Compliant actuators are employed in exoskeleton robots instead of stiff actuators for safe human-robot interaction. In parallel with this idea, we previously constructed a biomimetic compliant exoskeleton robot (BioComEx). In this study, to provide more stable and safe trajectory tracking even under disturbances, magneto-rheological (MR) brakes were added to all joints of BioComEx as variable damping actuators and a PID+D controller was proposed. To evaluate the robot and controller, first, BioComEx was hung on a platform and the controller was applied without device user under external forces. This primary test results showed that the proposed design and controller can effectively minimize disturbance effects and consequently reduce trajectory tracking oscillations. In the rest of the study, the similar control experiments were repeated with a user who has unilateral lower limb movement disorders. In these experiments, the movements of the user’s healthy leg were detected by force feedback impedance control algorithm and then were used as reference for the impaired leg with walking cycle delay in real time. The secondary test results showed that the variable impedance exoskeleton robot design with PID+D controller can ensure effective walking assistance for the impaired human legs.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
D. Lim, W. Kim, H. Lee, H. Kim, K. Shin, T. Park, J. Lee and C. Han, Development of a lower extremity exoskeleton robot with a quasi-anthropomorphic design approach for load car riage, IEEE/RSJ Int. Conf. Intell. Robot. Syst. (2015) 5345–5350.
S. K. Banala, S. K. Agrawal and J. P. Scholz, Active leg exo-skeleton (ALEX) for gait rehabilitation of motor-impaired patients, IEEE 10th International Conference on Rehabilitation Robotics (2007) 401–407.
R. J. Farris, H. A. Quintero and M. Goldfarb, Preliminary evaluation of a powered lower limb orthosis to aid walking in paraplegic individuals, IEEE Transactions on Neural Systems and Rehabilitation Engineering, 19 (6) (2011) 652–659.
A. B. Zoss, H. Kazerooni and A. Chu, Biomechanical design of the Berkeley lower extremity exoskeleton (BLEEX), IEEE/ ASME Transactions Mechatronics, 11 (2) (2006) 128–138.
J. F. Veneman, R. Kruidhof, E. E. Hekman, R. Ekkelenkamp, E. H. Van Asseldonk and H. Van Der Kooij, Design and evaluation of the LOPES exoskeleton robot for interactive gait rehabilitation, IEEE Transactions on Neural Systems and Rehabilitation Engineering, 15 (3) (2007) 379–386.
A. Tsukahara, R. Kawanishi, Y. Hasegawa and Y. Sankai, Sit-to-stand and stand-to-sit transfer support for complete paraplegic patients with robot suit HAL, Advanced Robotics, 24 (11) (2010) 1615–1638.
D. Miranda-Linares, G. Alrezage and M. O. Tokhi, Control of lower limb exoskeleton for elderly assistance on basic mobility tasks, 19th International Conference on System Theory, Control and Computing (2015) 441–446.
N. Aliman, R. Ramli and S. M. Haris, Design and development of lower limb exoskeletons: A survey, Robotics and Autonomous Systems, 95 (2017) 102–116.
W. Meng, Q. Liu, Z. Zhou, Q. Ai, B. Sheng and S. S. Xie, Recent development of mechanisms and control strategies for robot-assisted lower limb rehabilitation, Mechatronics, 31 (2015) 132–145.
J. Li, S. Li, Y. Ke and S. Li, Safety design and performance analysis of humanoid rehabilitation robot with compliant joint, Journal of Mechanical Science and Technology, 33 (1) (2019) 357–366.
G. A. Pratt and M. M. Williamson, Series elastic actuators, EEE/RSJ International Conference on Intelligent Robots and Systems (1995) 399–406.
H. Kizilhan, O. Baser, E. Kilic and N. Ulusoy, Comparison of controllable transmission ratio type variable stiffness actuator with antagonistic and pre-tension type actuators for the joints exoskeleton robots, 12th International Conference on Informatics in Control, Automation and Robotics, 2 (2015) 188–195.
J. E. Pratt, B. T. Krupp, C. J. Morse and S. H. Collins, The RoboKnee: An exoskeleton for enhancing strength and endurance during walking, Proc. of IEEE International Conference on Robotics and Automation, 3 (2004) 2430–2435.
