Let's build a low cost robot to help the scouts

[eric gregori]

The TI Launchpad has got me really excited about creating a VERY low cost robot to help the scouts with there new merit badge.  I wrote a blog about the new Robotics merit badge while I was at Freescale ( http://blogs.freescale.com/2011/04/25/robotics-there%E2%80%99s-a-me...).  Unfortunately, I was not able to get anyone at Freescale excited about supporting the new merit badge so I am extending my request to the robotics community.

 

Let's create a Open Source + Open Hardware low cost robot for the Boy Scouts.

 

I have some seed ideas, but these are strictly to start the discussion.  I encourage people with their own ideas how to make this work to provide input, or even start your own separate blog. 

 

What I think the goal should be:  A low cost Open Source + Open Hardware robot for the Boy Scouts

 

What I think it should have in terms of features:

 

1) Easy to build use common hardware that anyone can purchase on-line or at a local store (nothing proprietary)

2) Well documented assembly instructions

3) Expandable so if the scout is interested he/she can make the robot better or add more features.

4) Low-Cost - The base model should meet the merit badge requirements and be around $16.00.  I came up with this price based on the Pinewood derby kits on the BSA store ( http://www.boyscoutstore.com/pinewood-derby-en/ ).

 

Using the above criteria, I came up with this as a first pass

 

1) Use the TI Launchpad as the electronics and development software.  At $4.30 COMPLETE, there is nothing out their that is lower in cost.

 

2) Use the Tamiya 89915 Twin-Motor Gearbox Kit - Clear  as the drive, it's only $8.25

This would also be the base of the robot, or we could use a piece of balsa

 

3) Use 2 AA's for power ( The TI part runs between 3.3 and 1.8 volts - perfect for 2 AA's ) and the motors only require 3 volts.

 

4) Use a single NPN transistor drive for motor control ( The TI part has a built in PWM generator ).

Use CDS resistors for line/light sensing depending on the configuration of the robot ( The TI part has a built-in A/D ).

 

5) Use half a ping pong ball for the 3rd wheel, and ????? for the drive wheels

 

 

Parts:                 TI Launchpad   = $4.30

                          89915 drive      = $8.25

                          2AA bat holder = $0.80

                                                  ----------

                                                  $13.35

 

This leaves $2.65 for the wheels, ping pong ball, resistors, transistors, CDS cells, and pieces of wire.

I think we may have to get creative with the wheels to keep the price down.  Maybe provide instruction on how to make them from cardboard or balsa.

 

Now, I know what you are thinking - C programming for kids?

 

I have some ideas for that.  There is a 8K python VM out there called PYMite.  Python is a incredibly easy language to learn, and the time spent learning it can be applied directly to real-world applications.  Another choice would be Matlab.  Basic and RobotSee have the distinct disadvantage of being completely useless outside of the robotics hobby ( no one professionally writes straight BASIC anymore - VB is NOT straight BASIC ).

 

The time spent learning Python or Matlab can be applied directly to college classes and a future in engineering or computer science.

 

So, like I said,  this is just my 2 cents ( or $13.35 in this case ).  What are your thoughts?  

Either comment below, or feel free to start your own blog, and restart the conversation.

 

 

 

[Eddy Wright]

This is a tall order, I've worked with other individuals and groups who tried to do the same thing. It is possible but not easy.

 

For affordable tires, you can't beat the Tamiya truck tires - about $4 for 4 tires - http://www.wrighthobbies.net/catalog/product_info.php?cPath=38&...

 

The motors can pull upwards of 1A of current (not sure at 3v though). I use the FAN8200 with the twin & double gearboxes which allows for full control of the motors and it's cheap (and can be even cheaper for a project like this) - http://www.wrighthobbies.net/catalog/product_info.php?cPath=26_44&a...

 

What about the chassis?

Where do you put the discrete components?

 

I'd say most scouts would be OK with $20-$25 for a complete kit.

 

Eddy

 

[Sai Yamanoor]

Hi,

 

As far as the programming IDE goes, I think it should be something like the processing IDE. I have seen kids programming the arduino very easily. 

 

Microchip launched their own arduino IDE for the microchip arduino clone. As far as the chassis goes, I think it should be something like the TI Evalbot chassis. The TI evalbot has the board as the chassis

[eric gregori]

I like the TI Evalbot chassis as well.  The whole TI Evalbot concept would be perfect for this ( Snap apart PC board for all mechanical components.

