Feasibility Studies of Robot-Assisted Stroke Rehabilitation at Clinic and Home Settings Using RUPERT

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1 2011 IEEE Internatonal Conference on Rehabltaton Robotcs Rehab Week Zurch, ETH Zurch Scence Cty, Swtzerland, June 29 - July 1, 2011 Feasblty Studes of Robot-Asssted Stroke Rehabltaton at Clnc and Home Settngs Usng RUPERT Hang Zhang, Hroko Austn, Sharon Buchanan, Rchard Herman, Jm Koeneman and Jpng He Abstract Task based repettve therapy has been proposed to help stroke survvors to regan functonal control of arm movement. We developed a wearable exoskeleton rehabltaton robot wth assocated control algorthm and safety protecton mechansms, and a graphc user nterface that s easy to use and ntutve to patents and therapsts, as the framework for automated and customzable robot-asssted rehabltaton system for clnc and home based therapy. The system was tested n two feasblty studes. The frst study nvolved 6 patents to receve therapeutc tranng durng three tme weekly clnc vsts for 4 weeks. The second study set up the robot-asssted rehabltaton system at patent s house, where the therapeutc tranng was practced on a daly base. Two patents were recruted for the home applcaton study. Patents performances were assessed usng clncal evaluaton tools, ncludng Wolf Motor Functon Test and Fugl Meyer Assessment (FMA), both before and after the tranng. The performances of patents durng the tranng weeks were also objectvely evaluated by usng the robot sensory data. Keywords rehabltaton robot, at-home robot asssted therapy, stroke rehabltaton, vdeo based task tranng therapy I. INTRODUCTION I n USA, about 795,000 people experence a stroke each year. Stroke has become a leadng cause of serous and long term dsabltes[1]. Dependng on the severty of the stroke, tradtonal stroke rehabltaton optons nclude therapst based treatments n a rehabltaton unt n the hosptal, n a sub-acute care unt, n a rehabltaton hosptal, n home therapy, home wth outpatent therapy, or a long term care faclty that provdes therapy and sklled nursng care. Wth advancement n robotcs, robot-asssted rehabltaton has provded an alternatve to the tradtonal therapy strateges. Robot-asssted therapy for stroke patents s a hghly promsng approach and has become a productve research topc ever snce the frst report by Volpe et al. [2] n Its advantages nclude cost reducton by automatng the therapy procedure, thus allowng a therapst/physcan to work wth many patents at the same tme, offerng the capablty of assessng the moton ablty mprovement quanttatvely and objectvely, and generatng a wde varety of forces and motons for tranng. The capablty of generatng a wde varety of motons makes t possble to tran patents on tasks smulatng actvtes of daly lvng (ADL). Many clncal trals have demonstrated that robot-asssted therapy can ad n motor recovery[2-7]. Researchers have dentfed that tranng ntensty has Authors HZ, HA, SB, RH and JH are wth the Harrngton Bomedcal Engneerng, Arzona State Unversty, Tempe, AZ 85287, USA. (Send correspondence to jpng.he@asu.edu). JK s wth Knematc Muscles, Inc /11/$ IEEE sgnfcantly postve correlaton wth the effcency of rehabltaton for stroke patents[10 and 11]. It s also dentfed that long-term rehabltaton therapy s necessary for generatng sgnfcant gan n performng ADL[8 and 9]. However, the tradtonal and most of the exstng robot-asssted rehabltaton strateges requre ether clnc vsts for patents, and/or ntensve nvolvement of physcal therapsts. It makes the ntensve tranng nconvenent or unaffordable for most of the stroke patents. A rehabltaton robot whch can be mplemented n home settng thus becomes necessary and benefcal for stroke patents. A wearable robotc exoskeleton system for stroke rehabltaton, Robotc Upper Extremty Repettve Therapy (RUPERT), was developed by the research group at Arzona State Unversty and was frst ntroduced n 2005[12]. It evolved to the current generaton RUPERT IV that has 5 actvely asssted degrees of freedom (DOF): shoulder flexon, elbow extenson, forearm supnaton, wrst/hand extenson and humeral external rotaton, as shown n Fg. 1. For more detal please see our prevous publcatons for the mechancal desgn of RUPERT, and the structure of ts control system[12-14]. Fgure 1. 5-DOFs of RUPERT RUPERT s desgned to be home applcable, whch makes ntensve long-term therapeutc tranng convenent and affordable for stroke patents. Desgn specfcaton ncludes lght-weght, portablty, economcal, easy and safe to operate. These features are crtcal for the home applcaton. The caregver or lfe partner of a stroke patent can easly learn how to put on or take off RUPERT on the patent and how to operate the graphc-user-nterface of the software whch mplements the tranng therapy prescrbed by the physcal therapst. Physcal therapsts do not have to be present supervsng the therapeutc tranng. They can montor the progress of tranng through nternet by readng the statstcal reports automatcally generated by the computer usng the sensory data of the robot, and even adjust the therapy parameters remotely based on the progress. 703

