Click on the picture above for more information about the DARwIn-mini.

Friday, December 31, 2010

How the Other Guys can get a DARwIn-OP!

The only complaint that I have heard about the DARwIn-OP is the price. It will go on sale in 2011 for 12,000 USD. If you are in academia you can get it for 9600 USD. This is going to be the first in a series of post to my blog on how can the average person (like me) get access to this very cool robot platform! 

The first issue that I will address is cost. From all the information that I have been able to find out, Robotis is not going to be making a lot of money on this robot. If they do make money it will be on the sale of the RX-28M servos, which by the way is a very cool state of the art robotic servo. For people who have never bought a robot kit before, specially a humanoid kit. The servos in the kit are a very high percentage of its cost. Here are a few examples of what I mean. The Bioloid Premium Kit retails for about 1199.00. It has 18 AX-12s servos which retail for about 44.90 a piece. Total cost of servos in the kit is 808.20 or .67406 % of the total cost of the kit. Bioloid GP (cost 2500.00 USD) has 12 AX-18Fs (cost 94.90) and 6 AX-12s ( cost  44.90 ). Total cost of servos in the kit is 1138.80 + 269.40 = 1408.20 or 56 % of the total cost of the kit.

Now let us do some math on the cost of the DARwIn-OP. The listed retail price will be 12,000.00 USD. We do not know the cost of the RX-28M servos so we will have to do some quessestimation* (quesstimate). We will use an average of the GP’s servo percentage and the Premium Kit percentage 61.5% to figure the cost of the RX-28Ms. Servo cost for the DARwIn-OP will be 12,000 * 61.5% = 7380.00. Cost of the RX-28M will be 7380.00 / 18 = 410.00. There are 20 servos in the DARwIn-OP so I am guessing that the cost will be higher than with 18 servos so total servo cost will be around 20 * 410.00 = 8200 or .683 % of the total cost of the kit. I am thinking that this figure maybe low because the RX-28M is a whole new servo design. The cost of 20 EX-106+ which is Robotis most expense servo is 499.00 x 20 = 9980.00, which by the way is very close to the DARwIn-OP academic cost. This supports my thoughts that the 410.00 USD maybe low.  

As you can see with my math above the cost of the robot is mainly in servos, which then leads me to a few ideas. The DARwIn-OP is an open hardware and software platform so that you can build your own! That will lead you to some saving on the total cost of the robot. My main idea for this post though is to use a cheaper servo as a way to decrease the cost of the build. Yes your version may not be as cool but you will have a DARwIn-OP. Also use a servo with the same form factor if possible. That way you can upgrade with RX-28Ms in the future. Examples are 20 RX-28 for 20 x 209.00 = 4180.00 or 20 RX-24Fs for 20 X 139.00 =  2780.00. If 62% is the servo percentage cost for the DARwIn-OP then a RX-24F DARwIn-OP would cost around 2780.00 + ( 12000 * 38% ) = 7340.00 USD!!!!

As I said above this is a first in a series of post on how the Other Guys can get their own DARwIn-OP! I would be interested in feedback and your ideas on this. 



* My term for pulling figures out of your butt!


  1. I think you are over estimating the cost difference between RX-28 and RX-28M. I expect the RX-28M will not exceed $300 and will most likely be closer to $250. I think one reason you are off is that you are comparing simple motion replay robots with true autonomous robot. The SBC-FitPC will add around $350 and the CM-730 will also be more expensive.
    All that said, I agree that finding a lower cost actuator is still the key to making DARwin-OP more cost effective.

  2. Interesting, sounds like you agree with my post? We will see about the servo cost. The FitPC and the CM-730 cost will be in my third post. Sounds like I need to finish it!

  3. Is it aluminum frame? If so, it's just a matter to get the frames' plans. It would be great to have a cost estimate if you were to build one yourself.

  4. Yes, that is the ultimate goal to build one myself!! Right now I am working on a robot for the Robogame's mech-warfare competition in April!

  5. HS-805bb servo + Supermodified can easily replace the RX-28 and the pack will only cost like 80USD per servo ;)

  6. It may work but you lose some speed! Also you will not be able to use the CM-730 controller!