EFFICIENCY TESTING OF ELECTRIC ROTARY ACTUATORS WITH NON-STANDARD REDUCTION UNITS FOR LOWER LIMB EXOSKELETONS
Abstract
The purpose of this paper is to develop a method and instruments for identifying the efficiency of an electric rotary actuator for an electromechanical orthosis of a lower limb exoskeleton, which greatly influences its weight and dimensions. The reduction units currently used as part of electric drives for exoskeletons are made in accordance with a non-standard form factor design, which impedes the use of existing methods and tools for measuring their torque and performance without considerable errors caused by mechanical losses in the bearing assemblies of test equipment. The method proposed in this paper solves this problem by identifying the values of decelerating torque associated with friction between bearing elements. In the experimental part of this work, the proposed method and the measuring system were evaluated, and it was found that the measurement error was about 1.2%, which slightly exceeds the total level of random and systematic errors of instruments applied when measuring the desired values. On the basis of the obtained results, it is possible to conclude that the developed method can be used to control the efficiency of electric rotary actuators for exoskeletons both at the stage of their production and during their operation.
References
Manna, S.K., & Dubey, V.N. (2018). Comparative study of actuation systems for portable upper limb exoskeletons. Medical Engineering & Physics, 60, 1-13. doi:10.1016/j.medengphy.2018.07.017
Arumugam, P., & Kumar, A. (2014). Design methods for compliant mechanisms used in new age industries – a review. Journal of Applied Engineering Science, 14, 223-232. doi:10.5937/jaes14-8229
Ruiz-Olaya, A.F., Lopez-Delis, A., & Rocha, A.F. (2019). Upper and Lower Extremity Exoskeletons. (Eds.), Handbook of Biomechatronics. Academic Press, Elsevier Inc., p. 283-317. DOI: 10.1016/B978-0-12-812539-7.00011-8
Huysamen, K., Looze, M., Bosch, T., Ortiz, J., Toxiri, S., & O’Sullivan, L.W.O. (2018). Assessment of an active industrial exoskeleton to aid dynamic lifting and lowering manual handling tasks. Applied Ergonomics, 68, 125-131. doi:10.1016/j.apergo.2017.11.004
O'Sullivan, L., Nugent, R., & der Vorm, J. (2015). Standards for the safety of exoskeletons used by industrial workers performing manual handling activities: a contribution from the robo-mate project to their future development. Procedia Manufacturing, 3, 1418-1425. doi:10.1016/j.promfg.2015.07.306
Hyun, D.J., Park, H., Ha, T., Park, S., & Jung, K. (2017). Biomechanical design of an agile, electricity-powered lower-limb exoskeleton for weight-bearing assistance. Robotics and Autonomous Systems, 95, 181-195. doi:10.1016/j.robot.2017.06.010
Moreno, J.C., Figueiredo, J., Pons, J.L. (2018). Exoskeletons for lower-limb rehabilitation. Colombo, R., Sanguineti, V. (Eds.), Rehabilitation Robotics. Academic Press, Elsevier Inc., p. 89-99. DOI: 10.1016/B978-0-12-811995-2.00008-4.
Gasperini, G., Cannaviello, G., & Guanziroli, E. (2018). Exoskeleton and end-effector robots for upper and lower limbs rehabilitation: narrative review. PM&R, 10(9), 174-174. doi:10.1016/j.pmrj.2018.06.005
Hassani, W., Mohammed, S., Rifaï, H., & Amirat, Y. (2014). Powered orthosis for lower limb movements assistance and rehabilitation. Control Engineering Practice, 26, 245-253. doi:10.1016/j.conengprac.2014.02.002
Chen, B., Ma, H., Qin, L.-Y., Gao, F., Chan, K.-M. & et al. (2016). Recent developments and challenges of lower extremity exoskeletons. Journal of Orthopaedic Translation, 5, 26-37, DOI: 10.1016/j.jot.2015.09.007.
Aliman, N., Ramli, R., Haris, S.M. (2017). Design and development of lower limb exoskeletons: A survey. Robotics and Autonomous Systems, 95, 102-116, DOI: 10.1016/j.robot.2017.05.013.
Veale, A.J., & Xie, S.Q. (2016). Towards compliant and wearable robotic orthoses: A review of current and emerging actuator technologies. Medical Engineering & Physics, 38(4), 317-325. doi:10.1016/j.medengphy.2016.01.010
Kim, H., Shin, Y.U., Kim, J. (2017). Design and locomotion control of a hydraulic lower extremity exoskeleton for mobility augmentation. Mechatronics, 46, 32-45, DOI: 10.1016/j.mechatronics.2017.06.009.
Ouyang, X., Ding, S., Fan, B., Li, P.Y., Yang, H. (2016). Development of a novel compact hydraulic power unit for the exoskeleton robot. Mechatronics, 38, 68-75, DOI: 10.1016/j.mechatronics.2016.06.003.
Varghese, J., Akhil, V.M., Rajendrakumar, P.K., Sivanandan, K.S. (2017). A rotary pneumatic actuator for the actuation of the exoskeleton knee joint. Theoretical and Applied Mechanics Letters, 7(4), 222-230, DOI: 10.1016/j.taml.2017.08.002.
Long, Y., Du, Z., Chen, C., Wang, W., He, L. et al. (2017). Development and Analysis of an Electrically Actuated Lower Extremity Assistive Exoskeleton. Journal of Bionic Engineering, 14(2), 272-283, DOI: 10.1016/S1672-6529(16)60397-9.
Egorov, A., Kozlov, K., Belogusev, V. (2015). The method and instruments for induction motor mechanical parameters identification. International Journal of Applied Engineering Research, 10(17), 37685-37691.
Kotelnets, N., Akimova, N., Antonov, M. (2003). Tests, operation and maintenance of electric motors. Moscow: Akademiya.
Zhang, J., Cheah, C.C., Collins, S.H. (2017). Torque Control in Legged Locomotion. Sharbafi, M.A., Seyfarth, A. (Eds.), Bioinspired Legged Locomotion: Models, Concepts, Control and Applications. Butterworth Heinemann, Elsevier Inc., Oxford, p. 347-400. DOI: 10.1016/B978-0-12-803766-9.00007-5.
Potapov, L., Yuferov, F. (1974). Measurements of torques and rotational speeds of micromotors. Moscow: Energiya.
Morris, A.S., Langari, R. (2016). Mass, Force, and Torque Measurement. Morris, A.S., Langari, R. (Eds.), Measurement and Instrumentation (Second Edition): Theory and Application. Academic Press, Elsevier Inc., p. 547-564. DOI: 10.1016/B978-0-12-800884-3.00018-6.
Wegener, G., Andrae, J. (2007). Measurement uncertainty of torque measurements with rotating torque transducers in power test stands. Measurement, 40(7), 803-810, DOI: 10.1016/j.measurement.2006.08.001.
