Error in rosReadBin​aryOccupan​cyGrid

Hello I'm trying to subscribe /map topic from ROS and make occupancy map in simulink

So I use subscribe block in Simulink and connect msg to MATLAB function block.

the code of MATLAB function block is below

function fcn(u)
map = rosReadBinaryOccupancyGrid(u);
show(map)
end

But there is an error

This structure does not have a field 'MessageType'. Function 'rosReadBinaryOccupancyGrid.m'(#222.2006.2009)

Is there any solution or another way to plot occupancy map in simulink?

Answer 1

[Josh Chen]

Hi SEUNGSHIN,

Thanks for bringing this use case to our attention. As for now, there is no Simulink block for reading binary occupancy grid. We will consider to provide this functionality in a future release.

Meanwhile, as a workaround, you can use a combination of "MATLAB Function" and "Video Viewer" block to plot occupancy map in Simulink.

Here is the script in MATLAB function block for your reference:

function y = fcn(u)

% Specify the expected dimension of the occupancyMatrix

y = zeros(10,10,'logical');

dataLen = u.Data_SL_Info.CurrentLength;

if dataLen>0

% Create MATLAB message

msg = rosmessage("nav_msgs/OccupancyGrid","DataFormat","struct");

% Assign message fields based on input Simulink message bus

msg.Info.Height = u.Info.Height;

msg.Info.Width = u.Info.Width;

msg.Info.Resolution = u.Info.Resolution;

msg.Data = u.Data(1:dataLen);

% Use rosReadBin​aryOccupan​cyGrid to read occupancy grid

map = rosReadBinaryOccupancyGrid(msg);

% output occupancyMatrix

occupancyMatrix = map.occupancyMatrix;

y = occupancyMatrix(1:10,1:10);

end

Hope that helps,

Thanks,

Josh