The rover only has to follow simple comment given by scientist on Earth. This is a very simple task to do if we can control it in real time, but due the communication delay of about 20 minutes from Earth to Mars, it is not possible. You can have an idea of how difficult it is with the following experiment : Imagine you are given a command to walk from one room to another and pick up a glass of water on the table.

1. Scan the area, try and remember and plan out a route (to another room).
2. Close your eye and wait for at least 20 minutes
3. Try and walk to the location that you have picked without hitting anything while keeping your eyes close.

This is very similar to what the rover is doing. It has to first scan the area. Then it has to plan out a route to the assigned location. Of course the rover cannot analyse everything in front of it due to the memory and processing power on board. Then it has to move to the desired location, which could be a rock to carry out tests. I am going to explain how it is possible for a rover to carry out the requirements in terms of their applications. One of the most important tasks for the rover is to work out where its location is.

The rover has difficulty to know exactly how far it has travelled. This is because the rover can be travelling on a sandy and rocky surface which means that the actual distance travelled is much longer than the distance covered by the wheel. Further, the rover might have more grip on one side than on the other, this can be overcome by integration of rational speed measurement. However these data contains noise which causes errors which would accumulate and grow rapidly, resulting significant fault in the heading angle. These are some of the main problems that the rover faces. The solutions will be discussed one by one. Firstly we want to work out what direction the rover is facing. This can be calculated using a sun angle sensor.