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Volume 26, Issue 4
Displaying 1-16 of 16 articles from this issue
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Junichi SUGIYAMA, Shiro USUI1990 Volume 26 Issue 4 Pages 367-374
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSAcoustic impulse response of muskmelons was studied to evaluate their quality. First, linearity and the effects of supporting conditions on the acoustic signals were examined. Secondly we obtained acoustic signals at points which divide the equator of the sample into 24 equal parts. These signals were displayed in a three-dimensional diagram with axes of time, location and sound intensity, and in a two-dimensional map with a gradation of 257 colors. For a more complete visual comprehension, an animation display which shows time changes of the distribution of sound intensity was presented. As a result of these analyses, it became evident that the impulse waveform of acoustic signals induced by impact was transmitted along the surface of the equator with uniform velocity. This transmission velocity became lower as the muskmelon ripened. The lower transmission velocity in the time domain agreed with the lower peak frequency in the frequency domain, both theoretically and practically. Because the wave equation suggests that the transmission velocity depends on the tensile force of the sample, the nondestructive evaluation provides a more direct index of the quality of muskmelons.View full abstractDownload PDF (1860K) -
Hikaru YAMADA1990 Volume 26 Issue 4 Pages 375-381
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA new method of Differential Non-linearity (DNL) error correction for the successive approximation A/D converter (SAADC) is proposed.
The SAADC has very short conversion time and is very useful in various fields. But it has the largest DNL in comparison with any other type of ADC.
The DNL is the channel width irregularity of ADC, and is the most difficult error to deal with since it cannot be eliminated by adjustment.
The most famous research to equalize the channel width of SAADC is the Gatti's “Sliding Scale Method” proposed 28 years before approximately.
This new method of DNL error correction is based upon the peculiar feature of the SAADC.
First, the generation mechanism of DNL error is analyzed.
Second, a new method of DNL error correction is proposed.
Finally, the feasibility of this newly proposed method is confirmed through the computer simulations.View full abstractDownload PDF (791K) -
Takayoshi TOTANI, Masami HODATE1990 Volume 26 Issue 4 Pages 382-388
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA fixed-final-state linear optimal tracking problem can be solved by applying a compensation input to a steady-state optimal regulator, and the compensation input can be computed by specifying a desired trajectory and terminal conditions. This paper proposes a learning method in which the compensation input is modified to reduce the trajectory error by using the error obtained by each trial. It is shown that even when the dynamics of the real plant is different from its mathematical model, the trajectory error by this method is also reduced monotonously with the iterative procedure under a certain condition. As the proposed method does not have any differential or phase lead operations on the error, it is free from noises of this kind. Results of simulation and experiments on the trajectory control of a two-link arm are shown, and the applicability of this method to robot arms with nonlinearities and differences of dynamics from their mathematical models is examined.View full abstractDownload PDF (807K) -
A Transformation of Rational Functions to the Finite Laplace Transforms on the Basis of Smith FormKeiji WATANABE1990 Volume 26 Issue 4 Pages 389-396
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper is concerned with finite spectrum assignment of multivariable systems with commensurate delays. The control law over rational functions of a delay oprator is transformed to the one with polynomials of the delay operator and finite Laplace transforms by the proposed method which is based on the structure of the Smith form of the control matrix.View full abstractDownload PDF (816K) -
Katsuhisa ENDO, Yoshihisa ISHIDA, Takashi HONDA, Yasuo OGAWA1990 Volume 26 Issue 4 Pages 397-404
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes a method to control a pneumatic cylinder using digital techniques.
The pneumatic cylinder has been used as an actuator for industrial robots, because it is simple, small and economic. However it is difficult to decide precisely the position of the piston rod, owing to the air compression and the friction of the device itself.
There is a servo system in one of the cylinder's positioning controls. This method can realize the positioning control system with high accuracy. However, the overshoot becomes big when the moved distance is long.
We are trying to create a positioning control with least overshoot and high accuracy by using a new method of combined position control and speed control. However, the manipulated variable is often not continuous, and the overshoot becomes big if there is an error in the changing point from speed control to position control.
