Local Conditioning Index Research Articles

A Fish-Based Index of Biotic Integrity for Neotropical Rainforest Sandy Soil Streams—Southern Brazil

Multimetric indices are considered a low-cost and rapid means of assessing ecological integrity in streams. This study aimed to develop a fish-based Index of Biotic Integrity (N3S-IBI) in an agricultural region within the domains of the Atlantic rainforest in Brazil. We sampled 23 first-order streams and used large-scale land use and a local physical condition index to choose reference sites and to classify sites according to the disturbance level. N3S-IBI resulted in six metrics (Simpson’s dominance; the numbers of Characiformes and non-native individuals (Poecilia reticulata); and the percentages of Characidae species, intolerant insectivorous individuals, and tolerant species), contemplating tolerance, composition, abundance, richness, trophic habits, and origin. The low number of metrics contributes to a quick and easy biomonitoring process. N3S-IBI showed an excellent performance to separate least and most disturbed sites in our study area and can provide additional knowledge about anthropogenic effects within this impacted region. In fact, this tool could be utilized by managers to direct restoration actions for the most disturbed sites and to strengthen the preservation of the least disturbed sites.

Unified motion reliability analysis and comparison study of planar parallel manipulators with interval joint clearance variables

Motion reliability is a significant performance index for manipulators with uncertainties. This paper presents a unified motion reliability analysis method for general planar parallel manipulators (PPMs) with interval clearance variables of revolute and prismatic joints. The uncertainties of manufacturing and inputs are also considered and assumed to follow normal distributions. Two typical types of PPMs, 3RRR PPM and 3PRR PPM, are analyzed as examples to demonstrate the effectiveness of the method. For the purpose of a relatively fair comparison, the two PPMs are designed to have the same sizes of base platforms and moving platforms by using a traditional kinematic optimization based on the global conditioning index (GCI). Then, the comparison studies of the two PPMs are made with respect to performance indices of GCI, LCI (local conditioning index) and motion reliability. Furthermore, the index comparison between LCI and motion reliability is also carried out in detail through the two PPMs. The numerical analysis results indicate that: (i) the presented method could achieve a higher confidence estimate compared with the traditional probability method; (ii) the 3PRR PPM exhibits better motion reliability performance than the 3RRR PPM at the same uncertainty levels; and (iii) the traditional optimization based on the GCI cannot guarantee the good motion reliability performance of the PPM. This study provides support for the design and control of PPMs in terms of accuracy and motion reliability.

SQP Optimization of 6dof 3x3 UPU Parallel Robotic System for Singularity Free and Maximized Reachable Workspace

The determination of kinematic parameters for a parallel robotic system (PRS) is an important and a critical phase to maximize reachable workspace while avoiding singular configurations. Stewart Platform (SP) mechanism is one of the widely known PRS and it is used to demonstrate the proposed technique. In the related literature, GCI (Global Condition Index) and LCI (Local Condition Index) are the commonly used performance indexes which give a measure about the dexterity of a mechanism. In this work, Sequential Quadratic Programming (SQP) method is used to optimize kinematic parameters of a 6dof 3x3 UPU SP in order to reach maximum workspace satisfying small condition numbers. The radius of mobile and base platforms and the lengths of the legs used in the platform are chosen as kinematic parameters to be optimized in a multiobjective optimization problem. Optimization is performed at different stages and the number of optimized kinematic parameters is increased at each level. In conclusion, optimizing selected kinematic parameters at once by using SQP technique presents the best results for the PRS.

Analysis of flexible supported industrial robot on terminal accuracy

To meet comprehensive performance requirements of large workspace, lightweight, and low energy consumption, and flexible supported industrial robots emerge, which are usually composed of a six-degrees-of-rotational-freedom (6R) industrial robot and a flexible support. Flexible support greatly expands the motion range of the attached industrial robot. Flexible supported industrial robots have been adopted in surface coating of large structures such as aircrafts and rockets. However, the rigid–flexible coupling exists in these robot systems. When the industrial robot moves, the reaction force and torque of the robot disturb the flexible support and introduce vibration, which may result in the deterioration of the system’s terminal accuracy. This study focuses on both the robot body accuracy and system vibration suppression to improve the terminal accuracy of the flexible supported industrial robot. Firstly, based on kinematics analysis, accuracy of the industrial robot is investigated with the local conditioning index. Then, reaction force and torque ellipsoids are proposed with the deduced dynamic model to evaluate disturbances that the industrial robot applies to the flexible support. Considering these two aspects, the high-quality workspace of the flexible supported industrial robot is established. Numerical simulations show that reaction force and torque are effectively limited in the high-quality workspace, which greatly reduce the vibration energy and improve the terminal accuracy of the system.

