Ncmmi2014001

Proceedings of The National Conference on Man Machine Interaction 2014 [NCMMI 2014]

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A Patient Rehabilitation System using a ManǦ Machine Interface Design Binson V A, Jo Joy, Anish Thomas

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Assistant Professor, Department of AEI, Saintgits college, Kottayam, India Assistant Professor, Department of EEE, Saintgits college, Kottayam, India

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Assistant Professor, Department of AEI, Saintgits college, Kottayam, India

Abstract: This paper presents the design of a man machine interface for controlling of a rehabilitation robot that can perform active and passive exercises for lower limbs. The system with man machine interface and robot manipulator can learn physiotherapist manual exercises and perform them by itself like a physiotherapist. Thus the rehabilitation capability is conveyed to the patient directly. The System also provides a graphical user Interface by which the treatment period can be observed and recorded. This interface can also be used for webǦbased remote therapy. Rehabilitation of knee and hip are carried out and the test results are presented.

I. Introduction

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The role of the rehabilitation process is to restore functionality of previously damaged limbs. It is most important to return patients to society, reintegrate them into social life and therefore improve the patients' quality of life. Throughout therapy, physical exercises for extremities like arms and legs have a keyǦrole in the recovery of the patient. Therapeutic exercises consist of active or passive physical movements of the patient, carried out through the therapist, or of movements carried out of the patient with the assistance of the physiotherapist, depending on the condition of the patient. For rehabilitation either the patient has to go to a healthcare center, or the physiotherapist has to come to the patient. Studies for robots in rehabilitation have been increased due to the timeǦconsuming process of rehabilitation.

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Studies carried out in the closer past have proved many advantages of rehabilitation robots compared to classic therapy methods [2]. In addition robotic therapy provides better possibilities to acquire and store information such as the therapy response of the patient [3]. There are several studies that use intelligent techniques and their aims are to transfer physiotherapist rehabilitation capacity to patient directly. In this study, a man machine interface (MMI) has been designed in order to control a designed and produced rehabilitation robot. Unlike other existing projects the robot manipulator (RM) that is used in this study can perform active and passive exercises for lower limbs and it can perform knee flexionǦextension, hip extensionǦflexion and hip abductionǦadduction movements. Also the rehabilitation system that consists of human machine interface and robot manipulator can learn physiotherapist manual exercises and perform them by itself like a physiotherapist. So this rehabilitation capability is conveyed to patient directly. So, single physiotherapist rehabilitates more than one patient at the same time with this system. The humanǦ machine interface includes an easyǦtoǦuse graphical user interface. With this interface, the treatment period can be observed and saved. Furthermore, the interface has been designed to be fit for webǦbased remote therapy. Thus, difficulties of transferring patients to medical centers can be eradicated. Test results are presented for direct rehabilitation of knee and hip.

II. System Description The system consists of three basic components (See Figure 1) Physiotherapist, the man machine interface and robot manipulator(RM). The system can perform Physiotherapist’s manual exercises as well as to carry out all standard active and passive exercises. The modeling of the manual exercises has been named

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“robotheerapy”. In thee robotherap py mode, thee system opeerates in two o different m modes. These modes are direct th herapy and reeactive therap py. In direct therapy mod de, the system m can repeatt movementss taught by the Physsiotherapist fo for any requirred duration.. In reactive t therapy mode, the system m responds acccording to the patieent’s reaction ns, the boundary condition ns of the exerrcise carried o out keep changing over th he duration of the therapy. In thiss paper, only the direct therapy mode t test results haave been sho own.

Figure 1. Basic compo onents of the system.

The graaphical user i nterface enab bles the PT access to all inform mation conccerning the patient and therapyy mode, exeercise type etc. Th he standard d active an nd passive exercisees are carried d out throug gh the RM. Howeveer, for d direct therrapy the physioth herapist carrries out m movements while the t patient iis on the R RM. In the meantim me, the HM MI monitors and stores position n and forcee values. A All process parametters are storeed in the database. This mode h has been n named “direcct therapy teaching g” mode. The next step i is to switch over to “direct theraapyǦtherapy” mode. The RM is n now reproduccing the sam me positions and forces applied tto the patien nt as in the previou us teaching m mode.

A. Physiiotherapistt

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n designed to o be an aid The system has been for the physiotherap pist considerring a fixed numberr of physiotherapist in socciety, more patientss could be h helped in a better way using this techn nology. Fu urthermore, rehabiliitation sessiions could be held longer, which is an n additional advantage.

The syystem's aim isn't to reeplace the physioth herapist, it iss to support h him or her.

The phyysiotherapist decides on t the specific exercisees to be carrried out by tthe patient and teacches those to o the RM. The RM is fed with in nformation ab bout the paatient (ageǦ weight body length)) and detailss about the exercisee to be carried out. The physioth herapist th hen carries out the exercisees together w with the patiient. In the p, the RM caarries out th he exercises w with the pattient in the same way ass done beforre with the next step physioth herapist.

