Your robot looks cool. Do you have any encoder plates for the wheels to measure the travelled distance?
Since you don't tell much about the task, I guess we are allowed to fill in things. So if you talk about A and B and they can be defined in XY coordinates, I assume we can define A as origin, the robot starts heading in the x axis direction, point B is then defined in XY coordinates. And these coordinates are typed in with some device for your robot to know.
Then you hit start and the robot starts moving. Draw on paper what happens. First a turn so the robot heads to B. Then it starts moving, keeping track of how far it goes. For both turning and moving you need to read the encoders of the wheels. Then when an obstacle comes in the way, you need to draw a path around it. Can you make assumptions of the size and shape of the obstacles? Are they walls?