Hunt-Crossley Model Research Articles

Modeling and Admittance Control of a Piezoactuated Needle Insertion Device for Safe Puncture of Spinal Membranes

Abstract The most challenging procedure for lumbar puncture (LP) is accurately puncturing the spinal membrane (dura mater) based on an automatic needle insertion device (NID). Piezoactuated NID has shown its advantages in robotic-assisted LP with high precision and compact structure. Soft control of the NID is important for insertion safety; however, for stick-slip piezo-actuated NID, there are few studies due to the complex mechanism of stick-slip motion. Here, a modeling and admittance control method for a proposed stick-slip piezoactuated NID is proposed for safe puncture of the spinal membrane. To analytically model the NID, the compliant mechanism (CM) in the NID is reduced to a second-order system. The stick-slip friction and the spinal membrane are modeled based on the LuGre model and the Hunt-Crossley model, respectively. Based on these models, an admittance controller (AC) for the proposed NID is established to realize the precise control of the position and the safety protection against puncture errors. Simulations and preliminary experiments based on a prototype of the NID and a phantom of the spinal membrane were carried out to test the proposed modeling and control method. Results show that the proposed NID with AC has a maximum insertion error of 0.62 mm and the insertion depth decays by 80% when an unexpected force is applied. Therefore, the proposed model and control method have the potential to be used in real LP procedures by further development.

Real-time haptic characterisation of Hunt-Crossley model based on radial basis function neural network for contact environment

Dynamic soft tissue characterisation is an important element in robotic minimally invasive surgery. This paper presents a novel method by combining neural network with recursive least square (RLS) estimation for dynamic soft tissue characterisation based on the nonlinear Hunt-Crossley (HC) model. It develops a radial basis function neural network (RBFNN) to compensate for the error caused by natural logarithmic factorisation (NLF) of the HC model for dynamic RLS estimation of soft tissue properties. The RBFNN weights are estimated according to the maximum likelihood principle to evaluate the probability distribution of the neural network modelling residual. Further, by using the linearisation error modelled by RBFNN to compensate for the linearised HC model, an RBFNN-based RLS algorithm is developed for dynamic soft tissue characterisation. Simulation and experimental results demonstrate that the proposed method can effectively model the natural logarithmic linearisation error, leading to improved accuracy for RLS estimation of the HC model parameters.

Online elasticity estimation and material sorting using standard robot grippers

Stiffness or elasticity estimation of everyday objects using robot grippers is highly desired for object recognition or classification in application areas like food handling and single-stream object sorting. However, standard robot grippers are not designed for material recognition. We experimentally evaluated the accuracy with which material properties can be estimated through object compression by two standard parallel jaw grippers and a force/torque sensor mounted at the robot wrist, with a professional biaxial compression device used as reference. Gripper effort versus position curves were obtained and transformed into stress/strain curves. The modulus of elasticity was estimated at different strain points and the effect of multiple compression cycles (precycling), compression speed, and the gripper surface area on estimation was studied. Viscoelasticity was estimated using the energy absorbed in a compression/decompression cycle, the Kelvin-Voigt, and Hunt-Crossley models. We found that (1) slower compression speeds improved elasticity estimation, while precycling or surface area did not; (2) the robot grippers, even after calibration, were found to have a limited capability of delivering accurate estimates of absolute values of Young’s modulus and viscoelasticity; (3) relative ordering of material characteristics was largely consistent across different grippers; (4) despite the nonlinear characteristics of deformable objects, fitting linear stress/strain approximations led to more stable results than local estimates of Young’s modulus; and (5) the Hunt-Crossley model worked best to estimate viscoelasticity, from a single object compression. A two-dimensional space formed by elasticity and viscoelasticity estimates obtained from a single grasp is advantageous for the discrimination of the object material properties. We demonstrated the applicability of our findings in a mock single-stream recycling scenario, where plastic, paper, and metal objects were correctly separated from a single grasp, even when compressed at different locations on the object. The data and code are publicly available.

Iterative Kalman filter for biological tissue identification

Dynamic soft tissue identification plays an important role in robotic-assisted minimally invasive surgery to achieve realistic force feedback for precise and safe surgical operations. This article studies a dynamic soft tissue identification method by combination of the Hunt Crossley contact model with an iterated Kalman filter. The dynamic system equation of tool-tissue interaction is constructed by combining mechanical tool's kinematic dynamics with the Hunt Crossley contact dynamics. Upon this, an iterative Kalman filter is developed for online soft tissue identification by integrating the maximum a posteriori principle into the Kalman filtering framework to optimize the posterior state estimate to account for the strong nonlinearity of the Hunt Crossley contact model. Results and comparison analysis demonstrate that the proposed method can effectively identify the Hunt-Crossley model parameters, resulting in improved accuracy compared with the conventional recursive least square method and extended Kalman filter.

Rocking of rigid blocks standing on a horizontally-moving compliant base

In this paper the dynamic response of rectangular rigid blocks standing on a horizontally-moving compliant base that is not rigidly connected to its excitation source is investigated for the first time through a combination of analytical, numerical and experimental studies. A novel model combining the well-established studies of a rigid block supported by horizontally-moving rigid base and recent advances on the dynamics of a block rocking on compliant surfaces is derived. Specifically, the impact between the block and the moving base is modelled through a series of springs in parallel with dampers, leading to the generally known Winkler and Hunt–Crossley models. Model parameters are calibrated through forced harmonic rocking tests and then validated through extensive experimental tests with both free and forced rocking. Comparisons of numerically determined trajectories versus those experimentally determined highlight the accuracy of the compliant base model. The main advantage of the compliant base model over the traditionally adopted rigid base model is that it can better predict when rocking will be initiated. This feature is further highlighted from overturning charts numerically evaluated and experimentally verified.

