Showing papers by "Hiroshi Fujimoto published in 2001"
TL;DR: By generalizing the relationship between the sampling period of plant output and the controlperiod of plant input, the proposed method can be applied to various systems with hardware restrictions of these periods, which leads to higher performance.
Abstract: In this paper, a novel perfect tracking control method based on multirate feedforward control is proposed. The advantages of the proposed method are that: (1) the proposed multirate feedforward controller eliminates the notorious unstable zero problem in designing the discrete-time inverse system; (2) the states of the plant match the desired trajectories at every sampling point of reference input; and (3) the proposed controller is completely independent of the feedback characteristics. Thus, highly robust performance is assured by the robust feedback controller. Moreover, by generalizing the relationship between the sampling period of plant output and the control period of plant input, the proposed method can be applied to various systems with hardware restrictions of these periods, which leads to higher performance. Next, it is shown that the structure of the proposed perfect tracking controller is very simple and clear. Illustrative examples of position control using a DC servomotor are presented, and simulations and experiments demonstrate the advantages of this approach.
269 citations
Patent•
03 Dec 2001
TL;DR: In this article, a high-strength austenitic stainless steel strip exhibiting excellent flatness with Vickers hardness of 400 or more has been manufactured by solution-heating a steel strip having the above composition, cold-rolling the steel strip to generate a deformation-induced martensite, and then reheating at 500-700°C.
Abstract: A high-strength austenitic stainless steel strip exhibiting excellent flatness with Vickers hardness of 400 or more has the composition comprising: C up to 0.20 mass %, Si up to 4.0 mass %, Mn up to 5.0 mass %, 4.0-12.0 mass % Ni, 12.0-20.0 mass % Cr, Mo up to 5.0 mass %, N up to 0.15 mass % and the balance being Fe except inevitable impurities having a value Md(N) in a range of 0-125 defined by the formula Md(N)=580-520C-2Si-16Mn-16Cr-23Ni-26Cu-300N-10Mo. The material has a dual-phase structure of austenite and martensite involving a reverse-transformed austenite at a ratio of 3 vol. % or more. The material is manufactured by solution-heating a steel strip having the above composition, cold-rolling the steel strip to generate a deformation-induced martensite, and then re-heating at 500-700° C. to induce a phase reversion from martensite to at least 3 vol. % austenite. The reversion effectively flattens the steel strip.
41 citations
04 Dec 2001
TL;DR: In this paper, a multirate sampling controller is proposed for digital control systems, where the speed of the A/D converters is restricted to a slower rate than that of the D/A converters.
Abstract: Multirate sampling controllers are proposed for digital control systems, where the speed of the A/D converters is restricted to be slower than that of the D/A converters. The proposed feedback controller assures perfect disturbance rejection at M intersample points in the steady state. The proposed method is extended to systems with time delay, and the compensation method is proposed based on the observer including time delay model. Next, the scheme of repetitive control is proposed based on the open-loop estimation and switching function, which enables the rejection of periodical disturbance without any sacrifice of the closed-loop characteristics. Finally, the proposed controllers are applied to a visual servo system by introducing the workspace controller and nonlinear perspective transformation. The advantages of these approaches are demonstrated by simulations and experiments using a robot manipulator.
33 citations
Patent•
14 Sep 2001
TL;DR: In this article, a stainless steel sheet with a high Young's modulus of 200,000 N/mm 2 in the T direction and the L direction was proposed, which has a composition containing, by mass, 0.04 to 0.15% C, ≤2.0% Si, 10.0 to 20.2% rare earth metals and 0.1% Ca (0% denotes the case of no addition), and the balance Fe with inevitable impurities.
