State of the art and future directions for lower limb robotic exoskeletons

IEEE Transactions on Neural Systems and Rehabilitation Engineering

Volumn 25, Issue 2, 2017, Pages 171-182

  Young, Aaron J ^a   Ferris, Daniel P ^a  

^a UNIVERSITY OF MICHIGAN   (United States)

Author keywords

Gait; human performance augmentation; powered orthoses; rehabilitation; wearable robotics

Indexed keywords

PATIENT REHABILITATION; ROBOTICS; USER INTERFACES;

EMERGING TECHNOLOGIES; FLEXIBLE USER INTERFACES; GAIT; HUMAN PERFORMANCE; ORTHOSES; QUANTITATIVE EVALUATION; ROBOTIC EXOSKELETONS; WEARABLE ROBOTICS;

EXOSKELETON (ROBOTICS);

ARTICLE; ASSISTIVE TECHNOLOGY; ECHOGRAPHY; ELECTROENCEPHALOGRAPHY; ELECTROMYOGRAPHY; ENERGY TRANSFER; HUMAN; LOWER LIMB; MEDICAL TECHNOLOGY; MUSCLE CONTRACTION; PHYSICAL PERFORMANCE; ROBOTIC EXOSKELETON; SENSOR; BIOMEDICAL TECHNOLOGY ASSESSMENT; DEVICE FAILURE ANALYSIS; DEVICES; EQUIPMENT DESIGN; EXOSKELETON (REHABILITATION); FORECASTING; LIMB PROSTHESIS; NEUROREHABILITATION; PROCEDURES; ROBOTICS; TRENDS;

ARTIFICIAL LIMBS; EQUIPMENT DESIGN; EQUIPMENT FAILURE ANALYSIS; EXOSKELETON DEVICE; FORECASTING; HUMANS; LOWER EXTREMITY; NEUROLOGICAL REHABILITATION; ROBOTICS; TECHNOLOGY ASSESSMENT, BIOMEDICAL;

EID: 85015804314     PISSN: 15344320     EISSN: None     Source Type: Journal    
DOI: 10.1109/TNSRE.2016.2521160     Document Type: Article

References (110)

