Ankle rehabilitation robots are developed to enhance ankle strength, flexibility and proprioception after injury and to promote motor learning and ankle plasticity in patients with drop foot. This article reviews the design elements that have been incorporated into the existing robots, for example, backdrivability, safety measures and type of actuation. It also discusses numerous challenges faced by engineers in designing this robot, including robot stability and its dynamic characteristics, universal evaluation criteria to assess end-user comfort, safety and training performance and the scientific basis on the optimal rehabilitation strategies to improve ankle condition. This article can serve as a reference to design robot with better stability and dynamic characteristics and good safety measures against internal and external events. It can also serve as a guideline for the engineers to report their designs and findings.
DonatelliR. The biomechanics of the foot and ankle. Philadelphia, PA: F. A. Davis Company, 1996.
2.
OlmstedLCVelaLIDenegarCR. Prophylactic ankle taping and bracing: a numbers-needed-to-treat and cost-benefit analysis. J Athl Train2004; 39(1): 95–100.
3.
McKayGDGoldiePAPayneWR. Ankle injuries in basketball: injury rate and risk factors. Br J Sports Med2001; 35(2): 103–108.
4.
VerhagenEAvan MechelenWde VenteW. The effect of preventive measures on the incidence of ankle sprains. Clin J Sport Med2000; 10(4): 291–296.
5.
RoyAKrebsHIWilliamsDJ. Robot-aided neurorehabilitation: a novel robot for ankle rehabilitation. IEEE Trans Robot2009; 25(3): 569–582.
6.
ThomTHaaseNRosamondW. Heart disease and stroke statistics – 2006 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation2006; 113(6): 85–151.
7.
GlamcevskiMTIIPiersonJ. Prevalence of and factors associated with poststroke depression: a Malaysian study. J Stroke Cerebrovasc Dis2005; 14(4): 157–161.
8.
KwakkelGWagenaarRCTwiskJW. Intensity of leg and arm training after primary middle-cerebral-artery stroke: a randomized trial. Lancet1999; 354(9174): 191–196.
9.
LathamNKJetteDUWarrenRL. Pattern of functional change during rehabilitation of patients with hip fracture. Arch Phys Med Rehabil2006; 87(1): 111–116.
10.
van der LeeJH. Constraint-induced therapy for stroke: more of the same or something completely different?Curr Opin Neurol2001; 14(6): 741–744.
11.
GironeMBurdeaGBouzitM. Orthopedic rehabilitation using the ‘Rutgers ankle’ interface. Stud Health Technol Inform2000; 70: 89–95.
12.
DeutschJELatonioJBurdeaGC. Post-stroke rehabilitation with the Rutgers Ankle system: a case study. Presence2001; 10(4): 416–430.
13.
DeutschJELewisJABurdeaG. Technical and patient performance using a virtual reality-integrated telerehabilitation system: preliminary finding. IEEE Trans Neural Syst Rehabil Eng2007; 15(1): 30–35.
14.
GironeMBurdeaGBouzitM. A Stewart platform-based system for ankle telerehabilitation. Auton Robots2001; 10(2): 203–212.
15.
BoianRFBouzitMBurdeaGC. Dual Stewart platform mobility simulator. In: IEEE 9th international conference in rehabilitation robotics (ICORR 2005) (eds WestwoodJDHoffmanHMMogelGTRobbRAStredneyD), Chicago, IL, 28 June–1 July 2005, pp. 550–555. New York: IEEE.
16.
GironeMBurdeaGBouzitM. Orthopedic rehabilitation using the ‘Rutgers ankle’ interface. In: Medicine meets virtual reality. Amsterdam: IOS Press, 2000, pp. 89–95.
17.
DeutschJELatonioJBurdeaGC. Rehabilitation of musculoskeletal injuries using the Rutgers ankle haptic interface: three case reports. In: Eurohaptics conference, Birmingham, 1–4 July 2001, pp. 11–16. Birmingham: The University of Birmingham.
18.
MirelmanABonatoPDeutschJE. Effects of training with a robot-virtual reality system compared with a robot alone on the gait of individuals after stroke. Stroke2008; 40: 169–174.
19.
DeutschJEPaserclliaCVecchioneC. Improved gait and elevation speed of individuals poststroke after lower extremity training in virtual environments. J Neurol Phys Ther2004; 28: 185–186.
