Dynamic Contact Force Research Articles

POSFET tactile sensing arrays using CMOS technology

This work presents new tactile sensing chips consisting of 4×4 array of POSFET touch sensing devices (or taxels) and 4 diodes to measure contact temperature. In the new version presented here, the tactile sensing chips have been fabricated using CMOS technology. Both, the individual taxels and the array are designed to match spatio-temporal performance of the human fingertips. To detect contact parameters such as contact force, the taxels utilize the contact induced change in the polarization level of piezoelectric polymer (and hence the changes in the induced channel current of MOS). The performance of POSFET device has been evaluated in the dynamic contact forces range of 0.01–3N. The response of POSFET is linear in the tested range, with the sensitivity (without amplification) of 102.4mV/N – which is more than twice the response of POSFETs presented earlier.

Dynamic analysis of a hanger-supported beam with a movingoscillator

The dynamic responses of contact force and displacement are analyzed for a hanger-supported, tensioned beam with a moving oscillator. Two types of hanger models are considered in this study: slackness and non-slackness models. The slackness model can possess axial stiffness only when a hanger is subjected to a tensile force, while the non-slackness model has axial stiffness for both tensile and compressive forces. Using the finite element method and the generalized-α time integration method, the dynamic responses of the contact force and moving mass displacement are computed, and the effects of the hanger modeling and system parameters on the responses are investigated. It is found that the slackness of the hangers is helpful in reducing the dynamic contact force between the tensioned beam and the moving oscillator. This paper also shows that the contact forces computed with the slackness model have smaller magnitudes and fewer fluctuations than the forces computed with the non-slackness model.

Energy Harvesting, Ride Comfort, and Road Handling of Regenerative Vehicle Suspensions

This paper presents a comprehensive assessment of the power that is available for harvesting in the vehicle suspension system and the tradeoff among energy harvesting, ride comfort, and road handing with analysis, simulations, and experiments. The excitation from road irregularity is modeled as a stationary random process with road roughness suggested in the ISO standard. The concept of system H2 norm is used to obtain the mean value of power generation and the root mean square values of vehicle body acceleration (ride quality) and dynamic tire-ground contact force (road handling). For a quarter car model, an analytical solution of the mean power is obtained. The influence of road roughness, vehicle speed, suspension stiffness, shock absorber damping, tire stiffness, and the wheel and chasses masses to the vehicle performances and harvestable power are studied. Experiments are carried out to verify the theoretical analysis. The results suggest that road roughness, tire stiffness, and vehicle driving speed have great influence on the harvesting power potential, where the suspension stiffness, absorber damping, and vehicle masses are insensitive. At 60 mph on good and average roads, 100–400 W average power is available in the suspensions of a middle-sized vehicle.

微小穴あけにおけるドリル振れの穴位置精度への影響

Micro drilling operation is always exposed the risk of breakage of micro drills. Therefore, it is considered that micro drills should be rotated as accurately as possible. In the other hand, reasonable tolerance of rotating accuracy, however, should be defined for economical and engineering reason. In this paper, contact behavior of a run-out rotating drill tip with a work face is discussed according to measurement of high frequency contact force using a dynamometer. As a result, transient dynamic contact force reveals a run-out rotating drill tip is wandering just after making a contact with a work face. Wandering time depends on sliding characteristics of interface between a drill tip and a work face. For instance, centering behavior is better in drilling non-ferrous metal, where it takes 2-3 revolutions (5-7.5ms) until a drill tip stops wandering. However, it takes several times longer for hard-to-machine metals, where a drill tip diverges in the worst case . Additionally, the bending stress of a drill increases steeply with the increase of hole depth. In deep drilling, therefore, run-out of a drill must be depressed the least one for preventing drill breakage.

Time Domain Modeling and Analysis of Dynamic Gear Contact Force in a Wind Turbine Gearbox with Respect to Fatigue Assessment

The gearbox is one of the most expensive components of the wind turbine system. In order to refine the design and hence increase the long-term reliability, there has been increasing interest in utilizing time domain simulations in the prediction of gearbox design loads. In this study, three problems in time domain based gear contact fatigue analysis under dynamic conditions are discussed: (1) the torque reversal problem under low wind speed conditions, (2) statistical uncertainty effects due to time domain simulations and (3) simplified long term contact fatigue analysis of the gear tooth under dynamic conditions. Several recommendations to deal with these issues are proposed based on analyses of the National Renewable Energy Laboratory’s 750 kW land-based Gearbox Reliability Collaborative wind turbine.

