These topics describe controls for the HI IK Solver, which appear on the Motion panel.
The HI Solver is a history-independent solver that doesn't rely on the calculations from previous frames for the IK solution, so it is fast to use no matter the length of your animation. The history-independent solver uses a goal to manipulate the end of the chain. It uses a preferred angle that specifies a preference regarding which direction the link will rotate: positive or negative. The preferred angle can also be considered as the initial angle; that is, the angle at which the link was rotated at the time the solver was applied.
Here are the additional controls for the HI IK solver. The IK Solver Plane is controlled here through the Swivel Angle, which can be animated directly or using a target object.
Here are the controls to turn on and off a variety of gizmos in the viewport. The Goal and End effectors, the vector handle of the swivel angle manipulator, and the IK solver display itself, are all located in this rollout.
Here are the controls for setting the joint limits when using the HI Solver. You can turn X, Y, or Z axes on or off, limit them, and set those limits here. This is also where the preferred angle is defined, and adjusted. The preferred angle defines the direction a chain will bend, which angle a chain will tend to rotate toward.
