CCD - Joint Rotation Constraints (1st Attempt)

My current solution does nothing to prevent overextension of joints, nor tight configurations of joint angles which “cause the chain to form a loop, intersecting itself” (Mukundan, 2009, p. 304).

Figure 1: Common drawbacks of CCD, including chain intersection (Mukundan, 2009, p. 304)

The problems this creates are clear - an example is demonstrated in figure 2:

Figure 2: Unconstrained solution allows intersections and overextension of joints

The animations my solutions produce must preserve the natural limits of the human body. Limiting the range of each joints’ rotation, coupled with the comparatively low degree of freedom of human limbs and my controllable trajectory plotter, should prevent the above problems.

CCD - Multi-End Structures

During my research for joint bias, I came across the concept of multi-ended kinematic structures. While this was not in my initial development plan, it should provide more natural reaching behaviour and with my current functionality should be a simple to implement in addition to constraining rotation of chain joints this week.

Kenwright (2013, pp. 63-64) discusses how the typical CCD algorithm can be applied to multiple hierarchy structures with separate end effectors.

“It work inwards from the end-effectors and bias the constrain update order towards the starting end-effector (i.e., by bouncing back to the start each time a joint moves), we can avoid joint ownership fighting. In such situations, however, the last updated sequence of joints for an end-effector will get priority on the final orientation (or length) of joints.” (Kenwright, 2013, pp. 63-64)