A comparative study of human inverse kinematics techniques for lower limbs

Inverse Kinematics (IK) has been an active research topic and many methods have been introduced to provide a fast and accurate solution. However, high computational cost and the generation of unrealistic positions constitute the weak points in most existing IK methods. In this paper, a comparative study was established to analyze the performance of popular IK techniques applied to the human leg. The objective is to determine the most efficient method in terms of computation time and to reach the desired position with a realistic human posture while respecting the range of motion and joint comfort zones of every joint.

Kinematics and Dynamics Modeling of 7 Degrees of Freedom Human Lower Limb Using Dual Quaternions Algebra

Denavit and Hartenberg based methods as Cardan, Fick and Euler angles describe the position and orientation of an end-effector in Three Dimensional (3D) space. However, the generation of unrealistic human posture in joint space constitutes the weak point to these methods because they impose a well-defined rotations order. A method to handle the transformation homogeneous performance uses the dual quaternions. Quaternions have proven themselves in many fields as providing a computational efficient method to represent a rotation, and yet, they can not deal with the translations in 3D-space. The dual numbers can extend quaternions to dual quaternions. This paper exploits dual quaternions theory to provide a fast and accurate solution to the forward, inverse kinematics and recursive Newton-Euler dynamics algorithm for 7 Degree of Freedom (DOF) human lower limb in 3D-space.