Adaptive Control of Harmonic Drives

2006 ◽  
Vol 129 (2) ◽  
pp. 182-193 ◽  
Author(s):  
Wen-Hong Zhu ◽  
Erick Dupuis ◽  
Michel Doyon

Aimed at achieving ultrahigh control performance for high-end applications of harmonic drives, an adaptive control algorithm using additional sensing, namely, the joint and motor positions and the joint torque, and their practically available time derivatives, is proposed. The proposed adaptive controller compensates the large friction associated with harmonic drives, while incorporating the dynamics of flexspline. The L2∕L∞ stability and the L2 gain-induced H∞ stability are guaranteed in both joint torque and joint position control modes. Conditions for achieving asymptotic stability are also given. The proposed joint controller can be efficiently incorporated into any robot motion control system based on either its torque control interface or the virtual decomposition control approach. Experimental results demonstrated in both the time and frequency domains confirm the superior control performance achieved not only in individual joint motion, but also in coordinated motion of an entire robot manipulator.

1988 ◽  
Vol 110 (4) ◽  
pp. 343-349 ◽  
Author(s):  
P. N. Nikiforuk ◽  
K. Tamura

This paper discusses the design of a model reference type of adaptive control system for a linear unknown plant with system and observation disturbances. The disturbances are assumed to be approximately expressed by step, sinusoidal, and other analytical functions. The design of a controller, called a disturbance accommodating adaptive controller (DAAC), which eliminates the effect of these disturbances at the plant output, is described. Two types of bias DAAC are given as examples and are applied to the adaptive control of a DC-servo motor system. The plant (the DC-servo system) consists of two unknown loads connected through an electrical clutch and Coulomb friction. The effect of the friction on the plant is considered as an unknown bias disturbance and the DAAC is implemented on an analog computer. Experimental results for the position control of the DAAC system are given.


Author(s):  
Dong Sun ◽  
◽  
Y. X. Su ◽  
James K. Mills ◽  

A position control approach for direct-drive robot manipulators with permanent magnet AC (PMAC) motors is proposed. The conventional vector control architecture has been simplified by specifying the motor stator phase so that the rotating d-axis current is zero. The position control is designed to be an enhanced fuzzy PD controller, by incorporating two nonlinear tracking differentiators into a conventional fuzzy PD controller. The proposed control methodology is easy to implement, and exhibits better control performance than conventional control methods. Experiments conducted on a single-link manipulator directly driven by a PMAC motor demonstrate the validity of the proposed approach.


2004 ◽  
Vol 127 (3) ◽  
pp. 520-526 ◽  
Author(s):  
Juntao Fei ◽  
Shuhao Chen ◽  
Gang Tao ◽  
Suresh M. Joshi

A robust adaptive control approach using output feedback for output tracking is developed for discrete-time linear time-invariant systems with uncertain failures of redundant actuators in the presence of the unmodeled dynamics and bounded output disturbance. Such actuator failures are characterized by some unknown inputs stuck at some unknown fixed values at unknown time instants. Technical issues such as plant-model output matching, adaptive controller structure, adaptive parameter update laws, stability and tracking analysis, and robustness of system performance are solved for the discrete-time adaptive actuator failure compensation problem. A case study is conducted for adaptive compensation of rudder servomechanism failures of a Boeing 747 dynamic model presented in discrete time, verifying the desired adaptive system performance in the presence of uncertain actuator failures.


Author(s):  
Monisha Pathak* ◽  
◽  
Dr. Mrinal Buragohain ◽  

This paper briefly discusses about the Robust Controller based on Adaptive Sliding Mode Technique with RBF Neural Network (ASMCNN) for Robotic Manipulator tracking control in presence of uncertainities and disturbances. The aim is to design an effective trajectory tracking controller without any modelling information. The ASMCNN is designed to have robust trajectory tracking of Robot Manipulator, which combines Neural Network Estimation with Adaptive Sliding Mode Control. The RBF model is utilised to construct a Lyapunov function-based adaptive control approach. Simulation of the tracking control of a 2dof Robotic Manipulator in the presence of unpredictability and external disruption demonstrates the usefulness of the planned ASMCNN.


Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 134
Author(s):  
Hyodong Lee ◽  
Hwijin Park ◽  
Kwan Kyu Park ◽  
Hak Yi

This paper concerns the use of adaptive wave cancellation in a new multilayer smart skin sensor to attenuate the primary low-frequency noise underwater. The proposed multilayered system is designed with a piezoelectric actuator (Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 composite) and two layers of polyvinylidene fluoride to accelerate wave absorption. Furthermore, the use of a combination of an adaptive control scheme and a time-delay signal separation method has the potential to provide the proposed absorber system with a wave cancellation capability and thereby enable the absorber system to respond to environmental changes underwater. The use of smart piezoelectric materials and an adaptive control approach enables the absorber system to achieve the high attenuation level of the reflected waves, unlike typical absorber systems based on active noise control. Echo reduction experiments showed that the proposed piezoelectric-based multilayer sensor with an adaptive controller could attenuate reflected wave signals effectively.


2019 ◽  
Vol 16 (3) ◽  
pp. 172988141984671 ◽  
Author(s):  
Gen-Liang Xiong ◽  
Hai-Chu Chen ◽  
Jing-Xin Shi ◽  
Fa-Yun Liang

For robots with flexible joints, the joint torque dynamics makes it difficult to control. An effective solution is to carry out a joint torque controller with fast enough dynamic response. This article is dedicated to design such a torque controller based on sliding mode technique. Three joint torque control approaches are proposed: (1) The proportional-derivative (PD)-type controller has some degree of robustness by properly selecting the control gains. (2) The direct sliding mode control approach which fully utilizes the physical properties of electric motors. (3) The sliding mode estimator approach was proposed to compensate the parameter uncertainties and the external disturbances of the joint torque system. These three joint torque controllers are tested and verified by the simulation studies with different reference torque trajectories and under different joint stiffness.


Author(s):  
Hamid Roozbahani ◽  
Konstantin Frumkin ◽  
Heikki Handroos

Adaptive control systems are one of the most significant research directions of modern control theory. It is well known that every mechanical appliance’s behavior noticeably depends on environmental changes, functioning-mode parameter changes and changes in technical characteristics of internal functional devices. An adaptive controller involved in control process allows reducing an influence of such changes. In spite of this such type of control methods is applied seldom due to specifics of a controller designing. The work presented in this paper shows the design process of the adaptive controller built by Lyapunov’s function method for a hydraulic servo system. The modeling of the hydraulic servo system were conducting with MATLAB® software including Simulink® and Symbolic Math Toolbox™. In this study, the Jacobi matrix linearization of the object’s mathematical model and derivation of the suitable reference models based on Newton’s characteristic polynomial were applied. In addition, an intelligent adaptive control algorithm and system model including its nonlinearities was developed to solve Lyapunov’s equation. Developed algorithm works properly and considered plant is met requirement of functioning with. The results shows that the developed adaptive control algorithm increases system performance in use devices significantly and might be used for correction of system’s behavior and dynamics.


1985 ◽  
Vol 107 (4) ◽  
pp. 278-283 ◽  
Author(s):  
Qiusheng Zhang ◽  
Masayoshi Tomizuka

Multivariable direct adaptive control is tested on a nonlinear thermal mixing process and is compared with state space based nonadaptive controllers. The linear quadratic optimal control approach is used to design two nonadaptive controllers: one without integral action (ordinary LQ) and the other with integral action (LQI). The operating point is changed over a wide region in the experiment. The adaptive controller is verified to perform most consistently under the tested conditions.


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