Spatial Compliance Research Articles

Passive Realization of Object Spatial Compliance by a Hand Having Multiple Four-Joint Hard Fingers

Abstract This paper presents an approach to passively realize any specified object spatial compliance using the grasp of a robotic hand. The kinematically anthropomorphic hands considered have multiple 4-joint fingers making hard point contact with the held object, and the joints of each finger have selectable passive elastic behavior. It is shown that the space of passively realizable compliances is restricted by the kinematic structure of the anthropomorphic hand. To achieve an arbitrary compliant behavior, fingers must be able to adjust their orientation. Synthesis procedures for grasps having 3, 4, and 5 or more fingers are developed. These procedures identify the finger configurations and the individual finger joint compliances needed to passively achieve any specified spatial object compliance matrix in the 20-dimensional subspace of grasp-realizable behaviors.

Impact Assessment of Petrol Filling Stations on Groundwater Quality in Akure Metropolis, Ondo State

Abstract: The presence of PFSs in urban areas has increased significantly, leading to conflicts with existing land use planning and violations of the minimum environmental safety requirements set by the Department of Petroleum Resources (DPR) and have adverse social and environmental impacts despite their socioeconimic importance. This paper aim to investigate the spatial distribution of petrol filling stations and their impact on groundwater quality in Akure Metropolis of Ondo State. A total of 147 PFSs and 140 water wells were identified and recorded. Laboratory analysis was done purposefully on wells near PFSs that were both 26 years or older and still functional, as older underground storage tanks (USTs) pose a potential threat to groundwater safety. Findings revealed 119 functional filling stations, 28% located within residential area and 68% domiciled in commercial areas, 2% in outskirt of town and 1% in standalone environment. Findings showed all mapped filling stations were found to be within 50m from built up (residential) area, 104 mapped stations within residential and commercial areas violates the DPR standard. Using spatial analysis, it was also found that 116 of the 147 (78.9%) mapped filling stations were within 400m away from the next. 108 of the 147 (73.47%) mapped PFSs violated the standard of distance not less than 15meters from the edge of the road to the nearest pump. The findings also showed that groundwater system is contaminated by PAHs, which comprises; naphthalene.F, pyrene and acenaphthylene.F. Low mean concentrations of PAHs recorded in this study suggest that there is no major compromise in the quality of groundwater due to the operation of PFSs in Akure metropolise Hand-dug Wells in the study area. It is recommended that spatial compliance for siting PFSs should be strictly adhered to in order to avoid disaster that may occur due to the hazard they pose

Spatiotemporal Compliance Control for a Wearable Lower Limb Rehabilitation Robot.

Compliance control is crucial for physical human-robot interaction, which can enhance the safety and comfort of robot-assisted rehabilitation. In this study, we designed a spatiotemporal compliance control strategy for a new self-designed wearable lower limb rehabilitation robot (WLLRR), allowing the users to regulate the spatiotemporal characteristics of their motion. The high-level trajectory planner consists of a trajectory generator, an interaction torque estimator, and a gait speed adaptive regulator, which can provide spatial and temporal compliance for the WLLRR. A radial basis function neural network adaptive controller is adopted as the low-level position controller. Over-ground walking experiments with passive control, spatial compliance control, and spatiotemporal compliance control strategies were conducted on five healthy participants, respectively. The results demonstrated that the spatiotemporal compliance control strategy allows participants to adjust reference trajectory through physical human-robot interaction, and can adaptively modify gait speed according to participants' motor performance. It was found that the spatiotemporal compliance control strategy could provide greater enhancement of motor variability and reduction of interaction torque than other tested control strategies. Therefore, the spatiotemporal compliance control strategy has great potential in robot-assisted rehabilitation training and other fields involving physical human-robot interaction.

Development risk and unit size within the UK property market

PurposeThis paper aims to explore the relationship between market pricing and design quality within the development industry. Currently, there is a lack of research that examines real estate at the property level. Development quality is widely believed to have diminished over the past decades, while many investors seem uninterested in the design process. The study aims to address these issues through a pricing model that integrates design attributes. It is hoped that empirical findings will invite broader stakeholder interest in the design process.Design/methodology/approachThe research establishes a framework for assessing spatial compliance across residential developments within London. Compliance is assessed across ten boroughs, with technical space guidelines used as a proxy for design quality. Transaction prices and spatial assessments are aligned within a hedonic pricing model. Empirical findings are used to establish whether undermining spatial standards presents a significant development risk.FindingsFindings suggest a relationship between sale time and unit size, with “compliant” units typically transacting earlier than “non-compliant” units. Almost half of the 1,600 apartments surveyed appear to undermine technical guidelines.Research limitations/implicationsIt is suggested that an array of design attributes be explored that extend beyond unit size. Additionally, future studies may consider the long-term implications of design quality via secondary transaction prices.Practical implicationsPractical implications include the development of a more scientific approach to design valuation. This may enhance the position of product design management within the development industry and architectural services.Social implicationsSocial implications may include improvement in residential design.Originality/valueAn innovative approach combines a thorough understanding of both design and economic principles.