최적 러그 배치를 위한 골리앗 크레인의 와이어 로프와 선체 블록간의 동적 접촉력 계산

본 연구에서는 선체 블록의 운반 작업 중 발생하는 동적 하중 및 골리앗 크레인의 와이어 로프(wire rope)와 선체 블록간의 동적 접촉력을 고려한 최적 러그 배치 시스템을 설계하고, 다물체계 동역학 커널과 외력 계산 커널을 개발하였다. 다물체계 동역학 커널은 recursive formulation을 이용하여 운동 방정식을 구성하였고, 외력 계산 커널은 비선형 유체 정역학적 힘, 선형 유체 동역학적 힘, 풍력, 계류력을 계산할 수 있다. 개발된 커널의 효용성을 검증하기 위해, 이를 이용하여 와이어 로프와 블록간의 간섭과 이때 작용하는 동적 접촉력을 계산하였고, 마지막으로 계산 결과를 반영하여 러그가 부착된 블록에 대한 구조 해석을 수행하였다. In this study, dynamic load and dynamic contact force between a building block and wire ropes of a goliath crane are calculated during lifting or turn-over of a building block for the design of an optimal lug arrangement system. In addition, a multibody dynamics kernel for implementing the system were developed. In the multibody dynamics kernel, the equations of motion are constructed using recursive formulation. To evaluate the applicability of the developed kernels, the interferences and dynamic contact force between the building block and wire ropes were calculated and then the hull structural analysis for the block was performed using the calculation result.

Intelligent robotic impedance control using embedded system structure

For dexterous interactive manipulations, the robot end-effector must follow a motion trajectory and exert an appropriate force against the contacted environment to provide a specified dynamic working compliance. Hence, the robotic impedance is an important function for future applications of intelligent robots. For this purpose, a generalized hybrid control strategy is developed to monitor the motion trajectory and the end-effector interaction force in the task space simultaneously. Here, the Altera development board-based embedded robotic control structure is constructed and the related intelligent position/force hybrid control strategy is developed. A new model-free intelligent fuzzy sliding mode controller is designed to monitor the force and position specifications for hybrid impedance control purposes. It has the advantages of one-dimensional fuzzy control features with online gain scheduling and sliding mode stability. A force sensor is installed in a Mitsubishi robot end-effector to measure the dynamic contact force during compliant operations. The experimental results show that the dynamic performance of the proposed hybrid impedance control system can reach the contouring error of less than 1 mm and a contact force error of less than 3 N, respectively.

A Dynamic Contact Method in the LECEL Test for Heterogeneous Brittle Materials

Based on dynamic contact force and FEM, the contact – separation process of collision was investigated. Compared with other methods, the dynamic contact method needn’t modify the general stiffness matrix, and increase any additional iterative computation. So there should be less computation and high efficiency. By building simulation model LECEI(the technique of loading edge cracks by edge impact), the propagation of branching cracks were simulated. Compared with existing research results, the method can be suitable to the impact model such as LECEI.

A wheel set/crossing model regarding impact, sliding and deformation—Explicit finite element approach

A dynamic finite element model for the process of a wheel passing the crossing panel of a turnout is presented. This model accounts for the dynamic process, the elastic deformations of the wheel and the elastic–plastic deformations of the crossing. The axle and the second wheel are accounted for in terms of their influence on the angular velocity of the wheel.The model provides the dynamical contact forces between the wheel and the crossing parts, the vertical wheel displacement, the development of the angular velocity of the wheel as well as the stress fields and the plastic deformations in the crossing. Results that indicate the loading of the surface, such as the contact pressure and the microslip, are also provided by the model. From them, the specific frictional work and the maximum of the specific frictional power are derived. Those values are associated with surface damage such as wear and Rolling Contact Fatigue (RCF). An empirical relationship between the frictional work and wear is widely used and called Archard's wear law. For the formation and propagation of surface cracks there is no simple relationship.Results for the wheel initially running on the wing rail and then impacting onto the crossing nose (facing move) and the other direction (trailing move) are presented for three velocities.The presented model can help in the optimization of crossings in terms of geometry, bedding and material, depending on the loading conditions such as train velocity, axle load and wheel profile for both the facing and trailing move.