20.
BoianRFLeeCSDeutschJE. Virtual reality-based system for ankle rehabilitation post stroke. In: International workshop on virtual reality rehabilitation (mental health, neurological, physical, vocational) VRMHR 2002, Lausanne, 7–8 November 2002, pp. 77–86. Lausanne: Ecole Polytechnique Fédérale de Lausanne (EPFL).
21.
BoianRFDeutschJELeeCS. Haptic effects for virtual reality-based post-stroke rehabilitation. In: 11th symposium on haptic interfaces for virtual environment and teleoperator systems, Los Angeles, CA, 22–23 March 2003, pp. 247–253. New York: IEEE.
22.
CioiDKaleABurdeaG. Ankle control and strength training for children with cerebral palsy using the Rutgers ankle CP: a case study. In: 2011 IEEE international conference on rehabilitation robotics (ICORR 2011), Zurich, 29 June–1 July 2011, pp. 654–659. New York: IEEE.
23.
BurdeaGCCioiDAngadK. Robotics and gaming to improve ankle strength, motor control and function in children with cerebral palsy: a case study series. IEEE Trans Neural Syst Rehabil Eng2013; 21(2): 165–173.
24.
ZhangMDaviesTCXieS. Effectiveness of robot-assisted therapy on ankle rehabilitation – a systematic review. J Neuroeng Rehabil2013; 10: 30.
25.
JamwalPKXieSAwKC. Kinematic design optimization of a parallel ankle rehabilitation robot using modified genetic algorithm. Rob Auton Syst2009; 57(10): 1018–1027.
26.
HarwinWSRahmanTFouldsRA. A review of design issues in rehabilitation robotics with reference to North American Research. IEEE Trans Rehabil Eng1995; 3(1): 3–13.
27.
DaiJZhaoTNesterC. Sprained ankle physiotherapy based mechanism synthesis and stiffness analysis of a robotic rehabilitation device. Auton Robots2004; 16(2): 207–218.
28.
SieglerSChenJSchneckCD. The three-dimensional kinematics and flexibility characteristics of the human ankle and subtalar joints – part I kinematics. J Biomech Eng1988; 110: 364–373.
29.
ParenteauCSVianoDCPetitP. Biomechanical properties of human cadaveric ankle-subtalar joints in quasi-static loading. J Biomech Eng1998; 120(1): 105–111.
30.
TsoiYH. Modelling and adaptive interaction control of a parallel robot for ankle rehabilitation. PhD Thesis, Department of Mechanical Engineering, The University of Auckland, Auckland, 2011.
31.
PayneKABergKLatinRW. Ankle injuries and ankle strength, flexibility, and proprioception in college basketball players. J Athl Train1997; 32(3): 221.
32.
MattacolaCGDwyerMK. Rehabilitation of the ankle after acute sprain or chronic instability. J Athl Train2002; 37(4): 413–429.
33.
LiuGGaoJYueH. Design and kinematics analysis of parallel robots for ankle rehabilitation. In: 2006 IEEE/RSJ international conference on intelligent robots and systems (IROS 2006), Beijing, China, 9–15 October 2006, pp. 253–258. New York: IEEE.
34.
YeDSivakMWeinbergB. NUVABAT: Northeastern university virtual ankle and balance trainer. In: Haptics symposium 2010, Waltham, MA, 25–26 March, pp. 509–514. New York: IEEE.
35.
AndersenJBSinkjaerT. An actuator system for investigating electrophysiological and biomechanical features around the human ankle joint during gait. IEEE Trans Rehabil Eng1995; 3(4): 299–306.
36.
BlayaJAHerrH. Adaptive control of a variable-impedance ankle-foot orthosis to assist drop-foot gait. IEEE Trans Neural Syst Rehabil Eng2004; 12(1): 24–31.
37.
FerrisDPCzernieckiJMHannafordB. An ankle-foot orthosis powered by artificial pneumatic muscles. J Appl Biomech2005; 21(2): 189–197.
38.
BharadwajKSugarTGKoenemanJB. Design of a robotic gait trainer using spring over muscle actuators for ankle stroke rehabilitation. J Biomech Eng2005; 127(6): 1009–1013.
39.
