[ARTICLE] Vision-Based Pose Estimation for Robot-Mediated Hand Telerehabilitation – Full Text PDF/HTML

Abstract

Vision-based Pose Estimation (VPE) represents a non-invasive solution to allow a smooth and natural interaction between a human user and a robotic system, without requiring complex calibration procedures. Moreover, VPE interfaces are gaining momentum as they are highly intuitive, such that they can be used from untrained personnel (e.g., a generic caregiver) even in delicate tasks as rehabilitation exercises.

In this paper, we present a novel master–slave setup for hand telerehabilitation with an intuitive and simple interface for remote control of a wearable hand exoskeleton, named HX. While performing rehabilitative exercises, the master unit evaluates the 3D position of a human operator’s hand joints in real-time using only a RGB-D camera, and commands remotely the slave exoskeleton. Within the slave unit, the exoskeleton replicates hand movements and an external grip sensor records interaction forces, that are fed back to the operator-therapist, allowing a direct real-time assessment of the rehabilitative task.

Experimental data collected with an operator and six volunteers are provided to show the feasibility of the proposed system and its performances. The results demonstrate that, leveraging on our system, the operator was able to directly control volunteers’ hands movements.

1. Introduction

Traditional rehabilitation is performed in a one-to-one fashion, namely one therapist (or sometimes several) working with one patient, leading to high personnel and management costs, especially for demanding patients such as those with brain or post surgery injuries. Due to the high hospitalization costs, all these patients are leaving clinics and returning to their homes sooner than in the past [1], when their rehabilitative program is not yet finished. These patients can greatly benefit from a telerehabilitation equipment, which is able to provide remote assistance and relief without the burden of going to the clinic on a daily basis. On the other hand, therapists can surely benefit from non-invasive systems capable of acquiring information about their movements which are then sent to the patient (or even to many patients), possibly in real-time to allow a direct control; modern vision-based techniques offer interesting sparks in such way. The possibility to provide high quality rehabilitation programs regardless of patients physical location and leveraging on vision is thus certainly attractive.

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Figure 2. HX while holding the sensorized object in a pinch (a) and lateral (b) grasping exercise. The DoMs of the HX device are: (1) the flexion/extension of the index MCP; (2) of the index P-DIP (under-actuated); (3) of the thumb MCP and IP (under-actuated) and (4) the CMC opposition. Other Degrees-of-Freedom (DoF), like thumb intra/extra rotation and the index abduction/adduction, are passive [29]. The HX is used to grasp the sensorized object, whose squeezable soft-pads provide force information on the basis of a optoelectronic deformation transduction [34].