Custom Part Manufacturing Guide
Calculating Kinematics of a CTR
Graph Paper In-Plane Bending Experiment
Out-of-Plane Rotation Experiment
This page contains some frequently asked questions and common errors that occur when using the MATLAB Grader assignments.
Why are my tests not passing? I used the equations for link lengths from the paper!
You must find the location of all transition points, sort those points, and then take the difference of those points to find the link lengths. (You can use the built in MATLAB function sort(). Remember that there are $2n$ transition points, where $n$ is the number of tubes in your CTR. A transition point occurs either where the tube terminates ($\rho_i+d_i$) or when the tube changes curvature ($\rho_i$).
My robot seems like it is bending in the opposite direction of the example. What could cause this?
atan2() to calculate phi? If not, look up the difference between atan2() and atan(). atan2() is almost always better for use in kinematic applicationsatan2() already, check to make sure you are passing in chi and gamma correctly. In MATLAB, the function is: atan2(y,x). You should pass in atan2(gamma,chi).My $\kappa$ values pass the test, but my $\phi$ values don’t. How is this possible, since both of these depend on $\chi$ and $\gamma$?
You need to use $\Delta\phi$, or the difference between $\phi_j$ and $\phi_{j-i}$ to calculate your phi values: phil = [phi(1) phi(2)-phi(1) phi(3)-phi(2)].