1. A. Houtenvill, D. Brucker, and E. Lauer, Annual Compendium of Disability Statistics 2014 Online. Available: http://disabilitycompendium. org/
2. D. J. Farris, J. L. Hicks, S. L. Delp, and G. S. Sawicki, "Musculoskeletal modelling deconstructs the paradoxical effects of elastic ankle exoskeletons on plantar-flexor mechanics and energetics during hopping," J. Experimental Biol., vol. 217, pp. 4018-4028, 2014.
3. D. J. Farris, B. D. Robertson, and G. S. Sawicki, "Elastic ankle exoskeletons reduce soleus muscle force but not work in human hopping," J. Appl. Physiol., vol. 115, pp. 579-585, 2013.
4. R. Bogue, "Exoskeletons and robotic prosthetics: A review of recent developments," Ind. Robot, vol. 36, pp. 421-427, 2009.
5. E. Garcia, J. M. Sater, and J. Main, "Exoskeletons for human performance augmentation (EHPA): A program summary," in J. Robotics Soc. J., 2002, vol. 20, pp. 822-826.
6. E. Guizzo and H. Goldstein, "The rise of the body bots robotic exoskeletons," IEEE Spectrum, vol. 42, no. 1, pp. 50-56, Jan. 2005.
7. A. Chu, H. Kazerooni, and A. Zoss, "On the biomimetic design of the Berkeley lower extremity exoskeleton (BLEEX)," in Proc. IEEE Int. Conf. Robotics and Automation, 2005, pp. 4345-4352.
8. A. B. Zoss, H. Kazerooni, and A. Chu, "Biomechanical design of the Berkeley lower extremity exoskeleton (BLEEX)," IEEE/ASME Trans. Mechatron., vol. 11, pp. 128-138, 2006.
9. H. Kazerooni, A. Chu, and R. Steger, "That which does not stabilize, will only make us stronger," Int. J. Robotics Res., vol. 26, pp. 75-89, 2007.
10. H. Kazerooni, "Exoskeletons for human performance augmentation," in Handbook of Robotics. New York, NY, USA: Springer, 2008, pp. 773-793.
11. S. C. Jacobsen et al., "Research robots for applications in artificial intelligence, teleoperation and entertainment," Int. J. Robotics Res., vol. 23, pp. 319-330, 2004.
12. Raytheon XOS 2 Exoskeleton, Second-Generation Robotics Suit. 2010 Online. Available: http://www.army-technology.com/projects/ raytheon-xos-2-exoskeleton-us/.
13. H. Herr, "Exoskeletons and orthoses: Classification, design challenges and future directions," J. NeuroEng. Rehabil., vol. 6, p. 21, 2009.
14. A. M. Dollar and H. Herr, "Lower extremity exoskeletons and active orthoses: Challenges and state-of-the-art," IEEE Trans. Robotics, vol. 24, no. 2, pp. 144-158, Feb. 2008.
15. K. N. Gregorczyk, L. Hasselquist, J. M. Schiffman, C. K. Bensel, J. P. Obusek, and D. J. Gutekunst, "Effects of a lower-body exoskeleton device on metabolic cost and gait biomechanics during load carriage," Ergonomics, vol. 53, pp. 1263-1275, 2010.
16. J. M. Schiffman, K. N. Gregorczyk, C. K. Bensel, L. Hasselquist, and J. P. Obusek, "The effects of a lower body exoskeleton load carriage assistive device on limits of stability and postural sway," Ergonomics, vol. 51, pp. 1515-1529, 2008.
17. D. Lamothe, "Meet the exoskeleton the Navy is testing to make sailors stronger," Washington Post, 2014.
18. H. Hodson, "Robotic suit gives shipyard workers super strength," New Scientist, 2014.
19. France's Slender Hercule Exoskeleton is no Lightweight 2012 Online. Available: http://www.army-technology.com/features/featurefrench-hercule-robotic-exoskeleton/
20. M. Fontana, R. Vertechy, S. Marcheschi, F. Salsedo, and M. Bergamasco, "The body Extender: A full-body exoskeleton for the transport and handling of heavy loads," IEEE Robotics Automation Mag., vol. 21, no. 4, pp. 34-44, Dec. 2014.
21. K. English et al., "Comparison of knee and ankle dynamometry between NASA's X1 exoskeleton and biodex system 4," NASA Tech. Rep., 2014.
22. R. Rea, C. Beck, R. Rovekamp, M. Diftler, and P. Neuhaus, "X1: A robotic exoskeleton for in-space countermeasures and dynamometry," in Proc. AIAA SPACE Conf. Exposition, 2013.
23. A. Asbeck, S. D. Rossi, I. Galiana, Y. Ding, and C. Walsh, "Stronger, smarter, softer: Next-generation wearable robots," IEEE Robotics Automation Mag., vol. 21, pp. 22-33, Dec. 2014.
