• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2983-2985
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• 1999

This paper presents the attitude control of the double inverted pendulum with compliant joint. The biped robot with compliant ankle joint instead of a motor have a good contact between it's sole and ground in the uneven ground. The compliant ankle joint proposed here is composed of springs and mechanical constraint. The lower link is hinged on the plate to free for rotation in the vertical plate. The upper link is connected to the lower link through a DC motor. The DC motor is used to control the posture of the pendulum by adjusting the position of the upper link. The algorithm for controlling a proposed inverted pendulum is nonlinear feedback controller. Simulation with mathematical model are conducted to show the validity of the proposed controller.

• Journal of KSNVE
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• v.9 no.6
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• pp.1259-1266
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• 1999

The objective of this investigation is to develop a compliant track link model and apply this model to the multi-body dynamic analysis of high mobility tracked vehicles. Two major difficulties encountered in developing the compliant track models. The first one is that the integration step size must be kept small in order to maintain the numerical stability of the solution. This solution deals with high oscillatory signals resulting from the impulsive contact forces and stiff compliant elements to represent the joints between the track links. The second difficulty is due to the large number of the system equations of motion of the three dimensional multibody tracked vehicle model. This problem was sloved by decoupling the equations of motion of the chassis subsystem and the track subsystems. Recursive methods are used to obtain a minimum set of equations for the chassis subsystem. Several simulation scenarios were tested for the high mobility tracked vehicle including accelaeration, high speed cruising, braking, and turning motion in order to demonstrate the effectiveness and validity of the methods proposed in this investigation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.815-816
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• 2012

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.112-120
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• 2003

In this paper, dynamic track tension fur high mobility tracked vehicle is investigated by multibody dynamic simulation techniques. This research focuses on a heavy military tracked vehicle which has sophisticated suspension and rubber bushed rack systems. In order to obtain accurate dynamic track tension of track subsystems, each track link is modeled as a body which has six degrees of freedom. A compliant bushing element is used to connect track links. Various virtual proving ground models are developed to observe dynamic changes of the track tension. Numerical studies of the dynamic track tension are validated against the experimental measurements. The effects of pre-tensions, traction forces, fuming resistances, sprocket torques, ground profiles, and vehicle speeds, for dynamic responses of track tensions are explored, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.722-725
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• 1996

This paper presents a new control strategy for the position and force control of a flexible manipulator. The governing equation of motion of a two-link flexible manipulator which features a piezoceramic actuator is derived via Hamilton's principle. The control torque of the motor to command desired position and force is determined by a sliding mode controller. This controller is formulated to take account of parameter uncertainties and external disturbances. During the commanded motion, undesirable oscillation is actively suppressed by applying a feedback control voltage to the piezoceramic actuator. Consequently, an accurate compliant motion control of the flexible manipulator is achieved. Computer simulations are undertaken in order to demonstrate the effectiveness of the proposed control methodology.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.53-58
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• 2016

Various jumping robot platforms have been developed to carry out missions such as rescues, explorations, or inspections of dangerous environments. We suggested a jumping robot platform using energy conversion of the elastic body like the bar of a pole vault, which is the main part in which elastic force occurs. The compliant link was optimized by an optimization method based on Taguchi methodology, and the robot's leaping ability was improved. Among the parameters, the length, width, and thickness of the link were selected as design variables first while the others were fixed. The level of the design variables was settled, and an orthogonal array about its combination was made. In the experiment, dynamic simulations were conducted using the DAFUL program, and response table and sensitivity analyses were performed. We found optimized values through a level average analysis and sensitivity analysis. As a result, the maximum leaping height of the optimized robot increased by more than 6.2% compared to the initial one, and these data will be used to design a new robot.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.20-25
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• 1998

This paper proposes a new compliant contact control strategy for the robot manipulators accidentally interacting with an unknown environment. The main features of the proposed method are summarized as follows: First, each entry in the diagonal stiffness matrix corresponding to the task coordinate in Cartesian space is adaptively adjusted during con-tact along the corresponding axis based on the contact force with its environment. Second, it can be used for both unconstrained and constrained motions without any switching mechanism which often causes undesirable instability and/or vibrational motion of the end effector. Third, the adjusted stiffness gains are automatically recovered to initially specified stiffness gains when the task is changed from constrained motion to unconstrained motion. The simulation results show the effectiveness of the proposed method by employing a two-link direct drive manipulator interacting with an unknown environment.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.200-205
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• 1989

The performance of conventional robot arms is inhibited by trade-off between speed and accuracy. Because these systems measure only joint angles, in spite of slow speed, they must rely on a stiff structure in order to attain positioning accuracy. Lightweight links would allow faster motion, but their flexibility would also produce positioning errors. This research is involved with the development and evaluation of an End-point Control System whose major goal is to compensate for link deflections and thus mitigate the speed versus accuracy conflict in conventional manipulator.

• Journal of Korea Multimedia Society
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• v.15 no.12
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• pp.1464-1474
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• 2012

In this paper, we propose a QoS (Quality of Service)-aware and cooperative resource reservation scheme using cross-layer link adaptation for wireless high definition video transmission through UWB (Ultra Wide Band) network with D-MAC (Distributed Medium Access Control). A wireless high definition video transmission system usually requires stable high throughput even without line-of-sight, e.g., a destination device in another room separated by a wall. Since the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme causes lots of DRP resource reservation conflicts due to failure of beacon detection in wireless channel environment, overall performances of the WiMedia D-MAC can be deteriorated. And the current WiMedia MAC standard has not considered QoS provisioning even though QoS parameters such as a range of service rates are provided to each traffic stream. Therefore, we propose Relay DRP protocol with QoS-based relay node selection criterion, which makes a relay path to avoid DRP resource reservation conflicts and guarantee QoS more stably through cross-layer link adaptation of cooperative relay transmission scheme and is compliant with the current WiMedia D-MAC protocol. Simulation results demonstrate performance improvements of the proposed method for throughput and QoS provisioning.

• International Journal of Ocean System Engineering
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• v.1 no.4
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• pp.222-229
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• 2011

In this paper, we present the concept and main mission of the Crabster, an underwater walking robot. The main focus is on the modeling of drag and lift forces on the legs of the robot, which comprise the main difference in dynamic characteristics between on-land and underwater robots. Drag and lift forces acting on the underwater link are described as a function of the relative velocity of the link with respect to the fluid using the strip theory. Using the translational velocity of the link as the rotational velocity of the joint, we describe the drag force as a function of joint variables. Generalized drag torque is successfully derived from the drag force as a function of generalized variables and its first derivative, even though the arm has a roll joint and twist angles between the joints. To verify the proposed model, we conducted drag torque simulations using a simple Selective Compliant Articulated Robot Arm.