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MonkeyBot, Ready to Swing

The structural failures have been remedied and MonkeyBot back in action. We’ve had the bot swing around some and the servos are better than I could’ve hoped! Their feedback is more than adequate for our application and the software side of the project should have a good time dealing with them.

The following are details of MonkeyBot as he stands today.

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Full Passive Assembly

The robot utilizes a pair of Dynamixel RX-28 servos, a CM-700 microcontroller and a serial and power tether, all pictured above. In the near future, the robot will be outfitted with simple force sensors in the claw and an IMU in the body.

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Claw/Arm Interaction Detail

We created an aluminum plate that fit our current plastic parts such that this interface is much more robust.

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Servo Connection Detail

The servo connection consists of 12 2-56 button head screws holding the servo into the body and 8 M2 socket head cap screws holding the arm to the servo horn.
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Full Assembly and Failure

After getting in a few of the remaining pieces, the team put together the remainder of MonkeyBot.
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Arm Assembly Detail


We were eager to see the bot swing for the first time and we quickly ran into failure:

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Failure Detail

A resolution has been devised and we’re moving quickly to get MonkeyBot swinging again.
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MonkeyBot, in Plastic

The body and passive claw for MonkeyBot have been laser cut and partially assembled.
The following are photos of the parts and the passive claw.

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All the parts laid out.

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The passive claw: construction required only the 4 (2 visible) fasteners at the base of the claw.

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The body, securely capturing the two joint motors.
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MonkeyBot, in Pixels

This Thursday’s meeting was particularly productive. The body group and passive claw group finalized their designs for laser cutting tomorrow. The Mechanical Engineering Shop got a hold of a brand new laser cutter and we’ll be the first students to produce parts with the machine.

Here is what the bot will look like:

Passive MonkeyBot 1.0 extended

Passive MonkeyBot 1

Also the active claw group has modeled a feasible bi-stable, simply actuated claw.

Active Grasper Prototype
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MonkeybarBot Prototyping

In this week’s hardware meeting, the group moved forward with the insight gained from the previous meeting’s activities.

Last week the group prototyped basic ideas to get a sense of proportions and required degrees of freedom to accomplish the monkey bar crossing task. Here are two photos of some of the concepts that were constructed:

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A monkey bar set up with 2 bars and a passive, double hook at the end of each arm.

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A full scale model of what could be an active grasper.

More prototypes of the active graspers were made this week; examples are shown below.

Triggered Grasper
A possible (prototypical) implementation of a palm triggered grasper.

Triggered Grasper (simple)
A simple model demonstrating the functionality of the palm triggered concept.


This week we moved forward in the prototyping stage and also developed a timeline for the project and split our project into tasks. Group members elected to be in different parts of the project, a breakdown follows:

Active Gripper: Yannick, Rodrigo, Carl
Passive Gripper:
Chad
Robot Body:
Nathan, Priya
Monkey Bars:
Andy
Servos/Electronics:
Andy, Jeff

Veteran members including Pace, Harrison and me will fill in gaps as needed. The software aspect of MonkeybarBot will be dealt with at a task level by Jitu.

The deadline for a functioning physical robot is October 15, the Friday of Mid-Semester Break. This project will be concluded by the end of the semester, at which time we will have a finalized design for the quadrapedal HyLo robot. Construction of the HyLo robot will begin at the start of the second semester.
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Conceptualization

At the Thursday meeting this week we discussed some high level goals and brainstormed about the simplest way to go about independently solving each problem.

Below is a snapshot of of a some tasks that the robot might eventually complete.

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Listed with red bullets are:
  • Monkey Bars
  • Tight Rope ~cargo net
  • Crevice Crawling
  • Transfer [of] Small Objects
  • Drive on Wheels

We then went into more detail about how to solve the individual problems:

Monkey Bars:
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Tight Rope:
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Group members also got a chance to handle the newly arrived Dynamixel RX-28 servo motors.
Next week we will be moving forward with construction of some of the simple robots we conceived during the meeting and put the groups newly found SolidWorks modeling skills to use.
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HyLo Software Meeting

This meeting introduced members to ODE.

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ODE (Open Dynamic Engine, www.ode.org) is an open source dynamics simulation package. In HyLo, this software will be used to simulate simplified versions of actual robots so that it is possible to distribute a controllable platform.

In the future, we will move the control techniques employed in simulation onto the physical robot.

For now, you can find technical, software related notes on
Jitu Das's site.
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First HyLo Meeting

HyLo Meeting 9/9/10
v3.4-port-quality
Topics
  • Project Intro
  • Documentation Past
  • HyLo's New Goals
  • Current Direction and short term Objectives
  • Resources

Introduction
Welcome to the HyLo Project. This project group is about making robotic platforms that explore interesting ways to move around and do useful things. Originally the group set out to construct a relatively small robot capable of climbing up steps. This was seen as a problem for robots of similar size who only rolled along on wheels. To solve the issue of climbing stairs we built a robotic platform that has four legs as well as powered wheels to traverse large obstacles. Typically a robot can not climb anything taller than about half the diameter of its wheels, but by being able to pick up a foot and place it over an obstacle the usefulness of the wheel is extended. To further the idea of unbounded mobility we will be progressing the project upwards, literally. HyLo's new challenge will be to climb a tightrope and a ladder as well as be able to walk and roll.

Documentation Past
What documentation? Scattered and inaccessible. http://mikeornstein.com/projects/files/category-stairbot.php http://mikeornstein.com/stairbot/ http://www.roboticsclub.org/StairBot We will be making use of Redmine's wiki system to keep track of weekly progress (eventually).

Hylo's New Goals
Capable of walking up steps (eventually) Capable of balancing itself Strong enough to perform climbing tasks Built with modular feet in mind

Current Direction and short term Objectives
  • Mechanical Stuff
Let's make something to play with ASAP. Build a 3 link planar robot capable of brachiation (swinging from branch to branch). Make Environments to test. Learn ODE- Dynamics simulation software (C++). http://sourceforge.net/projects/opende/files/ODE/0.11.1/ode-0.11.1.zip/download
  • Electrical Stuff
Implement sensors. Learn about IMUs and their associated gospel (more resources to com): http://en.wikipedia.org/wiki/Inertial_measurement_unit Hardware level control- talk to microcontrollers and servos. Learn ODE- Dynamics simulation software (C++). http://sourceforge.net/projects/opende/files/ODE/0.11.1/ode-0.11.1.zip/download
  • Software Stuff
High level things. Learn ODE- Dynamics simulation software (C++). http://sourceforge.net/projects/opende/files/ODE/0.11.1/ode-0.11.1.zip/download

Resources
Examples to draw from:
Related to rolling and walking
http://www.youtube.com/watch?v=6y4PVjh0XBs&feature=related http://www.youtube.com/watch?v=p1xwF6y8MOs&NR=1
About Sloth locomotion (tightrope walking)
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8972000/8972024.stm
Paper about brachiation and dynamic control
http://kodlab.seas.upenn.edu/uploads/Kod/Nakanishi00.pdf

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Stairbot -> HyLo

With the upcoming semester looming, there is a need to get the Hybrid Locomotion project back on its feet. Stairbot is now named HyLo. Our goal for this iteration of the design is to use more powerful, accurate and sensitive servo motors at each joint and simplify the mechanical design to make the robot easier to program. Pace Nalbone is going to be in charge of our initial CAD work, designing a new robot of similar form factor that utilizes Dynamixel Servos. More on the new design soon.
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