New mechanism for a 3 DOF exoskeleton hip joint with five revolute and two prismatic joints

We present a new exoskeleton hip design representing the human hip ball joint by five revolute and two prismatic joints. The goal of the design is to increase wearing comfort and torque transmission by reducing misalignments between the human's and the exoskeleton's joint with a self-aligning yaw axis in the transverse plane. The required ranges of motions and joint velocities for the hip joint design were identified based on motion capture data consisting of 828 motion recordings of 26 different subjects. We present the kinematics of a new hip joint with five revolute and two prismatic joints and its first 3D printed prototype. For the experimental evaluation we focused on measuring interaction forces between the subject and the exoskeleton at the back, pelvis and thigh with different kinematic configurations. The results indicate that interaction forces between exoskeleton and user are reduced by the new hip exoskeleton.