3. Moving Around the Park
The questions for this analysis are: How does the rover get safely and reliably from one place to another, especially when it needs to get to a specific location?
What does the rover need to sense to move around the park, locate samples, and return them to the starting platform?
The first two problems a rover has is determining its bearing, i.e. compass direction, and location. The rover is powered up on the starting platform with limited information about its location or bearing. It knows it is on one of the three starting platforms with an uncertainty of 10 meters. (See rules C35 & C39 and locations of starting platforms on diagrams.)
As the rover moves about the park it needs to track its location for two reasons. One, it needs to know its position relative to the starting platform so it can return there. Second, it needs to know the area already searched to maximize the time searching new areas.
The rover needs to identify obstacles, human or park related, in the path and avoid them. (Driving up a tree resulted in a back-flip for a '13 rover. Another burned out a drive motor when it hit a tree.) It needs to identify the orange boundary fence.
Potential samples need to be identified at a distance and the rover brought into close proximity.
The park has some hills and minor drop-offs due to erosion so the rover needs to know if it is in danger of tumbling.
For Phase I where the robot must collect a pre-cached sample, the rovers need to navigate from the starting platform to a specified location. The location is the center of a 10 meter circle where the sample is located. Similarly, when returning to the starting platform to deposit a sample the rover is moving to a specific location.
Let's summarize the requirements:
- Initial bearing
- Initial location
- Dynamic bearing, i.e. as it moves
- Dynamic location
- Navigate to specific point
- Search coverage
- Obstacle detection
- Orange fence detection
- Detect potential sample, i.e. at a distance
- Approach sample
- Detect possible tumble
The first five requirements are related as:
Current bearing = function of (Initial Bearing, Dynamic Bearing changes)
Current location = function of (Initial Location, Dynamic Location changes)
and when a rover is seeking to the known location of the pre-cached sample or returning to the starting platform:
Seek Bearing = function of(Initial Location, Pre-Cached Location)
Return Bearing = function of(Initial Location, Current Location)
The search coverage (#6) is determined by:
Search Coverage =
function of (Initial Bearing, Dynamic Bearing changes,
Initial Location, Dynamic Location changes)
Since all of these requirements are related they are discussed further in Location and Bearing Analysis.
There is not much analysis required for the remaining requirements, numbers 6 through 11. All but number 11 are vision processing tasks. Requirement 11 requires an accelerometer to measure the tilt of the rover.
The page Summation of Analysis is a summation of all the analysis results for this page and others.