Minimally Model-Based Trajectory Tracking and Variable Impedance Control of Flexible-Joint Robots

This paper presents a novel control scheme that primarily provides a solution to the problem of simultaneously performing stable trajectory tracking and Variable Impedance Control (VIC), of flexible-joint robots. The existing asymptotically stabilising tracking controllers for compliant robots, rely upon several model-based terms and their derivatives. Contrarily, the proposed Minimally Model-based Trajectory Tracking Control scheme, requires knowledge of only the gravitational torque vector model. Although interaction and tracking performance enhancements are achievable through VIC, its operation introduces energy injections, thereby impacting on closed-loop stability/passivity. Existing VIC passivity preservation techniques deal exclusively with rigid-joint robots. To this end, the proposed method introduces the Minimally Model-based Trajectory Tracking Variable Impedance Control scheme, which ensures passivity/stability when performing VIC on flexible-joint robots. Numerical and experimental results corroborate the controllers' efficacy in terms of realising VIC interaction and tracking tasks, thus enabling flexible-joint robots to stably replicate biologically-inspired behaviours.

[1]  Nikolaos G. Tsagarakis,et al.  Online impedance regulation techniques for compliant humanoid balancing , 2018, Robotics Auton. Syst..

[2]  Neville Hogan,et al.  Impedance Control: An Approach to Manipulation , 1984, 1984 American Control Conference.

[3]  Dongjun Lee,et al.  Passive-Set-Position-Modulation Framework for Interactive Robotic Systems , 2010, IEEE Transactions on Robotics.

[4]  Peiman Naseradinmousavi,et al.  Novel analytical and experimental trajectory optimization of a 7-DOF baxter robot: global design sensitivity and step size analyses , 2017 .

[5]  Darwin G. Caldwell,et al.  Towards versatile legged robots through active impedance control , 2015, Int. J. Robotics Res..

[6]  Riccardo Muradore,et al.  An Energy Tank-Based Interactive Control Architecture for Autonomous and Teleoperated Robotic Surgery , 2015, IEEE Transactions on Robotics.

[7]  Nikolaos G. Tsagarakis,et al.  Balance and impedance optimization control for COmpliant huMANoid stepping , 2016, 2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS).

[8]  Kaspar Althoefer,et al.  A Novel Continuum Manipulator Design Using Serially Connected Double-Layer Planar Springs , 2016, IEEE/ASME Transactions on Mechatronics.

[9]  Rui Song,et al.  Active Impedance Control of Bioinspired Motion Robotic Manipulators: An Overview , 2018, Applied bionics and biomechanics.

[10]  P. Tomei.  A simple PD controller for robots with elastic joints , 1991 .

[11]  Lakmal Seneviratne,et al.  Adaptive Control Of Robot Manipulators , 1992, Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems.

[12]  Keyvan Hashtrudi-Zaad,et al.  Optimization-based Robot Compliance Control: Geometric and Linear Quadratic Approaches , 2005, Int. J. Robotics Res..

[13]  Alessandro De Luca,et al.  On the feedback linearization of robots with variable joint stiffness , 2008, 2008 IEEE International Conference on Robotics and Automation.

[14]  Nikolaos G. Tsagarakis,et al.  Variable impedance walking using Time-Varying Lyapunov Stability Margins , 2017, 2017 IEEE-RAS 17th International Conference on Humanoid Robotics (Humanoids).

[15]  Alin Albu-Schäffer,et al.  A passivity based Cartesian impedance controller for flexible joint robots - part II: full state feedback, impedance design and experiments , 2004, IEEE International Conference on Robotics and Automation, 2004. Proceedings. ICRA '04. 2004.

[16]  Ranjit Kumar Barai,et al.  Nonlinear state feedback controller design for underactuated mechanical system: a modified block backstepping approach. , 2014, ISA transactions.

[17]  Abderrahmane Kheddar,et al.  Motion learning and adaptive impedance for robot control during physical interaction with humans , 2011, 2011 IEEE International Conference on Robotics and Automation.

[18]  Cristian Secchi,et al.  A tank-based approach to impedance control with variable stiffness , 2013, 2013 IEEE International Conference on Robotics and Automation.

[19]  Alexander Dietrich,et al.  Generalizing Torque Control Concepts: Using Well-Established Torque Control Methods on Variable Stiffness Robots , 2015, IEEE Robotics & Automation Magazine.

[20]  M. Athans,et al.  Gain Scheduling: Potential Hazards and Possible Remedies , 1992, 1991 American Control Conference.