Kinematics, singularity, and optimal design of a novel 3T1R parallel manipulator with full rotational capability

Parallel manipulators (PMs) with 3T1R (three translational and one rotational degrees of freedom) or Schonflies motion are very useful in industry. However, most 3T1R PMs have a limited range of rotation less than 90° while many practical tasks require a large range of rotation over 180°. Furthermore, there are no 3T1R PMs with full rotational capability that has small number of single-DOF joints and fixed actuators. A novel 2-(RRR)2RH PM with full rotational capability is proposed, where R and H denote a revolute joint and a helical joint, respectively. The moving platform is connected to the fixed base by two identical (RRR)2RH chains, where (RRR)2 denotes a 2- RRR closed chain. First, kinematic analysis of the proposed 2-(RRR)2RH PM, including mobility analysis, inverse and direct kinematics, singularity analysis, and workspace is presented. Second, the local conditioning index is used to evaluate the kinematic performance of the PM. Finally, optimal kinematic design of the 2-(RRR)2RH PM is investigated. The 2-(RRR)2RH PM has only 16 single-DOF joints and can be actuated by four fixed revolute joints. These features make it a good candidate in many applications.

Kinematic Analysis and Performance Evaluation of Novel PRS Parallel Mechanism

In this paper, a 3 DoF (Degree of Freedom) novel PRS (Prismatic-Revolute- Spherical) type parallel mechanisms has been designed and presented. The combination of striaght and arc type linkages for 3 DOF parallel mechanism is introduced for the first time. The performances of the mechanisms are evaluated based on the indices such as Minimum Singular Value (MSV), Condition Number (CN), Local Conditioning Index (LCI), Kinematic Configuration Index (KCI) and Global Conditioning Index (GCI). The overall reachable workspace of all mechanisms are presented. The kinematic measure, dexterity measure and workspace analysis for all the mechanism have been evaluated and compared.

Transmission Index Research of Parallel Manipulators Based on Matrix Orthogonal Degree

Performance index is the standard of performance evaluation, and is the foundation of both performance analysis and optimal design for the parallel manipulator. Seeking the suitable kinematic indices is always an important and challenging issue for the parallel manipulator. So far, there are extensive studies in this field, but few existing indices can meet all the requirements, such as simple, intuitive, and universal. To solve this problem, the matrix orthogonal degree is adopted, and generalized transmission indices that can evaluate motion/force transmissibility of fully parallel manipulators are proposed. Transmission performance analysis of typical branches, end effectors, and parallel manipulators is given to illustrate proposed indices and analysis methodology. Simulation and analysis results reveal that proposed transmission indices possess significant advantages, such as normalized finite (ranging from 0 to 1), dimensionally homogeneous, frame-free, intuitive and easy to calculate. Besides, proposed indices well indicate the good transmission region and relativity to the singularity with better resolution than the traditional local conditioning index, and provide a novel tool for kinematic analysis and optimal design of fully parallel manipulators.

Dexterity characterization of the RPR parallel manipulator based on the local and global condition indices

In this paper, the kinematic performance of a planar parallel manipulator 3-RPR is investigated. Based on the constraint equations, robot geometric Jacobian matrix is calculated. Since the end-effector of the 3-RPR planar parallel manipulator performs both translational and rotational motions, robot geometric Jacobian matrix is transformed to a homogeneous form. This method defines a new Jacobian that transforms the linear velocities of two points on the end-effector to the actuator velocities. The velocity manipulability index is used for studying the ability of the manipulator to move. The manipulator distance singularity and kinematic accuracy is checked out by using the Local conditioning index (LCI) and Global conditioning index (GCI). The effect of Jacobian matrix homogenization on both the LCI and manipulability index is investigated in detail. Furthermore, the relation between LCI and the manipulability ellipsoids for certain moving platform orientations is studied. The paper is finally concluded by checking out the shapes of the manipulability ellipsoids for different moving platform orientations over the whole workspace.

Kinematic synthesis of a novel rapid spherical CRS/PU parallel manipulator

In this research work, a novel parallel manipulator with complex degrees of freedom (DoF) has been represented. Each active kinematic chain consisted of cylindrical-revolute-spherical joints located on a curved guide and passive middle link contains prismatic-universal joint. Each of curved guides mounted as a sector of a circle with specified radius and center point. Cylindrical joints are activated by a crank mechanism and motors which are located at the center of the curved guide, provide two rotational displacements around x and y axes and one translational displacement along z direction. The mobility analysis has been analyzed by Grübler-Kutzbach criterion, and kinematic equations are provided. Then, using a search algorithm, the boundary of workspace has been determined for a case study structure. Two different methods are used to make Jacobian matrix homogeneous. The performance indices such as Local Condition Index (LCI), Maximum Singular Value, and Minimum Singular Value have been investigated throughout the workspace. Two types of well-known parallel kinematic mechanisms have been optimized with regard to the workspace volume and compared base on some global indices. All results have demonstrated the well condition of the manipulator in positioning and orienting tasks with desired precision and speed.

