hmartiro / project-thesis Goto Github PK

• Weight, size, power (voltage, current), cost
• Look for if they come with/work with encoders or controllers
• What previous rhex models have used
• Website links

By proposal date, we should have some specific options we could put together in a budget

Use this page: Motors

There are lots of advantages to getting the EduBot running.

Waiting on Hal to give us code and CAD files, as well as the Ubuntu login/password.

Such that the units all match up, everything is realistic, and actual numerical testing can be done

Ask them about motor/gearbox/encoder package

Tell them that we want a position and speed controller that is light and see if they have any ideas

This is still what needs to be done to finish up the hardware portion of the test cart

1. Choose screws to hold on the motor mounts, then drill holes in the PVC base and motor mounts and tap the aluminum motor mounts. The mounts go on the bottom of the PVC baseplate to simulate our finalized robot.
2. Get our hands on an axle and some wheels for the back. The key to the room of requirement is no longer in the usual place, so maybe someone should ask Glenn nicely. These wheels need to be small enough that they don't interfere with the spinning legs
3. Once we get some wheels, machine a block to attach the PVC baseplate to the axle. Again drill holes in both the baseplate and the axle block, then tap into the axle block. We should probably use some plastic scrap for this part.

Hayk & Chris, Be ready to talk about pros and cons of different controllers/sensors we will meet at 3pm the day of the meeting to be on the same page.

Brendan, Greg & Tom, Be ready to talk about general mechanical design, (step vs normal) normal motors, materials (strength : weight)

Goal of meeting:
(1) Have some idea of cost associated with project. This will be critical for Oct 9th deadline
(2) See if Hal has any suggestions for adjustment to basic design, also, does he warn us against anything we are thinking of trying?
(3) How do we get our robot working?

@hmartiro @boleary134 @towlett @Hughzie

Justin Siepel from Berkeley just pointed us to the Canid, a quadruped with an actively actuated spine that Kodlab is working on. Along with it, there is a paper that has a ton of information, not just about the Canid but about all the RHex designs they have built.

http://kodlab.seas.upenn.edu/uploads/Main/spie12.pdf

It includes tables that compare all the different types of RHex designs they made, including dimensions, weights, motors, batteries, mechanical and electrical info, and exact parts they used. I think everyone should read this before we go any further with designs. This is the best guide we have so far by a lot.

@Hughzie @boleary134 @PayneTrain @towlett

Goal is to get ubuntu 12.04 on the 32GB sd card.

Learn and utilize finite element analysis in Creo.
Model bending and twisting on joint, check stresses and deflections

Here is my current response to Hal's comments. I'm gonna take a look at the papers before I send, but any comments or edits?

Hi Hal,

Thanks a lot for your comments - it's great to have your help. Reading through the remarks, we agree with your take but have two questions for you:

You recommend going for a quadruped design because it would be cheaper and simpler. However, we're concerned that the quadruped design would be a higher risk for us due to the decreased stability. I can't find any example of a quadruped using RHex-type locomotion, and Pei-Chun Lin's design, which seems to be this one looks like it has more complicated mechanisms with prismatic joints. To accomplish that seems like a harder feat than dealing with the added complexity of two spinal joints and six legs, especially since we are much stronger at design and manufacturing than at dynamics/control. We chose the RHex because it was relatively simple to control for a legged robot and it seems to us the four leg design would add difficulties that we may be less prepared to handle, versus the marginal cost of building another segment, which we think is much more doable. What do you think about this concern?

The other question we have for you is what part of this design project do you think will be the most difficult and time consuming? Is it the design, the mechanical construction, the electronics, or the software and control? It seems that you have some reservations about the feasibility of this project, so we're trying to get a picture of what the risks are. Since you've worked on the RHex, you probably have the best idea of this. From our current perspective, the design and mechanical construction seem within our reach in terms of time and budget. The implementation of controllers for the legs and the RHex gaits is more foreign to us, but we're hoping it is feasible, mostly because of the simplicity of actuation and abundance of papers on the topic and help from you and Prof. Holmes. What should we be worried about and budget extra time for?

@towlett @Hughzie @PayneTrain @boleary134

We have until Friday morning to determine the goal of our project, time to legitimately brainstorm.

My idea:
Add a storage compartment to the body and maximize the robot's load carrying capability, perhaps focusing on its load to weight ratio.
Application: (Military) Carrying small but essential supplies such as ammo, medicine, or food between positions in a hostile environment. Reduces risk of human life.
What's new: Requires a new body design capable of storing or attaching a reasonably sized object. Have to deal with the issue of minimizing the body weight while still ensuring the legs/motors and structure are capable of carrying an additional load. Varying loads will probably also affect the control system. Boston Dynamic's Big Dog is already designed to carry supplies, but this is not meant for battlefield conditions for obvious, lumbering, reasons.

How do we provide high-level feedback for steering and navigation? Looked at some papers which I uploaded to the research section, but since Holmes wrote some of them its probably easier to talk to him. Incorporate into simulation to follow a target.

