![](bg4.png)
sure the tracking of the desired trajectory. The control
is therefore only assisting the subject during this inter-
val. One can notice that the magnitude of the control
torque is lower than that delivered outside the assis-
tance phase, i.e. in the time intervals [0,8.5[s and
]28.5, 38] s. The control law ensures a good adap-
tation and trajectory tracking (first two plots of Fig-
ure 2) during the assistance and non-assistance phases
which guarantees the safety of the wearer.
Figure 3: Assistance results (A): Desired position (dashed
blue) and current position (red), (B): Human torque (dashed
blue) and exoskeleton torque (red).
In figure 3, the control is based on the wearer’s
intention. The wearer’s torque is estimated using the
lower limb anatomical model based on the use of the
modified hill-type muscle model. The raw EMG sig-
nals are measured from the quadriceps and hamstrings
muscles. During this experiment, the wearer is asked
to produce free flexion / extension movements of the
knee joint. The advantage of the proposed approach
consists in its nature which is subject centered where
no predefined position trajectory is imposed to the
wearer.
6 CONCLUSIONS
This paper treated the control of a knee-joint ortho-
sis. A model, of the shank and orthosis, is proposed
and its parameters has been identified. Two control
strategies were proposed, the first one deals with the
passive rehabilitation process. A desired knee joint
angle is needed and is supposed delivered by the re-
habilitation doctor. In this case the priority is given
to the desired task completion independently from
the human contribution. The second case study con-
cerns the human based control and lies within the as-
sistive strategy. Muscular activities of the muscles
spanning the knee joint are measured and the result-
ing knee joint torque is amplified through the use of
the orthosis to ensure a desired movement initiated
by the wearer. Experimental validations of the pro-
posed strategies were conducted in real-time with a
young healthy subject using the EICOSI orthosis of
the LISSI Lab.
ACKNOWLEDGEMENTS
The EICOSI project is sponsored by the regional
council of Ile-De-France.
REFERENCES
Aguirre-Ollinger, G., Colgate, J., Peshkin, M., and
Groswami, A. (2007). A 1-DOF assistive exoskeleton
with virtual negative damping: Effects on the kine-
matic response of the lower limbs. In Proceedings
of International Conference on Intelligent Robots and
Systems, pages 1938–1944, San Diego, CA, USA.
Aguirre-Ollinger, G., Colgate, J., Peshkin, M., and
Groswami, A. (2010). Design of an active 1-DOF
lower-limb exoskeleton with inertia compensation. In-
ternational Journal of Robotics Research, 30(4):486–
499.
Bonutti, P., Marulanda, G., McGrath, M., Mont, M., and
Zywiel, M. (2010). Static progressive stretch im-
proves range of motion in arthrofibrosis following toal
knee arthroplasty. Knee surgery, sports traumatology,
arthroscopy, 18(2):194–199.
Chang, Y., Liang, J., Hsu, M., Lien, H. Fang, C., and
Lin, C. (2013). Effects of continuous passive mo-
tion on reversing the adapted spinal circuit in humans
with chronic spinal cord injury. Archives of Physical
Medicine and Rehabilitation.
Cherry, M.-S., Choi, D.-J., Deng, K.-J., Kota, S., and Fer-
ris, D.-P. (2006). Design and fabrication of an elastic
knee orthosis: Preliminary results. In Int. design engi-
neering technical conf. & Conputers and information
in engineering conf., pages 565–573, USA.
Fleischer, C. and Hommel, G. (2008). A human-
exeskeleton interface utilizing electromyography.
IEEE Transactions on Robotics, 24(4):872–882.
Hassani, W., Mohammed, S., and Amirat, Y. (2013). Real-
time emg driven lower limb actuated orthosis for as-
sistance as needed movement strategy. In Robotics:
Science and Systems Conference.
Jansen, C., Windau, J., Bonutti, P., and Brillhart, M. (1996).
Treatment of a knee contracture using a knee orthosis
incorporating stress-relaxation techniques. Journal of
Physical Therapy Association, 76(2):182–186.
Mohammed, S., Amirat, Y., and Rifai, H. (2012). Lower-
limb movement assistance through wearable robots:
state of the art and challenges. Advanced Robotics,
26(1-2):1–22.
Rifai, H., Hassani, W., Mohammed, S., and Amirat, Y.
(2011). Bounded control of an actuated lower limb or-
thosis. In Decision and Control and European Control
Conference (CDC-ECC), 2011 50th IEEE Conference
on, pages 873–878.
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