Reaction Force Observer based Torque Control

Year 2021, Volume: 24 Issue: 4, 1629 - 1635, 01.12.2021

Erim Can Özçınar Regaip Barkan Uğurlu

https://doi.org/10.2339/politeknik.848036

Cited By: 1

Abstract

In this article, a reaction force observer-based torque controller was designed and experimentally implemented to a non-backdrivable actuator unit. Torque control is of importance when considering physical human-robot interaction and researchers usually use torque sensors or custom-built torsional springs. These elements lead to relatively more complicated systems and increase the total weight. In contrast, reaction force observers can estimate external forces acting on the system and thus enable torque control with no need of torque sensing. The estimation process performs better for backdrivable systems, therefore, its implementation to non-backdrivable systems, e.g., systems with a gear ratio of 1:100, is limited. To remedy this issue, a reaction force observer-based torque controller was designed and implemented. As a result, experimental data showed that reaction force observer leads to favorable torque control performance when supported with friction compensation.

Keywords

Torque control, reaction force observer, disturbance observer, friction compensation

Tepki Kuvveti Gözetleyicisi Tabanlı Tork Kontrolü

Abstract

Bu makalede tepki kuvveti gözetleyicisi baz alınarak bir tork kontrolcüsü tasarlanmış ve etkinliği geri sürülebilir olmayan bir eyleyici ünitesi üzerinde deneysel olarak sınanmıştır. Fiziksel insan-robot etkileşimi için son derece yüksek bir öneme haiz olan tork kontrolü için genellikle tork sensörleri veya özel olarak üretilen burulma yayları kullanılmaktadır. Bu ekipmanlar ise hem sistemi karmaşıklaştırmakta, hem de toplam ağırlığı arttırmaktadır. Tepki kuvveti gözetleyici yöntemi ise sisteme etkiyen dış kuvvetleri kestirebilmekte ve bu sayede sensör kullanmaksızın tork kontrolünün uygulanmasına olanak sağlamaktadır. Bu kestirim genellikle geri sürülebilir sistemlerde daha sağlıklı işlemektedir, dolayısıyla geri sürülemeyen sistemlerde (örneğin 1:100 dişli oranlı sistemler) uygulaması sınırlıdır. Bu noktadan hareketle, geri sürülemeyen bir sistem için tepki kuvveti gözetleyicisi bazlı bir tork kontrolü tasarlanmış ve uygulanmıştır. Sonuç olarak sürtünme kompanzasyonu sağlandığında tepki kuvveti gözetleyicisinin tork kontrolünü sağlayabildiği deneysel bulgular ışığında saptanmıştır.

Keywords

Tork kontrolü, tepki kuvveti gözetleyici, bozunum gözetleyici, sürtünme kompanzasyonu

References

• [1] De Santis A., Siciliano B., De Luca A., and Bicci A., “An atlas of physical human–robot interaction,” Mechanism and Machine Theory, 43: 253-270, (2008).
• [2] Albu‐Schäffer A., Haddadin S., Ott C., Stemmer A., Wimböck T., and Hirzinger G. “The DLR lightweight robot: design and control concepts for robots in human environments,” Industrial Robot, 34: 376-385, (2007).
• [3] Gautier M. and Jubien A., “Force calibration of KUKA LWR-like robots including embedded joint torque sensors and robot structure,” in IEEE International Conference on Intelligent Robots and Systems, Chicago, US, 416–421, (2014).
• [4] Yildirim M. C., Sendur P., Bilgin O., Gulek B., Yapici G. G., and Ugurlu B., “An Integrated Design Approach for a Series Elastic Actuator: Stiffness Tuning, Fatigue Analysis, Thermal Management,” in IEEE International Conference on Humanoid Robots, Birmingham, UK, 384–389, (2017).
• [5] Sariyildiz E., Oboe R., and Ohnishi K., “Disturbance observer-based robust control and its applications: 35th anniversary overview,” IEEE Transactions on Industrial Electronics, 67: 2042-2053, (2020).
• [6] Sariyildiz E., and Ohnishi K., “Stability and robustness of disturbance-observer-based motion control systems,” IEEE Transactions on Industrial Electronics, 62: 414-422, (2014).
• [7] Ohnishi K., Shibata M., and Murakami T., “Motion Control for Advanced Mechatronics,” IEEE Transactions on Mechatronics, 1: 56-67, (1996).
• [8] Kaneko K., Kanehiro F., Morisawa M., Yoshida E., and Laumond J.-P., “Disturbance Observer that estimates External Force acting on Humanoid Robots,” in IEEE International Workshop on Advanced Motion Control, Sarajevo, Bosnia and Herzegovina, 1–6, (2012).
• [9] Ugurlu B., Nishimura M., Hyodo, K., Kawanishi M., and Narikiyo T., “Proof of Concept for Robot-aided Upper Limb Rehabilitation Using Disturbance Observers,” IEEE Transactions on Human-Machine Systems, 45: 110-118, (2015).
• [10] Sariyildiz E., and Ohnishi K., “On the explicit robust force control via disturbance observer,” IEEE Transactions on Industrial Electronics, 62: 1581-1589, (2014).
• [11] Benallegue M., Gergondet P., Audren H., Audren A., Morisawa M., Lamiraux F., Kheddar A., and Kanehiro F., “Model-Based External Force/Moment Estimation for Humanoid Robots With No Torque Measurement,” in IEEE International Conference on Robotics and Automation, Brisbane, Australia, 3122–3129, (2018).
• [12] Albu-Schaffer A., Hirzinger G., “Cartesian impedance control techniques for torque controlled light-weight robots,” in IEEE International Conference on Robotics and Automation, Washington, US, 3122–3129, (2018).
• [13] Yildirim M. C., Kansizoglu A. T., Emre S., Derman M., Coruk S., Soliman, A. F., and Ugurlu B., “Co-Ex: A Torque-Controllable Lower Body Exoskeleton for Dependable Human-Robot Co-Existence,” in IEEE International Conference on Rehabilitation Robotics, Toronto, Canada, 605–610, (2019).
• [14] Coruk S., Yildirim, M. C., Kansizoglu, A. T., Dalgic, O, and Ugurlu B., “Design and Development of a Powered Upper Limb Exoskeleton with High Payload Capacity for Industrial Operations,” in IEEE International Conference on Human-Machine Systems, Rome, Italy, 1–4, (2020).