I have to use raspberry with Arduino on a mobile robot. And access raspberry pi on pc through WiFi. Is it possible? Please explain how to do it.
To access your RPi over the WiFi, you can use any SSH client like PuTTY.
Once you have established a connection between your RPi and computer, then you can control GPIOs through a TCP connection. Use Socket Library in Python for this. You have to set a static IP for your RPi though, and use it in your code. Hope it would help.