Next Up ... Hacking Chumby

Now that I have set up the Chumby for use at work (because occasionally I will want to bring it in for its normal purpose), I can concentrate on breaking into the case to see the goodies. One thing about this, I will need to make sure that I have backups and can duplicate the environment that the Chumby was developed under. That means that I need to assure myself that I can remove the original micro-SD and replace it with one that does the same thing without simply copying the information from one to another. That way I can be assured that I know enough to be dangerous. The instructions are on the Chumby wiki site to do this. If I have time over the weekend to do this I will, otherwise, it will have to wait a while. I do have some work things that I need to get accomplished in the meantime.

I Was Finally Successful with Work Chumby Hookup

As I reported previously, the capture page at work was difficult to break into.  Up until this moment I had not been able to use our guest wireless access (requiring a user name and password) which is Cisco based.  It turns out that the problem was the value that I was returning for the buttonSelected parameter. Should you feel inclined, the best way to find out what a capture page requires is to capture the POST message before it gets back to the server.  For this I used "Tamper Data" on Firefox.  What I was able to do was to see the values for each of the parameters prior to its receipt by the wireless port.  I found out that in this particular instance the buttonSelected parameter was 4.  As soon as I corrected the value in the debugchumby file on my USB drive the Chumby hooked up.  Now I can use the Chumby as advertised at work.  I wanted to make sure that I had this working because I intend to be able to get back to a regular Chumby in between efforts at building robots (yep, probably more than one now).

Decided to Hold on Tablet

I thought that I had the perfect tablet for use in controlling the spiderbot in the Panvision, but I have decided to wait based upon my decision on the simulator. That may turn into an error but it is what it is. Right now things are on an even straightaway. I need to get a lost if things to do on this site and keep it updated.

Simulation Looking Much Better as Alternative

In hindsight, what I can do is build a simulation which incorporates a minimal set of hardware parts and shows the functioning of the bot in a virtual environment. This is the cheapest way to get a spiderbot running and I can then decide if I want to pursue it further. The math equations will need to be worked out anyway (that's part of the fun). I like standing up simulations and it will still give my grandson some programming experience.

It looks like next challenge on the board is to research existing sim systems, such as Tokkotsu which is based on Player and Ogre with a physics engine. Good stuff!

I May Have to Scale Back a Little

I just did a short computation on what the hardware is going to cost to build the SpiderBot.  And for cheap, it is going to be just under $1000.  That is $200 over budget, of which I have already spent $100.  Thus I need to figure out how to save $300 to get it done.  That is why I have been thinking about buying bits and pieces and constructing the rest myself.  The problem that I forsee, is the weight of the thing.  I need to keep the weight down in order to have something that can be run with the current set of servos that are available.  This is one reason that I have been looking at trying different avenues to getting the parts.  The basic spiderbot hardware, sans servos, servo controllers, and processor is around $260.  I could live with that purchase, buying a little bit at a time.  The servos that I want cost about $40 apiece, pretty cash hungry.  So anyway, I think that I should go back to the drawing board and rethink this a little.  On a positive note, I could simulate the parts and just use the Chumby as the go between for simulating what happens to the servos and display a simulation on the screen.  In that way, I could contain the costs of the project (just takes a lot of time to program the simulation) and still use programming on the Chumby as the way to do it.

Taping into the guest account at work ...

Well crap! I seem to not be able to tap into the guest account at work. Not sure of what the problem is, I get a connection via wireless but the "debugchumby" file is not working as advertised. Seems like it is not authenticating even though I have called up the correct portions of the form. I have narrowed the problem down to the IP site that is needed to authenticate (I may not have the right ip address), or the POST message is not using the correct form name. Just a little agrivating.

The Chumby is in ...