We therefore guide the speed control system from the position control system by applying the optimal control theory that pays attention to the inside condition of the system. This new method gives continuity of the manipulated variable. As a result, we have been getting comparatively high precision with least overshoot.
Furthermore we propose a method that is able to obtain the positioning accuracy below resolution of a sensor.View full abstractDownload PDF (1028K) -
Katsumasa SUZUKI1990 Volume 26 Issue 4 Pages 405-411
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA new type of hydraulic pressure intensifier was previously proposed by the author, which operates on the principle that an oil hammer is generated continuously in the pipeline by the on-off operation of a solenoid operated valve located at the downstream end of the pipeline and only the high pressure fluid is discharged through a check valve. In addition, a method to utilize the intensifier for pressure control of a hydraulic cylinder by adjusting a pulse to the solenoid operated valve was already proposed.
In this paper, a pressure control system utilizing this intensifier is developed to generate a wave form according to a desired input. The empirical formula which relates the pulse width to the corresponding pressure increase is established in advance and memorized in a computer. When the desired pressure is given to the computer, it calculates the pulse width automatically through the empirical formula and sends a pulse to a solenoid operated valve. This system generates a pressure higher than the supply pressure. As the inertia of the fluid is utilized for pressure control instead of usual pressure losses, it has a possibility of pressure control with higher efficiency than the usual method.View full abstractDownload PDF (795K) -
Keiju MATSUI, Kazuo TSUBOI, Saburo MUTOU1990 Volume 26 Issue 4 Pages 412-419
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSFor the voltage source type inverters of comparably small capacity, in order to control the feed back power from the load, the discharge resistance which is parallel-connected to dc link circuit is commonly used.
For such application as feeding back power repeatedly, or for the comparably large capacity, however, the discharge resistance method can not be applied. Instead of its method, it is well known that the line commutated inverter method is often applied. However, this method has the demerit of providing the identical two bridges of thyristors, and largely lowering the power factor as the regenerative power varies.
For the next type of regeneration control, the PWM converter has often reported, but is slightly different in contrast of the view of this paper. But, this converter has excellent characteristics. For the larger power capacity, however, the cost of the converter would be high. In the case that aims principally the regeneration control and does not care the improvement of the output waveforms, its application would be restricted. Under such circumstances, the first purpose of this paper, apart from the improvement of the output waveforms, is the proposal of a few regeneration method which can be realized at lower cost. From such viewpoints, the authors have investigated to accomplish the purpose. In the proposed equipments, the rectifier bridge can be also used for inversion through the medium of the dc reactor or the capacitor. The second purpose, in order to analyze the output current waveforms, is to propose a new frequency analysis method by using the switching function. The appropriateness of its theory has been experimentally confirmed.View full abstractDownload PDF (1062K) -
Hiroyuki KOJIMA, Shinji IKEDA, Takashi TABATA1990 Volume 26 Issue 4 Pages 420-426
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA robot consisting of step motors and reduction gear is utilized as industrial robots owing to the light weight design and the low cost. Then, it is useful to investigate theoretically the dynamic characteristics of the robot driven by the step motors in consideration of the transient vibrations excited by intermittent motions of the step motors.
In this paper, the dynamic characteristics of the horizontal two-link robot driven by step motors and harmonic drive gears is investigated by the numerical simulation and the experiments. In the numerical simulation analysis, the equation of motion is derived in consideration of the transient vibration of step motors and the nonlinear flexibility of the harmonic drive gears. Then, it is clarified that the distinguish resonance frequency agree with the drive frequency of the step motors at the resonance of the system. When the step motors controlled by the trapezoidal velocity curve are driven with the distinguish resonance frequency of the system in the period of constant velocity, the resonance vibrations with big amplitudes are generated, especially in the step motors. Then, the vibration amplitudes of the links are smaller than the ones of the step motors. Furthermore, it is proved experimentally that the distinguish resonance phenomenon of the robot driven by the trapezoidal velocity curve occurs.View full abstractDownload PDF (844K) -
Zhi-wei LUO, Masami ITO1990 Volume 26 Issue 4 Pages 427-434
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper considers the problems of control design of robot performing compliant manipulation.