24. A. T. Asbeck, R. J. Dyer, A. F. Larusson, and C. J. Walsh, "Biologically-inspired soft exosuit," in Proc. IEEE Int. Conf. Rehabilitation Robotics, 2013, pp. 1-8.
25. J. A. Blaya and H. Herr, "Adaptive control of a variable-impedance ankle-foot orthosis to assist drop-foot gait," IEEE Trans. Neural Syst. Rehabil. Eng., vol. 12, no. , pp. 24-31, Jan. 2004.
26. R. Jimenez-Fabian and O. Verlinden, "Review of control algorithms for robotic ankle system: In lower-limb orthoses, prostheses, and exoskeletons," Medical Eng. Phys., vol. 34, pp. 397-408, 2012.
27. P.-C. Kao and D. P. Ferris, "Motor adaptation during dorsiflexion-assisted walking with a powered orthosis," Gait Posture, vol. 29, pp. 230-236, 2009.
28. A. W. Boehler, K. W. Hollander, T. G. Sugar, and D. Shin, "Design, implementation and test results of a robust control method for a powered ankle foot orthosis (AFO)," in Proc. IEEE Int. Conf. Robotics and Automation, 2008, pp. 2025-2030.
29. Y. Bai, F. Li, J. Zhao, J. Li, F. Jin, and X. Gao, "A powered ankle-foot orthoses for ankle rehabilitation," in Proc. IEEE Int. Conf. Automation and Logistics, 2012, pp. 288-293.
30. A. Agrawal, V. Sangwan, S. K. Banala, S. K. Agrawal, and S. A. Binder-Macleod, "Design of a novel two degree-of-freedom ankle-foot orthosis," J. Mechanical Design, vol. 129, pp. 1137-1143, 2007.
31. D. P. Ferris, K. E. Gordon, G. S. Sawicki, and A. Peethambaran, "An improved powered ankle-foot orthosis using proportional myoelectric control," Gait Posture, vol. 23, pp. 425-428, Jun. 2006.
32. K. E. Gordon, G. S. Sawicki, and D. P. Ferris, "Mechanical performance of artificial pneumatic muscles to power an ankle-foot orthosis," J. Biomechanics, vol. 39, pp. 1832-1841, 2006.
33. D. P. Ferris, J. M. Czerniecki, and B. Hannaford, "An ankle-foot orthosis powered by artificial pneumatic muscles," J. Appl. Biomechanics, vol. 21, pp. 189-197, May 2005.
34. K. A. Shorter, G. F. Kogler, E. Loth, W. K. Durfee, and E. T. Hsiao-Wecksler, "A portable powered ankle-foot orthosis for rehabilitation," J. Rehabil. Res. Develop., vol. 48, pp. 459-472, 2011.
35. K. E. Gordon and D. P. Ferris, "Learning to walk with a robotic ankle exoskeleton," J. Biomechanics, vol. 40, pp. 2636-2644, 2007.
36. G. S. Sawicki and D. P. Ferris, "Mechanics and energetics of level walking with powered ankle exoskeletons," J. Experimental Biol., vol. 211, pp. 1402-1413, May 2008.
37. G. S. Sawicki and D. P. Ferris, "Mechanics and energetics of incline walking with robotic ankle exoskeletons," J. Experimental Biol., vol. 212, pp. 32-41, Jan. 2009.
38. L. Mooney, E. Rouse, and H. Herr, "Autonomous exoskeleton reduces metabolic cost of human walking during load carriage," J. NeuroEng. Rehabil., vol. 11, p. 80, 2014.
39. S. H. Collins, M. B. Wiggin, and G. S. Sawicki, "Reducing the energy cost of human walking using an unpowered exoskeleton," Nature, 2015.
40. G. Elliott, G. S. Sawicki, A. Marecki, and H. Herr, "The biomechanics and energetics of human running using an elastic knee exoskeleton," in Proc. IEEE Conf. Rehabilitation Robotics, 2013.
41. M. S. Cherry, S. Kota, and D. P. Ferris, "An elastic exoskeleton for assisting human running," in Proc. ASME Int. Design Eng. Technical Conf. Comput. and Inform. Eng. Conf., 2009, pp. 727-738.
42. M. Cherry, S. Kota, A. Young, and D. Ferris, "Running with an elastic lower limb exoskeleton," J. Appl. Biomechanics, 2015.
43. G. Zeilig, H. Weingarden, M. Zwecker, I. Dudkiewicz, A. Bloch, and A. Esquenazi, "Safety and tolerance of the ReWalk™ exoskeleton suit for ambulation by people with complete spinal cord injury: A pilot study," J. Spinal Cord Medicine, vol. 35, pp. 101-196, 2012.
44. A. Esquenazi, "New bipedal locomotion option for individuals with thoracic level motor complete spinal cord injury," J. Spinal Res. Found., vol. 8, pp. 26-28, 2013.
45. D. B. Fineberg et al., "Vertical ground reaction force-based analysis of powered exoskeleton-assisted walking in persons with motor-complete paraplegia," J. Spinal Cord Medicine, vol. 36, pp. 313-321, 2013.