H. K. Kwa, J. H. Noorden, M. Missel, T. Craig, J. E. Pratt and P. D. Neuhaus, Development of the IHMC mobility assist exo-skeleton, IEEE International Conference on Robotics and Automation (2009) 2556–2562.
H. Vallery, J. Veneman, E. Van Asseldonk, R. Ekkelenkamp, M. Buss and H. Van Der Kooij, Compliant actuation of rehabilitation robots, Robotics & Automation Magazine, 15 (3) (2008).
J. F. Veneman, R. Ekkelenkamp, R. Kruidhof, F. C. van der Helm and H. van der Kooij, A series elastic-and bowden-cable-based actuation system for use as torque actuator in exoskele-ton-type robots, The International Journal of Robotics Research, 25 (3) (2006) 261–281.
M. Dezman and A. Gams, Rotatable cambased variable-ratio lever compliant actuator for wearable devices, Mechanism and Machine Theory, 130 (2018) 508–522.
R. V. Ham, B. Vanderborght, M. V. Damme, B. Verreist and D. Lefeber, MACCEPA, the mechanically adjustable compliance and controllable equilibrium position actuator: Design and implementation in a biped robot, Robotics and Autonomous Systems, 55 (10) (2007) 961–768.
M. Cestari, D. Sanz-Merodio, J. C. Arevalo and E. Garcia, ARES, a variable stiffness actuator with embedded force sen-sor for the ATLAS exoskeleton, Industrial Robot: An International J., 41 (6) (2014) 518–526.
P. Cherelle, V. Grosu, P. Beyl, A. Mathys, R. Van Ham, M. Van Damme and D. Lefeber, The MACCEPA actuation system as torque actuator in the gait rehabilitation robot ALTACRO, 3rd IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (2010) 27–32.
J. Zhu, Y. Wang, J. Jiang, B. Sun and H. Cao, Unidirectional variable stiffness hydraulic actuator for load-carrying knee exoskeleton, International J of Advanced Robotic Systems, 14 (1) (2017).
M. Cestari, D. Sanz-Merodio, J. C. Arevalo and E. Garcia, An adjustable compliant joint for lower-limb exoskeletons, ASME Transactions on Mechatronics, 20 (2) (2015) 889–898.
B. Ugurlu, C. Doppmann, M. Hamaya, P. Forni, T. Teramae, T. Noda and J. Morimoto, Variable ankle stiffness improves balance control: Experiments on a bipedal exoskeleton, ASME Transactions on Mechatronics, 21 (1) (2015) 79–87.
A. Enoch, A. Sutas, S. I. Nakaoka and S. Vijayakumar, BLUE: A bipedal robot with variable stiffness and damping, International Conference on Humanoid Robots (2012) 487–494.
O. Baser, H. Kizilhan and E. Kilic, Biomimetic compliant lower limb exoskeleton (BioComEx) and its experimental evaluation, Journal of the Brazilian Society of Mechanical Sciences and Engineering, 41 (5) (2019) 226.
O. Baser and M. A. Demiray, Comparison of 4-pole with 225 coil-turns and 6-pole with 150 coil-turns multi-pole inner coil rotary MR brake designs, International J. of Materials, Mechanics and Manufacturing (2017) 5–3.
M. Laffranchi, L. Chen, N. Kashiri, J. Lee, N. G. Tsagarakis and D. G. Caldwell, Development and control of a series elastic actuator equipped with a semi active friction damper for human friendly robots, Robotics and Autonomous Systems, 62 (12) (2014) 1827–1836.
E. Garcia, J. C. Arevalo, G. Muhoz and P. Gonzalez-de-Santos, Combining series elastic actuation and magneto-rheological damping for the control of agile locomotion, Robotics and Autonomous Systems, 59 (10) (2011) 827–839.
C. Zhao and L. Guo, On the capability of PID control for nonlinear uncertain systems, IFAC Papers Online, 50 (1) (2017) 1521–1526.
B. Gonenc and H. Gurocak, Blending algorithm for position control with a hybrid actuator made of DC servomotor and brake, Industrial Robot: An International J., 38 (5) (2011) 492–499.
T. Nakamura, Y. Midorikawa and H. Tomori, Position and vibration control of variable rheological joints using artificial muscles and magneto-rheological brake, International J. of Humanoid Robotics, 8 (1) (2011) 205–222.
