# Match real X, Y, Z, positions with calculated positions

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Mete Özcan 2022년 1월 12일
댓글: DGM 2022년 1월 18일
Hello, I am a student and I am using a Matlab code on my prototype project. I am using IMU sensors to track a tool's position. I have a 3 columns matrix data of positions x, y, z comes from IMU sensor. I also have 3 columns excel table of the positions x, y, z of objects that I need to add another column that includes for each row a scanning of the other table that comes from the sensor and tells matched or not matched. But since it cannot match exactly it needs an approximation such as +-2cm.

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### 채택된 답변

DGM 2022년 1월 13일
편집: DGM 2022년 1월 13일
This is a generalized example of finding and evaluating distances. I'm assuming here that simple euclidean distance is an appropriate metric for the task.
Dtolerance = 0.5;
% example location data
[x y z] = ndgrid(1:4);
partloc = [x(:) y(:) z(:)];
toolloc = rand(100,3)*3+1;
% find closest part, evaluate distance
D = sqrt((toolloc(:,1)-partloc(:,1).').^2 + ...
(toolloc(:,2)-partloc(:,2).').^2 + ...
(toolloc(:,3)-partloc(:,3).').^2);
[Dmin closestpart] = min(D,[],2);
iscloseenough = Dmin <= Dtolerance;
% show results
[iscloseenough closestpart]
ans = 100×2
0 27 1 30 1 26 1 13 0 28 0 58 0 30 0 33 1 11 1 18
% plot the points; draw lines between tool and closest part
plot3(partloc(:,1),partloc(:,2),partloc(:,3),'o'); hold on
plot3(toolloc(:,1),toolloc(:,2),toolloc(:,3),'*');
axis equal
grid on
for k = 1:numel(closestpart)
a = toolloc(k,:);
b = partloc(closestpart(k),:);
if iscloseenough(k)
plot3([a(1) b(1)],[a(2) b(2)],[a(3) b(3)],'g')
else
plot3([a(1) b(1)],[a(2) b(2)],[a(3) b(3)],'r:')
end
end
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DGM 2022년 1월 18일
That's what the example does. It checks all sensor positions (toolloc) against all object positions (partloc). It finds the closest object by euclidean distance and tests whether the closest object is within a specified euclidean distance. The rest of the code is just visualization for sake of demonstration.
If you want to test axial distance instead of euclidean distance (the valid region being a cube instead of a sphere), then you can do that too.
Dtolerance = 0.3;
% example location data
[x y z] = ndgrid(1:4);
partloc = [x(:) y(:) z(:)];
toolloc = rand(100,3)*3+1;
% find closest part, evaluate distance
D = sqrt((toolloc(:,1)-partloc(:,1).').^2 + ...
(toolloc(:,2)-partloc(:,2).').^2 + ...
(toolloc(:,3)-partloc(:,3).').^2);
[Dmin closestpart] = min(D,[],2);
% is part within a tolerance box?
iscloseenough = all([abs(toolloc(:,1)-partloc(closestpart,1))<Dtolerance, ...
abs(toolloc(:,2)-partloc(closestpart,2))<Dtolerance, ...
abs(toolloc(:,3)-partloc(closestpart,3))<Dtolerance],2);
% show results
[iscloseenough closestpart]
ans = 100×2
1 28 0 22 0 59 0 34 0 56 0 24 0 43 0 8 1 44 0 20
% plot the points; draw lines between tool and closest part
plot3(partloc(:,1),partloc(:,2),partloc(:,3),'o'); hold on;
plot3(toolloc(:,1),toolloc(:,2),toolloc(:,3),'*');
axis equal
grid on
for k = 1:numel(closestpart)
a = toolloc(k,:);
b = partloc(closestpart(k),:);
if iscloseenough(k)
plot3([a(1) b(1)],[a(2) b(2)],[a(3) b(3)],'g')
else
plot3([a(1) b(1)],[a(2) b(2)],[a(3) b(3)],'r:')
end
end
Note that Dtolerance does not need to be scalar. It can also be specified as a three-element vector for per-axis tolerance. The logical test would need to address the corresponding elements of said vector, of course.

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