hello everyBody,
We’re a group of italian students trying to make a model of the human
upper limb. In the elbow, we’re trying to drive a two-axis universal joint
with a Fourier-Cos driver.The motion should be around just one axis with:
theta(t) = (A/w^2)(1-cos(wt))
or, in terms of angular acceleration:
alpha(t) = Acos(wt)
where alpha(t) = d2(theta(t))/dt^2 and A,w are constants.
does anyone know how to write this in AnyScript?
thanks
Raphael Bartalesi
Dear Raphael,
I’ve made a simple example which shows how to write this function in an
AnyScript with use of a Fourier driver of the type cosinus.
I hope this makes things clear.
Greetings, Mark
–
Mark de Zee, Ph.D., Research Assistant Professor
Aalborg University, Institute of Mechanical Engineering
Pontoppidanstraede 101, Aalborg East,9220 Denmark
Phone: +4596359317, Fax: +4598151675
E-mail: mdz@ime.auc.dk
The AnyBody Group: http://anybody.auc.dk
rph@inventati.org wrote:
>hello everyBody,
>
>We’re a group of italian students trying to make a model of the human
>upper limb. In the elbow, we’re trying to drive a two-axis universal joint
>with a Fourier-Cos driver.The motion should be around just one axis with:
>theta(t) = (A/w^2)(1-cos(wt))
>
>or, in terms of angular acceleration:
>
>alpha(t) = Acos(wt)
>
>where alpha(t) = d2(theta(t))/dt^2 and A,w are constants.
>
>does anyone know how to write this in AnyScript?
>thanks
>
>Raphael Bartalesi
>
>
>
>
>To unsubscribe from this group, send an email to:
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>
>
>
>
>
>
</td></tr></table>
Main = {
// The actual body model goes in this folder
AnyFolder MyModel = {
// Global Reference Frame
AnyFixedRefFrame GlobalRef = {
AnyRefNode ElbowNode = {sRel = {0,0,0};};
AnyDrawRefFrame DrwGlobalRef = {
ScaleXYZ = {0.2,0.2,0.2};
RGB = {1, 0, 0};
};
}; // Global reference frame
// Definition of a simple segment
AnySeg Arm = {
Mass = 2;
Jii = {0.1,0.01,0.1};
AnyRefNode ElbowNode = {sRel = {0,0.5,0};};
AnyDrawSeg DrwSeg = {};
};
AnyUniversalJoint Elbow = {
Axis1 = x;
Axis2 = z;
AnyRefNode &GroundNode = .GlobalRef.ElbowNode;
AnyRefNode &ArmNode = .Arm.ElbowNode;
};
/*
In the following driver I will drive the z-axis of the elbow joint with the
following function:
theta(t) = (a/w2)(1-cos(wt));
= a/w2 - (a/w2)cos(wt);
The x-axis will be kept contstant. You can change this constant position for
example like this:
A = {{0.3*pi,0},{a/(w^2),-a/(w^2)}};
Within in the driver I defined two variables a and w, which I gave an
arbitrary value.
w = 2*pi*Freq, therefore Freq is defined as w/(2*pi).In this example that
will result in
a frequency of 1 Hz.
Be aware that in this example I set the reaction type on 1, because I didn't
define
any muscles. In your case it must be set to 0 (the muscles will deliver the
necessary force).
/
AnyKinEqFourierDriver ElbowMovement = {
AnyUniversalJoint &Jnt = .Elbow;
Type = Cos;
AnyVar a = pi;
AnyVar w = 2pi;
Freq = w/(2*pi);
A = {{0,0},{a/(w^2),-a/(w^2)}};
B = {{0,0},{0,0}};
Reaction.Type = {1.0,1.0};
};
};
// The study: Operations to be performed on the model
AnyBodyStudy MyStudy = {
AnyFolder &Model = .MyModel;
RecruitmentSolver = MinMaxSimplex;
Gravity = {0.0, -9.81, 0.0};
tEnd = 10;
nStep = 500;
};
}; // Main