2 In ths paper, we report prelmnary results from two feasblty studes of RUPERT asssted stroke rehabltaton. The purpose of the frst study s to test the mechancal structure, the control strategy, the safety, and the feasblty of RUPERT asssted stroke rehabltaton. The second study s to evaluate the feasblty of settng up the RUPERT at patent s house and to be operated for at-home therapy. The patent s lfe partner or caregver operated RUPERT to provde therapeutc tranng on a daly base. The stablty of the system operaton, the safety of home applcaton, and the feasblty of at-home tranng are tested. II. METHODS Moton Tasks In both feasblty studes, the moton task that the patents were traned and tested on was a 3-D reachng-out task when RUPERT was worn by patents. The target of each reachng out movement was one of the 8 targets n a 3-D space, as shown n Fg. 2. In each tral, the specfc target was presented to the patent n a 3-D vrtual realty (VR) dsplayed on a vdeo screen. Multple sequental targets were also set up for some patents to smulate some ADLs such as sweepng or grabbng a water bottle to drnk, f the performance of reachng all 8 statc targets has recovered adequately based on the Fgure 2. Locatons of 8 targets shown n VR assessment of therapsts. In tasks wth multple sequental targets, the next target was shown on the screen rght after the prevous one was successfully ht. Trunk compensaton s a frequent spontaneous strategy adopted by stroke patents to complete many ADLs. However, trunk compensaton should be avoded n task orented rehabltaton tranng snce t attenuates the tranng effects, and some trunk compensaton strateges even brng dffcultes to functons under tranng. For nstance, shoulder shruggng or trunk leanng forward was a frequently observed trunk compensaton strategy by many patents n our feasblty studes. It made the shoulder flexon (arm up) more dffcult though the movement was a crtcal functon n the reachng out task. Snce RUPERT does not record the gesture of the body trunk and measures the arm movement from the orgn located n the shoulder jont, trunk compensaton to facltate reachng targets n VR was not recognzed nor rewarded by the system. In the feasblty studes, patents were encouraged to take self-restrant strateges to avod or reduce trunk compensaton by holdng the char they were sttng on usng ther unaffected hands. They were also learned quckly that trunk compensaton dd not mprove ther performance n the tasks. Therapeutc Tranng Modes Three therapeutc tranng modes are mplemented n the current verson of RUPERT: Contnuous Passve Moton (CPM), Co-Operatve Mode (COM), and Testng Mode. CPM - In ths mode, the subject should be relaxed and the robot does all the work n drvng the arm to the target locaton. A smooth trajectory for each DOF s planned based on the mnmal jerk prncple from the ntal poston to the target value. The mnmal jerk trajectory s: x( t) x ( x x )(10( t / T) 15( t / T) 6( t / T) ) where T x and T x are the ntal and target values of the DOF, respectvely. Parameter T s the planned duraton to complete the change of DOF. In RUPERT for the reported study, T was set between 10~20s, whch was determned by the therapst based on the functonal mparment of the patent. The pneumatc muscle was turned on to drve each DOF to follow the planned trajectory. Co-operatve Mode - Ths mode requres that the robot and the subject work together to acheve a partcular therapy task. Dfferent from CPM, n ths mode, there s voluntary partcpaton from the subject. The patents were requred to maxmze ther partcpaton n the reachng task. As n CPM, a smooth trajectory was also planned for each DOF. If the change of a DOF was faster than the planned trajectory, no assstance from RUPERT was provded. Otherwse, the actuator of that DOF was actvated to provde assstance so that the real trajectory of the DOF can follow the planned one. Testng Mode- In ths mode, the patent was requred to reach the target all by hmself wth the RUPERT assstance turned off. Ths mode s used to evaluate the performance of patent n reachng targets n the begnnng of a tranng sesson, and after tranng by Co-operatve Mode n each tranng sesson. A typcal tranng