Check out this great WiFi Robot project that used an app called Wifi Bot Control.
“Features
- Uses WiFi only to control the robot and view the IP Camera stream
- Configurable camera URLs (up to 3)
- 3 Joystick Modes: Default, Simple Mode and Orientation Sensor
- Supports up to 8 additional commands via Command Buttons.
- Configurable WiFi packet interval.
- Supports a number of micro controllers – requires WiFi module/capabilities.
- Sample Arduino sketch provided (below link).
- Screen automatically re-sizes for smaller phones.”