RoyAKrebsHIPattersonSL. Measurement of human ankle stiffness using the anklebot. In: IEEE 10th international conference on rehabilitation robotics (ICORR 2007), Noordwijk, 13–15 June 2007, pp. 356–363. New York: IEEE.
40.
RoyAForresterLWMackoRF. Short-term ankle motor performance with ankle robotics training in chronic hemiparetic stroke. J Rehabil Res Dev2011; 48(4): 417–429.
41.
ForresterLWRoyAKrebsHI. Ankle training with a robotic device improves hemiparetic gait after a stroke. Neurorehabil Neural Repai2011; 25(4): 369–377.
42.
KhannaIAnindoRRodgersMM. Effects of unilateral robotic limb loading on gait characteristics in subjects with chronic stroke. J Neuroeng Rehabil2010; 7: 23.
43.
SellesRWLiXLinF. Feedback-controlled and programmed stretching of the ankle plantarflexors and dorsiflexors in stroke: effects of a 4-week intervention program. Arch Phys Med Rehabil2005; 86: 2330–2336.
44.
YoonJRyuJLimK. Reconfigurable ankle rehabilitation robot for various exercises. J Robotic Systems2006; 22(S1): S15–S33.
45.
LinCKJuMChenS. A specialized robot for ankle rehabilitation and evaluation. J Med Biol Eng2008; 28(2): 79–86.
46.
HommaKUsubaM. Development of ankle dorsiflexion/plantarflexion exercise device with passive mechanical joint. In: IEEE 10th international conference on rehabilitation robotics (ICORR 2007), Noordwijk, 13–15 June 2007, pp. 292–297. New York: IEEE.
47.
SagliaJATsagarakisNGDaiJS. A high performance 2-dof over-actuated parallel mechanism for ankle rehabilitation. In: 2009 IEEE international conference in robotics and automation (ICRA 2009), Kobe, Japan, 12–17 May 2009, pp. 2180–2186. New York: IEEE.
48.
CordoPLutsepHCordoL. Assisted movement with enhanced sensation (AMES): coupling motor and sensory to remediate motor deficits in chronic stroke patients. Neurorehabil Neural Repair2009; 23: 67–77.
49.
JamwalPKXieSQHussainS. An adaptive wearable parallel robot for the treatment of ankle injuries. IEEE/ASME Trans Mechatron2012; 19: 64–75.
50.
RenYXuTWangL. Develop a wearable ankle robot for in-bed acute stroke rehabilitation. In: 33rd annual international conference of the IEEE engineering in medicine and biology society, Boston, MA, 30 August–3 September, pp. 7483–7486. New York: IEEE.
51.
WuYNHwangMRenYP. Combined passive stretching and active movement rehabilitation of lower-limb impairments in children with cerebral palsy using a portable robot. Neurorehabil Neural Repair2011; 25: 378–385.
52.
ZhouZZhouYWangN. A proprioceptive neuromuscular facilitation integrated ankle robotic system for post-stroke rehabilitation. Rob Auton Syst, in press.
53.
WheelerJWKrebsHIHoganN. An ankle robot for a modular gait rehabilitation system. In: 2004 IEEE/RSJ international conference on intelligent robots and systems (IROS 2004), Sendai, Japan, 28 September–2 October 2004, pp. 1680–1684. New York: IEEE.
54.
FerrisDPGordonKESawickiGS. An improved powered ankle-foot orthosis using proportional myoelectric control. Gait Posture2006; 23(4): 425–428.
55.
CainSMGordonKEFerrisDP. Locomotor adaptation to a powered ankle-foot orthosis depends on control method. J Neuroeng Rehabil2007; 4: 48.
56.
SawickiGSDomingoAFerrisDP. The effects of powered ankle-foot orthoses on joint kinematics and muscle activation during walking in individuals with incomplete spinal cord injury. J Neuroeng Rehabil2006; 3: 3.
57.
BharadwajKSugarTG. Kinematics of a robotic gait trainer for stroke rehabilitation. In: IEEE 11th international conference in robotics and automation (ICRA 2009), Orlando, FL, 15–19 May 2006, pp. 3492–3497. New York: IEEE.
58.
WardJABalasubramanianSSugarT. Robotic gait trainer reliability and stroke patient case study. In: IEEE 10th international conference on rehabilitation robotics (ICORR 2007), Noordwijk, 13–15 June 2007, pp. 554–561. New York: IEEE.
