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ABSTRACT: A variable structure control (VSC) algorithm is proposed with a nonlinear time-varying (NTV) sliding sector for a class of nonlinear time-variant systems represented in a state-dependent linear time-variant form. The NTV sliding sector, a subset of the state space is designed by the state-dependent differential Riccati equation (SDDRE). A VSC law is designed such that the system enters the sliding sector in finite time and a Lyapunov function candidate decreases inside the NTV sliding sector. An NTV control and a sliding mode control algorithms are proposed based on the solution of the SDDRE as well.
IEEE Transactions on Automatic Control 09/2009; · 2.11 Impact Factor
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ABSTRACT: In recent years, the use of electronic throttle valve systems has been very popular in the automotive industry. However, there exist difficulties in controlling the electronic throttle valve because of multiple nonsmooth nonlinearities including stick-slip friction, backlash, and a discontinuous nonlinear spring involved in the system. To alleviate the aforementioned difficulties in controlling the opening angle of a throttle plate and to realize a highly robust controller against uncertainties in the throttle body's mathematical model with limited cost, the variable structure concept is utilized after the employment of feedback backstepping techniques in the intermediate stages of design. Furthermore, the sliding mode observer design technique with equivalent control is exploited in order to estimate the values of necessary states that are not measured. The performance of the proposed controller is evaluated by performing some experiments on the throttle valve setup. First, small scale reference signals that pass through the nonsmooth nonlinearities are tracked even in different disturbed situations by the throttle valve plate, and then, the performance of the controller is tested for large-scale reference signals to observe the reaction time of the controller to sudden changes. For all the cases, the controller works rather well and meets the performance specifications.
IEEE Transactions on Industrial Electronics 12/2008; · 5.16 Impact Factor
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ABSTRACT: It has been observed in our bimanual operation experiment with two XY-stages that the motion of one hand effects the another hand in high frequency and this coupling becomes weaker for skilled operators. This paper explains this phenomenon from the viewpoint of decoupling control.
Systems, Man and Cybernetics, 2007. ISIC. IEEE International Conference on; 11/2007
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ABSTRACT: Bipedal robots are able to move and walk in narrow spaces; however, it is difficult to make them walk on uneven terrain only by the use of their own mechanism. Multiped walking can be easily realized for walking on uneven terrain with the help of a stick. We propose a uneven terrain walking control strategy using a stick for a bipedal robot. The advantages of using a stick are that walking is more robust with good energy efficiency and the number of actuators does not increase.
SICE, 2007 Annual Conference; 10/2007
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ABSTRACT: This paper proposes a variable structure control algorithm, with which a system can be stabilized by switching the system control input among a set of feedback control laws. Each feedback control law is easy to be designed because it uses only one state variable with a fixed plus or minus feedback gain. For an n-order system, 2n feedback control laws are needed to realize the proposed variable structure control. The concept of the sliding sector is used in the paper to show that there exists an area for the system with each feedback control law, inside which a Lyapunov function decreases with the control law although the system may not be stabilized by it alone. A common Lyapunov function for all control law exists if the system is controllable. Based on the extremum seeking control algorithm, a sliding mode is defined such that the common Lyapunov function tracks a pre-determined decreasing function. Thus a variable structure control rule is designed such that the common Lyapunov function decreases in every period when the control input is switched once through all feedback control laws. The proposed variable structure control system is quadratically stable. Simulation results are given to show the convergence of the proposed variable structure control algorithm
Decision and Control, 2006 45th IEEE Conference on; 01/2007
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ABSTRACT: This paper presents our recently research results on skill acquisition for machine operation. An assistance system with force feedback for skill acquisition is designed. An operation task is to balance an inverted pendulum. For that purpose, a virtual pendulum that is calculated real-time with computer graphics is developed. A human operator manipulates an X-Y stage as the human-machine interface with haptic function. An assistant controller is designed based on the Kawato-model. An experiment result shows effectiveness of this system for developing the skill.
Systems, Man and Cybernetics, 2006. SMC '06. IEEE International Conference on; 11/2006
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ABSTRACT: Two XY-stages have been designed and are ready for human bimanual cooperative operation experiments for human adaptive mechatoronics. Each XY-stage is equipped with two DC motors, a six-dimension force sensor, and two encoders. A human operator can move the XY-stage through a grip mounted on the force sensor. The human dynamic characteristics are investigated at first, based on which the XY-stage specification is determined. A PID controller with the virtual internal model of the XY-stage is designed such that the XY-stages can follow the trajectory given by the human operator's operation, including the position and force commands. The response of the XY-stage control systems is measured without the human's operation to adjust the parameters of the PID controller. Then the human operator's responses to sinusoidal signal of different frequency are measured to obtain the Bode diagram of human response. The characteristics of human operators with single hand and bimanual operations are investigated using the XY-stages experimentally.