Estimation of Dynamic Contact Force Between a Pantograph and Catenary Using the Finite Element Method

This paper presents a model of the catenary and pantograph and an analysis of their dynamic interaction, using the finite element method. An analytical procedure to calculate the length of droppers is introduced. The calculated dropper length is applied to the catenary model and the static deformation due to gravity is simulated. The presag result of the contact wire is validated by comparison with the design specification. The wave propagation speed of the catenary model is acquired by applying the impact force to the contact wire. The result, regarding the wave propagation speed, agrees well with the reference speed as defined by the UIC code. On the contrary, the pantograph model is unified with the finite element catenary model, and the dynamic interaction of the catenary-pantograph is simulated. An optimization technique to find the material properties of the pantograph model is proposed. Based on the following performance test data, the optimum values of the material properties are found by using the response surface analysis method. The reliability of the pantograph-catenary model is verified by comparing the contact force results obtained from the simulation and test. When the pantograph drives at 305 km/h, 370 km/h, and 430 km/h, the contact force variation and the possibility of loss of contact are discussed.

In vivo evaluation of edge-loading in metal-on-metal hip resurfacing patients with pseudotumours

ObjectivesPseudotumours (abnormal peri-prosthetic soft-tissue reactions) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) have been associated with elevated metal ion levels, suggesting that excessive wear may occur due to edge-loading of these MoM implants. This study aimed to quantify in vivo edge-loading in MoMHRA patients with and without pseudotumours during functional activities.MethodsThe duration and magnitude of edge-loading in vivo was quantified during functional activities by combining the dynamic hip joint segment contact force calculated from the three-dimensional (3D) motion analysis system with the 3D reconstruction of orientation of the acetabular component and each patient’s specific hip joint centre, based on CT scans.ResultsEdge-loading in the hips with pseudotumours occurred with a four-fold increase in duration and magnitude of force compared with the hips without pseudotumours (p = 0.02).ConclusionsThe study provides the first in vivo evidence to support that edge-loading is an important mechanism that leads to localised excessive wear (edge-wear), with subsequent elevation of metal ion levels in MoMHRA patients with pseudotumours.

Measuring Model of Dynamic Contact Force

There are no systematic studies reported on measuring model of dynamic contact force between pantograph and overhead line. Keep this in view, the high-speed measuring model of dynamic contact force between pantograph and overhead line is discussed in details in this article. Based on the analysis of forces acting on the pantograph, measuring model of dynamic contact force is constructed with the mass correction and aerodynamic compensation. The results of verifying running test are given in the end of article to show that the measuring model is effective practically.

POSFET touch sensor with CMOS integrated signal conditioning electronics

This paper presents the design, fabrication and evaluation of the new version of POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) touch sensing device based tactile sensing chip. Implemented using CMOS (Complementary Metal Oxide Semiconductor) technology, the chip consists of POSFET device and the integrated bias and signal conditioning circuitry. In particular, a high compliance current sink and an output buffer have been integrated to respectively bias the POSFET device and to decouple the sensor from chip output. The performance of tactile sensing chip has been evaluated in the dynamic contact forces range of 0.01–3N and the sensitivity of POSFET devices (without amplification) is 102.4mV/N.

POSFET Tactile Sensing Arrays using CMOS Technology

This work presents the advanced version of novel POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) devices based tactile sensing chip. The tactile sensing chip in the new version, presented here, has been fabricated using CMOS (Complementary Metal Oxide Semiconductor) technology. The chip consists of 4 × 4 POSFET touch sensing devices, four temperature diodes, and the electronic circuitry comprising of multiplexers, current mirrors, high compliance current sinks and voltage output buffers. The on chip POSFET devices have linear response in the tested dynamic contact forces range of 0.01-3N and the sensitivity (without amplification) is 102.4 mV/N.