59.
AgrawalASangwanVBanalaSK. Design of a novel two degree-of-freedom ankle-foot orthosis. J Mech Des2007; 129(11): 1137–1143.
60.
HwangSKimJYIJ. Development of an active ankle foot orthosis for the prevention of foot drop and toe drag. In: International conference on biomedical and pharmaceutical engineering (ICBPE 2006), Singapore, 11–14 December 2006, pp. 418–423. New York: IEEE.
61.
KimJHwangSKimY. Development of an active ankle-foot orthosis for hemiplegic patients. In: Proceedings of the 1st international convention on rehabilitation engineering & assistive technology: in conjunction with 1st Tan Tock Seng Hospital Neurorehabilitation meeting 2007, Singapore, 23–26 April 2007, pp. 110–113. New York: ACM.
62.
HittJKOymagilMASugarTG. Dynamically controlled ankle foot orthosis (DCO) with regenerative kinetics: incrementally attaining user portability. In: 2007 IEEE international conference in robotics and automation (ICRA 2007), Roma, 10–14 April 2007, pp. 1541–1546. New York: IEEE.
63.
OymagilAMHittJKSugarT. Control of a regenerative braking powered ankle foot orthosis. In: IEEE 10th international conference on rehabilitation robotics (ICORR 2007), Noordwijk, 13–15 June 2007, pp. 28–34. New York: IEEE.
64.
BoehlerAWHollanderKWSugarTG. Design, implementation and test results of a robust control method for a powered ankle foot orthosis (AFO). In: 2008 IEEE international conference in robotics and automation (ICRA 2008), Pasadena, CA, 19–23 May 2008, pp. 2025–2030. New York: IEEE.
65.
FurushoJTokudaM TKakehashiT. Development of shear type compact MR brake for the intelligent ankle-foot orthosis and its control. In: IEEE 10th international conference on rehabilitation robotics (ICORR 2007), Noordwijk, 12–15 June 2007, pp. 89–94. New York: IEEE.
66.
NaitoHAkazawaYTagayaK. An ankle-foot orthosis with a variable-resistance ankle joint using a magnetorheological-fluid rotary damper. J Biomech Sci Eng2009; 4(2): 182–191.
67.
TanidaSKikuchiTKakehashiT. Intelligently controllable Ankle Foot Orthosis (I-AFO) and its application for a patient of Guillain-Barre syndrome. In: IEEE 11th international conference on rehabilitation robotics (ICORR 2009), Kyoto, Japan, 23–26 June 2009, pp. 857–862. New York: IEEE.
68.
KikuchiTTanidaSOtsukiK. Development of third-generation intelligently controllable ankle-foot orthosis with compact MR fluid brake. In: 2010 IEEE international conference in robotics and automation (ICRA 2010), Anchorage, AK, 3–7 May 2010, pp. 2209–2214. New York: IEEE.
69.
SaticiACErdoganAPatogluV. Design of a reconfigurable ankle rehabilitation robot and its use for the estimation of the ankle impedance. In: IEEE 11th international conference on rehabilitation robotics (ICORR 2009), Kyoto, Japan, 23–26 June 2009, pp. 257–264. New York: IEEE.
70.
WardJSugarTStandevenJ. Stroke survivor gait adaptation and performance after training on a Powered Ankle Foot Orthosis. In: 2010 IEEE international conference in robotics and automation (ICRA 2010), Anchorage, AK, 3–7 May 2010, pp. 211–216. New York: IEEE.
71.
ShorterKAKoglerGFLothE. A portable powered ankle-foot orthosis for rehabilitation. J Rehabil Res Dev2011; 48: 459–472.
72.
ParkY-LChenB-rPérez-ArancibiaNO. Design and control of a bio-inspired soft wearable robotic device for ankle-foot rehabilitation. Bioinspir Biomim2014; 9: 016007.
Duschau-WickeAZitzewitzJLünenburgerL. Patient-cooperative control: adapting robotic interventions to individual human capabilities. In: World Congress on Medical Physics and Biomedical Engineering, Munich, 7–12 September 2009. Berlin, Heidelberg: Springer.
75.
MaierICde Haller BeerSM. Transfer of technology into clinical application. In: DietzVTobiasNWilliam ZevR (eds) Neurorehabilitation technology. London: Springer, 2012, pp. 303–323.
