• The Journal of Korea Robotics Society
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• v.7 no.2
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• pp.101-112
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• 2012

It is well-known that when singularities are located within the workspace of the parallel mechanism (PM), the usefulness of its workspace is significantly deteriorated. To handle this problem, we suggest an optimal design method which leads to more useful and larger workspace of the PM by taking its singularity locations into consideration in design process. Kinematic models of three selected planar PMs, a 5R type PM, a 3-RPR type planar PM, and a 3-RRR type planar PM, are derived via screw theory and their singularity analyses are conducted. Then workspace optimal designs for those three PMs are conducted to verify that the suggested design method leads more useful and larger workspace in which deterioration by singularity is minimal.

• Journal of Mechanical Science and Technology
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• v.15 no.8
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• pp.1119-1131
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• 2001

In this paper we formulate an optimization based approach to determining the maximally inscribed rectangle in a robots workspace. The size and location of the maximally inscribed rectangle is an effective index for evaluating the size and quality of a robots workspace. Such information is useful for, e. g., optimal worktable placement, and the placement of cooperating robots. For general robot workspaces we show how the problem can be formulated as a constrained nonlinear optimization problem possessing a special structure, to which standard numerical algorithms can be applied. Key to the rapid convergence of these algorithms is the choice of a starting point; in this paper we develop an efficient computational geometric algorithm for rapidly obtaining an approximate solution suitable as an initial starting point. We also develop an improved version of the algorithm of Haug et al. for calculating a robots workspace boundary.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.75-82
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• 2011

The objective of this study was to identify risk factors associated with the occurrence of musculo-skeletal symptoms of cashiers and provide suggestions for an improved workspace design. Workload and exertion of each task were measured using job analysis and posture analysis. The three most time-consuming tasks were waiting (43.8%), scanning (23.5%) and payment transaction (22.9%). It was analyzed that the workspace can be improved by applying Korean anthropometric data to the design of the desk height. The most common posture was a standing posture with neutral back, and bent lower arms and hands. Finally, it was revealed that 'scanning' and 'payment transaction' seemed more stressful than other operations. The result of the ergonomic evaluation would be a useful basis for designing an improved workspace.

• Construction Engineering and Management
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• v.4 no.1 s.13
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• pp.55-60
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• 2003

Unstructured workspaces which are typical in construction contain unpredicable activities as well as changing environments. Most automated and semi-automated construction tasks require real-time information about the local workspace in the form of 3D geometric models. This paper describes and demonstrates a new rapid, local area geometric data extraction and 3D visualization method for unstructured construction workspaces that combines human perception, simple sensors, and descriptive CAD models. The rapid approach will be useful in construction in construction in order to optimize automated equipment tasks and to significantly improve safety and a remote operator's spatial perception of the workspace.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.1063-1072
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• 1996

Fruit harvesting robots should have more diversity and flexibility in the working conditions and environments than industrial robots. This paper presents an efficient optimization algorithm for redundant manipulators to avoid obstacles using dynamic performance criteria, while the optimization schemes of the previous studies used the performance criteria using kinematic approach. Feasibility and effectiveness of this algorithm were tested through simulations on a 3-degrees-of-freedom manipulator made for this study. Only the position of the end-effector was controlled , which requires only three degrees of freedom. Remaining joints, except for the wrist roll joint, which does not contribute to the end-effector linear velocity, provide two degrees of redundancy. The algorithm was effective to avoid obstacles in the workspace even through the collision occurred in extended workspace, and it was found be to a useful design tool which gives more flexibility to design conditions nd to find the mechanical constraints for fruit harvesting robots.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1585-1588
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• 1997

In this paper, divide total workspace of robot manipulator into several subspaces and construct PID controller ineach subspace. Using EvolutionSTrategy we optimize the gains of PID controller in each subspace. But the gains may have a large difference on the boundary of subspaces, which can cause bad oscillatory performance. So we use Aritificial Neural Network to have continuous gain curves htrough the entire subspaces. Simualtion results show that the proposed method is quite useful.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.176-187
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• 2005

This paper presents an evaluation of joint configurations of a robotic finger based on kinematic analysis. The evaluation is based on an assumption that the current control methods for the fingers require that the contact state specified by the motion planner be maintained during manipulation. Various finger-joint configurations have been evaluated for different contact motions. In the kinematic analysis, the surface of the manipulated object was represented by B-spline surface and the surface of the finger was represented by cylinders and a half ellipsoid. Three types of contact motion, namely, 1) pure rolling, 2) twist-roiling, and 3) slide-twist-rolling are assumed in this analysis. The finger-joint configuration best suited for manipulative motion is determined by the dimension of manipulation workspace. The evaluation has shown that the human-like fingers are suitable for maintaining twist-rolling and slide-twist-rolling but not for pure rolling. A finger with roll joint at its fingertip link, which is different from human fingers, proved to be better for pure rolling motion because it can accommodate sideway motions of the object. Several kinds of useful finger-joint configurations suited for manipulating objects by fingertip surface are proposed.

• Architectural research
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• v.12 no.1
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• pp.9-14
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• 2010

The present study explored the applicability of Visibility Graph Analysis (VGA) techniques to workplace design research. Six types of VGA measures in Depthmap encompassing visual connectivity, three types of visual integration, mean depth, and visual entropy were employed for the analysis of individual privacy for task concentration and group relationship behavior in the open-plan office environment. Data comprised 136 workers in 6 open-plan offices filled with low-paneled (1.2-1.5m) cubicle workspaces. For the statistical analysis, Spearman's rho correlations and t-tests were applied for the spatial and behavioral measures. The results showed that workspace VGA measures have a potential to be useful information to account for workers' concentration privacy and, limitedly, also informal relationships with team members. Visual entropy values especially offer reliable information to predict various aspects of office workers' privacy behavior while visual integration can be used to account for the workers' sense of trust in group relations. The study also discussed the limitation of VGA applications to the workplace context.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.4
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• pp.350-356
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• 2004

This paper presents a farce manipulability analysis of multi-legged walking robots, which calculates force or acceleration workspace attainable from joint torque limits of each leg. Based on the observation that the kinematic structure of the multi-legged walking robots is basically the same as that of multiple cooperating robots, we derive the proposed method of analyzing the force manipulability of walking robot. The force acting on the object in multiple cooperating robot systems is taken as reaction force from ground to each robot foot in multi-legged walking robots, which is converted to the force of the body of walking robot by the nature of the reaction force. Note that each joint torque in multiple cooperating robot systems is transformed to the workspace of force or acceleration of the object manipulated by the robots in task space through the Jacobian matrix and grasp matrix. Assuming the torque limits are given in infinite norm-sense, the resultant dynamic manipulability is derived as a polytope. The validity of proposed method is verified by several examples, and the proposed method is believed to be useful for the optimal posture planning and gait planning of walking robots.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.511-521
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• 2012

JXTA technology is a set of open protocols that enable any connected device on the internet or MANET(Mobile Adhoc NETwork) to communicate in a P2P manner. In this paper, we present a JXTA-based smartphone collaborative application. For this, we define the core services and collaborative services necessary for a P2P network, and design proper protocols to support the services. The developed application provides the effective environment for group works in smartphones, supporting the various virtual workspaces. Since application supports the group works among users in close-range without relying on the mobile network, it could be very useful in various situations such as the disaster area.