After spending about 30 minutes at the UPS transfer point, located some 16 miles from where I wanted the Chumby delivered, I now have it in my hands. The device itself is not particularly spectacular in appearance, but it is functional. Last night, I was on the Chumby site at http://www.chumby.com and was able to set up the Chumby to download some apps from the main site. The way that they have the Chumby set up is that it will always connect with the main site. The main site for chumby.com is located in San Diego, CA 92130. That does not mean that the main server for the chumby is located in the same place, but bets are, this is the location. I only say that because the device is made in China and could potentially have a backdoor to a server in China. See how trusting I really am? I am not afraid since I don't have anything at my house worth stealing and most of my network is closed off anyway. But back to the story. My hands are off to the Chumby people in terms of their ease of setup on the device. You have to have a computer nearby to finish the setup since it does interact with the Chumby site. There is an ID number that is exchanged with the Chumby site that authenticates your new Chumby so that you can make changes to the app structure. I still have a lot of exploration to make prior to hacking the box, but it is nice to see that they have put a lot of thought into what the device is capable of doing. My gameplan is to hack the Chumby and use it as a robotics controller. the Chumby itself weighs very little, which is a great advantage. It has a wifi capability which enhances its communication power with my laptop. I have not bee successful at hooking the Chumby into our guest wireless at work due to the capture page issue. I haven't figured out what completely is needed to do that yet. The debugchumby file that I created does not hook into our Cisco system. One thing, I do not have a real good sense of the IP address of the proxy and the fact that the form is not named from the proxy may have something to do with it. More later.

Simulator

It occurred to me that I would be able to program the robot without actually building the hardware by use of a simulator. I could simulate the actions of a robot down to what you put into the servos by using some software design methods to isolate the robot hardware and simulator using an "interface" and "adapter" design pattern.

Crap ... messed up the address

I am sitting here at the dining room table. I do not have a Chumby to dissect and play with because I forgot the suite number on the shipping address. I don't know what happens now, maybe they will send the Chumby back to Costco, I don't know. It doesn't appear that they could figure out my address information. Let that be a lesson to me for future purchases.

Waiting for the UPS Truck to Arrive

Well, I am at work and waiting for the UPS truck to arrive and bring the Chumby. When I open the package I will be getting photos together so we can see what this thing is. I have pretty much decided that one of the first things that I will do is take out the micro SD and make a copy of it, just so that I have a way of getting back to ground zero. I also have convinced myself to take another micro SD and setup a development environment under Ubuntu (on my laptop) and recompile the Chumby system onto it. Has anyone here used VMworks player? I might set up a virtual development system on my XP laptop to do the Chumby work. Anyway, I want to be able to reconstruct the Chumby system at any time.

Started Looking at Equations Again

Man, I am a glutton for punishment. I am starting to research equations for spiderbot leg articulation. Seems like I am dying to get back to geometry, trig, and algebraic equations. I don't really have to deal with calculus since the spiderbot will not be doing that much change that will require the calculations. I do need to define the overall requirements for what I want to do. In a nutshell, I want to take into account errors in construction and controlling (esp. things dealing with descrete commands), and also to define everything by a central point under the spiderbot. Alignment of parts will be an issue that needs to be dealt with in any of the equations. Hey, I haven't even gotten to the part about what the bot will look like have I?

Ordered a Chumby!

In an effort to get a jump on the game, I have decided to order a Chumby (http://www.chumby.com) for myself to start some experimentation. I ordered it online from CostCo for $104.99 counting tax. The specs for this device are interesting: chumby one specs * 3.5 inch LCD color touchscreen * Access to free content * Uses rechargeable lithium ion battery (not included) * USB 2.0 high-speed port * Stereo headphone output * 2W mono speaker * Volume knob * FM radio tuner * Accelerometer (motion sensor) * Wi-fi connectivity (802.11 b/g) * USB ethernet compatible * Over-the-air software updates * Dimmable backlight * 454 MHz ARM processor * 64 MB DDR SDRAM * Internal microSD card firmware * AC adapter included * 3.5" wide x 4" tall x 3.5" deep Apparently there is instruction on the inside of the case for the compatible Lithium-Ion battery that is compatible with the circuit. I should have some fun with this.