An account has been created for the group to use, with Jo-Ann's credit card
Username: Mugatu
Password: xjus2012

@hmartiro @PayneTrain

I think this is basically the founding paper on the Rhex, from Kodlab:

http://kodlab.seas.upenn.edu/Kod/IJRR2001

Kodlab released this as research in 2001, and Boston Dynamics got hold of it and commercialized it in 2003.

It's a really useful paper and very understandable (even for ELE pleebs), so I think all of us should read it to get some background on the motivation behind Rhex, the pros/cons, and the dynamics involved, so we don't sound like retards when we talk about it.

Torque and size requirements
Where to purchase them
How to attach them with ability to replace them

size up everything, get an idea of the physical layout, etc

@Hughzie @towlett @boleary134

Place all on-board components
Determine dimensions of all 3 segments based off of on-board components.

Discuss making middle section longer than front and back, in order to increase control over pitch stiffness

• Take an inch off the length of front and back segments and add it to middle section...?

Meet with adviser this Monday to discuss preliminary system

While the CNC machine is free we should begin to machine the parts for the test cart. Many of these parts will be useable on the final robot, assuming that we don't discover any issues in our model. I'll start by CNCing the motor mounts.

linux drivers, etc. we need the beagleboard connected.

-Determine material with appropriate properties
-Find source
-Get quote

GitHub lets you make a public webpage for your project, so I just activated ours here. It's a public page for our private repository.

It's basically just a wiki page with a theme, you edit the page here. I want to throw in some pictures and stuff so we can show people what we're up to.

quite annoying, needs to go away before videos are made

Confirm material/shear modulus to be used.
Check stresses and deflectioin etc.
Update CAD model accordingly

Arduino, PIC, psoc, gumstix, raspberry pi

Have a good choice by the proposal date

Use this page: Microcontrollers

I think we need to be using the issue tracker and wiki a lot more to stay on top of shit. Honestly we've been getting real sloppy in the last couple of weeks, and we need to do better.

Can everyone just take a few minutes to go to the issues page and open some issues for yourself based on what you're doing? They should be small and specific things, like stuff that would take a few hours max. "Make base plate for test cart" would be a good one, but "Finalize CAD model for robot" would not be.

Also, honestly just make a page and write stuff on the wiki about your progress. Think about how much easier the paper will be if we have some shit about the legs, the cover, the joint, the batteries, the computer, and whatever else we do. Remember, we don't have a girl in the group to write the report..

@boleary134 @towlett @PayneTrain @Hughzie

Why is it coming up for the interpolation mode?

Looks like the best choice is the BeagleBoard XM, based on the research here

We should probably go ahead and purchase this. @boleary134 do you know how we purchase things with Jo Ann's card?

By the end of this wknd

Talk to relevant professors this week and get it figured out.....I just got approval from Andrew Houck to be my adviser. ( http://www.princeton.edu/ee/people/display_person/?netid=aahouck )

Need to fill out SEAS form, make changes based on Hal's comments, and then turn them in

Tell him about our project and ask for

• Username/password for edubot
• Any knowledge we need to run it
• Relevant papers

based on the motor controller documents

I've got a simulation of our robot w/ a flexible design via torsional springs, which can be made rigid. I want to put out a set of videos on Youtube that show the effects of each degree of freedom vs the rigid version on a simulated obstacle course / natural rough terrain.

See here

• Use the axle to provide torsion on its own with cantilever springs controlling pitch
• Use a cantilever spring as the axle to provide pitch and a large torsion spring for roll
• Use a single flexible axle which twists and pitches according to requirements

Our plan is to control the robot through remote desktop or VNC

Begun writing goals and design requirements, then solution

• Include pictures of various stages of design
• Matlab results
  -FEA Creo results

I tried to commit a large file ~400MB and it broke git for the beagleboard, now it runs out of memory while pulling. Need to somehow erase the file from its history.

Start with Greg's outline here and from what Nosenchuck told us today

I think 1-2 people should write a draft on that wiki page and then others should edit it. Who wants to start?

@boleary134 @PayneTrain @Hughzie @towlett

dsfdsf

I am putting the finishing touches on the test cart CAD model.

Hello

Analog line 1 and 4 need to be manually pulled from the cable and attached to (+) and (-)

to apply smoothing for the damping

Important Dates:
October 9 - Funding Proposal Due - Needs to have advisor's signature.
Oct 15 - SEAS Funding Due ( ~$600 max)
October 22 - Marshall and McKinzie fund proposal
November 12 - Supplemental fund proposal

Info on this page: Funding
Will look into Keller Center to see if the cough up some dough.

Leg construction consists of 4 items:

1. Run Pro-E analysis to determine the correct spring steel thickness based on the weight of the robot. Order it from McMaster.
2. Machine the mounts that connect the legs to the motor.
3. ...
4. Profit!!!

*Will a 24V switch slower than a 12V powered motor via PWM