A Design For An Exoskeletal Device With Reduced Reliance On Joint Alignment As robotic exoskeletons begin to find more use in the areas of medicine and rehabilitation, efforts to improve comfort and reduce the chance of injury for wearers have resulted in the development of joint mechanisms with extra passive degrees of freedom. The added redundancy in such mechanisms enables the system to accommodate for joint axis misalignments between the exoskeleton and the human skeleton, as well as deviations from ideal circular motion that are inherent in normal human body motion. However, proper measurement of joint positions and torques, and by extension proper position and impedance control of the exoskeleton still relies on the approximate alignment of these joint axes. This paper presents a method for such a system to calculate the pose and torque about a human elbow joint for a wider variety of possible mounting positions. Using the developed calibration procedure, the main joint of the exoskeleton can be located as much as 110 mm away from the elbow and still position the elbow to within 10 degrees of a given flexion angle and measure torques to within 13 percent of the actual value. An elbow exoskeleton was developed employing this system and tested for comfort. The wearer was able to comfortably move their elbow in any desired motions using the devicexe2x80x99s passive mode. These results demonstrate the feasibility of using such a system on a robotic rehabilitation device and open up more possibilities for future exoskeleton designs not limited by joint placement.

A Threedimensional Finger Motion Measurement System of a Thumb and an Index Finger Without a Calibration Process Various wearable systems have been investigated to measure hand motion, but some challenges remain. Many systems require a calibration process to map sensor signals to actual finger joint angles by the principle of measuring the length change of the finger, or bending sensors. Also, few studies have investigated how to measure thumb motion accurately using the wearable systems. This paper proposes an exoskeleton system with linear Hall sensors to measure threedimensional hand motion without a calibration process. The calibration process is avoided by measuring finger joint angles through an absolute rotation measurement. A new wearing method with lower parts underneath the hand joints and rubber bands is proposed to fix the structure to the hand and adapt it for various hand sizes. As the thumb has a complex biomechanical feature at carpometacarpal (CMC) joint, a new measuring method of the CMC joint is proposed to directly calculate the orientation of the metacarpal. The prototype of the thumb and index finger was manufactured, and the performance was verified experimentally by using an optical motion capture system.