Gain Scheduling Control for a Class of Variable Stiffness Actuators Based on Lever Mechanisms

This paper is concerned with the design of a control strategy for variable stiffness actuators in series configuration, exploiting the lever concept to adjust the stiffness at the transmission. A control strategy based on gain scheduling is proposed, which is able to regulate both stiffness and position at output link. The gain scheduling is designed based on a set of linear quadratic regulators (LQRs), because LQR's inherent robustness properties can accommodate significant variation in the actuation plant parameters. The link positioning relies on continuous adjustment of the control effort based on the current transmission stiffness; the stiffness perceived at the output link is regulated through combined action of the transmission stiffness and the positioning gains of the scheduling strategy. The effectiveness of the controller is verified in simulation and experiments on the actuator with adjustable stiffness. The overall strategy has been proven to be locally stable.

[1]  R. E. Kalman,et al.  Contributions to the Theory of Optimal Control , 1960 .

[2]  Gene F. Franklin,et al.  Feedback Control of Dynamic Systems , 1986 .

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

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

[5]  Christopher G. Atkeson,et al.  Constructive Incremental Learning from Only Local Information , 1998, Neural Computation.

[6]  Wilson J. Rugh,et al.  Research on gain scheduling , 2000, Autom..

[7]  Antonio Bicchi,et al.  Compliant design for intrinsic safety: general issues and preliminary design , 2001, Proceedings 2001 IEEE/RSJ International Conference on Intelligent Robots and Systems. Expanding the Societal Role of Robotics in the the Next Millennium (Cat. No.01CH37180).

[8]  J. Corres,et al.  Instantaneous speed and disturbance torque observer using nonlinearity cancellation of shaft encoder , 2002, 2002 IEEE 33rd Annual IEEE Power Electronics Specialists Conference. Proceedings (Cat. No.02CH37289).

[9]  Antonio Bicchi,et al.  Design and Control of a Variable Stiffness Actuator for Safe and Fast Physical Human/Robot Interaction , 2005, Proceedings of the 2005 IEEE International Conference on Robotics and Automation.

[10]  M. Dahleh.  Laboratory for Information and Decision Systems , 2005 .

[11]  Ludovic Righetti,et al.  Programmable central pattern generators: an application to biped locomotion control , 2006, Proceedings 2006 IEEE International Conference on Robotics and Automation, 2006. ICRA 2006..

[12]  Koichi Koganezawa,et al.  Antagonistic control of multi-DOF joint by using the actuator with non-linear elasticity , 2006, Proceedings 2006 IEEE International Conference on Robotics and Automation, 2006. ICRA 2006..

[13]  Stephen P. DeWeerth,et al.  Novel Nonlinear Elastic Actuators for Passively Controlling Robotic Joint Compliance , 2007 .

[14]  Bram Vanderborght,et al.  MACCEPA, the mechanically adjustable compliance and controllable equilibrium position actuator: Design and implementation in a biped robot , 2007, Robotics Auton. Syst..

[15]  G. Hirzinger,et al.  A new variable stiffness design: Matching requirements of the next robot generation , 2008, 2008 IEEE International Conference on Robotics and Automation.

[16]  Martin Buss,et al.  Compliant actuation of rehabilitation robots , 2008, IEEE Robotics & Automation Magazine.

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

[18]  Sungchul Kang,et al.  Design of a robot joint with variable stiffness , 2008, 2008 IEEE International Conference on Robotics and Automation.

[19]  Jan F. Veneman,et al.  The Effects on Kinematics and Muscle Activity of Walking in a Robotic Gait Trainer During Zero-Force Control , 2008, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[20]  Giorgio Grioli,et al.  VSA-II: a novel prototype of variable stiffness actuator for safe and performing robots interacting with humans , 2008, 2008 IEEE International Conference on Robotics and Automation.

[21]  Nikolaos G. Tsagarakis,et al.  MACCEPA 2.0: Adjustable compliant actuator with stiffening characteristic for energy efficient hopping , 2009, 2009 IEEE International Conference on Robotics and Automation.

[22]  Bram Vanderborght,et al.  Proxy-based Sliding Mode Control of a Planar Pneumatic Manipulator , 2009, Int. J. Robotics Res..

[23]  Andrej Gams,et al.  On-line learning and modulation of periodic movements with nonlinear dynamical systems , 2009, Auton. Robots.

[24]  Alessandro De Luca,et al.  Nonlinear decoupled motion-stiffness control and collision detection/reaction for the VSA-II variable stiffness device , 2009, 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[25]  Jae-Bok Song,et al.  Hybrid dual actuator unit: A design of a variable stiffness actuator based on an adjustable moment arm mechanism , 2010, 2010 IEEE International Conference on Robotics and Automation.

[26]  Nikolaos G. Tsagarakis,et al.  A novel actuator with adjustable stiffness (AwAS) , 2010, 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[27]  Marc Bodson,et al.  Adaptive Algorithms for the Rejection of Sinusoidal Disturbances Acting on Unknown Plants , 2010, IEEE Transactions on Control Systems Technology.

[28]  Stefano Stramigioli,et al.  Modeling and design of energy efficient variable stiffness actuators , 2010, 2010 IEEE International Conference on Robotics and Automation.

[29]  Alin Albu-Schäffer,et al.  Dynamic modelling and control of variable stiffness actuators , 2010, 2010 IEEE International Conference on Robotics and Automation.

[30]  Nikolaos G. Tsagarakis,et al.  A new variable stiffness actuator (CompAct-VSA): Design and modelling , 2011, 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[31]  Alin Albu-Schäffer,et al.  State feedback damping control for a multi DOF variable stiffness robot arm , 2011, 2011 IEEE International Conference on Robotics and Automation.

[32]  Gianluca Palli,et al.  Output-Based Control of Robots with Variable Stiffness Actuation , 2011, J. Robotics.

[33]  Stefano Stramigioli,et al.  Energy-Efficient Variable Stiffness Actuators , 2011, IEEE Transactions on Robotics.

[34]  Nikolaos G. Tsagarakis,et al.  Exploiting natural dynamics for energy minimization using an Actuator with Adjustable Stiffness (AwAS) , 2011, 2011 IEEE International Conference on Robotics and Automation.

[35]  Nikolaos G. Tsagarakis,et al.  A position and stiffness control strategy for variable stiffness actuators , 2012, 2012 IEEE International Conference on Robotics and Automation.

[36]  Nikolaos G. Tsagarakis,et al.  On-line estimation of variable stiffness in flexible robot joints , 2012, Int. J. Robotics Res..

[37]  N. G. Tsagarakis,et al.  A Novel Intrinsically Energy Efficient Actuator With Adjustable Stiffness (AwAS) , 2013, IEEE/ASME Transactions on Mechatronics.

[38]  Nikolaus Correll,et al.  C-FOREST: Parallel Shortest Path Planning With Superlinear Speedup , 2013, IEEE Transactions on Robotics.

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

[40]  M. Hoagland,et al.  Feedback Systems An Introduction for Scientists and Engineers SECOND EDITION , 2015 .