Abstract: PROBLEM TO BE SOLVED: To provide a stainless steel sheet which has a high Young's modulus of 200,000 N/mm 2 in the T direction and the L direction therein. SOLUTION: The steel sheet has a composition containing, by mass, 0.04 to 0.15% C, ≤2.0% Si, ≤2.0% Mn, 10.0 to 20.0% Cr, 0.5 to 4.0% Ni, 0 to 2.0% Cu, ≤0.10% N, 0 to 2.0% Mo, 0 to 0.05% Al, 0 to 0.50% Nb, 0 to 0.30% V, 0 to 0.50% Ti, 0 to 0.015% B, 0 to 0.2% Y, 0 to 0.2% rare earth metals and 0 to 0.1% Ca (0% denotes the case of no addition), and the balance Fe with inevitable impurities, and has a fine duplex structure in which the old austenite mean grain diameter is ≤7 μm in a duplex structure of ferrite +40 to 95 vol.% martensite. This steel sheet is produced by heating a worked steel sheet obtained at a cold rolling rate of ≥20%, and having a ferrite single phase structure, e.g. to the temperature range of 950 to 1,100°C, and cooling the steel sheet. COPYRIGHT: (C)2003,JPO
13 citations
21 May 2001
TL;DR: Novel multirate controllers are proposed for digital control systems, where it is restricted that the sampling period of plant output is longer than the controlperiod of plant input, based on the open-loop estimation and switching function.
Abstract: In this paper, novel multirate controllers are proposed for digital control systems, where it is restricted that the sampling period of plant output is longer than the control period of plant input. The proposed controllers can assure perfect disturbance rejection at M intersample points in the steady state. Moreover, the novel scheme of repetitive control is proposed based on the open-loop estimation and switching function, which enables to reject periodical disturbance without any sacrifice of the feedback characteristics. The proposed methods are applied to the visual servo system, and the advantages of these approaches are demonstrated by simulations.
13 citations
Patent•
10 May 2001
TL;DR: In this article, a stainless steel strip having excellent shape fixability in which the defects of shape such as springback or twist appearing in a formed product can be reduced by using an inexpensive material having a low Ni content, and a production method therefor.
Abstract: PROBLEM TO BE SOLVED: To provide a stainless steel strip having excellent shape fixability in which the defects of shape such as springback or twist appearing in a formed product can be reduced by using an inexpensive material having a low Ni content, and to provide a production method therefor SOLUTION: Ferritic stainless steel having a composition containing, by mass, <=010% C, <=10% Si, <=20% Mn, <=0050% P, <=0020% S, <=30% Ni, 80 to 220% Cr and <=005% N, and, if required, further containing one or more kinds selected from <=10% Mo, <=10% Cu, <=010% Al, 001 to 050% Ti, 001 to 050% Nb, 001 to 030% V, 001 to 030% Zr and 00010 to 00100% B, and the balance Fe with inevitable impurities is hot-rolled and thereafter heated to the Ac1 point or higher on process annealing to uniformly disperse an austenitic phase into a ferritic phase
9 citations
Patent•
07 Jun 2001
TL;DR: In this article, the authors proposed a high strength stainless steel strip for a metal gasket such as a cylinder head gasket and an exhaust manifold gasket which has an excellent fatigue performance and setting resistance.
Abstract: PROBLEM TO BE SOLVED: To provide a high strength stainless steel strip for a metal gasket such as a cylinder head gasket and an exhaust manifold gasket which has an excellent fatigue performance and setting resistance. SOLUTION: The stainless steel strip has a composition containing one or more kinds selected from 0.01 to 0.15% C, 0.3 to 1.0% Si, 10.0 to 20.2% Cr, one or more kinds selected from Ni, Mn and Cu by 0.3 to 5.0% in total, 0 to 0.015% B and 0 to 1.0% Mo, and satisfying C+N/2=0.03 to 0.15%, γ max =20 to 95, and (C+N/2)×γ max ≥3.0, and having a dual phase structure of ferrite + martensite including ferrite of ≥5 vol.%. The steel strip is produced by subjecting a cold rolled steel strip to dual phase formation annealing where the steel strip is introduced into a continuous annealing furnace, is heated at a temperature of 950 to 1,100°C in which a dual phase region of ferrite + austenite is formed, and is thereafter cooled: γ max =(420C+470N+23Ni+7Mn+9 Cu)-(11.5Cr+11.5Si+12Mo+49Ti+52Al)+189...(1). COPYRIGHT: (C)2003,JPO
7 citations
Patent•
13 Nov 2001
TL;DR: In this paper, an epoxy resin coating material composition for clean rooms is presented, which is composed of an amine-based resin curing agent, an organic solvent having a boiling point of =80 (relative value taking the evaporation rate of butyl acetate as 100) and a pigment.
