Sliding Mode Control for a Hybrid Force Control Scheme of a Robot Manipulator Under Uncertain Dynamics

Seul Jung 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.5

This paper presents the sliding mode control method for separate position and force control of a hybrid force control scheme in robot manipulation. Integral sliding mode control (ISMC) functions are defined and applied to both position and force controlled direction separately to improve the control performances by minimizing the ill effect of uncertain dynamics. Stability of integral sliding mode control for both position and force-controlled direction is analyzed in a Lyapunov sense under the decomposed sub-dynamics configurations based on the independent axis control. The sliding mode force control scheme was expected to show the better tracking performance by taking care of not only external disturbance but also internal uncertainties of a robot manipulator. Force control tasks of a three-link robot manipulator are tested with nonmodel dynamics under unknown uncertainties and their performances are compared.

후연소실 전단층 유동 진동의 증폭

김도영(Doyeong Kim),이설하(Sulha Lee),이창진(Changjin Lee) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.11

최근 연구 결과에 의하면 하이브리드 로켓 엔진에서 20Hz의 저주파수 연소 불안정성 외에 500Hz의 주파수 특성이 나타남이 보고되었다. 본 연구에서는 미연 연료 유입과 후연소실 형상이 이와 같은 변화를 일으키는 것으로 예측하여 LES기법을 이용한 수치 계산을 수행하였다. 미연 연료의 유입은 벽면분출 효과로 모사하였으며 효과가 적용된 경우와 그렇지 않은 경우를 비교하여 영향을 예측하였다. 연구 결과, 벽면 분출 효과가 적용된 경우 St = 0.25 - 0.3의 주파수가 후류에서 증폭됨을 알 수 있었으며 주파수를 차원화하면 500Hz 주파수에 해당하는 것을 알 수 있었다. 또한 후연소실의 팽창비를 변화시킴으로써 어떠한 유동 특성의 변화가 나타나는 지 예측해보았다. Recent studies identify that combustion pressure in hybrid rocket engine has another peak frequency of about 500Hz other than dominant peak frequency of around 20Hz. In this study, we suspect the unburned fuel inflow to the post-chamber causes the flow characteristics to activate peak frequency of about 500Hz in the post chamber. Numerical calculation was performed using LES (Large Eddy Simulation) methodology to investigate the effect of influx of unburned fuel flow on the evolution of flow dynamics. Results show that wall blowing, which is simulating evaporative fuel flow, produces flow dynamics showing peak frequency of about Strouhal number, St=0.25~0.3.

Destabilization of the shear layer in the post chamber of a hybrid rocket

김도영,이창진 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

Recent studies have determined that the combustion pressure in a hybrid rocket engine has another peak frequency of approximately 500 Hz aside from the dominant peak frequency of around 20 Hz; these two peak frequencies exhibit in-phase coupling upon lowfrequency instability occurrence. In this study, we suspect that the unburned fuel inflow to the post chamber causes the flow characteristics to activate the peak frequency of about 500 Hz in the post chamber. Numerical calculation was performed with large eddy simulation method to investigate the effect of the influx of unburned fuel flow on the evolution of flow dynamics. Two different boundary conditions, namely, without blowing and with blowing, were employed for the inlet wall surface, which simulates evaporative fuel flow. Results show that the effect of wall blowing from the inlet wall surface does not significantly affect the time-averaged flow field but further increases turbulent kinetic energy to the downstream part. However, wall blowing produces unique flow dynamics, showing a peak frequency that approximates the Strouhal number, that is, St = 0.25-0.3. Proper orthogonal decomposition analysis reveals that the appearance of the peak frequency of St = O(0.3) is closely associated with the destabilization of small-scale motions in the shear layer caused by the influx of unburned fuel flow. The instantaneous axial profiles of velocity and passive scalar are qualitatively similar. Therefore, passive scalar distribution is closely related to flow characteristics, such that mixing is influenced by flow characteristics change.