46. A. Esquenazi, M. Talaty, A. Packel, and M. Saulino, "The ReWalk powered exoskeleton to restore ambulatory function to individuals with thoracic-level motor-complete spinal cord injury," Amer. J. Physical Medicine Rehabil., vol. 91, pp. 911-921, 2012.
47. S. Maeshima et al., "Efficacy of a hybrid assistive limb in post-stroke hemiplegic patients: A preliminary report," BMC Neurol., vol. 11, p. 116, 2011.
48. A. Nilsson, K. S. Vreede, V. Haglund, H. Kawamoto, Y. Sankai, and J. Borg, "Gait training early after stroke with a new exoskeleton-the hybrid assistive limb: A study of safety and feasibility," J. NeuroEng. Rehabil., vol. 11, p. 92, 2014.
49. M. Sczesny-Kaiser et al., "Neurorehabilitation in chronic paraplegic patients with the HAL® exoskeleton-preliminary electrophysiological and fMRI data of a pilot study," in Converging Clinical and Engineering Research on Neurorehabilitation. New York, NY, USA: Springer, 2013, pp. 611-615.
50. M. Aach et al., "Exoskeletal neuro-rehabilitation in chronic paraplegic patients-initial results," in Converging Clinical and Engineering Research on Neurorehabilitation. New York, NY, USA: Springer, 2013, pp. 233-236.
51. M. Aach et al., "Voluntary driven exoskeleton as a new tool for rehabilitation in chronic spinal cord injury-A pilot study," Spine J., 2014.
52. H. Kawamoto and Y. Sankai, "Power assist system HAL-3 for gait disorder person," in Computers Helping People with Special Needs. New York, NY, USA: Springer, 2002, pp. 196-203.
53. H. Kawamoto, S. Lee, S. Kanbe, and Y. Sankai, "Power assist method for HAL-3 using EMG-based feedback controller," in Proc. IEEE Int. Conf. Systems, Man and Cybernetics, 2003, pp. 1648-1653.
54. H. Kawamoto and Y. Sankai, "Power assist method based on phase sequence and muscle force condition for HAL," Advanced Robotics, vol. 19, pp. 717-734, 2005.
55. S. A. Kolakowsky-Hayner, J. Crew, S. Moran, and A. Shah, "Safety and feasibility of using the EksoTM bionic exoskeleton to aid ambulation after spinal cord injury," J. Spine, 2013.
56. Y. Kusuda, "In quest of mobility-Honda to develop walking assist devices," Industrial Robot: Int. J., vol. 36, pp. 537-539, 2009.
57. C. Buesing et al., "Effects of a wearable exoskeleton stride management assist system (SMA®) on spatiotemporal gait characteristics in individuals after stroke: A randomized controlled trial," J. NeuroEng. Rehabil., vol. 12, p. 1, 2015.
58. R. J. Farris, H. A. Quintero, and M. Goldfarb, "Preliminary evaluation of a powered lower limb orthosis to aid walking in paraplegic individuals," IEEE Trans. Neural Syst. Rehabil. Eng., vol. 19, no. 4, pp. 652-659, Jul. 2011.
59. H. A. Quintero, R. J. Farris, and M. Goldfarb, "A method for the autonomous control of lower limb exoskeletons for persons with paraplegia," J. Medical Devices, vol. 6, p. 041003, 2012.
60. N.-S. Kwak, K.-R. Muller, and S.-W. Lee, "Toward exoskeleton control based on steady state visual evoked potentials," in Proc. Int. Winter Workshop Brain-Comput. Interface, 2014, pp. 1-2.
61. A. Kilicarslan, S. Prasad, R. G. Grossman, and J. L. Contreras-Vidal, "High accuracy decoding of user intentions using EEG to control a lower-body exoskeleton," in Proc. Int. Conf. IEEE Eng. in Medicine and Biology Soc., 2013, pp. 5606-5609.
62. J. Gancet et al., "MINDWALKER: Going one step further with assistive lower limbs exoskeleton for SCI condition subjects," in Proc. RAS EMBS Int. Conf. Biomedical Robotics and Biomechatronics, 2012, pp. 1794-1800.
63. L. Wang, S. Wang, E. H. V. Asseldonk, and H. V. d. Kooij, "Actively controlled lateral gait assistance in a lower limb exoskeleton," in Proc. IEEE/RSJ Int. Conf. Intelligent Robots and Syst., 2013, pp. 965-970.
64. F. Sylos-Labini et al., "EMG patterns during assisted walking in the exoskeleton," Front. Human Neurosci., vol. 8, 2014.
65. L. Jorgensen, B. Jacobsen, T. Wilsgaard, and J. Magnus, "Walking after stroke: Does it matter? changes in bone mineral density within the first months after stroke. A longitudinal study". Osteoporosis Int., 11, 381-387. 2000.