Compliant manipulation fundamentally requires that the controlled robot can not only follow up the input trajectory exactly in free motion space, but also move adaptively in constrained space while making compliant contact with its dynamic environment. However generally, since there exists no mechanical link between robot and its operating environment, because of the dynamic interaction, the contact discontinuity may probably cause. So even if the total system including robot and its environment is analyzed to be stable when thinking of nothing on such contact discontinuity, the real system may be unstable.
In this paper, with the formulation of environment dynamics, the simplification of robot body dynamics by nonlinear feedback compensation, and the definition of compliancy and environment adaptability that clarifies the control design objectives, we present a model matching approach for the control design of robot compliant manipulation considering the contact discontinuity.
The problems of how to select the reference model considering the environment dynamics, its dynamic uncertainty and robot actuator's output limitation, and how to implement such model in the control system are analyzed.
Also the effectiveness of this approach is illustrated by some simulation results.View full abstractDownload PDF (1000K) -
Kazuyuki NAGATA, Tsukasa OGASAWARA, Toru OMATA1990 Volume 26 Issue 4 Pages 435-442
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSControlling manipulators during the transition from the free space to the constraint space is important to avoid vibration or crashing of a grasped object in assembly tasks. This paper discusses smoothing the contact of an articulated manipulator with the object in the transition from the free space to the constraint space.
We point out that lateral velocities significantly change the momentum of the manipulator and thus much reduce the contact impact while keeping the pose of the manipulator and the desired velocity in the direction perpendicular to the contact surface.
First, we derive the optimal bumping velocity which minimizes the error between a desired steady state force and an impact force, and apply this method to a 2-link manipulator. Next, the relationship between the optimal bumping velocity and the momentum is considered in terms of energy ellipsoid. Further, we examine the optimal bumping velocity when time delay of contact detection exists. Lastly, simulation results of bumping by the 2-link manipulator are shown.View full abstractDownload PDF (819K) -
Koji ITO, Toshio TSUJI, Minoru SUGINO1990 Volume 26 Issue 4 Pages 443-450
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn the present paper, we discuss how the human subject controls the hand position and force depending on task objects, and what roles the arm redundancy and the muscle impedance regulation play in rotation movements.
From the measurement of the hand force and the arm posture in the execution of crank rotations, it was found that the subject made the wrist joint impedance large and generated the hand force in the direction normal as well as tangential to the crank rotation. Impedance analysis demonstrated that the high impedance of the wrist joint, realized by the simultaneous activities of flexor and extensor muscles, was able to provide for the posture of redundant arm without limiting the hand manipulatability. Then it was shown that the hand force in the outer and normal directions contributed to increase the robustness of the hand manipulation against the external disturbance.View full abstractDownload PDF (1042K) -
Tatsuo ARAI, Tatsuya NAKAMURA, Masato SATO1990 Volume 26 Issue 4 Pages 451-458
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA 3-D automated sewing system with a direct-drive manipulator is proposed to improve productivity and to promote automation in the apparel industry. To keep high sewing precision and to avoid complex path-teaching, trace motion technique based on the hybrid position/force control is adopted for moving a sewing machine. The control algorithm is designed for a real time control of the actual 6 DOF manipulator. The experiments of circle sewing, assuming sleeve attaching task, show the effectiveness of the proposed algorithm compared with the conventional teach and play-back method.View full abstractDownload PDF (2654K) -
Akihito SANO, Junji FURUSHO1990 Volume 26 Issue 4 Pages 459-466
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA biped locomotion robot is expected to be very useful in indoor space designed for human locomotion. In order to achieve a smooth dynamic walking like a human being, it is very important to control a quantity which can represent the state of the biped system as a whole. In regard to biped locomotion systems, an angular momentum of the whole system can be considered as a good index, since it is a stable quantity, as seen from ‘the law of the conservation of angular momentum.’ A control method divided the walking into motions in the sagittal plane and in the lateral plane is adopted. For motion in the sagittal plane, we put the angular momentum close to the smooth reference function given in advance by controlling the ankle torque of supporting leg. For motion in the lateral plane, we treated the motion control as a regulator problem with two equilibrium states. The effectiveness of the proposed control method was examined by the experiments with our walking robot BLR-G2. The BLR-G2 achieved three-dimensional walking where the walking speed is 0.35m/s with stride length 35cm.View full abstractDownload PDF (2491K) -
Tamiki HOSOKAWA, Yuh YAMASHITA, Masasuke SHIMA1990 Volume 26 Issue 4 Pages 467-473
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn this paper, we study the stabilization problem of a spacecraft with three independent torque actuators via state feedback. We describe its attitude with the quaternion q_??_(q1, q2, q3, q4), ||q||2_??_q12+q22+q32+q42=1, instead of the rotation matrix R∈SO(3), which is known to have the manifold structure. The purpose of this paper is to derive a global static feedback law such that quaternion q converges to (0, 0, 0, 1).