Requirements on the Spatial Distribution of Elastic Components Used in Compliance Realization

In this letter, necessary conditions on the locations and orientations of elastic components in a compliant mechanism used to realize any given spatial compliance are identified. The topologies considered are either fully parallel or fully serial mechanisms having an arbitrary number of lumped elastic components. It is shown that the requirements on elastic components are characterized by a sphere for the location distribution and by three cones for the orientation distribution. The easy to assess conditions on the set of components can be used to achieve a more desirable mechanism geometry when used in conjunction with existing spatial compliance synthesis procedures.

A New Nonlinear Spatial Compliance Model Method for Flexure Leaf Springs with Large Width-to-Length Ratio under Large Deformation.

Flexure leaf spring (FLS) with large deformation is the basic unit of compliant mechanisms with large stroke. The stiffness along the non-working directions of FLSs with large width-to-length ratio (w/L) is high. The motion stability of the compliant mechanism based on this type of FLS is high. When this type of FLS is loaded along the width direction, the shear deformation needs to be characterized. Nevertheless, currently available compliance modeling methods for FLS are established based on Euler–Bernoulli beam model and cannot be used to characterize shear models. Therefore, these methods are not applicable in this case. In this paper, a new six-DOF compliance model for FLSs with large w/L is established under large deformation. The shear deformation along the width direction model is characterized based on the Timoshenko beam theory. The new constraint model and differential equations are established to obtain a high-precision compliance model expression for this type of FLS. The effects of structural parameters on the compliance of the FLS are analyzed. Finally, the accuracy of the model is verified both experimentally and by finite element simulation. The relative error between theoretical result and experiment result is less than 5%.

Spatial compliance modeling and optimization of a translational joint using corrugated flexure units

Compliant mechanisms with corrugated flexure units have been attracting increasing attention due to their large range of motion. However, most research has considered in-plane compliance, whereas the out-of-plane performance, which affects the load-carrying ability, has seldom been studied. In this paper, an analytical model for the spatial compliance of a corrugated flexure translational joint is formulated. The in-plane compliance of the corrugated flexure translational joint is modeled by the Maxwell–Mohr method and compliance matrix method. For the out-of-plane compliance, a modification method is proposed for the closed-form analytical solution based on a finite element analysis with shell elements. The corrugated flexure translational joint is further optimized to achieve a high in-plane and out-of-plane off-axis stiffness ratio, low first-order natural frequency, and large range of motion. Experiments were conducted to verify the effectiveness of the method.

Spatial Compliance Measurement of a Clamping Table with Integrated Force Sensors

Spatial Compliance Measurement of a Clamping Table with Integrated Force Sensors

Spatial Compliance Modeling and Optimization of a Translational Joint Using Corrugated Flexure Units

Spatial Compliance Modeling and Optimization of a Translational Joint Using Corrugated Flexure Units

Efficient spatial compliance analysis of general initially curved beams for mechanism synthesis and optimization

Compliant Mechanisms (CMs) present several desired properties for mechanical designs. Conventional rigid-body mechanisms composed of rigid links connected at kinematic joints, serve as devices to transfer motion, force and energy by the movements of rigid links whereas CMs are able to present the same function only through deflection of flexible members. Most designs of CMs in the current literature employ straight beams as the elementary flexible members whereas initially curved beams (ICBs) also provide potential advantages for CMs such as large range of motion and small strain range. This paper presents an efficient spatial compliance analysis method of general ICBs. The spatial compliance analysis of different types of ICBs (such as varying-curvature beams and varying-cross-section beams) was conducted, followed by Finite Element Analysis (FEA) verification. Next, the modeling and optimization of two types of CMs including ICB-based parallelogram mechanisms and ICB-based Ortho-planar springs were carried out by applying screw theory under the framework of position space concept and parameter normalization strategy where a class of anti-buckling translational parallelograms with high load-bearing capacity and a type of compact 2R1T (2 rotational DOF and 1 translational DOF) compliant kinematic joints were obtained. The corresponding FEA was conducted to verify the optimal results.

