I did some research but I cannot find analytical IK solutions for CRX type of robot, what I ended up with is IKFast. It returns multiple solutions without configuration information.
During the analytical study, I found that paper [1] mentioned that CRX robot is cuspidal type of robot. This type of robot can pass through different configurations without going across singularities, quite difficult to imagine.
In another paper [2], the author proposed a method for Kinova robot inverse kinematics. This Kinova is the same with CRX (Fig. 2 of [2]). They use polynomial method and provides source code. I haven't got a chance to reimplement to CRX robot.
If you guys got an more elegant solution, I would be very much appreciate it!
[1] A review of cuspidal serial and parallel manipulators
[2] Kinova Gen3 Lite manipulator inverse kinematics optimal polynomial solution