sesson started wth a CPM block and a Co-operatve block on target R4 (see fgure 2). The purpose of CPM and Co-operatve blocks at the begnnng of each tranng sesson s two folds. Frst, they warmed up the patents maxmally snce R4 s the target where all jonts extend maxmally. Second, they got the patents acquanted wth the reachng task, and warmed up the patents percepton on the VR. Then, the patent was tested under Testng Mode on all 8 targets, n a random order, twce per target. If any tral was faled, tranng trals on the faled targets were provded under Co-operatve Mode, n an ascendng order of dffculty to hm/her. Each tranng block conssted of 10 tranng trals, and two testng trals followed mmedately. The tranng target dd not change as long as he/she faled n httng t n ether testng trals. The tranng sesson stopped once the 704

3 maxmum allowed tranng tme was reached, obvous fraglty was observed by the caregver or therapst, or requested by the patent. Two Feasblty Studes The frst feasblty study was a clnc based therapy. Each patent had the clnc vst 3 tmes per week, for 4 weeks. Durng each vst up to 45-mnute actual tranng from RUPERT was provded to the patent. In each sesson, a physcal therapst provded assstance to DON/DOFF RUPERT, launched the computer program and the control system, and montored the tranng. The second feasblty study was at-home therapy after set up RUPERT at patent s house. Each patent was requred to use RUPERT for rehabltaton tranng once per weekday for 4 consecutve weeks. Tranng n weekends was also allowed upon the patent s wllngness. Tranng twce n a sngle day was also allowed as long as the fatgue was acceptable to hm/her. Each therapy sesson was around 45 mnutes, wth actual tranng for 30 mnutes. A physcal therapst would vst the patent s house once per week to make sure that the system was workng properly and then adjust therapy parameters based on the progress of functonal mprovement. The therapst may change the set of testng/tranng targets as n Fgure 2, downsze/upsze the target to ncrease/decrease the task dffculty snce small/bgger target sze leads to longer/shorter movng dstance and accuracy requrement n each tral. The spouse or caregver of the patent was responsble for DON/DOFF RUPERT, runnng the computer programs, and launchng the control system for each sesson. In both studes we evaluated each subject twce, before and after the therapeutc tranng, on Wolf Motor Functon Test (WMFT) and Fugl Meyer Assessment (FMA). Both evaluatons were performed by the same occupatonal therapst not nvolved or even aware of the therapy. WMFT conssts of 15 moton tests, lsted n Table 1. There are two metrcs to descrbe how well a patent completed a task. One s how fast the task was completed. It s n the unt of seconds. If a task was not completed n 120 seconds, t was gven up and 120 seconds was recorded. The other metrc s the qualty of the movement. It was ranked 1~5, where 1 stands for the lowest, and 5 stands for the hghest qualty. Table Moton Tasks of WMFT Tasks Forearm to table (sde) Forearm to box (sde) Extend elbow (sde) Extend elbow (sde wth weght) Hand to table (front) Hand to box (front) Reach & Retreve Lft can Lft Pencl Lft Paper clp Stack checkers Flp cards Turn key n lock Fold towel Lft basket Statstcal Tests to Evaluate Functonal Improvement Usng Robot Sensory Data To evaluate the functonal mprovement of patents after recevng the therapeutc tranng objectvely, we used the RUPERT sensory data collected durng the voluntary movements: the trals under the testng mode. Snce on each tranng day, each target was only tested for a small number of trals to prevent fragle, statstcally testng the performance mprovement on a daly base wll most lkely fal to draw concluson of sgnfcance. So, we conducted the statstcal tests on a weekly base,.e., by poolng data n each calendar week together. The sgnfcance level of the statstcal tests was α=0.05. We frst employed χ 2 tests to nvestgate the change of the proporton of httng each target successfully n the frst and the last weeks. The χ 2 tests were also conducted to nvestgate the homogenety of the proportons n the tranng weeks. In addton to the proporton of httng targets successfully, we are also nterested to the qualty of voluntary movements. We used smoothness metrcs to measure the qualty of voluntary movements. Then, we conducted ANOVA on the smoothness metrcs to compare whether the means of the smoothness n the frst and last weeks changed sgnfcantly. There are multple metrcs to measure the movement smoothness, ncludng jerk metrc (JM), speed metrc, mean arrest perod rato, peaks metrc, and tent metrc [15], and the spectral methods [13]. Table 2. Demographc data of patents Post-Stroke Group ID Age Gender Hstory (Months) F M M F M M 49 Mean F/4M 57 Clnc-vstng Home -App JM t t f (3) ( t) dt M F 10 x 2, where t and t f are the ntal and fnsh tme nstants of the movement, and T x t ) [ x ( t), x ( t), x ( t)] s the locaton of the end pont ( ( n) of the affected upper lmb n 3-D space at tme t. x ( t) s the module of the n th order dervatve of x(t). Hgher value of JM stands for smoother movement. We employed all of the above metrcs to assess the movement smoothness though we presented only JM as JM s the most popular measurement of movement smoothness [15]. 705