[21]  Hikaru Inooka,et al.  Variable impedance control of a robot for cooperation with a human , 1995, Proceedings of 1995 IEEE International Conference on Robotics and Automation.

[22]  Alin Albu-Schäffer,et al.  Human-Like Adaptation of Force and Impedance in Stable and Unstable Interactions , 2011, IEEE Transactions on Robotics.

[23]  Alin Albu-Schäffer,et al.  Robots Driven by Compliant Actuators: Optimal Control Under Actuation Constraints , 2013, IEEE Transactions on Robotics.

[24]  Emmanouil Spyrakos-Papastavridis,et al.  Passivity Preservation for Variable Impedance Control of Compliant Robots , 2020, IEEE/ASME Transactions on Mechatronics.

[25]  Toru Tsumugiwa,et al.  Variable impedance control based on estimation of human arm stiffness for human-robot cooperative calligraphic task , 2002, Proceedings 2002 IEEE International Conference on Robotics and Automation (Cat. No.02CH37292).

[26]  Shahid Hussain,et al.  Adaptive Impedance Control of a Robotic Orthosis for Gait Rehabilitation , 2013, IEEE Transactions on Cybernetics.

[27]  Patrizio Tomei,et al.  Design of global tracking controllers for flexible-joint robots , 1993, J. Field Robotics.

[28]  Neville Hogan,et al.  On the stability of manipulators performing contact tasks , 1988, IEEE J. Robotics Autom..

[29]  Alessandro De Luca,et al.  PD control with on-line gravity compensation for robots with elastic joints: Theory and experiments , 2005, Autom..

[30]  J. Wen,et al.  A Passivity/Lyapunov Approach for the Control of Flexible Joint Manipulators , 1993, 1993 American Control Conference.

[31]  Matthew M. Williamson,et al.  Series elastic actuators , 1995, Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots.

[32]  Alin Albu-Schäffer,et al.  Elastic Structure Preserving (ESP) Control for Compliantly Actuated Robots , 2018, IEEE Transactions on Robotics.

[33]  Roland Siegwart,et al.  The hand of the DLR Hand Arm System: Designed for interaction , 2012, Int. J. Robotics Res..

[34]  R. Ortega,et al.  On Tracking Control of Rigid and Flexible Joint Robots , 1995 .

[35]  Alexander Dietrich,et al.  Passive Hierarchical Impedance Control Via Energy Tanks , 2017, IEEE Robotics and Automation Letters.

[36]  Jian S. Dai,et al.  Selective-Compliance based Lagrange Model and Multilevel Non-Collocated Feedback Control of a Humanoid Robot , 2018 .

[37]  Stefan Schaal,et al.  Learning variable impedance control , 2011, Int. J. Robotics Res..

[38]  Lin Tian,et al.  Robust adaptive control of flexible joint robots with joint torque feedback , 1995, Proceedings of 1995 IEEE International Conference on Robotics and Automation.

[39]  Aude Billard,et al.  Stability Considerations for Variable Impedance Control , 2016, IEEE Transactions on Robotics.

[40]  Yan Peng,et al.  Adaptive Impedance Control of Human–Robot Cooperation Using Reinforcement Learning , 2017, IEEE Transactions on Industrial Electronics.

[41]  Nikos G. Tsagarakis,et al.  A New Actuator With Adjustable Stiffness Based on a Variable Ratio Lever Mechanism , 2014, IEEE/ASME Transactions on Mechatronics.

[42]  Nikolaos G. Tsagarakis,et al.  Online impedance parameter tuning for compliant biped balancing , 2015, 2015 IEEE-RAS 15th International Conference on Humanoid Robots (Humanoids).

[43]  Andrea Giusti,et al.  Combined inverse-dynamics/passivity-based control for robots with elastic joints , 2017, 2017 IEEE International Conference on Robotics and Automation (ICRA).

[44]  Darwin G. Caldwell,et al.  A task-parameterized probabilistic model with minimal intervention control , 2014, 2014 IEEE International Conference on Robotics and Automation (ICRA).

[45]  Itzhak Barkana,et al.  Defending the beauty of the Invariance Principle , 2014, Int. J. Control.

[46]  M. Spong.  Modeling and Control of Elastic Joint Robots , 1987 .

[47]  Hongxu Ma,et al.  Active Variable Impedance Control for Hydraulic-Driving Articulated Robotic Leg , 2018, 2018 13th World Congress on Intelligent Control and Automation (WCICA).