Hybrid curved beam compliant mechanism with six degrees of freedom and large working space

Compliant mechanism has the advantages of compact structure, high precision and easy miniaturization. It has been widely used in the fields of robotics, precision engineering, bio-engineering and so on. In this work, a six degrees of freedom hybrid curved beam spatial compliance mechanism is proposed. The spatial six degrees of freedom are realized by means of series-parallel combination of curved beam compliant elements. The structure consists of an outer base, an inner base, a worktable, driving frame, curved beam compliance elements and piezoelectric ceramic actuators. The working principle of motion in six degrees of freedom is analysed, and statics analysis is carried out to verify the feasibility of the structure.

A fragmented environmental state? Analysing spatial compliance patterns for the case of transparency legislation in China

Do Chinese cities compete for investments with lax environmental law enforcement? The here presented study suggests that this is true for some municipalities but not all of them. Based on data for 126 key environmental protection cities and regional economic hubs between 2010 and 2012 we show that economic decentralization and political centralization both shape spatial patterns of compliance with environmental transparency legislation. Our results give reason to suppose that the Chinese economy moved beyond homogenous preferences for low-cost regulatory arrangements. The emerging jurisdictional interaction is in line with a Tiebout sorting process, where cities compete with diverse factor packages to attract an optimal amount of investments.

MR-FLIP: a new method that combines a functional lumen imaging probe with anatomical information for spatial compliance assessment of the anal sphincter muscles.

Continence results from a complex interplay between anal canal (AC) muscles and sensorimotor feedback mechanisms. The passive ability of the AC to withstand opening pressure - its compliance - has recently been shown to correlate with continence. A functional lumen imaging probe (FLIP) is used to assess AC compliance, although it provides no anatomical information. Therefore, assessment of the compliance specific anatomical structures has not been possible, and the anatomical position of critical functional zones remains unknown. In addition, the FLIP technique assumes a circular orifice cross-section, which has not been shown for the AC. To address these shortcomings, a technique combining FLIP with a medical imaging modality is needed. We implemented a new research method (MR-FLIP) that combines FLIP with MR imaging. Twenty healthy volunteers underwent MR-FLIP and conventional FLIP assessment. MR-FLIP was validated by comparison with FLIP results. Anatomical markers were identified, and the cross-sectional shape of the orifice was investigated. MR-FLIP provides compliance measurements identical to those obtained by conventional FLIP. Anatomical analysis revealed that the least compliant AC zone was located at the proximal end of the external anal sphincter (EAS). The cross-sectional shape of the AC was found to deviate only slightly from circularity in healthy volunteers. The proposed method is equivalent to classical FLIP. It establishes for the first time direct mapping between local tissue compliance and anatomical structure, which is key to gaining novel insights into (in)continence. In addition, MR-FLIP provides a tool for better understanding conventional FLIP measurements in the AC by quantifying its limitations and assumptions.

Analytical compliance analysis and finite element verification of spherical flexure hinges for spatial compliant mechanisms

This paper introduces and investigates a novel Spherical Flexure (SF), specifically conceived for application on spherical compliant mechanisms. The flexure features an arc of a circle as a centroidal axis and an annulus sector as cross-section, circle and annulus having a common center coinciding to that of the desired spherical motion. In this context, each element of the SF spatial compliance matrix is analytically computed as a function of both flexure dimensions and employed material. The theoretical model is then validated by relating analytical data with the results obtained through three-dimensional Finite Element Analysis. Finally, SFs are compared to Circularly Curved-Beam Flexures (CCBFs) in terms of parasitic motions.

Dynamic virtual fixture on the Euclidean group for admittance-type manipulator in deforming environments.