Systems, Man and Cybernetics, 2006. SMC '06. IEEE International Conference on; 11/2006
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ABSTRACT: This paper presents an adaptive controller for a new type prismatic manipulator. This adaptive controller is designed with the sliding mode, by which on-line parameters estimation mechanism is implemented and the control input is determined adaptively combining the estimation mechanism. The derivative of the signal is estimated by an adaptive VS-differentiator
Variable Structure Systems, 2006. VSS'06. International Workshop on; 07/2006
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ABSTRACT: This paper proposes a variable structure (VS) controller with sliding sector for hybrid systems where subsystems do not need to be stable and may be unknown. The controller is designed to switch among subsystems to stabilize the hybrid system by a variable structure switching law. The concept of the sliding sector is used in the paper to show that there exists an area, inside which a Lyapunov function decreases, for any system no matter whether it is stable or unstable. A Lyapunov function is designed by assuming that a stable convex combination of the subsystems exists. Then the VS controller is designed such that the Lyapunov function decreases in every period for the hybrid system to be switched once through all subsystems. The extremum seeking control algorithm is used to determined the switching rule such that the Lyapunov function track a pre-determined decrease signal. The proposed VS system is quadratically stable. Simulation results are given to show the convergence of the proposed VS control system
Variable Structure Systems, 2006. VSS'06. International Workshop on; 07/2006
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ABSTRACT: Based on a new concept of a human-in-the-loop system called Human Adaptive Mechatronics(HAM), an assist-control for a force/vision interactive haptic system is discussed in this paper. An assist-control scheme proposed here consists of a 'variable dynamics' unit and an online identifier of an operator's control characteristics. The former unit is realized by tuning an impedance of the haptic device's virtual model according to the identified operator's parameters. At a stage of the controller design, a human and a machine are considered as a plant and a controller respectively. A role of the controller is to tune dynamics of the machine so as to enhance operator's control performance. The tuning law is derived by utilizing a Lyapunov candidate function. We developed a HAM-haptic device test system, executed evaluation experiments with the apparatus, and analyzed the measured data. It was confirmed that the operator's characteristics can be estimated sufficiently and that operator's performance was enhanced by the variable dynamics assist-control.
Decision and Control, 2005 and 2005 European Control Conference. CDC-ECC '05. 44th IEEE Conference on; 01/2006
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ABSTRACT: A purpose of this paper is to discover catholic characteristic of human skill in machine manipulation for realization of a human adaptive mechatronics (HAM). HAM is a novel concept of intelligent mechanical systems that adapt themselves to the user's skill and assist to improve the user's skill. This paper reports experimental analyses of human characteristic in machine operation by utilizing a stabilization task. By using a force-feedback haptic device and a real-time computer graphics of a virtual pendulum, skill processes of subjects were observed, and three kinds of analyses were applied. The first is probability distribution analysis of motion, the second is monitoring of brain cortical by a near-infrared spectroscopy (NIRS), and the last is correlation analysis to estimate human control law. It could be confirmed that human who mastered the stabilization task sufficiently (i) utilizes sensory information of wide body part, (ii)reinforces on active visual sensing, and (iii) predicts velocity information by using dynamics model which is formed in brain
Neural Networks and Brain, 2005. ICNN&B '05. International Conference on; 11/2005
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ABSTRACT: This paper proposes a variable structure (VS) control algorithm for a hybrid system where all of subsystems are unstabilizable, i.e. there exists at least one uncontrollable and unstable subspace for each subsystem. It has been shown that there exists a norm decrease subspace called sliding sector inside which a Lyapunov function decreases without any control effort even if the system is unstable. In this paper, the sliding sector is used to find a norm decrease subspace for each subsystem and a feedback law is designed so that each point in the state space is inside at least a sliding sector of some subsystem. Therefore the VS control law of the hybrid system is to switch the hybrid system among unstabilizable subsystems to ensure the decrease of the Lyapunov function in the state space. Simulation results are given to show the efficiency of the proposed hybrid control algorithm.
Machine Learning and Cybernetics, 2005. Proceedings of 2005 International Conference on; 09/2005
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ABSTRACT: This paper presents an Internet-based tele-control system for a wheeled mobile robot. A real-time embedded controller using Labview was designed to control the mobile robot remotely through Internet by a Web browser, for example, Internet Explorer or Netscape. A CCD camera is mounted on the mobile robot to acquire information, which is displayed inside the browser for the remote operator's operation. The IEEE 802.11x (WiFi) wireless LAN linking the robot to Internet and long run batteries are used so that the mobile robot can move without any cable connected to power supply or Internet. The designed mobile robot can be remotely operated from anywhere around the world as long as there is a set of computer with keyboard, mouse, display and connection to Internet.