Seven-bar mechanical press with hybrid-driven mechanism for deep drawing; Part 2: Dynamic modeling and simulation

Hui Li,Yuping Zhang 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.11

Modeling and dynamic analysis of the electromechanical coupling system of a hybrid-driven mechanical press were undertaken. A dynamic model of a two-degrees-of-freedom seven-bar linkage was developed using Lagrange’s equation. According to the equivalent circuit of a DC motor and a brushless servomotor, a dynamic model and negative feed-back model were separately developed. The fourth-order Runge-Kutta method, an explicit method, was employed as the integration technique in a computer simulation, and the time history of the hybrid-driven press was obtained.

Dynamics modeling and simulation of a new nine-bar press with hybrid-driven mechanism

Hui Li,Yuping Zhang,Haiqi Zheng 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.12

A novel hybrid-driven mechanical press for precision drawing is presented. This new press is composed of a ninebar linkage which has two degrees of freedom determined by inputs from a dc constant speed motor and a dc servomotor. Therefore, the generalized coordinates are the angular displacement of two cranks. The kinetic energy, potential energy and generalized torques are analyzed. According to the equivalent circuit of the dc motor and the brushless servomotor, their dynamical model and position negative feedback model are developed separately. Then, a dynamical model for the hybrid-driven press is developed by using Lagrange’s formulation. The dynamical equation is then transformed into a system of first order equations. Six first order differential equations are obtained in the state variables. In the end, the fourth fourth order Runge-Kutta method, an explicit method, is chosen as the integration technique of computer simulation. Two motors’ current, two cranks’ position and two cranks’ angular velocity are treated as unknowns and the time response of the hybrid-driven press is obtained by integrating the system of first order equations through time.

멀티스케일 하이브리드 기법을 이용한 나노 채널에서의 Poiseuille 유동에 대한 수치적 연구

정명근(Myunggeun Jeong),김영진(Youngjin Kim),하만영(Man Yeong Ha) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

This study shows the multi-scale hybrid method of the nano-channel flow system. In the nano-scale region, the continuum hypothesis breaks down and the conventional continuum models are no longer valid. To escape this phenomenon, we divided simulation procedures by two steps. For the first step, the fluid properties and fluid-solid combination effect are obtained by molecular dynamics. For the second step, the Finite Volume Method (FVM) used for a nano-channel flow using the fluid properties and the slip boundary condition at wall surface also simulates from the molecular dynamics results. This multi-scale hybrid method can be reduced a computational time compared to that of previous one.

Study on secondary suspension of Maglev Conveyor with an EMPM Hybrid

Ki-Jung Kim(김기정),Jong-Boo Han(한종부),Hyung-Suk Han(한형석),Chang-Hyun Kim(김창현),Seok-Jo Yang(양석조) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

In this paper, the use of a multibody dynamic model for EM-PM hybrid-type maglev conveyor was proposed in order to accurately predict dynamic characteristics, and to analyze the effect of spring and damper in suspension device. In the Maglev conveyor based on virtual prototyping, the mechanical components, joints, and force elements are represented by multibody dynamic modeling techniques. The electromagnets, permanent magnets and their control systems are also included in the mechanical model. With the coupled model, the numerical simulations were carried out to predict and analyze dynamic responses, and a prototype of the Maglev conveyor for carrying LCD glass cassette was manufactured for experimental confirmation. Some experiments were performed to confirm the practicality of the prototype. The results of simulation and test are shown and analyzed in this paper. All results indicated that the effects of the levitation control algorithm and the secondary suspension are competent for use in this suspension system with EM-PM Hybrid.

Mechanical and Dynamic Mechanical Studies on Epoxy-Cobaltous Sulfate Polymer Hybrids

Shruti S. Devangamath,Blaise Lobo,Saraswati P. Masti,Shivayogi Narasagoudr 한국섬유공학회 2018 Fibers and polymers Vol.19 No.7