First of all, we cover the manifold SO(3) with four local co-ordinates A: (q1, q2, q3), B: (q1, q2, q4-1), C: (q1, q2, q4-1), D: (q2, q3, q4-1). And, by means of the nonlinear control theory, we obtain four local control laws u=uA(x), u=uB(x), u=uC(x), u=uD(x) corresponding to them. But, each control law has singular points where the inputs diverge. If we adopt an idea that the control laws are switched according to the value of the quaternion in order to avoid the problem of the singular points, the control inputs are not smooth at the switching point. So, we synthesize a new control law u=q42uA+q32uB+q22uC+q12uD from local control laws. The new control law, of which each term is equal to zero at the singular points, is smooth and gives globally stable closed-loop system. Furthermore, its structure is much simpler than four local control laws. This method is applicable to both gas-jet actuators and reaction wheel actuators. The control law for gas-jet actuators is the special case of the control law derived in Ref. 5).View full abstractDownload PDF (733K) -
Takahiro ITO, Akira SHINDO1990 Volume 26 Issue 4 Pages 474-481
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes a method of motion planning for a dualhand assembly system. Two major possibilities of two-arm robots are as follows
(1) coordination between the two arms (for example, assembling bolts and nuts);
(2) being able to perform two different tasks at the same time. However, there is an increasing degree of teaching complexity when two manipulators must be coordinated in contrast to working independently. Therefore, a plan generator is required to be developed for two-arm robots. In this paper, a knowledge-based approach is introduced to actualize multimanipulator coordination planning.
A data model which is used for generating plans is described. Assembly parts are divided into two categories, “plan” and “world”. In describing this structure, a “frames” system is used. “Plan” describes the simple assembly structure in an assembly plan. According to this structure, the sequence of parts-transfer is generated. “World” consists of parts on an actual assembly cell. In these models, the three-dimensional information attached to them such as, the coordinates of points, are represented.
After the sequence of parts-transfer is obtained, it has to be translated into the motions of each manipulator. However, there sometimes is a deadlock problem. This deadlock occurs when each manipulator arrives at the shared space at the same time. To prevent collision, each must wait until the other completes its task and therefore, may be in a complete standstill.
To avoid this deadlock, priority is set to each manipulator in every unit of motion. The assembly is well performed when this priority is adjusted according to each motion. This is called this “adaptive priority method”, which is tested by computer simulation. To get the best priority combination, an optimal-search method is employed. Using this method, the sequence with the shortest total performance time can be selected.View full abstractDownload PDF (1006K) -
Masahiro OYA, Yukio NISHIMURA, Yoh YONEZAWA1990 Volume 26 Issue 4 Pages 482-484
Published: April 30, 1990
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA model following control method for systems containing a nonlinearity at the input is proposed. In the control system, an integral compensator is used so that the steady states of the object agree with that of the model.View full abstractDownload PDF (367K)
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