• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.576-583
• /
• 2000

A robust position control using a sliding mode controller is adopted for the stable dynamic walking of the biped. For the biped robot that is modeled with 14 degrees of freedom rigid bodies using the method of the multibody dynamics, the joint angles for simulation are obtained by the velocity transformation matrix using the given Cartesian foot and trunk trajectories. Hertz force model and Hysteresis damping element which is used in explanation of the energy dissipation during contact with ground are used for modeling of the ground reactions during the simulation. By the obtained that forces which contains highly confused noise elements and the system modeling uncertainties of various kinds such as unmodeled dynamics and parameter inaccuracies, the biped system will be unstable. For that problems, we are adopting a nonlinear robust control using a sliding mode controller. Under the assumption that the esimation error on the unknown parameters is bounded by a given function, that controller provides a successful way to preserve stability and achieve good performance, despite the presence of strong modeling imprecisions or uncertainties.

• 드라이브 ㆍ 컨트롤
• /
• 제21권3호
• /
• pp.9-19
• /
• 2024

Many modern hydraulic excavators now use EPPRVs (Electronic Proportional Pressure Reducing Valves) in their pilot systems to control the spool displacement of the main hydraulic system. However, the performance of these systems is often limited by factors such as magnetic hysteresis, mechanical wear, and transient responses influenced by operating conditions and component installation. This paper presents a pressure feedback controller for excavator pilot systems that utilize EPPRVs. This controller significantly reduces steady-state pressure control errors and mitigates the hysteresis effects commonly seen in traditional open-loop systems. To achieve this, we integrated EPPRVs with the main hydraulic valve and injected a chirp signal into the solenoid current. By doing so, we were able to measure the frequency response of the pilot system across different operating pressures and estimate the system dynamics model. Using these models, we designed a set of PI pressure feedback controllers that are guaranteed to be stable. These controllers were then integrated with a gain scheduler based on a lookup table. Experimental results demonstrate that when the developed pressure feedback controller is incorporated into the conventional open-loop controller, it effectively reduces steady-state pressure control errors and mitigates hysteresis.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.660-663
• /
• 2003

This paper proposes a systematic approach for an accurate control of the Terfenol-D actuator taking into account hysteresis, modeled by applying the classical Preisach operator with memory curve. A desired input displacement is calculated by using the hysteresis inverter, which is fed into the actuator. Then the PI compensator corrects the error between the commanded and actual displacements. Experiments with the step responses show that the PI controller settles in 70 ms and the hybrid controller in 20 ms. It means that the concurrent application of two control schemes is effective to control the actuator.

• Journal of Mechanical Science and Technology
• /
• 제18권10호
• /
• pp.1755-1762
• /
• 2004

Friction phenomenon can be described as two parts, which are the pre-sliding and sliding regions. In the motion of the sliding region, the friction force depends on the velocity of the system and consists of the Coulomb, stick-slip, Streibeck effect and viscous frictions. The friction force in the pre-sliding region, which occurs before the breakaway, depends on the position of the system. In the case of the motion of the friction in the sliding region, the LuGre model describes well the friction phenomenon and is used widely to identify the friction model, but the motion of the friction in the pre-sliding such as hysteresis phenomenon cannot be expressed well. In this paper, a modified friction model for the motion of the friction in the pre-sliding region is suggested which can consider the hysteresis phenomenon as the Preisach model. In order to show the effectiveness of the proposed friction model, the sliding mode controller (SMC) with hysteresis friction compensator is synthesized for a ball-screw servo system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.525-527
• /
• 1996

Hysteresis current control is one of the simplest techniques used to control currents for high speed drive systems, because of its simplicity of implementation, fast current control response, and inherent peak current limiting capability. However the conventional fixed-band hysteresis control has a variable switching frequency throughout the fundamental period, and consequently the load current harmonics spreaded on the wide frequency range. In this paper, a simple, novel alterative approach is proposed for a variable-hysteresis band current controller which uses feedback techniques to achieve constant switching frequency with good dynamic response. The method is easily implemented in hardware, the resultant controller is easily tuned to a particular load, and has good immunity to variation in PV parameter and dc supply voltage.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제11권2호
• /
• pp.73-79
• /
• 2011

This paper describes a reset-free delay-locked loop (DLL) for a memory controller application, with the aid of a hysteresis coarse lock detector. The coarse lock loop in the proposed DLL adjusts the delay between input and output clock within the pull-in range of the main loop phase detector. In addition, it monitors the main loop's lock status by dividing the input clock and counting its multiphase edges. Moreover, by using hysteresis, it controls the coarse lock range, thus reduces jitter. The proposed DLL neither suffers from harmonic lock and stuck problems nor needs an external reset or start-up signal. In a 0.13-${\mu}m$ CMOS process, post-layout simulation demonstrates that, even with a switching supply noise, the peak-to-peak jitter is less than 30 ps over the operating range of 500-1200 MHz. It occupies 0.04 $mm^2$ and dissipates 16.6 mW at 1.2 GHz.

