Sensorless displacement estimation of a shape memory alloy coil spring actuator using inductance

To measure the displacement of a shape memory alloy (SMA) coil spring actuator for feedback control, displacement sensors larger than the actuator are normally required. In this study, a novel method for estimating the displacement of an SMA coil spring actuator without a sensor is proposed. Instead of a sensor, coil inductance is used for estimating the displacement. Coil inductance is estimated by measuring the voltage and the transient response of the current. It has a one-to-one relationship with the displacement of the coil and is not affected by load. Previous methods for estimating displacement using resistance measurements are heavily affected by load variations. The experimental results herein show that displacement is estimated with reasonable accuracy under varying loads using coil inductance. This sensorless method of estimating the displacement of an SMA coil spring actuator can be used to build a compact feedback controller because there is no need for a bulky displacement sensor.

[1]  A. Kurdila,et al.  Hysteresis Modeling of SMA Actuators for Control Applications , 1998 .

[2]  J. Jayender,et al.  Modelling and gain scheduled control of shape memory alloy actuators , 2005, Proceedings of 2005 IEEE Conference on Control Applications, 2005. CCA 2005..

[3]  Craig A. Rogers,et al.  One-Dimensional Thermomechanical Constitutive Relations for Shape Memory Materials , 1990 .

[4]  Jay Fineberg,et al.  The dynamics of rapid fracture: instabilities, nonlinearities and length scales , 2013, Reports on progress in physics. Physical Society.

[5]  Z. J. Pu,et al.  Variation of Electrical Resistance and the Elastic Modulus of Shape Memory Alloys under Different Loading and Temperature Conditions , 1995 .

[6]  L. Brinson.  One-Dimensional Constitutive Behavior of Shape Memory Alloys: Thermomechanical Derivation with Non-Constant Material Functions and Redefined Martensite Internal Variable , 1993 .

[7]  Koji Ikuta,et al.  Micro/miniature shape memory alloy actuator , 1990, Proceedings., IEEE International Conference on Robotics and Automation.

[8]  Tadahiro Hasegawa,et al.  Modeling of shape memory alloy actuator and tracking control system with the model , 2001, IEEE Trans. Control. Syst. Technol..

[9]  Toshiharu Tominaka.  Inductance calculation for helical conductors , 2005 .

[10]  Koji Ikuta,et al.  Shape memory alloy servo actuator system with electric resistance feedback and application for active endoscope , 1988, Proceedings. 1988 IEEE International Conference on Robotics and Automation.

[11]  K. Tanaka.  A THERMOMECHANICAL SKETCH OF SHAPE MEMORY EFFECT: ONE-DIMENSIONAL TENSILE BEHAVIOR , 1986 .

[12]  Kyu-Jin Cho,et al.  Engineering design framework for a shape memory alloy coil spring actuator using a static two-state model , 2012 .

[13]  Kyu-Jin Cho,et al.  Omega-Shaped Inchworm-Inspired Crawling Robot With Large-Index-and-Pitch (LIP) SMA Spring Actuators , 2013, IEEE/ASME Transactions on Mechatronics.

[14]  Hashem Ashrafiuon,et al.  Nonlinear Control of a Shape Memory Alloy Actuated Manipulator , 2002 .

[15]  Kyu-Jin Cho,et al.  Towards a bio-mimetic flytrap robot based on a snap-through mechanism , 2010, 2010 3rd IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics.

[16]  Ertan Güner,et al.  Three-finger SMA robot hand and its practical analysis , 2002, Robotica.

[17]  Carrie A. Dickinson,et al.  Feedback Control Using Shape Memory Alloy Actuators , 1998 .

[18]  Kyu-Jin Cho,et al.  Flea-Inspired Catapult Mechanism for Miniature Jumping Robots , 2012, IEEE Transactions on Robotics.

[19]  K. Tanaka,et al.  A thermomechanical description of materials with internal variables in the process of phase transitions , 1982 .

[20]  D. Lagoudas.  Shape memory alloys : modeling and engineering applications , 2008 .

[21]  D. Griffiths.  Introduction to Electrodynamics , 2017 .

[22]  Michele Pozzi,et al.  The electrical transport properties of shape memory alloys , 1999 .

[23]  K Yang,et al.  A novel robot hand with embedded shape memory alloy actuators , 2002 .

[24]  F Schiedeck,et al.  Design of a robust control strategy for the heating power of shape memory alloy actuators at full contraction based on electric resistance feedback , 2011 .

[25]  Paolo Dario,et al.  Shape memory alloy micromotors for direct-drive actuation of dexterous artificial hands , 1989 .

[26]  X. Wu,et al.  The variation of electrical resistance of near stoichiometric NiTi during thermo-mechanic procedures , 1999 .

[27]  David W. L. Wang,et al.  Modeling and L2-stability of a shape memory alloy position control system , 1998, IEEE Trans. Control. Syst. Technol..

[28]  Kyu-Jin Cho,et al.  Architecture design of a multiaxis cellular actuator array using segmented binary control of shape memory alloy , 2006, IEEE Transactions on Robotics.

[29]  Gangbing Song,et al.  Position control of shape memory alloy actuators with internal electrical resistance feedback using neural networks , 2004 .