4 Legs or Eight?

I have always been intregued by the notion that a spiderbot should have the number of legs in real life. According to the wikipedia entry at http://en.wikipedia.org/wiki/Spider, spiders have eight legs. That is probably because of the environment that they move in requires a little more dexterity and having eight legs gives them the dexterity for the task. However, since more legs will cost more money, I am willing to compromise on the leg thing. I am going to go with six legs primarily because it provides a stable platform for walking and most spiderbots that I have seen on the internet have six. This also leads to an interesting way of movement. The cockroach has six legs and moves with a combination of three legs on the ground at any one moment, giving it a very stable platform. The cockroach movement is actually two on one side with a third leg on the opposite side on the ground while the remaining legs move. It also gives the cockroach the ability to move quickly and turn quickly, something that I would like to try out. However, I am still going to refer to Bob as a SpiderBot, not a RoachBot.

Budget?

Ok, I need to limit myself to a budget to buy parts for the spiderbot. Since I am going to piecemeal the robot together I will limit the cost to $800. This is a nice round figure and represents the amount of money that I have saved up for an iPad. Sorry Apple, it looks like I will not be getting one of your got-to-have toys for myself. My wife normally limits me to buying technology with cash because she knows that I will not part with cash unless I really want something bad and I have saved up for a long time. We do have a checking account and various savings accounts and credit cards but I refuse to use them for something like this. By reacting that way, I have been able to maintain a minimum of debt for a long time. Mortgage is paid off by the way so I do have a bit of other cash floating around. So $800 limit it is.

Next on the Horizon - Robot Choice!

I can't help but notice that there are innumerable options for building robots. As I look around the internet it occurs to me that there are parts and kits and ideas that pop up, giving me a headache just thinking about the options available. I think that what I will do is go for a robot type that I have always wanted to be able to build, a Spider Robot or SpiderBot for short. I think that this will be my goal. Not only will my grandson and I have to figure out how to make this robot walk, but we might even be able to give the robot some character. I think that I will name him Bob, just because that is typical of the walk of most SpiderBots. I am not sure that a spiderbot will be allowed to compete in the KIPR Open next year in Orange County, CA but I think that I have a reasonable choice made. I do reserve the right to change my mind as time and cost go along.

Blog Purpose

Having just come back from the 2010 Global Conference on Educational Robotics held at the Southern Illinois University at Edwardsville, I am really pumped to do my own robot. I accompanied 7 high school students as a chaperone and was very impressed with what was being done by these students in the area of robotics. I was also impressed when I realized that they were going through an engineering development process which involved aspects of EE, computer science, mechanical engineering, general design, and general problem solution. No matter what the students do in later life, they will have learned some valuable lessons on problem resolution. My grandson was one of the programmers on the team and will be going into his senior year in the fall. I have resolved to build a robot from spare parts to help coach him along in his programming. Also it should be a lot of fun, hence the name of this blog.

Is Chumby the Right Controller?

After having worked with the high schoolers in BotBall, I noticed that they were using a CBC to program the robots. CBC stands for Chumby BotBall Controller. This turns out to be a handy little device, with a linux operating system, that has an ARM processor, plenty of RAM (64MB), a flashable ROM, internal simplified C programming, and an interface to robotics control ports. I proceeded to look for this controller on the BotBall site but did not have much luck, and the price is around $300 which is a bit rich for my budget. On the other hand, I was able to locate the Chumby One at http://www.chumby.com which seems to be a more likely choice for what I want. In fact, this device is on sale at CostCo for $99.99. The device in and of itself is a highly usable internet appliance. But, it is also highly hackable, both in hardware and in software. I am interested in the processor because it has both Wi-Fi capabilities as well as a USB port. I am thinking that if I use the USB port for the robot interface that it would simplify the construction of the spiderbot. Hmm... more to follow.