Cobaltous sulfate heptahydrate (CoSO4·7H2O) was incorporated as filler into diglycidyl ether of bisphenol A (DGEBA) based epoxy resin system, to prepare organic-inorganic polymer hybrid materials. Mechanical tensile studies and dynamic mechanical analysis (DMA) were carried out in order to study the static and dynamic mechanical properties of the prepared hybrid films. Mechanical tensile studies were carried out at room temperature, at a test speed of 30 mm/min. Highest tensile strength of 24.74±2.42 MPa was achieved for 4.44 wt% filler level (FL), along with an increase in the value of Young’s modulus. Storage modulus (E'), loss modulus (E''), damping factor (tan δ) were obtained by DMA studies. Glass transition temperature (Tg) was obtained for pure epoxy and filled epoxy, for various FLs varying from 0.28 wt% to 5.00 wt%. Pure epoxy showed highest Tg value compared to filled epoxy hybrids. Highest storage modulus of 9.5 GPa was obtained for 2.22 wt% FL, which also showed highest loss modulus peak. Parameters like effectiveness coefficient (C) and crosslink density were calculated from the storage modulus data. Loss modulus and tan δ curves were analyzed to study the energy dissipation properties of prepared hybrid films. Activation energy (Ea) value for glass transition was obtained from damping factor (tan δ), which showed highest Ea value of 630.5 kJmol-1, for 4.44 wt% FL. DMA studies for various FLs were carried out at different test frequencies in order to study the changes in dynamic mechanical properties of the prepared hybrid materials with respect to frequency.

Configuration Design and Optimization of a Novel Two-Mode Compound Power-Split Hybrid System

Hu Minghui,Zeng Li,Fu Guangshun,Zhou Anjian,Li Zhonghua,Qin Datong 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.4

Through the analysis of a CHS (Chinese hybrid system) compound power-split configuration, it is found that enhancing the system's speed decoupling ability can reduce the electric power loss, optimize the engine operating point distribution, and enhance the vehicle dynamics. This paper proposes a novel compound power-split configuration with a twospeed AMT (Automated manual transmission), which includes an electric-vehicle mode, a low-speed power-split mode, and a high-speed power-split mode. First, the electric power characteristics and rotational speed/torque characteristics of the CHS compound power-split configuration are analyzed using the lever method, theoretically demonstrating the rationality of the two-speed AMT+ compound power-split configuration. Then, the genetic algorithm is employed to optimize the multiparameters and multi-objectives in terms of the vehicle dynamics and economy. Finally, a comparative simulation and analysis of the vehicle’s economic and dynamic properties is performed for the new two-speed AMT+ compound power-split configuration and the original CHS compound power-split configuration. The results show that the vehicle economy is increased by 6.9 % for the new configuration, the acceleration time per 100 kilometers is decreased by 27.5 %, and the maximum speed is increased by 13.2 %.

Dynamic response of a laminated hybrid composite cantilever beam with multiple cracks & moving mass

Saritprava Sahoo,Sarada Prasad Parida,Pankaj Charan Jena 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.6

A novel laminated-hybrid-composite-beam (LHCB) of glass-epoxy infused with flyash and graphene is constructed for this study. The conventional mixture-rule and constitutive-relationship are modified to incorporate filler and lamina orientation. Eringen’s non-local-theory is used to include the filler effect. Hamilton’s principle based on fifth-order-layer-wiseshear- deformation-theory is applied to formulate the equation of motion. The analogous shear-spring-models for LHCB with multiple-cracks are employed in finite-element-analysis (FEA). Modal-experimentations are conducted (B&K-analyser) and the findings are compared with theoretical and FEA results. In terms of dimensionless relative-natural-frequencies (RNF), the dynamic-response in cantilevered support is investigated for various relative-crack-severities (RCSs) and relative-crackpositions (RCPs). The increase of RCS increases local-flexibility in LHCB thus reductions in RNFs are observed. RCP is found to play an important role, cracks present near the end-support cause an abrupt drop in RNFs. Further, multiple cracks are observed to enhance the nonlinearity of LHCB strength. Introduction of the first to third crack in an intact LHCB results drop of RNFs by 8%, 10%, and 11.5% correspondingly. Also, it is demonstrated that the RNF varies because of the lamina-orientation, and filler addition. For 0° lamina-orientation the RNF is maximum. Similarly, it is studied that the addition of graphene reduces weight and increases the stiffness of LHCB in contrast to the addition of flyash. Additionally, the response of LHCB to moving mass is accessed by appropriately modifying the numerical programs, and it is noted that the successive introduction of the first to ninth crack results in an approximately 40% to 120% increase in the dynamic-amplitude-ratio.