After successfully make this robot run on a local network, the next step is to connect this robot to the world (via internet). After a few google hunt, they say I need to do a port forward and ip public is needed. If i dont have ip public I can use dynamic DNS service, but most of them does not come for free. Because It need a little bit hectic configuration and I also don't have any international money account (difficult country regulation), I need find the another option.
Then I found pagekite from http://pagekite.net/, it is a service that based on python. I just download a few files and sign up free. After that just launch the pagekite app and the robot now can be access online anywhere. But there is still problem with this, because it only have one month trial and to continue the service I have to pay, the service is really cheap actually but I dont have any account to make the payment.
After another google hunt I found about tunneling, and there are a lot of tunneling service. Then I choose ngrok from https://ngrok.com/ because of its simplycity. After signing up and get a token key, I insert the token to the raspberry pi and then launch the ngrok application. because I have already sign up I can choose any subdomain I want as long as it is not been used by other user. And the very great thing about this service is, it is free forever and does not require any difficult configuration.