PERFORMANCE MEASUREMENT AND DYNAMIC ANALYSIS OF TWO DOF ROBOTIC ARM MANIPULATOR

Forward and inverse kinematic analysis of 2DOF robo t is presented to predict singular configurations. Cosine function is used for servo motor simulation of kinematics and dynamics u sing Pro/Engineer. The significance of joint-2 for reducing internal singularities is highlighted. Performance analysis in terms of co ndition number, local conditioning index and mobili ty index is carried out for the manipulator. Dynamic analysis using Lagrangian’s an d Newton’s Euler approach is worked out analyticall y using MATLAB and results are plotted for their comparison.

Optimal Design of a Planar Five-Bar Parallel Manipulator Driven by Two Orthogonal Layout Actuators

This paper addresses geometry design of a new kind of 2-DOF five-bar parallel manipulator actuated by two orthogonal layout linear actuators. Although the manipulator has only one geometric parameter, i.e., the link length, the distribution of performance index is more complex. Here, we propose a design approach utilizing a performance chart and local condition index. The key problem in the design of the manipulator is the determination of not the link length but the workspace satisfying the design index. This paper gives an effective method to obtain the basic good-condition workspace without dimension. Then, based on the optimum non-dimensional result, the optimum dimensional parameters are achieved which is suitable for the desired workspace. The optimum methodology of this paper is convenient and can be extended to other parallel manipulators

Multi-Objective Optimal Kinematic Design of 3-TPS/TP Parallel Robot Manipulator

The purpose of this research work is to find the optimized kinematic structural parameters of the 3-TPS/TP parallel manipulator while taking into consideration the workspace, kinematic properties and other factors. The Ranked Pareto Particle Swarm Optimization (RP-PSO) approach is applied to solve the multi-objective optimization problems. Firstly, the structure of the parallel manipulator and its kinematic model are devised. Then, we set up the kinematical performance indices for the evaluation of manipulator working properties, including Local Condition Index (LCI), Global Condition Index (GCI) and Good Condition Workspace (GCW). The optimization is further carried out in a Parameter Design Space (PDS) with normalized geometry parameters. Then the geometry optimization problems are solved using a PDS based RP-PSO approach. Finally, the feasibility of this approach is supported by examples given this paper.

Capital use intensity and productivity biases

Measures of productivity growth are often pro-cyclical. This paper focuses on measurement errors in capital inputs, associated with unobserved variations in capital utilization rates, as an explanation for the existence of pro-cyclical patterns in measures of productivity. Recently constructed national and state-specific indexes of inputs, outputs, and productivity in U.S. agriculture for 1949–2002 are used to estimate production functions that include proxy variables for changes in the utilization of durable inputs. The proxy variables include an index of farmers’ terms of trade and an index of local seasonal growing conditions. We find that utilization responses by farmers are significant and bias measures of productivity growth in a pro-cyclical pattern. We quantify the bias, adjust the measures of productivity for the estimated utilization responses, and compare the adjusted and conventional measures.

Weighted local conditioning index of a positioning and orienting parallel manipulator

In the presence of positioning and orienting tasks, the singular values of Jacobian matrices have different units, thereby making it impossible to order them and calculate the associated condition numbers. Here, this dimensional in-homogeneity is resolved by introducing a weighting factor. In this method, both the Jacobian and twist vector are made homogeneous, simultaneously. Moreover, relations between the weighting factors used here to the homogeneous Jacobian matrices derived by others are given. This factor should be constant throughout the workspace, while it is pose dependent in the latter methods. As a case study, both methods are applied to a Tricept parallel manipulator with complex degrees of freedom. A local conditioning index, as a dexterity index, is plotted in the workspace. Although both methods lead to homogeneous Jacobian matrices, obvious differences between the plotted local conditioning indices are revealed here. Therefore, those homogeneous Jacobian matrices derived by others, and the associated dexterity indices are unreliable.

Capitation registration and social deprivation in England. An inverse 'dental' care law?

To examine associations between NHS child dental registration data and area deprivation scores of English Health Authorities (N= 100) in 1996/97 and 1997/98. The Department of the Environment index of local conditions and the Jarman Underpriviledge Area Score from the 1991 census were used to measure deprivation. Prior to September 1997, children got free dental treatment under a capitation scheme with an NHS dentist. If they did not attend within 24 months their registration lapsed on the last day of December of the second registration year and they were deleted from the capitation list. After September 1997 the registration period was reduced to 15 months. Curve-linear regression of the Health Authority (HA) percentage of children registered, lapses in capitation registrations and deprivation scores. In England 68% of children were registered in December 1996. The percentage registered in each Health Authority was associated with deprivation (DoE, r2=0.33, Jarman, r2=0.27 p<0.01). In January 1997, 17.8% (1,345,142) of children registered lapsed (HA range 12.8% to 30.3%) and this was also significantly associated with deprivation (DoE r2=0.66, Jarman, r2=0.51 p<0.01). Similar results were found in 1997/98. Registration and lapse rates were significantly associated with social deprivation confirming that there is an inverse 'dental' care law for children in England. NHS capitation may widen dental health inequalities.