BackgroundIn a deforming anatomic environment, the motion of an instrument suffers from complex geometrical and dynamic constraints, robot assisted minimally invasive surgery therefore requires more sophisticated skills for surgeons. This paper proposes a novel dynamic virtual fixture (DVF) to enhance the surgical operation accuracy of admittance-type medical robotics in the deforming environment.MethodsA framework for DVF on the Euclidean Group SE(3) is presented, which unites rotation and translation in a compact form. First, we constructed the holonomic/non-holonomic constraints, and then searched for the corresponded reference to make a distinction between preferred and non-preferred directions. Second, different control strategies are employed to deal with the tasks along the distinguished directions. The desired spatial compliance matrix is synthesized from an allowable motion screw set to filter out the task unrelated components from manual input, the operator has complete control over the preferred directions; while the relative motion between the surgical instrument and the anatomy structures is actively tracked and cancelled, the deviation relative to the reference is compensated jointly by the operator and DVF controllers. The operator, haptic device, admittance-type proxy and virtual deforming environment are involved in a hardware-in-the-loop experiment, human-robot cooperation with the assistance of DVF controller is carried out on a deforming sphere to simulate beating heart surgery, performance of the proposed DVF on admittance-type proxy is evaluated, and both human factors and control parameters are analyzed.ResultsThe DVF can improve the dynamic properties of human-robot cooperation in a low-frequency (0 ~ 40 rad/sec) deforming environment, and maintain synergy of orientation and translation during the operation. Statistical analysis reveals that the operator has intuitive control over the preferred directions, human and the DVF controller jointly control the motion along the non-preferred directions, the target deformation is tracked actively.ConclusionsThe proposed DVF for an admittance-type manipulator is capable of assisting the operator to deal with skilled operations in a deforming environment.

Screw theoretic view on dynamics of spatially compliant beam

Beams with spatial compliance can be deformed as bending in a plane, twisting, and extending. In terms of the screw theory on rigid body motions, the concept of “deflection screw” is introduced, a spatial compliant beam theory via the deflection screw is proposed, and the spatial compliance of such a beam system is presented and analysed based on the material theory and fundamental kinematic assumptions. To study the dynamics of the spatially compliant beam, the potential energy and the kinetic energy of the beam are discussed by using the screw theory to obtain the Lagrangian. The Rayleigh-Ritz method is used to compute the vibrational frequencies based on discussions of boundary conditions and shape functions. The eigenfrequencies of the beam with spatial compliance are compared with those of individual deformation cases, pure bending, extension, or torsion. Finally, dynamics of a robot with two spatial compliant links and perpendicular joints is studied using the spatial compliant beam theory. Coupling between the joint rigid body motions and the deformations of spatial compliant links can easily be found in dynamic simulation. The study shows the effectiveness of using the screw theory to deal with the problems of dynamic modeling and analysis of mechanisms with spatially compliant links.

Compliance Analysis of Mechanisms with Spatial Continuous Compliance in the Context of Screw Theory and Lie Groups

This paper investigates the compliance effect on both serial and parallel mechanisms based on study of deflections of a finite segment of elastic beam with spatial compliance and applies eigenvectors and eigenvalues to identify principal screws in the mechanisms and parallel devices with spatial continuous compliance. With the analysis, compliance characteristics of both serial mechanisms and parallel devices can be identified with effect of compliance. Case studies are presented with numerical examples.

SCREW THEORY ON THE ANALYSIS OF MECHANICAL SYSTEMS WITH SPATIAL COMPLIANT LINKS

The mechanical system with spatial compliant links, that is the link under the deflections of bending in the plane, twisting and extending, is studied using screw theory. The elastic equations of a spatial compliant beam are built based on the material theory, and then, this beam theory is applied to the compliance and kinematics analysis of the serial robot with spatial compliant links. The vibrating bowl feeder for industry assembling work is further studied by considering its' legs as leaf springs. Finally, the spatial compliance of the coiled springs is discussed. The Lie groups and Lie algebras is successfully extended to study the mechanical system with spatial compliant links.

On the compliance of coiled springs

The 6×6 spatial compliance matrix for a helical spring is computed. The method used is to find the compliance of infinitesimal elements along the length of the spring. Then integration is used to sum the compliances and produce the total compliance of the spring. A key point in the method is that the compliance matrix for each element must be expressed in a common coordinate frame. The results produced are significantly different from the those given in elementary texts. However, it is shown how these results can be recovered by making the standard “closely coiled” approximation. Next, the principal wrenches and eigencompliances of the spring are studied, both for the closely coiled spring and for the case where these assumptions are not made. Finally, some numerical examples are given.

Analysis of spatial compliance behavior of coiled springs via screw theory

A new method is presented to describe and analyze the spatial compliance of coiled springs using screw theory.After an abbreviated description for the deformation of a beam element using screw theory, the spatial compliance den-sity for a beam element is derived based on the fundamental material theory and reasonable assumptions, and the spatialcompliance of the beam with finite length is obtained by integral. The spatial compliance of coiled springs is furtheranalyzed using the spatial compliance density of the beam element. By calculating the eigencompliance and Ball's prin-ciple screws for the whole compliance of system, the compliance properties varying with the basic physical parameters ofthe system are illustrated in detail. The basic ideas can be used for the design and application of the coiled springs and theother compliant mechanisms with spatial compliant beam element.