• 한국인터넷방송통신학회논문지
• /
• 제22권2호
• /
• pp.123-128
• /
• 2022

SRM(Switched Reluctance Motor)의 토크는 인덕턴스의 기울기에 비례하여 발생하기 때문에 비선형 토크 특성을 가지며 토크 맥동이 크고 소음이 심한 단점을 가지고 있다. 특히 SRM의 상용화에 가장 큰 장해 요인으로 작용하고 있는 것은 회전축에서 발생하는 맥동 토크로 이에 의해 기기자체는 물론이고 주변장치에까지 여러 가지 악영향을 미친다. 따라서 맥동 토크를 저감시키는 방법으로 다양한 방안이 국내외 연구자들에 의하여 발표되었고 히스테리시스 제어기의 경우 초핑 제어에 비해 평활한 전류를 흘려줄 수 있다는 장점이 있다는 연구결과가 있다. 그러나 히스테리시스 밴드를 결정함에 있어서 밴드가 너무 작을 경우 많은 스위칭으로 인한 스위칭 손실과 엔코더의 사용 시 불안정한 초기 기동을 야기할 수 있는 둥의 단점을 가지고 있다. 따라서 본 논문에서는 속도오차에 따른 히스테리시스 밴드의 변화를 통하여 보다 안정적이고 빠른 속도응답을 가지면서 정상상태에서 토크 리플을 줄일 수 있는 가변 히스테리시스 제어기에 대하여 연구하였다.

• 한국정밀공학회지
• /
• 제18권5호
• /
• pp.137-146
• /
• 2001

A robust controller with the sliding mode is proposed for stable dynamic walking of the biped robot in this paper. For the robot system to be controlled, which is modeled as 14 DOF rigid bodies by the method of multi-body dynamics, the joint angle trajectories are determined by the velocity transformation matrix. Also Hertz force model and Hysteresis damping element are utilized for the ground reaction and impact forces during the contact with the ground. The biped robot system becomes unstable since those forces contain highly confused noise components and some discontinuity, and modeling uncertainties such as parameter inaccuracies. The sliding mode control is applied to solve above problems. Under the assumption of the bounded estimation errors on the unknown parameters, the proposed controller provides a successful way to achieve the stability and good performance in spite of the presence of modeling imprecisions of uncertainties.

• Journal of Power Electronics
• /
• 제17권6호
• /
• pp.1523-1534
• /
• 2017

A Current Error Space Phasor (CESP) based hysteresis controller with online computation of the boundary for two-level inverter fed Induction Motor (IM) drives is presented in this paper. The stator voltages estimated along the ${\alpha}$-and ${\beta}$-axes and the orthogonal current error components of the motor are used in the online computation of the hysteresis boundary. All of the inherent benefits of space phasor based hysteresis controllers such as its quick dynamic response and nearby voltage vector switching are present in the proposed scheme with the added benefit of suppressing switching frequency variations. The similarity in the frequency spectrum of the phase voltage obtained at the output of the inverter using the proposed scheme and Bus Clamping Pulse Width Modulation (BCPWM) based drive is justified with the help of extensive MATLAB SIMULINK simulations. The controller is experimentally verified with a three phase, 2.2 kW IM drive for steady state and transient conditions and the obtained results match the simulation results.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.2048-2053
• /
• 2005

The aim of this paper is to compensate hysteresis phenomena in Shape Memory Alloy (SMA) actuators by using numerical inverse Preisach model. This is used to design a controller that correct hysteresis effects and improve accuracy for the displacement of SMA actuators. Firstly, hysteresis is identified by numerical Preisach model implementation. The geometrical interpretation from first order transition curves is used for hysteresis modeling. Secondly, the inverse Preisach model is formulated and incorporated in open-loop control system in order to obtain desired input-output relationship with hysteresis reducing. The experimental results for hysteresis compensation by using this method are also shown in this paper.