Abstract: PROBLEM TO BE SOLVED: To obtain an epoxy resin coating material composition for clean rooms produced by excluding risky components as far as possibly, using a solvent emitting a volatile gas component quickly decaying in the drying step and excluding a component derived from a volatile organic material having high boiling point and remaining over a long period. SOLUTION: This epoxy resin coating material composition for clean rooms contains (A) an epoxy resin having an epoxy equivalent of 100-30,000, (B) an amine-based resin curing agent selected from aliphatic polyamines, aromatic polyamines, alicyclic polyamines, polyamide amines and their modified materials, (C) an organic solvent having a boiling point of =80 (relative value taking the evaporation rate of butyl acetate as 100) and (D) a pigment. The composition has a phosphorus content of <=100 ppm and a boron content of <=100 ppm.
5 citations
Patent•
31 Aug 2001
TL;DR: In this paper, a high-strength austenitic stainless steel strip with Vickers hardness of 400 or more is proposed, which has a dual-phase structure of austenite and martensite.
Abstract: A high-strength austenitic stainless steel strip excellent in flatness of
shape with Vickers hardness of 400 or more is newly proposed, which has the
composition consisting of C up to 0.20 mass %, Si up to 4.0 mass %, Mn up to
5.0 mass %, 4.0-12.0 mass % Ni, 12.0-20.0 mass % Cr, Mo up to 5.0 mass %, N
up to 0.15 mass % and the balance being Fe except inevitable impurities
under the condition that a value Md(N) defined by the formula (1) is in a
range of 0-125. It has a dual-phase structure of austenite and martensite
involving reverse-transformed austenite at a ratio of 3 vol.% or more. It is
manufactured by solution-heating a steel strip having the composition,
cold-rolling the steel strip to generate deformation-induced martensite, and
then re-heating at 500-700°C to induce reversion. The reversion effectively
flattens a shape of the steel strip.
Md(N) =580-520C-2Si-16Mn-16Cr-23Ni-26Cu-300N-10Mo
3 citations
Patent•
10 Oct 2001
TL;DR: In this article, an austenitic stainless steel sheet which can be stamped into a product having little amount of sag and precise stamped fracture surface has been proposed, where the tensile elongation at break is regulated to be 60% or less by means of controlling the number of the crystal grain size prescribed in JIS G0551 to be 8-11 through coldrolling after annealing and pickling, or in an annealed state, provides a product with little amounts of sag after finely stamped.
Abstract: PROBLEM TO BE SOLVED: To provide an austenitic stainless steel sheet which can be stamped into a product having little amount of sag and precise stamped fracture surface SOLUTION: The austenitic stainless steel sheet has -120 to -10 of austenitic stability index Md 30 defined by the expression (1): Md 30 (°C)=551-462(C+N)-92Si-81Mn-29(Ni+CU)-137Cr-185Mo, 30 or higher of stacking fault difficulty index SFE defined by the expression (2): SFE (mJ/m 2 )=22Ni+6Cu-11Cr-13Si-12Mn+32, an amount of dissolved Cu in a matrix kept to a range of 10-40 mass%, by regulating Cu contained in precipitates to be 10 mass% or less, and 600 N/mm 2 or less of tensile strength after annealed and pickled Furthermore, the austenitic stainless steel sheet of which the tensile elongation at break is regulated to be 60% or less by means of controlling the number of the crystal grain size prescribed in JIS G0551 to be 8-11 through cold-rolling after annealing and pickling, or in an annealed state, provides a product having little amounts of sag after finely stamped COPYRIGHT: (C)2003,JPO
2 citations
01 Jan 2001