76.
FerrisDPSawickiGSDomingoAR. Powered lower limb orthoses for gait rehabilitation. Top Spinal Cord Inj Rehabil2005; 11(2): 34–49.
77.
KluteGKCzernieckiJMHannafordB. Artificial muscles: actuators for biorobotic systems. Int J Rob Res2002; 21(4): 295–309.
78.
PuseyJFattahAAgrawalS. Design and workspace analysis of a 6 cable-suspended parallel robot. Mech Mach Theory2004; 39: 761–778.
79.
JacobsenSCOlivierMSmithFM. Research robots for applications in artificial intelligence, teleoperation and entertainment. Int J Rob Res2004; 23(4–5): 319–320.
80.
NokataMTejimaN. A safety strategy for rehabilitation robots. In: BienZZStefanovD (eds) Advances in rehabilitation robotics (lecture notes in control and information system). Berlin, Heidelberg: Springer, 2004, vol. 306, pp. 177–185.
81.
PennycottAWyssDValleryH. Towards more effective robotic gait training for stroke rehabilitation: a review. J Neuroeng Rehabil2012; 9: 65.
82.
ReinkensmeyerDAoyagiDEmkenJ. Tools for understanding and optimizing robotic gait training. J Rehabil Res Dev2006; 43(5): 657–670.
83.
ReinkensmeyerDPattonJ. Can robots help the learning of skilled actions?Exerc Sport Sci Rev2009; 37: 43–51.
84.
CaiLFongALiangY. Assist-as-needed training paradigms for robotic rehabilitation of spinal cord injuries. In: 2006 IEEE international conference in robotics and automation (ICRA 2006), Orlando, FL, 15–19 May 2006, pp. 3504–3511. New York: IEEE.
85.
EmkenJBobrowJReinkensmeyerD. Robotic movement training as an optimization problem: designing a controller that assists only as needed. In: IEEE 9th international conference on rehabilitation robotics (ICORR 2005), Chicago, IL, 28 June–1 July 2005, pp. 307–312. New York: IEEE.
86.
ValleryHDuschau-WickeARienerR. Generalized elasticities improve patient-cooperative control of rehabilitation robots. In: IEEE 11th international conference on rehabilitation robotics (ICORR 2009), Kyoto, Japan, 23–26 June 2009, pp. 535–541. New York: IEEE.
87.
Marchal-CrespoLReinkensmeyerD. Review of control strategies for robotic movement training after neurologic injury. J Neuroeng Rehabil2009; 6: 20–34.
88.
HoganN. Impedance control: an approach to manipulation: part I – applications. J Dyn Syst Meas Control1985; 107(2): 17.
89.
SerajiHColbaughR. Force tracking in impedance control. Int J Rob Res199716(1): 97–117.
90.
ChiaveriniSSciaviccoL. The parallel approach to force/position control of robotic manipulators. IEEE Trans Rob Autom1993; 9(4): 361–373.
91.
LuZGoldenbergAA. Robust impedance control and force regulation: theory and experiments. Int J Rob Res1995; 14(3): 225–254.
92.
TsoiYHXieSQ. Impedance control of ankle rehabilitation robot. In: 2009 IEEE international conference on robotics and biomimetics (ROBIO 2009), Bangkok, Thailand, 22–25 February 2009, pp. 840–845. New York: IEEE.
Van der LoosHM. Rehabilitation and health care robotics. In: BrunoSOussamaK (eds) Springer handbook of robotics. Berlin, Heidelberg: Springer, 2008, pp. 1223–1251.
YoonJKumarRPÖzerA. An adaptive foot device for increased gait and postural stability in lower limb Orthoses and exoskeletons. Int J Control Autom Syst2011; 9(3): 515–524.
97.
KoceskaNKoceskiSZobelPB. Control architecture for a lower limbs rehabilitation robot system. In: 2009 IEEE international conference on robotics and biomimetics (ROBIO 2009), Bangkok, Thailand, 22–25 February 2009, pp. 971–976. New York: IEEE.
98.
TsoiYHXieSQGrahamAE. Design, modeling and control of an ankle rehabilitation robot: Studies in computational intelligence, vol. 177. Berlin, Heidelberg: Springer, 2009, pp. 377–399.
