Based on this diagram from your kinematics video, the end point of the leg is currently at the tip of the foot. However, as you stated in the video, the tip of the foot is not necessarily the point touching the ground. To account for this the end point of the leg should actually be at the center of the foot when doing the calculations. The point touching the ground would then be one foot's radius from this point.

Based on this diagram from your kinematics video, the end point of the leg is currently at the tip of the foot. However, as you stated in the video, the tip of the foot is not necessarily the point touching the ground. To account for this the end point of the leg should actually be at the center of the foot when doing the calculations. The point touching the ground would then be one foot's radius from this point.