66. S. J. Harkema, J. Hillyer, M. Schmidt-Read, E. Ardolino, S. A. Sisto, and A. L. Behrman, "Locomotor training: As a treatment of spinal cord injury and in the progression of neurologic rehabilitation," Arch. Physical Medicine Rehabil., vol. 93, pp. 1588-1597, Sep. 2012.
67. G. Chen, C. K. Chan, Z. Guo, and H. Yu, "A review of lower extremity assistive robotic exoskeletons in rehabilitation therapy," Critical Rev. Biomed. Eng., vol. 41, pp. 343-363, 2013.
68. R. W. Horst, "A bio-robotic leg orthosis for rehabilitation and mobility enhancement," in Proc. Int. Conf. IEEE Eng. in Medicine and Biology Soc., 2009, pp. 5030-5033.
69. J. G. Vose, A. McCarthy, E. Tacdol, and R. W. Horst, "Modification of lower extremity kinetic symmetry during sit-to-stand transfers using a robotic leg orthosis with individuals post-stroke," in Converging Clinical and Engineering Research on Neurorehabilitation. New York, NY, USA: Springer, 2013, pp. 811-814.
70. J. G. Vose, A. McCarthy, E. Tacdol, and R. W. Horst, "Optimization of lower extremity kinetics during transfers using a wearable, portable robotic lower extremity orthosis: A case study," in Converging Clinical and Engineering Research on Neurorehabilitation. New York, NY, USA: Springer, 2013, pp. 99-102.
71. N. N. Byl, "Mobility training using a bionic knee orthosis in patients in a post-stroke chronic state: A case series," J. Medical Case Rep., vol. 6, p. 216, 2012.
72. C. K. Wong, L. Bishop, and J. Stein, "A wearable robotic knee orthosis for gait training: A case-series of hemiparetic stroke survivors," Prosthetics Orthotics Int., vol. 36, pp. 113-120, 2012.
73. C. Patten, T. E. McGuirk, and S. Patil, "Effects of 'intention-based' robotic exoskeleton on muscle activation patterns during overground walking," in Converging Clinical and Engineering Research on Neurorehabilitation. New York, NY, USA: Springer, 2013, pp. 109-113.
74. M. Vukobratovic, Biped Locomotion: Dynamics, Stability, Control and Application. New York, NY, USA: Springer-Verlag, 1990.
75. M. Vukobratovic, D. Hristic, and Z. Stojiljkovic, "Development of active anthropomorphic exoskeletons," Medical Biological Eng., vol. 12, pp. 66-80, 1974.
76. J. Pratt, B. Krupp, and C. Morse, "Series elastic actuators for high fidelity force control," Industrial Robot: Int. J., vol. 29, pp. 234-241, 2002.
77. J. M. Hollerbach, I. W. Hunter, and J. Ballantyne, "A comparative analysis of actuator technologies for robotics," in Robotics Review 2. Cambridge, MA, USA: MIT Press, 1991, pp. 299-342.
78. M. R. Tucker et al., "Control strategies for active lower extremity prosthetics and orthotics: A review," J. NeuroEng. Rehabil., vol. 12, p. 1, 2015.
79. W. v. Dijk and H. V. d. Kooij, "XPED2: A passive exoskeleton with artificial tendons," IEEE Robotics Automation Mag., vol. 21, no. 4, pp. 56-61, Dec. 2014.
80. A. J. V. d. Bogert, "Exotendons for assistance of human locomotion," Biomedical Eng. Online, vol. 2, pp. 1-8, 2003.
81. A. M. Oymagil, J. K. Hitt, T. Sugar, and J. Fleeger, "Control of a regenerative braking powered ankle foot orthosis," in Proc. IEEE Int. Conf. Rehabilitation Robotics, 2007, pp. 28-34.
82. T. Yan, M. Cempini, C. M. Oddo, and N. Vitiello, "Review of assistive strategies in powered lower-limb orthoses and exoskeletons," Robotics Autonomous Syst., vol. 64, pp. 120-136, 2015.
83. K. M. Youssef, A. J. Zaddach, C. Niu, D. L. Irving, and C. C. Koch, "A novel low-density, high-hardness, high-entropy alloy with closepacked single-phase nanocrystalline structures," Materials Res. Lett., vol. 3, pp. 95-99, 2015.
84. S. Bleakley, The Effect of the Myomo Robotic Orthosis on Reach Performance After Stroke. Pittsburgh, PA, USA: Univ. Pittsburgh Press, 2013.
85. R. F. Weir, P. R. Troyk, G. A. DeMichele, D. A. Kerns, J. F. Schorsch, and H. Maas, "Implantable myoelectric sensors (IMESs) for intramuscular electromyogram recording," IEEE Trans. Biomed. Eng., vol. 56, no. 2, pp. 159-171, Mar. 2009.
86. P. Irazoqui and R. Bercich, "Wirelessly-Powered Implantable EMG Recording System," U.S.A./Google 13/955,808, 2013.
