I am trying to find the joint angles or at least theta to be used to find the Denavit-Hartenberg Parameter for a robotic arm (Baxter's right arm). I have the link lengths and such, but I don't know how to find theta using the link lengths or anything. Help with anything would be appreciated.
Since that arm is redundant, there are an infinite number of solutions for the inverse kinematics. Fortunately, Dr. Williams at Ohio U has developed the forward and inverse kinematics for this arm here. He describes the complete forward kinematics, and the inverse kinematics two ways: once for the case where $\theta_3$ is fixed at zero degrees, and again using a numerical approach to resolve the redundant system.