• Journal of Institute of Control, Robotics and Systems
• /
• v.6 no.1
• /
• pp.73-80
• /
• 2000

The stewart platform manipulator proposed by stewart is the parallel manipulator which is composed of several independent actuators connecting the upper plate with the base plate and capable of executing a six degree of freedom motion. The manipulator has a structure of a closed loop form, and provides better load-to-weight ratio and ratio and rigidity than a serial manipulator with an open loop form. Moreover, the manipulator has high positional accuracy because position errors of actuators are not additive. Because of these advantages, this manipulator is widely used in many engineering applications such as a driving simulator, a tool of machining center, a force/torque sensor and so on. When this Stewart platform manipulator is controlled in joint space, it is difficult to design a controller using an analytic method due to nonhnearity and unknown parameters of actuators. Therefore, a PID controller is often used because of easiness in applications. To find the PID control gain, a trial-and-error method is generally used. This method is time-consuming, and does not guarantee a optimal gain. Thus, this paper proposes a GA-PID controller which selects an optimal PID control gain using genetic algorithms. And this proposed controller is evaluated experimentally and shows acceptable performance.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1598-1602
• /
• 2003

The parallel-type mechanism provides more accurate and stiff motion than the serial-type mechanism. However, in case of using the haptic device, the performance of the force reflection can be deteriorated due to the singular points existing in workspace. In this paper, we propose a redundantly actuated parallel 3-DOF haptic device, which is singularity-free in the workspace and has an improved force reflection capability. In addition, we propose a new force distribution algorithm, which can reflect force of both high and low resolution, using two sets of actuator with different size. Redundant actuators are attached to the base frame in order to minimize the inertia of the system. Moreover, a wire and gear reduction system is employed to achieve high force reflection along with soft feeling. We confirm the performance of the force reflection capability throughout simulation.

• International Journal of Precision Engineering and Manufacturing
• /
• v.2 no.1
• /
• pp.76-80
• /
• 2001

A binary parallel robot manipulator uses actuators that have only two stable states being built by stacking variable geometry trusses on top of each other in a long serial chain. Discrete characteristics of the binary manipulator make it impossible to analyze an inverse kinematic problem in conventional ways. We therefore introduce new definitions of workspace and inverse kinematic solution, and the apply a genetic algorithm to the newly defied inverse kinematic problem. Numerical examples show that our genetic algorithm is very efficient to solve the inverse kinematic problem of binary robot manipulators.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.174.2-174
• /
• 2001

Increasing demand for safety features, driving comfort and operational convenience in automobiles requires an intensive use of electronic components such as sensors, actuators and Electronic Control Unit(ECU)'s. These growing number of electronics has given rise to problems concerning the increasing number, size and weight of the wiring harnesses. In order to resolve these problems, multiplexed wiring systems such as Controller Area Network(CAN) serial communication protocol are applied in vehicle. This paper introduces the development of Body Control Module(BCM)s using multiplexed wiring systems. The BCM's were developed and implemented using CAN, the most popular choice of in-vehicle communication protocols.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.7
• /
• pp.1632-1642
• /
• 1994

The Stewart Platform is a six-degree-of-freedom in-parallel-actuated manipiulator mechanism. The kinematic behavior of parallel mechanisms shows inverse characteristics as compared that of serial mechanisms; i.e, the inverse kinematic problem of Stewart Platform is straightforward, but no closed form solution of the forward kinematic problem has been previously presented. Thus it is difficult to calculate the 6 DOF displacement of the platform from the measured lengths of the six actuators in real time. Here, a real-time estimation algorithm which solves the Stewart Platform kinematic problem is proposed and tested through computer simulations and experiments. The proposed algorithm shows stable convergence characteristics, no estimation errors in steady state and good estimation performance with higher sampling rate. In experiments it is shown that the estimation result is the same as that of simulation even in the presence of measurement noise.