Mechatronics and Automation, 2005 IEEE International Conference; 02/2005
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ABSTRACT: The Control Authority Transition (CAT) system project (supported by The OSU Center for Automotive Research and Intelligent Transportation Consortium) has led to emulation of the control authority transition algorithms in the physical half-car environment through The Ohio State Virtual Environment System (OSU-VES). By creation of the artificial traffic environment and possible accident hazards scenarios, the CAT system's interventions to the "inattentive" or "inadequate" drivers are under consideration. The development and improvement of the CAT, OSU-VES and half-car platform is a test-bed for the study of driver's perception-reaction time, behavior, driver-vehicle interactions, crash avoidance maneuvers, advanced safety systems, and Intelligent Transportation System technologies.
Intelligent Vehicles Symposium, 2003. Proceedings. IEEE; 07/2003
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ABSTRACT: In this paper, we propose an algorithm to solve the Nash equilibrium solution for an n-person noncooperative dynamic game by the extremum seeking control approach with sliding mode. For each player, a switching function is defined as the difference between the player's cost function and a reference signal. The extremum seeking controller for each player is designed so that the system converges to a sliding boundary layer defined in the vicinity of a sliding mode corresponding to the switching function and inside the boundary layer, the cost function tracks the reference signal and converges it to the Nash equilibrium solution.
Decision and Control, 2002, Proceedings of the 41st IEEE Conference on; 01/2003
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ABSTRACT: This paper focuses on the design of a controller for the throttle valve that is used in combustion engines for the purpose of adjusting air-fuel ratio. Due to the right-hand side discontinuities and uncertainties in the throttle body's mathematical model, sliding mode concept is utilized after the employment of feedback linearization techniques in the intermediate stages of design. Finally, the performance of the proposed controller is evaluated with the simulation and experimental studies.
American Control Conference, 2002. Proceedings of the 2002; 02/2002
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ABSTRACT: In this paper, we propose three kinds of discrete-time extremum seeking control algorithms. As the static map from the setpoint to the cost function can be approximately represented by a polynomial, the extremum can be easily found according to the polynomial. In the first algorithm, the extremum seeking control is realized by the least square estimation method. In the second and third algorithms, the extremum point is estimated by approximating the static map as a parabola and an ellipse, respectively. The simulation results show the feasibility of the proposed algorithms.
American Control Conference, 2002. Proceedings of the 2002; 02/2002
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ABSTRACT: Drivers differ significantly in their skill levels, driving
habits, capabilities and decisions especially when impaired by drugs,
fatigue or physical handicaps. Late or inadequate responses to hazards
and dangers may cause severe results. It may be possible to improve the
ability of a driver to operate a vehicle safely if certain parameters in
the control of the vehicle axe adjusted according to the driver's normal
characteristics. Value has already been established for tailoring
certain attributes such as seat, pedals, steering wheel position and
mirrors to a given driver through memory functions. This research
concentrates on assessing a driver's operating characteristics and
modifying the control of the vehicle to improve safe operation of the
vehicle on a real-time basis
Intelligent Transportation Systems, 2001. Proceedings. 2001 IEEE; 02/2001
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ABSTRACT: The use of an electronic controlled throttle valve can increase
the efficiency and performance of an engine since the control of the
throttle valve, which is determined according to the desired amount of
air flow calculated from the desired speed and engine torque, is
independent from the position of the accelerator. In this paper, a
variable structure (VS) controller is designed for the electronic
throttle valve. The model of the electronic throttle valve is discussed
at first. Then the VS controller is proposed by using the backstepping
approach. Finally, simulation and experimental results are given
Vehicle Electronics Conference, 2001. IVEC 2001. Proceedings of the IEEE International; 02/2001
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ABSTRACT: Unlike a conventional throttle valve which is connected to the
accelerator directly by a wire, an electronic throttle valve is driven
by a DC motor and can move independently from the position of the
accelerator. This feature provides flexibility in determining the amount
of air flow into the engine. However, it is difficult to control the
electronic throttle valve as the valve system involves nonsmooth
nonlinearities such as stick-slip friction, gear backlash, and nonlinear
spring. The electronic throttle valve system is modeled with the
nonsmooth nonlinearities considered. A discrete-time sliding mode
controller and observer are designed to realize robust tracking control
of the valve system. Experimental results are presented
Decision and Control, 2001. Proceedings of the 40th IEEE Conference on; 02/2001
