81 lines
3.4 KiB
Matlab
81 lines
3.4 KiB
Matlab
function [stewart] = initializeParameters(stewart)
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%% Connection points on base and top plate w.r.t. World frame at the center of the base plate
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stewart.pos_base = zeros(6, 3);
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stewart.pos_top = zeros(6, 3);
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alpha_b = stewart.BP.leg.ang*pi/180; % angle de décalage par rapport à 120 deg (pour positionner les supports bases)
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alpha_t = stewart.TP.leg.ang*pi/180; % +- offset angle from 120 degree spacing on top
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height = (stewart.h-stewart.BP.thickness-stewart.TP.thickness-stewart.Leg.sphere.bottom-stewart.Leg.sphere.top-stewart.SP.thickness.bottom-stewart.SP.thickness.top)*0.001; % TODO
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radius_b = stewart.BP.leg.rad*0.001; % rayon emplacement support base
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radius_t = stewart.TP.leg.rad*0.001; % top radius in meters
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for i = 1:3
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% base points
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angle_m_b = (2*pi/3)* (i-1) - alpha_b;
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angle_p_b = (2*pi/3)* (i-1) + alpha_b;
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stewart.pos_base(2*i-1,:) = [radius_b*cos(angle_m_b), radius_b*sin(angle_m_b), 0.0];
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stewart.pos_base(2*i,:) = [radius_b*cos(angle_p_b), radius_b*sin(angle_p_b), 0.0];
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% top points
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% Top points are 60 degrees offset
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angle_m_t = (2*pi/3)* (i-1) - alpha_t + 2*pi/6;
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angle_p_t = (2*pi/3)* (i-1) + alpha_t + 2*pi/6;
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stewart.pos_top(2*i-1,:) = [radius_t*cos(angle_m_t), radius_t*sin(angle_m_t), height];
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stewart.pos_top(2*i,:) = [radius_t*cos(angle_p_t), radius_t*sin(angle_p_t), height];
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end
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% permute pos_top points so that legs are end points of base and top points
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stewart.pos_top = [stewart.pos_top(6,:); stewart.pos_top(1:5,:)]; %6th point on top connects to 1st on bottom
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stewart.pos_top_tranform = stewart.pos_top - height*[zeros(6, 2),ones(6, 1)];
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%% leg vectors
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legs = stewart.pos_top - stewart.pos_base;
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leg_length = zeros(6, 1);
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leg_vectors = zeros(6, 3);
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for i = 1:6
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leg_length(i) = norm(legs(i,:));
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leg_vectors(i,:) = legs(i,:) / leg_length(i);
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end
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stewart.Leg.lenght = 1000*leg_length(1)/1.5;
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stewart.Leg.shape.bot = [0 0; ...
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stewart.Leg.rad.bottom 0; ...
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stewart.Leg.rad.bottom stewart.Leg.lenght; ...
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stewart.Leg.rad.top stewart.Leg.lenght; ...
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stewart.Leg.rad.top 0.2*stewart.Leg.lenght; ...
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0 0.2*stewart.Leg.lenght];
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%% Calculate revolute and cylindrical axes
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rev1 = zeros(6, 3);
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rev2 = zeros(6, 3);
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cyl1 = zeros(6, 3);
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for i = 1:6
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rev1(i,:) = cross(leg_vectors(i,:), [0 0 1]);
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rev1(i,:) = rev1(i,:) / norm(rev1(i,:));
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rev2(i,:) = - cross(rev1(i,:), leg_vectors(i,:));
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rev2(i,:) = rev2(i,:) / norm(rev2(i,:));
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cyl1(i,:) = leg_vectors(i,:);
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end
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%% Coordinate systems
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stewart.lower_leg = struct('rotation', eye(3));
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stewart.upper_leg = struct('rotation', eye(3));
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for i = 1:6
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stewart.lower_leg(i).rotation = [rev1(i,:)', rev2(i,:)', cyl1(i,:)'];
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stewart.upper_leg(i).rotation = [rev1(i,:)', rev2(i,:)', cyl1(i,:)'];
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end
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%% Position Matrix
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stewart.M_pos_base = stewart.pos_base + (height+(stewart.TP.thickness+stewart.Leg.sphere.top+stewart.SP.thickness.top+stewart.jacobian)*1e-3)*[zeros(6, 2),ones(6, 1)];
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%% Compute Jacobian Matrix
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aa = stewart.pos_top_tranform + (stewart.jacobian - stewart.TP.thickness - stewart.SP.height.top)*1e-3*[zeros(6, 2),ones(6, 1)];
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stewart.J = getJacobianMatrix(leg_vectors', aa');
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end
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