• Proceedings of the KSME Conference
• /
• 2001.11a
• /
• pp.686-691
• /
• 2001

In this paper, the pneumatic service robot with a hybrid type is developed. A pneumatic has the advantage of good compliance, high payload-to-weight and payload-to-volume ratios, high speed and force capabilities. Using pneumatic actuators which have low stiffness, the service robot can guarantee safety. By suggesting a new serial-parallel hybrid type for the service robot which separates into positioning motion and orienting motion, we can achieve large workspace and high strength-to-moving-weight ratio at the same time. A sliding mode controller can be designed for tracking the desired output using the Lyapunov stability theory and structural properties of pneumatic servo systems. Through many experiments of circular trajectory, the pneumatic service robot is evaluated and verified.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.23 no.2
• /
• pp.164-172
• /
• 2014

This paper presents a method for analyzing the stiffness of full and low DOF (degree of freedom) planar parallel manipulators with serially connected legs. The individual stiffness of each leg is obtained by applying reciprocal screws to the leg twist using passive joints and elastic elements consisting of actuators and links. Because the legs are connected in parallel, the manipulator stiffness is determined by summing the individual leg stiffness values. This method does not require the assumption that springs should be located along reciprocal screws and is applicable to a planar parallel manipulator with a generic or singular configuration. The stiffness values of three planar parallel manipulators with different DOFs are analyzed. The numerical results are confirmed using ADAMS S/W.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.901-906
• /
• 1994

In designing and evaluating manipulators, itis important to understand the capability of kinematic and static performances. Both workspace and manipulability can be considered as such performance measures. In general, the measure of manipulability is related to the kinematics for serial type manipulators. However.in case of parallel manipulators such as Stewart Platform, the manipulability can be interpreted as the static capability of transforming the input forces of actuators to the wrench of the end-effector. In this paper, the mathematical and physical meanings of manipulability suggested in some research works have been examined, and more meaningful measure of manipulability using the absolute minimum eigenvalues of J $^{T}$ .del. J has been suggested, which has been applied to a Stewart Platform in order to investigate the manipulability of this mechanism..

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.1
• /
• pp.137-146
• /
• 2009

We present a micromechanical digital-to-analog (DA) variable capacitor using a parallel digital actuator array, capable of accomplishing high-Q tuning. The present DA variable capacitor uses a parallel interconnection of digital actuators, thus achieving a low resistive structure. Based on the criteria for capacitance range ($0.348{\sim}1.932$ pF) and the actuation voltage (25 V), the present parallel DA variable capacitor is estimated to have a quality factor 2.0 times higher than the previous serial-parallel DA variable capacitor. In the experimental study, the parallel DA variable capacitor changes the total capacitance from 2.268 to 3.973 pF (0.5 GHz), 2.384 to 4.197 pF (1.0 GHz), and 2.773 to 4.826 pF (2.5 GHz), thus achieving tuning ratios of 75.2%, 76.1%, and 74.0%, respectively. The capacitance precisions are measured to be $6.16{\pm}4.24$ fF (0.5 GHz), $7.42{\pm}5.48$ fF (1.0 GHz), and $9.56{\pm}5.63$ fF (2.5 GHz). The parallel DA variable capacitor shows the total resistance of $2.97{\pm}0.29\;{\Omega}$ (0.5 GHz), $3.01{\pm}0.42\;{\Omega}$ (1.0 GHz), and $4.32{\pm}0.66\;{\Omega}$ (2.5 GHz), resulting in high quality factors which are measured to be $33.7{\pm}7.8$ (0.5 GHz), $18.5{\pm}4.9$ (1.0 GHz), and $4.3{\pm}1.4$ (2.5 GHz) for large capacitance values ($2.268{\sim}4.826$ pF). We experimentally verify the high-Q tuning capability of the present parallel DA variable capacitor, while achieving high-precision capacitance adjustments.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.2
• /
• pp.205-212
• /
• 2011

The high performance intelligent robots have become to use a lot of sensors, actuators and controllers which are connected via bus-type networks while the point to point connection was widely used in-robot networks of existing robots. The bus topology makes the robot system share data internally and it can also reduce the weight of the robot because of smaller wiring harness. The CAN is one of serial bus communication protocols typically used for in-vehicle networks and now it can also be used for in-robot networks because of its low cost and reliability. A performance evaluation system for this type of networked system is developed to analyze the real-time operation and the reliability of a serial-bus network, and the usefulness of the developed evaluation system is shown by some experiments for a network of many CAN nodes.