A methodology for the development of a Hinged Ankle-Foot Orthosis compatible with natural joint kinematics

This work presents a new concept to design Hinged Ankle-Foot Orthoses (HAFOs), based on the definition of a special mechanical articulation able to mimic the physiological behavior of the human ankle joint. Current commercial braces typically do not take into account the natural variability of the ankle joint axis. As the hinge location as well as the rotation axis variability are both relevant for the overall function of the device, and strongly depend on the subject-specific characteristics, a methodology for the development of a HAFO with a floating axis of rotation, based on the in-vivo kinematic analysis of the ankle joint, is here proposed. The kinematic analysis was performed by calculation of the instantaneous and mean helical axes over the collected stereo-photogrammetric data of joint motion. This procedure was tested on a healthy subject, leading to the design and fabrication of a first customized prototype of the orthosis. The performance of this HAFO was experimentally verified by motion analysis. All relevant results are presented, and further possible future improvements of the procedure are discussed

A methodology for the customization of hinged ankle-foot orthoses based on in vivo helical axis calculation with 3D printed rigid shells

This study aims to develop techniques for ankle joint kinematics analysis using motion capture based on stereophotogrammetry. The scope is to design marker attachments on the skin for a most reliable identification of the instantaneous helical axis, to be targeted for the fabrication of customized hinged ankle-foot orthoses. These attachments should limit the effects of the experimental artifacts, in particular the soft-tissue motion artifact, which affect largely the accuracy of any in vivo ankle kinematics analysis. Motion analyses were carried out on two healthy subjects wearing customized rigid shells that were designed through 3D scans of the subjects’ lower limbs and fabricated by additive manufacturing. Starting from stereophotogrammetry data collected during walking and dorsi-plantarflexion motor tasks, the instantaneous and mean helical axes of ankle joint were calculated. The customized shells matched accurately the anatomy of the subjects and allowed for the definition of rigid marker clusters that improved the accuracy of in vivo kinematic analyses. The proposed methodology was able to differentiate between subjects and between the motor tasks analyzed. The observed position and dispersion of the axes were consistent with those reported in the literature. This methodology represents an effective tool for supporting the customization of hinged ankle-foot orthoses or other devices interacting with human joints functionality

Dynamic Modeling and Experimental Validation of a Haptic Finger Based on a McKibben Muscle

The paper deals with the implementation of a McKibben pneumatic muscle in a tele-operation robotic system provided with haptic feedback, aimed to the generation of the perception force at the operator’s fingertip. The architecture of the device is presented and a dynamic model of the system is proposed. A prototype of the device has been tested in dynamic conditions, and the outcomes have been compared with the numerical results, highlighting that the use of a pneumatic muscle is suitable for the actuation of a haptic finger device

Identification of physical parameters in a robotized IPC device interacting with human

Intermittent Pneumatic Compression devices are widely used for various therapies concerning the cardio-circulatory or lymphatic system, and also for performance recovery in sports activity. The development and setup of such devices are mainly based on empirical procedures, while few researches adopt an engineering approach based on mathematical modeling and identification. In this approach the most critical point is the definition of parameters concerning the human-machine interaction. This paper proposes an original and simple method to identify such parameters, which allows to describe in effective way the main dynamic characteristics, fundamental for a correct design and control of the device