87. P. M. Rossini et al., "Double nerve intraneural interface implant on a human amputee for robotic hand control," Clin. Neurophysiol., vol. 121, pp. 777-783, 2010.
88. D.-H. Kim et al., "Epidermal electronics," Science, vol. 333, pp. 838-843, 2011.
89. M. Sonka, V. Hlavac, and R. Boyle, Image Processing, Analysis, and Machine Vision. Stamford, CT, USA: Cengage Learning, 2014.
90. S. Miyakoshi, G. Taga, Y. Kuniyoshi, and A. Nagakubo, "Three dimensional bipedal stepping motion using neural oscillators-towards humanoid motion in the real world," in Proc Int. Conf. Intelligent Robots Syst., 1998, pp. 84-89.
91. G. Taga, Y. Yamaguchi, and H. Shimizu, "Self-organized control of bipedal locomotion by neural oscillators in unpredictable environment," Biological Cybern., vol. 65, pp. 147-159, 1991.
92. Y. Futakata and T. Iwasaki, "Entrainment to natural oscillations via uncoupled central pattern generators," IEEE Trans. Automat. Contr., vol. 56, no. 6, pp. 1075-1089, Jun. 2011.
93. R. Ronsse, N. Vitiello, T. Lenzi, J. v. d. Kieboom, M. C. Carrozza, and A. J. Ijspeert, "Human-robot synchrony: Flexible assistance using adaptive oscillators," IEEE Trans. Biomed. Eng., vol. 58, no. 4, pp. 1001-1012, Apr. 2011.
94. R. Ronsse et al., "Oscillator-based assistance of cyclical movements: Model-based and model-free approaches," Medical Biological Eng. Computing, vol. 49, pp. 1173-1185, Oct. 2011.
95. F. Giovacchini et al., "A light-weight active orthosis for hip movement assistance," Robotics Autonomous Syst., 2014.
96. T. Lenzi, M. C. Carrozza, and S. K. Agrawal, "Powered hip exoskeletons can reduce the user's hip and ankle muscle activations during walking," IEEE Trans. Neural Syst. Rehabil. Eng., vol. 21, no. 5, pp. 938-948, Sep. 2013.
97. M. D. Lewek, A. J. Osborn, and C. J. Wutzke, "The influence of mechanically and physiologically imposed stiff-knee gait patterns on the energy cost of walking," Arch. Phys. Medicine Rehabil., vol. 93, pp. 123-128, 2012.
98. A. Zissimopoulos, S. Fatone, and S. A. Gard, "Biomechanical and energetic effects of a stance-control orthotic knee joint," J. Rehabil. Res. Develop., vol. 44, pp. 503-514, 2007.
99. E. Hanada and D. C. Kerrigan, "Energy consumption during level walking with arm and knee immobilized," Arch. Phys. Medicine Rehabil., vol. 82, pp. 1251-1254, 2001.
100. T. M. Cook, K. P. Farrell, I. A. Carey, J. M. Gibbs, and G. E. Wiger, "Effects of restricted knee flexion and walking speed on the vertical ground reaction force during gait," J. Orthopaedic Sports Phys. Therapy, vol. 25, pp. 236-244, 1997.
101. P. Stegall, K. N. Winfree, and S. K. Agrawal, "Degrees-of-freedom of a robotic exoskeleton and human adaptation to new gait templates," in Proc. IEEE Int. Conf. Robotics and Automation, 2012, pp. 4986-4991.
102. C. Davies, "Honda Walking Assist Device Goes Into Broad Hospital Trial," Slash Gear, 2013 Online. Available: www.slashgear.com/ honda-walking-assist-device-goes-into-broad-hospital-trial-29284034
103. D. Lamothe, "New competition launched in develop: U.S. military's 'Iron Man' suit," Washington Post, 2014.
104. AUSA-Revision 2013 Online. Available: http://soldiersystems.net/ tag/revision/
105. B. H. Dobkin, "Wearable motion sensors to continuously measure real-world physical activities," Current Opinion Neurol., vol. 26, pp. 602-608, 2013.
106. P. Abbeel, A. Coates, and A. Y. Ng, "Autonomous helicopter aerobatics through apprenticeship learning," Int. J. Robotics Res., vol. 29, pp. 1608-1639, 2010.
107. C. L. Ventola, "Medical applications for 3D printing: Current and projected uses," Pharmacy Therapeutics, vol. 39, pp. 704-711, Oct. 2014.
108. Gartner Jan. 6, 2016 Online. Available: http://www.gartner.com/ newsroom/id/3114217
109. D. P. Ferris, "The exoskeletons are here," J. NeuroEng. Rehabil., vol. 6, p. 17, 2009.
110. D. P. Ferris, G. S. Sawicki, and M. A. Daley, "A physiologist's perspective on robotic exoskeletons for human locomotion," Int. J. Humanoid Robotics, vol. 4, pp. 507-528, 2007.