrees/sec, which I arrived at by empirically observing that it takes approximately 4.1 seconds for the physical model's legs to perform one complete rotation (360 degrees / 4.1 seconds is roughly 88 degrees per second).
		+
		+	Algthough there were some differences between the physical and virtual model, I feel that the virtual model I created had reasonable fidelity to the physical model, which is bourne out in the simulation video of the virtual model. In the simulation video, the robot appears to walk with much the same lurching gait as the real model, and the head and tail both swing up and down as in the real model. I have included a simulated video of my virtual model walking, as well as the actual file for my virtual model.
		+
		+
		+
		+	One aspect of virtual simulation I have explored is tolerance and parametric testing on the virtual model. When building a physical prototype, it can be far too expensive in time and materials to perform full testing of a parametric space, so in building a suitable virtual model many more tests can be run in a repeatable and efficient manner. For instance, I only had access to one motor for my robot, so I couldn't tell the top speed supported by my robot's gait. Through using the virtual model, I was able to keep increasing the rotational speed until the legs collapsed from underneath the center of gravity of the robot, which occurs around
		+	similarties and diffs of model to reality, how helps
		+
		+
		+
		+
		+
		+	I have also created a video tutorial that shows creating part of a robot similar to mine. This tutorial demonstrates creating a robot body, attaching a hip gear as a revolute joint to the body, adding a rotational motion to the hip gear, adding a leg attached to the hip on a rotational joint, adding a foot onto the leg with a fixed joint, creating a ground plane, and adding contact forces between the ground and the foot (I realize now that I forgot to add frictional force, which is just a modification of the contact force between the ground and the leg). I also show how to set a simulation going in this tutorial. Following the tutorial step-by-step will now arrive at robot like mine with four complete legs forward walking motion, but it will demonstrate most of the steps needed to construction such a robot. I have also uploaded the robot model that was created during the tutorial, which can be loaded into an Adams environment.

	== Useful Links and Resources ==		== Useful Links and Resources ==

← Older revision		Revision as of 19:23, 18 December 2006
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	The legs are attached to the hip gears via two rotational joints, one joint connecting the cylindrical leg extender to the hip gear, and one joint connecting the cylindrical leg extender to the leg itself. These cylindrical hip extenders create additional distance of the legs and feet from the body, which provides extra stability. The legs are fixed into the feet of the robot and are also wide for stability--just like the polar bear's wide feet which help reduce pressure by distributing the weight over a larger area, helping to prevent falls through thin ice (of course this is just wild speculation, but it sounds plausible and I wanted to highlight the bio-inspired theme again).		The legs are attached to the hip gears via two rotational joints, one joint connecting the cylindrical leg extender to the hip gear, and one joint connecting the cylindrical leg extender to the leg itself. These cylindrical hip extenders create additional distance of the legs and feet from the body, which provides extra stability. The legs are fixed into the feet of the robot and are also wide for stability--just like the polar bear's wide feet which help reduce pressure by distributing the weight over a larger area, helping to prevent falls through thin ice (of course this is just wild speculation, but it sounds plausible and I wanted to highlight the bio-inspired theme again).
−
−
−	~~{\| border="1" align="center"~~
−	~~\|+ '''Robot Leg'''~~
−	~~! width="350"\|Description!! width="250"\|Thumbnail Image (click for full size)~~
−	\|-
−	~~\| align="center"\|An exploded view of the leg and foot and cylindrical connector.~~
−	~~\| [[Image:Mjg robot explodedleg.JPG \|center\|thumb\|200px]]~~
−	\|-
−	~~\|align="center"\|A view of the robot leg and foot and cylindrical connector.~~
−	~~\| align="center"\|[[Image:Mjg robot leg.JPG\|center\|thumb\|200px]]~~
−	\|-
−	~~\|align="center"\|A view of the robot leg and foot and cylindrical connector, connected into a hip gear~~
−	.
−	~~\| align="center"\|[[Image:Mjg robot legandgear.JPG\|center\|thumb\|200px]]~~
−	\|-
−	~~\|align="center"\|A view of the complete leg and foot, attached to the robot body at the hip gear.~~
−	~~\| [[Image:Mjg robot motorhidden.JPG \|center\|thumb\|200px]]~~
−	\|}
−

@@ Line 288: / Line 288: @@
 {| border="1" align="center"
-|+ '''Drive Train Assembly Bill of Materials (x1)'''
+|+ '''Body Frame with Leg Axles Assembly Bill of Materials (x1)'''
 ! width="50" | Quantity!! width="350"|Description!! width="250"|Thumbnail Image (click for full size)
 |-
@@ Line 330: / Line 330: @@
 [[Image:MJG bodyframe tophalfexploded.JPG|center|thumb|250px]]
 == Virtual Model and Physics Based Simulation ==