D. A. Winter, Biomechanics and Motor Control of Human Movement, 4th ed., Wiley, New Jersey (2009).
J. Perry, Gait Analysis: Normal and Pathological Function, New Jersey, SLACK, Inc. (2002).
A. Hansen, D. Childress, S. Miff, S. Gard and K. Mesplay, The human ankle during walking: implications for design of biomimetic ankle prostheses, J. of Biomechanics, 37 (10) (2004) 1467–1474.
W. H. Clark and J. R. Franz, Activation-dependent changes in soleus length-tension behavior augment ankle joint quasistiffness, Journal of Applied Biomechanics, 35 (2019) 182–189.
S. Kuitunen, P. V. Komi and H. Kyröläinen, Knee and ankle joint stiffness in sprint running, Medicine and Science in Sports and Exercise, 34 (1) (2002) 166–173.
K. Shamaei, G. S. Sawicki and A. M. Dollar, Estimation of quasi-stiffness and propulsive work of the human ankle in the stance phase of walking, PLoS ONE, 8 (3) (2013) e59935.
K. Shamaei, G. S. Sawicki and A. M. Dollar, Estimation of quasi-stiffness of the human knee in the stance phase of walking, PloS ONE, 8 (3) (2013) e59993.
K. Shamaei, G. S. Sawicki and A. M. Dollar, Estimation of quasi-stiffness of the human hip in the stance phase of walking, PloS ONE, 8 (12) (2013) e81841.
O. Baser and H. Kizilhan, Mechanical design and preliminary tests of VS-AnkleExo, J. of the Brazilian Society of Mechanical Sciences and Engineering, 40 (9) (2018) 442.
O. Baser, H. Kizilhan and E. Kilic, Mechanical design of a biomimetic compliant lower limb exoskeleton (BioComEx), Autonomous Robot Systems and Competitions (2016) 60–65.
C. Zhang, G. Liu, C. Li, J. Zhao, H. Yu and Y. Zhu, Development of a lower limb rehabilitation exoskeleton based on realtime gait detection and gait tracking, Advances in Mechanical Engineering, 8 (1) (2016) 1–9.
M. R. Homaeinezhad and S. Yaqubi, Discrete-time sliding-surface based control of parametrically uncertain nonlinear systems with unknown time-delay and inaccessible switching mode detection, International J. of Control (2019) 1–20.
R. H. Bishop, Mechatronic System Control, Logic, and Data Acquisition, 2nd Ed, CRC Press (2007).
The authors thank the Scientific and Technological Research Council of Turkey for the financial support of a research project titled as “Design and Control of a Biomimetic Exoskeleton Robot” and numbered 213M297.
Recommended by Editor Ja Choon Koo
Ozgur Baser received the M.S. and Ph.D. from Middle East Technical University, Turkey, in 2006 and 2012, respectively, all in mechanical engineering. He is currently an Associate Professor of Mechanical Engineering at Suleyman Demirel University, Turkey. His research interests include control systems, exoskeleton robots, MR brakes and haptic devices.
Ergin Kilic received the M.S. and Ph.D. from Middle East Technical University, Turkey, in 2007 and 2012, respectively, all in mechanical engineering. He is currently an Associate Professor of Mechanical Engineering at Suleyman Demirel University, Turkey. His research interests include fuzzy-logic control, artificial neural networks, rehabilitation robots and EMG signal processing.
Hasbi Kizilhan received the M.S. from Department of Mechanical Engineering of Süleyman Demirel University, Turkey, in 2015. He is currently a Research Assistant and studying for his Ph.D. at the same department and university. His research interests include robotics, exoskeleton robots and human-robot interaction.
About this article
Cite this article
Baser, O., Kizilhan, H. & Kilic, E. Employing variable impedance (stiffness/damping) hybrid actuators on lower limb exoskeleton robots for stable and safe walking trajectory tracking. J Mech Sci Technol 34, 2597–2607 (2020). https://doi.org/10.1007/s12206-020-0534-4
- Lower limb exoskeleton
- Variable stiffness actuator
- Variable damping actuator
- Magneto-rheological brake
- Hybrid actuator
- Walking trajectory tracking