4 Table 4. FMA Settng Scores of 8 mprovement, nor Patents (Maxmum score=66) sgnfcant Group ID FMA Settng functonal Pre Post deteroraton on the httng rate. Fgure demonstrated the proporton of successfully reachng targets where the proporton changed Home sgnfcantly -App between the frst and the last weeks. Targets that were not plotted n Fgure 3 were those whose proporton of successful reachng dd not change sgnfcantly. The three patents demonstratng sgnfcant functonal mprovement were stroke survvors post-stroke at 110 months (patent 003), 49 months (patent Clnc-vstng Clnc-vstng Table 3. WMFT Scores and Seconds of 8 Patents WMFT(Score) WMFT(Sec) Group ID Pre Post Pre Post Home App III. RESULTS Recrutment of Patents Totally 8 chronc stroke patents wth at least 6 months post stroke hstory were recruted for the two feasblty studes. Sx of the 8 patents were for clnc-vstng study, and the remanng 2 were for home applcaton study. Table 2 provdes the demographc data of the 8 patents. Results of Clncal Assessment The summaton WMFT of each of the 8 patents was shown n Table 3. Table 4 presented the summaton of the FMA settng scores of each patent. In both tables, functonal mprovement (ncrease n scores or decrease n seconds) dentfed by the tests was hghlghted by yellow shadows, and functonal deteroraton (decrease n scores or ncrease n seconds) was hghlghted by shadows wth slash lnes. From Table 3, we can see that patents 002 and 003 both showed functonal mprovement n both WMFT scores and seconds. Patent 007 showed functonal deteroraton n WMFT score, but mprovement n WMFT seconds. Home applcaton patent 019 showed the opposte trend as patent 007. The remanng 4 patents showed deteroraton n both WMFT score and seconds. In Talbe 4, patents 002, 009, and 019 showed functonal mprovement, and the remanng 4 patents showed functonal deteroraton. Statstcal Tests for Clnc-vstng Feasblty Study We frst conducted χ2 test to nvestgate the change of the proporton of httng the 8 targets between the frst and the last tranng weeks durng trals under testng mode. Among the 6 clnc-vstng patents, 3 of them demonstrated sgnfcant mprovement n the proporton of successfully httng at least one target. The remanng 3 showed nether sgnfcant (a) (b) (c) Fgure 4. Movement Smoothness JM durng voluntary movements for clnc-vstng patents ( : statstcal sgnfcance) Fgure 3. Sgnfcantly changed proportons of successful ht durng voluntary movements n the frst and last weeks for clnc-vstng patents 003, 017, and 002 (left to rght). 706

5 017), and 41months (patent 002). Patents 003 and 002 experenced ascendng trend of smoothness JM comparng the frst and the last weeks on multple targets, and no descendng trend on any other target (Fgure 4 (a) and (c)). Patent 017 experenced ascendng trend of JM on 4 targets R2~R4, and descendng trend on C3~C4 (Fgure 4 (b)). see that patent 019 experenced a nearly monotone ncrease n httng target C3 successfully. The ncrease s sgnfcantly. Although Fgure 5(b) shows ncrease on some other targets, (a) (a) (b) Fgure 6. Smoothness JM durng successful voluntary movements to targets of patent 018 (a) and 019 (b). ( : statstcal sgnfcance) snce the number of trals on those targets was too small, sgnfcant concluson cannot be draw. Patent 018 had strong (b) Fgure 5. Proporton of successfully httng targets of patent performance n the begnnng on all targets except on target R3. Hs strong performance on those 7 targets was reserved 018 (a) and 019 (b). ( : statstcal sgnfcance) over the 1 month tranng. Statstcal Tests for Home-applcaton Feasblty Study From Fgure 6, we can see that patent 018 dd not We conducted the same performance evaluaton as the clnc-vstng patents. Fgures 5 and 6 show the change of experence ascendng nor descendng trend n smoothness JM. proporton of httng targets, and the smoothness JM durng Patent 019 experenced ncrease trend n movement smoothness JM on target C1, and sgnfcant ncrease on C3. successful voluntary trals under testng