$1$ Description

This project builds directly on the last one. Now that we can get the robot to follow a plan, we turn to building

aplan.

$2$ Start up

$1.$ You will be given a folder called project$6$ which contains a lot of familiar$-$looking files.

$2.$ The control program is in the file make$-$plan.cc$,$ so first build that:

$./$build make$-$plan

then run player on the config file world$6.$cfg:

player world$6.$cfg

$3.$ The robot, as it has at the start of previous projects, will trundle off to the south$-$east.

$4.$ However, before it starts to move, it will display something new

$5.$ This is an occupancy grid with a resolution of $0\mathrm{.}5$ meters $($for the format of the grid, see below$).$ For

the purposes of the project, this is a map.

$6.$ The program will also display a plan, just like last time.

$3$ Map format

$1.$ In terms of this project, an occupancy grid map is an array of integers.

$2.$ A $1$ indicates that a square is occupied, a $0$ indicates that it is not occupied.

$3.$ The code in make$-$plan.cc assumes that the map is square, so there is only one parameter that

controls the size of the map.

$4.$ In the example in the folder project$6,$ each grid square is half a meter on each side.

$5.$ This example map is for a map that is $16$ meters on each side.

$6.$ An example map is given in Figure $1($b$),$ while Figure $1($a$)$ shows the corresponding simulated world

from Stage.

$7.$ Note that this is NOT the world you$$ll be using in the project $($though it is probably familiar from

previous projects$).$

$8.$ In addition, the occupancy grid in Figure $1($b$)$ is lower resolution than the map in make$-$plan.cc

$$ each square is one meter on each side. $($a$)$ An example woeld in which the robot operabes.

$($b$)$ An occupuncy grid map.

Figure $1$: A simulated world and the corresponding occupancy grid map$4$ Use the map to plan

$1.$ The big task for this week is to write a robot controller that can use an occupancy grid to plan a

route through the world represented by the occupancy grid.

$2.$ The task assumes that you start with an occupancy grid, a set of coordinates that the robot starts

at$,$ and a set of coordinates that the robot has to end up at$.$

$3.$ The task is then to generate a plan that is a sequence of sets of coordinates. The first of these sets

of coordinates is the initial location of the robot, the last set of coordinates is the final location of

the robot, and each intermediate point is a point that the robot should pass through on its way from

the initial location to its final location.

$4.$ You need to choose the intermediate locations carefully so that the robot can move in a straight line

from one to the next without encountering an obstacle.

$5.$ A suitable way to create the plan is to use the wavefront planner we discussed in class. You could

also use the A$*$ search algorithm, which is considered optimal.

$6.$ You should use the map that came in make$-$plan.cc $($map$.$txt$),$ which corresponds $($well enough$)$

to the map that world$6.$cfg will load. Please note, the readMap$()$ function used in the sample

make$-$plan.cc reads the map in a way that the lower$-$left corner of the grid cell coordinates is

treated as the origin $($map$[0][0]).$ If you would rather the top$-$left corner to be the origin, you need

to modify the code slightly. Obviously then you also need to consider the conversion between the

real map coordinates $(-8$m to $8$m in both x and y coordinates$)$ and the grid coordinates $(0$ to $31).$

Please also note that in map$[$i$][$j$],$ i represents vertical and j represents horizontal, whereas in

your representation of a point $($x$,$ y$)$ in a real map, x represents horizontal and y represents vertical.

$7.$ Your final program should be able to create a plan from the map and then follow the plan. The

plan following can just be the code you wrote for the last project. A correct plan is worth $7$

points. As the output of your program you need to create a plan$-$out.txt file which contains

only the waypoints $($not all the trail points of your search algorithm$$s output$).$ To help me out in

understanding your plan, you should also make use of the provided writeMap$()$ function to

output a map$-$out.txt file, where among other $0$s and $1$s$,$ you place the number $2$ at the

coordinates where a waypoint should be$.$

$8.$ The robot actually following the plan is worth $1$ point, for which you might need to consider

dilating the obstacle occupancies to plan around the corners.

$9.$ The start point for the robot is where it starts in the simulation, $(6,6).$ The end point is $(6\mathrm{.}5,$

$6\mathrm{.}5).$

$10.$ Once your controller can do this, save your working program as $($your$-$names$)-$proj$6.$cc and

make sure you put your name in the comments.

$11.$ You$$ll need to submit the $.$cc file together with the plan$-$out.txt and map$-$out.txt files to me

after you are done with the project