Towards Tactile Sensing System on Chip for Robotic Applications

This paper presents the research on tactile sensing system on chip. The tactile sensing chips comprise of 5 × 5 array of Piezoelectric Oxide Semiconductor Field Effect Transistor (POSFET) devices and temperature sensors. The POSFET devices are obtained by spin coating piezoelectric polymer, poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), films directly on to the gate area of Metal Oxide Semiconductor (MOS) transistors. The tactile sensing chips are able to measure dynamic contact forces and temperatures. The readout and the data acquisition system to acquire the tactile signals are also presented. The chips have been extensively tested over wide range of dynamic contact forces and temperatures and the experimental results are presented. The paper also reports the research on tactile sensing chips with POSFET array and the integrated electronics.

Contact analysis and modeling of standing wave linear ultrasonic motor

A contact model for describing the contact mechanics between the stator and slider of the standing wave linear ultrasonic motor was presented. The proposed model starts from the assumption that the vibration characteristics of the stator is not affected by the contact process. A modified friction models was used to analyze the contact problems. Firstly, the dynamic normal contact force, interface friction force, and steady-state characteristics were analyzed. Secondly, the influences of the contact layer material, the dynamic characteristics of the stator, and the pre-load on motor performance were simulated. Finally, to validate the contact model, a linear ultrasonic motor based on in-plane modes was used as an example. The corresponding results show that a set of simulation of motor performances based on the proposed contact mechanism is in good agreement with experimental results. This model is helpful to understanding the operation principle of the standing wave linear motor and thus contributes to the design of these types of motor.

Bond graph modeling of planar prismatic joints

Neglecting dynamic load during design of a prismatic joint for high-speed operation may lead to unpredictable failures. A slider joint is usually a part of a pneumatic or hydraulic actuation device which may further involve complicated control systems. Thus, design/analysis of prismatic joints calls for a multi-energy domain modeling approach such as bond graph for reusability of the model in different application scenarios. The slider is treated to be a multibody system composed of two separate rigid bodies which are constrained to produce the desired motion. The constraints generate the dynamic contact forces which are used to compute the dynamic frictional forces. The bond graph model of the planar slider component developed in this article accurately calculates the dynamic loads. The model is first validated through numerical simulations performed on a Rapson slide. Thereafter, a multi-energy model for a V-twin engine and its mounting is developed to show how bond graph modeling makes it possible to create an integrated model of thermal, pneumatic and mechanical systems. Finally, the bond graph model of a three-dimensional prismatic joint is developed.

Laser-based excitation of nonlinear solitary waves in a chain of particles

Highly nonlinear solitary waves (HNSWs) are stress waves that can form and travel in highly nonlinear systems. They are characterized by a constant spatial wavelength and by a tunable propagation speed, dependent on the wave amplitude. Conventionally, HNSW's are generated in one-dimensional chains of spherical particles by means of a mechanical impact. In this paper, we demonstrate that short-duration laser pulses can be used to generate HNSW's, and we characterize their propagating properties in terms of shape, speed, and duration. We compare the waves' characteristics with theoretical predictions, finding excellent agreement. In addition a simplified formulation is given to estimate the dynamic contact force generated by laser pulses onto the chain.

Assessment of reginal plantar shear forces at sub-MTH pad/foot-supporting interface in walking

The plantar soft tissue that pads underneath the metatarsal heads (MTH) (i.e. sub-MTH pad) at the ball of the forefoot are exposed to substantial dynamic contact forces during gait. Variations in v...

A Proposed Tool to Determine Dynamic Load Distribution between Corrugated Boxes

This paper summarizes the dynamic analysis of the interaction of corrugated boxes in transport using a pressure‐mapping system. The dynamic contact forces on the contact area between boxes in both vertical and horizontal directions were measured, and the position of the instantaneous centre of force was traced, from which the pitch motion of boxes relative to each other was studied. The level‐crossing diagrams of the contact forces show a Rayleigh distribution for the vertical contact and a Gaussian distribution for the horizontal contacts. The contact force and acceleration power spectral density from accelerometers and pressure‐mapping system were compared.The results show that a pressure‐mapping system is an interesting tool for the analysis of the dynamic performance of systems of corrugated boxes under different stacking and loading conditions. Copyright © 2011 John Wiley & Sons, Ltd.