What to do with the hardware of the Mars rover

Today we had a general meeting. The linetracker is almost finished so our target is now the mars mission. The hardware of the linetracker will be the basis for our Mars rover. Thus it will be a rover with two big wheels, driven by a motor and checked by a rotation sensor. There are lots of possibilities to place the sensors. We came up with two of them. The are drawn in understanding figure.

Explanation of the letters: RS = Rotation Sensor, LS = Light Sensor, M = Motor and RCX = LEGO RCX. Both possibilities have two wheels and the motors and rotation sensors are both placed on RCX 1. The main difference is the way the light sensors are located and to which RCX they are connected. 

In the left rover, there is a light sensor going from the left to the right in front of the rover to check for edges. The motor and light sensor are also placed on RCX 1. The other two light sensors and temperature sensor are placed on RCX 2. The advantage of this option is that the rover can drive and check for edges with only one RCX. So there is no need for immediate connection with the other RCX. When an edge is detected, the rover will drive very slowly until the other two light sensors determine where the edge is and pass this information back to RCX 1. If there is a lake in front of them, the temperature will be measured and driven by the motor that also drives the light sensor placed on RCX 1. 

The light sensors on the right rover in the figure are placed in line in front of the rover. These light sensors are all connected to RCX 2. The temperature sensor, motor and rotation sensor to let the temperature sensor go in the lake are placed on RCX 1 together with the motors and rotation sensors for the wheels. The advantage for this option is that it is easier to determine what kind of edge the rover is detecting. Only the problem is that RCX 1 and RCX 2 continuously need to communicate to each other. The question is how good this connection will work.

After a discussion we have chosen for the second option. The problem with the communication will be solved with the idea that if RCX 1 doesn’t get data from RCX 2, the rover will not move any further. Only when the connection is reestablished, the rover will drive again. With this solution the risk of falling off the platform is much smaller in comparison to the first option in which edge detection is quite difficult. On the RCX 2 only three sensors are placed, which leaves probably much room to store mapping-data. 

With this conclusion we divided the work in a few groups. The work that needs to be done for now:

• Research on how the camera works, how it gets its data, etc.
• Improving the edge detection (how to deal with varying surface, etc.)
• What to do at the start (safe driving)
• Architecture
• Mapping
• Hardware