Answer L9-C1

** Here are the correct answers to this question:

* Answer A "SLAM will be hard" is correct.
* Answer B "SLAM is optimal" is NOT correct.

** Explanation

The question is about performing SMAL (Simultaneous Localisation and Mapping) using a very specific sensor for radiation sources. The question is: "In the design of a robot for intervention in nuclear disasters, you equip the robot with a radiation sensor. As often for this type of sensors, the sampling frequency is low (5 Hz) and the detection angle is very small (1 degree). The sensor can measure the distance of the radiation source. You equip a mobile robot with this sensor, mounted to look in a fixed direction, straight forward. The goal of the robot is to map the disaster area, both for obstacles and radiation sources. Which of the following sentence apply to this case?". 

Here the main issue is the mismatch between the type of sensor (fixed direction, slow frequency and very narrow perception cone) and the requirement of SLAM, where one would have a view at the same time on a mapped area (to localize) and on the unexplored area. Using this sensor require to the robot to move around, which introduces movements and therefore uncertainties in localisation between one sensing and the other, when in SLAM the several sensing need to be related precisely one to another.

Two statements are proposed:

* Statement A. "Performing SLAM with the radiation sensor will be extremely hard or slow, because of the angle of view." is correct. SLAM requires to have a perception of an existing part of the map and at the same time an unexplored part. This very narrow-angle sensor does not allow that, if not having the robot turning on place, reducing precision. All this makes the process complex and slow. 
In the explanation of the student we would like to see that they understand the requirements of SLAM being to have a perception of an existing part of the map and at the same time an unexplored part.

* Statement B. "Performing SLAM with the radiation sensor is optimal, especially when the robot is moving forward, because of the placement of the sensor in front of the robot." is NOT correct. 
The placement of the sensor in front can perhaps help in some navigation tasks, but not in SLAM.
In the explanation of the student we would like to see that they understand the requirements of SLAM being to have a perception of an existing part of the map and at the same time an unexplored part.