mode, respectvely. It should be noted that the box plot of dfferent targets and From Fgure 5, we can see n the last week patent 018 experenced sgnfcant ncrease n httng target R3 dfferent patents mght have dfferent scale on the y axs. successfully from the frst week (Fgure 5(a)). Patent 019 Snce we are only concerned wth the change of smoothness of experenced sgnfcant ncrease n httng target C3 each patent on each ndvdual target, readers should not be successfully (Fgure 5(b)). Patent 019 had very weak msled by the dfferent scales. performance n the begnnng. In order to prevent too early IV. CONCLUSION & FUTURE WORK fatgue, her tranng mostly focused on targets C1~C3 and R1~R2 snce the other targets were too dffcult to her. We can In ths study, RUPERT was tested n two feasblty studes 707

6 to valdate the relablty and safety of RUPERT, and ts feasblty of home settng applcaton. Sx patents receved RUPERT-asssted rehabltaton therapy for 4 weeks wth 12 one-hour therapy sessons durng clnc vsts. Two other patents receved 4~5 weeks daly therapeutc tranng n a home-applcaton settng. Clncal tests were conducted to assess the functons before and after the therapeutc tranng. Clncal tests showed functonal mprovement on some patents, but deteroraton on some others. There are three possble explanatons to t. Frst, the varance among the nvolved ndvduals s too large. The post-stroke hstory ranges between 10 and 110 months. Second, the tranng ntensty and duraton (1 month) mght not be enough to generate consstent mprovements on all patents. Thrd, as we observed, the clncal tests were not consstently conducted on all patents. Statstcal tests were conducted to evaluate the performance mprovement after the therapeutc tranng n both feasblty studes usng the data collected durng voluntary trals where RUPERT was worn. Three out of sx clnc-vstng patents demonstrated sgnfcant ncrease n the proporton of successfully reachng one or more of the 8 targets, and no sgnfcant functon deteroraton to other targets. These three clnc-vstng patents also experenced ncrease n the movement smoothness on reachng multple targets. Both two patents n the home-applcaton settng demonstrated functonal mprovement after the tranng. They each experenced sgnfcant ncrease n the proporton of successfully httng one of the 8 targets, and the one on other targets dd not change. They also demonstrated sgnfcant ncrease n the movement smoothness on reachng some target. Both clncal tests and objectve statstcal tests from robot sensory data agree on the functonal mprovement of patent 002. They gve nconsstent conclusons on other patents. There are several possble reasons for the nconsstency. Frst, the number of patents s too small. Because of the small effect sze of the clncal studes on stroke rehabltaton, as dentfed by other researchers [16 and 17], a much bgger sample sze s needed before a sgnfcant and consstent concluson can be drawn from the clncal tests. Second, RUPERT IV was at ts prototype stage when both feasblty studes were conducted. Safety, operablty, and home-settng applcablty were the major concerns. The sensory nose was not carefully controlled. Thrd, we only developed a sngle RUPERT system. Durng clnc-vstng study, the mechancal parameters of RUPERT were adjusted back and forth to ft dfferent patents. Each week conssted of tranng sessons for at least two patents. Although we tred to repeat the mechancal parameters for each patent n dfferent sessons, varance was stll ntroduced due to the adjustment. Fnally, varance ntroduced by fttng mght overwhelm the performance mprovement. These ssues need to be further addressed n our future research. References [1] Natonal Stroke Assocaton. [2] B.T. Volpe, H.I. Krebs, N. Hogan, L. Edelsten, C. Dels, and M. Asen (2000). A novel approach to stroke rehabltaton: Robot-aded sensormotor stmulaton. Neurology, Vol. 54, pp [3] G. Colombo, M. Wrz, and V. Detz, "Drven gat orthoss for mprovement of locomotor tranng n paraplegc patents," Spnal Cord, vol. 39, pp , May [4] P. S. Lum, C. G. Burgar, P. C. Shor, M. Majmundar, and M. Van der Loos, "Robot-asssted movement tranng compared wth conventonal therapy technques for the rehabltaton of upper-lmb motor functon after stroke," Arch Phys Med Rehabl, vol. 83, pp , Jul [5] D. J. Renkensmeyer, P. S. Lum, J. Wnter, and G. Vanderheden, "Emergng Technologes for Improvng Access to Movement Therapy followng Neurologc Injury," n Emergng and Accessble Telecommuncatons, Informaton and Healthcare Technologes-Emergng Challenges n Enablng Unversal Access, Anonymous, Ed.: IEEE Press, [6] B. T. 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