Rehabilitador De Tobillo

A Parallel Robot for Ankle Rehabilitation-Evaluation and its Design Specifications.
Christos E. Syrseloudis and Ioannis Z. Emiris
Abstract— This paper investigates several robotic mechanisms for ankle function evaluation, measurement and physiotherapy. For the choice, design and operation of the mechanism the kinematics of the foot is described. This is based on a kinematics model of footadopted from biomechanics literature, under the hypothesis that foot kinematics is similar to that of a 2R serial robot. A 3D scanner and an inertial sensor were used in order to fully specify the design framework by studying a larger sample of healthy subjects. Our experimental analysis confirms and enhances the 2R foot model, and leads us to the choice of the specific mechanism. We compute the requiredworkspace and thus address the issues required for a complete and efficient design. We compare mechanisms based on serial and parallel robots, and choose a parallel tripod with an extra rotation axis for its simplicity, accuracy and generality. The robot must be capable to perform several multi-axis motions and sustain a significant range of forces and torques. The kinematic analysis of the robotconfirms that it can follow all the range of foot movements.

to a device with adaptation to the specific characteristics of each patient’s foot.

Fig. 1.

Elastic-band rehabilitation exercise.

I. I NTRODUCTION Many people have kinetic problems that are owed in ankle injuries since they are very common and so they often require rehabilitation. The equipment used for ankle rehabilitation isusually simple devices such as elastic bands (fig. 1), foam rollers and wobble boards [23]. These rehabilitation devices are typically used in regimens that include exercises both in the clinic and at home. They don’t provide diagnostic and networking capabilities to allow therapists to remotely monitor the patient’s progress. In addition, they are rarely interactive, making exercising monotonous.More importantly, they cannot be used for assessment, and execution of all rehabilitation tasks, hence the interest for an automatic device for complete physiotherapy and evaluation is big. Several researchers proposed automatic mechanisms to help the physiotherapist [1]. Quite successful is the work at Rutgers University, including a haptic interface for ankle and hand rehabilitation. For anklerehabilitation, a haptic interface was developed [5], based on a Stewart platform that applies variable forces and virtual reality exercises on the foot, including remote control operation. However, its 6DOF structure is redundant and there is no report for the design criteria; we aim at a smaller and more economic alternative, easier to move and operate. We also emphasise
Manuscript received July5, 2008. C.E. Syrseloudis is with the Department of Informatics and Telecommunications, National Kapodistrian University of Athens (NKUA), GREECE (phone: +302107275342;

e-mail:c.sirsel@di.uoa.gr) (e-mail:emiris@di.uoa.gr)

I.Z. Emiris is with the Department of Informatics and Telecommunications, National Kapodistrian University of Athens (NKUA), GREECE

In [8], the study of ankle injuriesand ankle functional anatomy was based on an orientation image space; 3 platform-type ankle rehabilitation mechanisms were considered and their mobility, stiffness and constraints analyzed. But other design criteria are not analyzed nor is the construction and functional operation of such platforms. Parallel robot design concerns the geometric parameters calculation of a parallel robot with specificarchitecture satisfying several criteria [17]. A method for parallel robot design is based on interval analysis as it is proposed [12]. This involves multidesign criteria (workspace covering, accuracy bounds satisfaction, stiffness etc). A procedure with multiobjective optimization design was proposed in [6]. We focus on the design specifications of a simple robot for ankle injuries treatment....