 

Eddy, at 3volts those motors only draw about 300ma. A single NPN3904 will be fine as long as we keep a PWM duty cycle of less the 66%. I agree, that FAN8200 would be perfect depending on the final cost we agree to.  I have asked everyone on my Facebook friend list ( about 300 people ) and my linkedin list to chime in.  I am trying to solicit input from people who actually have kids in the scouts, and may be trying to get this badge.

 

Sai,  I like the idea of using the Arduino IDE.  I found the Microchip Arduino press release (http://www.microchip.com/pagehandler/en-us/chipKIT-Development-Plat...) the kits cost $50.00.

 

So this brings up another question, is it possible to build a Arduino compatable board for less then $10.00?

 

 

[eric gregori]

I missed this:

The platform provides an unprecedented level of features for the Arduino community, and four times the performance of any existing Arduino solution at a low price—the boards start at just $26.95 each.  A video can be viewed online at (feel free to embed on your site): http://www.microchip.com/get/D268.

 

It has to be possible to make an Arduino compatible board for less the $10.00!!!!!

[Sai Yamanoor]

Eric,

The microchip arduino clone from Digilent costs 25.00$. I am not sure if it is possible to design within 10$ but if there is a toy motor along with wheels cut from the PCB like the TI evalbot, I think it is definitely possible. But all the parts need to be sourced in batches...

 

But the cheapest method would be without a microcontroller. Will that defeat the purpose?

There are many 

[Sai Yamanoor]

I tried using the Microchip clone. It does not have some features like servo libraries. But some users have created custom libraries for servo motors control. I am currently using it for my project and I find it very useful. 

 

The boarduino from ada fruit is a low cost arduino board. If it is possible to source the controller for dirt cheap price, sourcing the toy motor is going to be really easy. Then it is possible to make one really low cost product :)

[Eddy Wright]

The MCU isn't the only cost point, there's the onboard USB chip too. Those 2 chips alone will push it close to $10.

$15 might be a more achievable price point. We'll see what others come up with.

 

 

[Sai Yamanoor]

This product does not use an FTDI chip. Instead it comes with a cable with the chip embedded in it. This is something to think about

[eric gregori]

The Boy Scout Merit Badge rules are spelled out here:

http://meritbadge.org/wiki/index.php/Robotics

 

You can also find the scout worksheet here:

http://meritbadge.org/wiki/images/7/7a/Robotics.pdf

 

Also,  the BoeBot from Parallax has already been "approved" by the BSA.  They have a great page here:

http://www.parallax.com/tabid/928/Default.aspx

 

about using their BoeBot for the merit badge.

 

Robotics requirements
1. Safety. Do each of the following: a. Explain to your counselor the most likely hazards you may encounter while working with robots and what you should do to anticipate, mitigate and prevent, and respond to these hazards. Describe the appropriate safety gear and clothing that should be used when working with robotics. b. Discuss first aid and prevention for the types of injuries that could occur while participating in robotics activities and competitions, including cuts, eye injuries, and burns (chemical or heat). 2. Robotics industry. Discuss the following with your counselor: a. The kinds of things robots can do and how robots are best used today. b. The similarities and differences between remote-control vehicles, telerobots, and autonomous robots. c. Three different methods robots can use to move themselves other than wheels or tracks. Describe when it would be appropriate to use each method. 3. General knowledge. Discuss with your counselor three of the five major fields of robotics (human-robot interface, mobility, manipulation, programming, sensors) and their importance to robotics development. Discuss either the three fields as they relate to a single robot system OR talk about each field in general. Find pictures or at least one video to aid in your discussion. 4. Design, build, program, test. Do each of the following: a. With your counselor's approval, choose a task for the robot or robotic subsystem that you plan to build. Include sensor feedback and programming in the task. Document this information in your robot engineering notebook. b. Design your robot. The robot design should use sensors and programming and have at least 2 degrees of freedom. Document the design in your robot engineering notebook using drawings and a written description. c. Build a robot or robotic subsystem of your original design to accomplish the task you chose for requirement 4a. d. Discuss with your counselor the programming options available for your robot. Then do either option 1 OR option 2. (1) Option 1. Program your robot to perform the task you chose for your robot in 4a. Include a sample of your program's source code in your robot engineering notebook. (2) Option 2. Prepare a flowchart of the desired steps to program your robot for accomplishing the task in 4a. Include procedures that show activities based on sensor inputs. Place this in your robot engineering notebook. e. Test your robot an

[eric gregori]

The TI launchpad includes a fully programmable USB converter in the kit.

The kit has a built-in TUSB3410  USB part.

 

If you google this part, you will find not only does it do USB to serial conversion, it has it's own internal bootloader, and it's a fully programmable part onto itself.  You could build a robot just using one of these.