B. Man n Machine I Interface

The MM MI is the centrral unit betw ween physioth herapist and the RM. It co onsists of thee impedance controller, rule basee, data base, graphical usser interface and central interface uniits. A detaileed block diag gram of the

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MMI is g given in Figurre 2 which is also known a as Human maachine interfaace(HMI). Th he MMI progrramming is realized i in Matlab/Sim mulink.

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MI/MMI Figurre 2. Detailed Block Diagraam of the HM Central Interface Unit: The central inteerface unit provides communication n between all system componeents.

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Graphiccal User Inte erface (GUI): Enables th he user to co ommunicate with the HM MI. The maiin menu as shown in n Figure 3 is used to inpu ut the patientts' data. Thesse data is useed in order to o calculate a number of mechanical parameteers. The bodyy limb which is to be exercised and thee exercise typ pe are selecteed from the main meenu as well. R Results from p previously caarried out exeercises can bee accessed from the main n menu and are displlayed graphiccally as show wn in Figure 4 4. The graph hics display th he patients' r range of mottion (ROM) and corrresponding fo orces. These results are sttored in the database for documentattion and can be printed out optio onally.

Impedan nce Controller: Impedaance controll aims at co ontrolling po osition and fforce by adjjusting the mechanical impedancce of the end dnjeffector to external forcces generated d by contact with the maanipulator’s environm ment. Mechaanical impedance is roug ghly an exten nded concep pt of the stiffness of a m mechanism against aa force appllied to it. It is accepteed to be thee most apprropriate conttrol techniqu ue for the physioth herapy and is used in man ny rehabilitattion robot ap pplications [5,6] [8] [11,12])). Because of f this it was used in t this applicatiion as main c control meth hod. For direcct rehabilitattion, its param meters were selected as appropriiate for PT m moves patien nt limbs smo oothly and eaasily. In ordeer to select appropriate impedance parameteers values, so ome experimeents were reaalized with diffferent param meters in diffe ferent speeds..

Data an nd Rule Basse: All data rrelevant to tthe patient iss stored in tthe data and d rule base. The stored informattion containss personal daata, impedan nce controllerr parameters, saved exerccises from th he teaching mode an nd exercise results.

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Proceedings of The National Conference on Man Machine Interaction 2014 [NCMMI 2014]

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Figure 5. Robot Manip pulator

I III. Results s and Discu ussion

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IIn the experriments with h the RM, h healthy test persons are used. Each t test person's leg is connected to the R RM with tw wo points, thigh and a ankle.

“Direcct therapy ǦǦ teaching” m mode is selec cted from the GUI. The e experiments carried out cover knee f flexionǦexten nsion, hip flexionǦ e extension an d abductionǦǦadduction.

T The physiottherapist teeaches the e exercises together with h the test p person direct tly on the RM M. Position a and force me easurement results from t taught exerccises are stored in the d database.

In n the following step “ “direct theraapy – therapyy” mode is s selected from m the GUI. Th he RM now c carries out evvery stored eexercise for t patient independentlly from the the p physiotherap pist. Figure 6 shows e exemplary ttest results for knee e extensionǦfle xion. In this figure, first g graphic shows physio otherapist’s e exercise traajectory in teaching m mode, secon nd graphic sshows RM’ exercise trajectory in therapy mod de and the lasst graphic sho ows trajectorry error betweeen physioth herapist and RM exerrcises. The reesults show a very much h accurate reepetition of the PT's mo ovements as learned in teaching g mode. In Figure 7, teach hing and therrapy results a are shown fo or hip flexion nǦextension m movements.

RM’s Lin nk 1 is the hip p link, Link 2 2 is the kneee link. For hip flexion and d extension b both hip join nt and knee joint aree moving sim multaneouslyy. Every graaph shows th he teaching trajectory as a well as th he therapy trajectoryy. As for Figu ure 8, abducttionǦadductio on movementts are shown. AbductionǦadduction m movement is realized by the drive mounted un nderneath th he patient, byy moving thee hip about th he vertical zǦǦaxis of the

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Proceedings of The National Conference on Man Machine Interaction 2014 [NCMMI 2014]

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RM. Botth Figures 7 7 and 8 sh how successfful realizatio on of hip m movement previously tau ught by a physioth herapist.

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Figure 6. Teeaching Posittion, Direct T Therapy Posittion and Erro or

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IV.Conclusion

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The paper describes a ManǦmachineǦinterface to translate the capabilities of a physiotherapist directly to a robot manipulator. Furthermore, standard active and passive exercises can be performed by this HMI. The graphical user interface created for the HMI gives the user an easy access to all functions of the HMI. Using the developed HMI the physiotherapist can teach exercises into RM through performing exercises directly on the patient. The exercises covered are knee and hip flexionǦextension as well as hip abductionǦ adduction. The previously taught exercises can be repeated effectively by the RM itself. The exercise results are evaluated automatically and displayed by numerical and graphical means. The results are stored in a database for later use. The realized interfacing system is made of flexible nature to be fit for webǦbased application.

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