Optimum design of 3-DOF spherical parallel manipulators with respect to the conditioning and stiffness indices

This paper concerns the use of evaluation criteria, such as, the conditioning index, the stiffness to select the link lengths of 3-DOF spherical parallel manipulators (3-DOF SPMs) and analyze their operational performance. The atlases of the global conditioning index and the global stiffness index are obtained in the solution space to optimize the link lengths of 3-DOF SPMs; the dexterity and stiffness maps of the manipulators are presented to analyze the operational performance, from which we can see that the global or local conditioning index is identical with global or local stiffness index. A method for obtaining these maps for 3-DOF SPMs is presented. The maps will reveal the existence of zones where the stiffness is not acceptable and will also help the designer by proving a more accurate representation of the properties of the manipulator. The technique has wide application in the design of the serial and parallel robots.

The Use of Indicators for Targeting Public Expenditure: The Index of Local Deprivation

The UK government places considerable emphasis on the targeting of resources to areas most in need. For the Single Regeneration Budget and other purposes, use is made of the Index of Local Deprivation (ILD), formerly the Index of Local Conditions (ILC), to identify eligible areas. In this paper we show that this index suffers from such serious structural defects that it is unsuitable for the purpose to which it is put. These defects include the scale dependency of the index, the inappropriate treatment of positive and negative numbers, the unequal weights assigned to the indicators used and the difficulties introduced by using a nonlinear structure for the index. Recent decisions to modify the ILD do not address these defects and one change that has been mooted would exaggerate the scale bias. Suggestions are made for what should be done in replacing and supplementing the ILD to provide a better basis for assessing relative need.

Developing Indicators to Assess the Potential for Urban Regeneration: Improvements Using the 1991 Census of Population Samples of Anonymised Records

This paper explores possibilities for improvements in the quality of indicators to assess the potential for urban regeneration. A new source of data—the 1991 Census of Population Samples of Anonymised Records—is investigated. Refinements and improvements in the quality and targeting of indicators for the Single Regeneration Budget and other regeneration initiatives are recom mended. It is concluded that the 2 per cent Sample of Anonymised Records represents an invaluable resource supplementing the Index of Local Conditions and other databases as a source of information for regeneration based policy assessments.

'My ward is more deprived than yours'.

Increasingly, additional resources for infrastructure development and healthcare are directed at deprived areas. The commitment of the present government to reducing inequalities in health is likely to focus attention on identifying and providing special help to areas considered to be particularly deprived. This study compares the use of different deprivation measures at electoral ward level to rank wards according to deprivation and illustrates how the use of different deprivation measures may influence resourcing decisions. The 20 local authority electoral wards making up the city of Plymouth, Devon, were studied. Some of the wards within Plymouth are amongst the most deprived in England. The scores for each ward for different measures of deprivation--Townsend, Jarman, the Department of Environment's Index of Local Conditions and Breadline Britain--were calculated and the wards ranked according to the deprivation score for each measure. Decisions on funding bids and resource allocation for wards within Plymouth were reviewed in the light of the relative deprivation status of the wards according to the various measures. The ranking of electoral wards for the selected measures of deprivation showed variation according to the measure used. The measure of deprivation chosen may have influenced resourcing decisions. Measures of deprivation are closely correlated one with another. However, by judicious choice of the deprivation measure used a ward can achieve a marked change in rank order. This may exert considerable influence on the decisions made by government departments, local authorities and health authorities when allocating resources.

Crime risk in urban neighbourhoods: the use of insurance data to analyse changing spatial forms

Summary The recent British Crime Surveys have confirmed that there are significant spatial variations in the distribution of crime risk. However, it is notoriously difficult to represent the spatial patterns in Britain convincingly, owing to the statistical inadequacy of the official crime data. This paper discusses the use of home contents insurance data as a proxy measure of crime risk, and examines the changing spatial distribution of crime risk in the two Northern conurbations of Merseyside and Greater Manchester. The analysis provides an explicit urban focus in order to establish links between the spatial distribution of crime risk and other patterns of deprivation or inequality in the urban environment. Since insurance data is used as a proxy measure of crime risk in the Department of the Environment's Index of Local Conditions, this analysis serves as an interesting basis for both academic and policy discussion.