When I try to generate C++ code for generalize​dInverseKi​nematics I get the following error Dimension 2 is fixed on the left-hand side but varies on the right ([1 x 8] ~= [1 x

This is the class and entry point function that I am trying to convert to c++ code

%_____________________________________________________________________________________________

classdef GeneralizedIK

%UNTITLED Summary of this class goes here

% Detailed explanation goes here

properties

robot

gik

ik

posTgt1

posTgt2

posTgt3

posTgt4

weights

initialguess

pos

end

methods

function obj = GeneralizedIK()

%UNTITLED Construct an instance of this class

% Detailed explanation goes here

obj.robot = importrobot('baxter.urdf');

pos = 'position';

obj.gik = generalizedInverseKinematics(...

'ConstraintInputs',{pos,pos,pos,pos},...

'RigidBodyTree',obj.robot,...

'SolverAlgorithm','LevenbergMarquardt');

obj.ik = inverseKinematics('RigidBodyTree',obj.robot,...

'SolverAlgorithm','LevenbergMarquardt');

obj.weights = [0 0 0 1 1 1];

obj.initialguess = obj.robot.homeConfiguration;

obj.posTgt1 = constraintPositionTarget('right_lower_shoulder');

obj.posTgt2 = constraintPositionTarget('right_lower_elbow');

obj.posTgt3 = constraintPositionTarget('right_lower_forearm');

obj.posTgt4 = constraintPositionTarget('right_hand');

end

function [sol] = compute_theta(obj,vec1,vec2,vec3,vec4)

%METHOD1 Summary of this method goes here

% Detailed explanation goes here

obj.posTgt1.TargetPosition = vec1;

obj.posTgt2.TargetPosition = vec2;

obj.posTgt3.TargetPosition = vec3;

obj.posTgt4.TargetPosition = vec4;

tform1 = trvec2tform(vec1);

tform2 = trvec2tform(vec2);

sol = obj.ik('right_lower_shoulder',tform1,obj.weights,obj.initialguess);

sol = obj.ik('right_lower_elbow',tform2,obj.weights,sol);

sol = obj.gik(sol,obj.posTgt1,obj.posTgt2,obj.posTgt3,obj.posTgt4);

end

end

end

%_____________________________________________________________________________________________

function [sol] = gik_main() %#codegen

%UNTITLED Summary of this function goes here

% Detailed explanation goes here

robot = importrobot('baxter.urdf');

gik = GeneralizedIK();

randconfig = robot.randomConfiguration;

tform1 = getTransform(robot,randconfig,'right_lower_shoulder','base');

vec1 = tform2trvec(tform1);

tform2 = getTransform(robot,randconfig,'right_lower_elbow','base');

vec2 = tform2trvec(tform2);

tform3 = getTransform(robot,randconfig,'right_lower_forearm','base');

vec3 = tform2trvec(tform3);

tform4 = getTransform(robot,randconfig,'right_hand','base');

vec4 = tform2trvec(tform4);

%[randconfig.JointPosition]

sol = gik.compute_theta(vec1,vec2,vec3,vec4);

%[sol.JointPosition]

end

[Michael]

Do you know what line the error is pointing to? It is hard to debug without this. If I were you, I'd try to generate the mex first and then move to C++ generation. I recently ran through the same issues on my own code. Mex generation produces errors that are more easy to digest. Once you get the mex running well, then move onto C++ generation.

You may want to look at coder. varsize to deal with issues related to varables of mixed sizes.

[Aravindh Deiva G]

This is the error:

??? Dimension 2 is fixed on the left-hand side but varies on the right ([1 x 8] ~= [1 x :?]).

More information

Error in ==>> generalizedInverseKinematics Line: 364 Column: 17

Code generation failed: View Error Report

The code fragment which the error is pointing to is

function set.ConstraintInputs(obj, value)

validateattributes(value, {'cell','string'}, {'row'}, ...

'set.ConstraintInputs', 'ConstraintInputs');

for i = 1:numel(value)

value{i} = validatestring(value{i}, {'orientation', ...

'position', ...

'pose', ...

'cartesian', ...

'aiming', ...

'joint', ...

'jointbounds', ...

'distance', ...

'prismaticjoint', ...

'revolutejoint', ...

'fixedjoint'}, ...

'generalizedInverseKinematics', 'ConstraintInputs');

end

obj.ConstraintInputs = value;

end

I've attached an image above regarding the same. I think it has to do with the declaration of generalizedInverseKinematics in here

function obj = GeneralizedIK()

%UNTITLED Construct an instance of this class

% Detailed explanation goes here

obj.robot = importrobot('baxter.urdf');

pos = 'position';

obj.gik = generalizedInverseKinematics(...

'ConstraintInputs',{pos,pos,pos,pos},...

'RigidBodyTree',obj.robot,...

'SolverAlgorithm','LevenbergMarquardt');

obj.ik = inverseKinematics('RigidBodyTree',obj.robot,...

'SolverAlgorithm','LevenbergMarquardt');

obj.weights = [0 0 0 1 1 1];

obj.initialguess = obj.robot.homeConfiguration;

obj.posTgt1 = constraintPositionTarget('right_lower_shoulder');

obj.posTgt2 = constraintPositionTarget('right_lower_elbow');

obj.posTgt3 = constraintPositionTarget('right_lower_forearm');

obj.posTgt4 = constraintPositionTarget('right_hand');

end

[Karsh Tharyani]

Hi Aravindh,

I would suggest you reach out to our Technical Support team with the reproducible of the issue. That will enable us to diagnose this in an efficient manner.

Best,

Karsh

Answer 1

[Michael]

@Aravindh Deiva G,

I looks like you are trying to save the output of the validatestring function over the entries in value, which I assumed is preallocated earlier in the program. Since your valid strings input to the function are listed in a cell array, the function output should be a character vector (see the validatestring documentation on the matchedStr input argument). That means that the output will be a variable sized. See the difference between the declarations below:

ex1 = 'an example';
size(ex1)
%ans =
%     1    10
ex2 = "an example";
size(ex2)
%ans =
%     1    1

Coder probably sees each entry of value as fixed size. You could probably specify each entry as a variable size using something like

value = cell(3,1);
entryA = 'A char array';
entryB = 'B char array';
coder.varsize(entryA);
coder.varsize(entryB);
value{1} = entryA;
value{2} = entryB;

but this likely is two 'hard-coded'. Insteade, I would probably try to cast the output of validatestring as a string and then save as a separate array to avoid variable size issues. You likely should also be initially specifing the entryies of value as strings rather than char arrays. This way the size of each entry of value is a fixed 1x1 string rather than a variable size 1x: character array. Something like this:

entryA = "A short string";
entryB = "A much longer string to show the size of entryB is still 1x1";
value = {entryA; entryB};
tempValue = 'preAllocCharArray';
coder.varsize(tempValue,[1,100],[1 0]);%Is 100 enough for your application?
for i = 1:numel(value)
    tempValue = validatestring(value{i},{'orientation','position','etc...'},'generalizedInverseKinematics','ConstraintInputs')
    value(i) = convertCharsToStrings(tempValue);
end

Note that I haven't checked this code with coder, but I think it will work. I had to go through my code recently and covert a bunch of character arrays to strings to deal with this variable size business.

I hope this helps.

-Michael