Mathematical Modelling and Experimental Validation of Bifurcation Dynamics of One-Degree-of-Freedom Oscillator with Duffing-Type Stiffness and Rigid Obstacle

PurposeIn the work there are presented results of the synthesis and additional validation of previously developed mathematical models of two different mechanical oscillators with 1 degree of freedom and harmonic excitation: (i) with magnetically modified elasticity generating a double symmetrical minimum of potential; (ii) with linear mechanical springs and with a one-sided limiter of motion.MethodsIn the first case, original mathematical models of non-linear magnetic springs were developed, allowing for effective and fast numerical simulations of the bifurcation dynamics of a real mechanical oscillator with Duffing type stiffness. In the second system, various models of impact were proposed and tested: continuous models based on the generalized Hunt–Crossley model and original discontinuous versions of this model based on the restitution coefficient and with a finite duration of the collision. In the frame of the present work, a system consisting of magnetic springs used in the first system and obstacles from the second oscillator was built and investigated. The system was built as a new configuration of a special universal stand used in the earlier studies mentioned here.Results and ConclusionIn the current study, the parameters of the models identified in previous studies on two different systems were used, the synthesis of which is the current work. A very good agreement was obtained between numerical simulations and experimental data, thus demonstrating the correctness and effectiveness of the adopted mathematical models.

A new discontinuous impact model with finite collision duration

In the work it is proposed a new discontinuous impact model based on the restitution coefficient and the finite duration of the collision, which are functions of the velocity before the collision. The model was validated during modelling, experimental and simulation studies of the bifurcation dynamics of an oscillator of one-degree-of-freedom with a one-sided limiter. The simulation results using the new discontinuous impact model were compared with numerical solutions obtained with the use of the continuous five-parameter Hunt-Crossley model assuming the obstacle compliance. It was shown that the new discontinuous model produces results that are as realistic and consistent with the experimental data as the compliant impact model. Moreover, the significance of the dependence of the restitution coefficient on the speed before the collision and the contact time during the collision in obtaining a good agreement of the simulation results with the experimental data were shown.

A continuous switching contact model for virtual environment based teleoperation

Virtual environment (VE), as the proxy of slave contact environment, is the most promising technology to solve the time-delay problems in teleoperation. The accuracy of the predicted force depends not only on the reliability of the contact model but also on the estimation algorithm’s adaptability. A new contact model is proposed to be applicable in various materials, which includes both the Kelvin–Voigt model (KVM) and Hunt–Crossley model (HCM). An extra parameter is set in the model to express the capacity of continuous switching between KVM and HCM, whose rationality is proved based on the energy loss. The energy loss is proportional to a power of impact velocity, and the exponent is bounded at [2,3], which exactly lies between KVM and HCM. Furthermore, to estimate the parameters with a single-stage method, the nonlinear model is linearized approximatively with logarithm function and polynomials. Then, the recursive least squares (RLS) algorithm combining forgetting factor and self-perturbing action is designed to identify the four parameters online. Finally, the model’s continuous switching is verified with ideal simulation, and the model parameters are continuously changed without jumpy switch error. In the experiment, sponge, foam, and human hand represent the complex contact materials of the slave environment where the predicted force is shown to follow the real contact force with enough accuracy. Therefore, the virtual model can be considered the substitution of slave contact environment so that the feedback force in master can be calculated in real-time.

Simulating finger-tip force using two common contact models: Hunt-Crossley and elastic foundation

Musculoskeletal models of the hand rarely include fingerpad contact mechanics, thereby limiting our ability to simulate and examine hand-object interactions. The objective of this study was to evaluate whether two common contact models (Hunt-Crossley and Elastic Foundation) can accurately represent the fingerpad. Two musculoskeletal models of the index finger were created by adding fingerpad contact geometry using either the Hunt-Crossley or Elastic Foundation contact models. Key contact parameters (target force, contact area, and stiffness) were then systematically varied through 432 forward dynamic simulations to examine how these parameters influenced estimation of finger-tip forces. Across all simulations, variation in target force, contact area, and stiffness parameters impacted the computation time required to complete the simulations and the accuracy of the predicted finger-tip force. Computation time was over three times longer in simulations with high versus low values of contact area and stiffness in both contact models. For both contact models, larger contact area and stiffness values resulted in simulations that more closely predicted target force. However, across all simulations, the Hunt-Crossley model produced a greater proportion of accurate finger-tip force simulations than the Elastic Foundation model, suggesting that the Hunt-Crossley contact model may be preferable for modeling the fingerpad. Overall, our study demonstrates how the Hunt-Crossley and Elastic Foundation contact models behave in low-force biomechanical scenarios, such as those experienced during hand-object manipulation, and provides a foundation for incorporating contact mechanics into musculoskeletal models of the hand.

Dynamic modeling and simulation of impact in hydraulic cylinders

In this paper, modeling impact dynamics of a piston and its cylinder body in a hydraulic cylinder is investigated. The studied system consists of two identical hydraulic cylinders controlled by a pressure sequence valve. The impact is assumed as a linear one dimensional and purely translational viscoelastic impact of rigid bodies. Four impact models, the Kelvin-Voigt, the Maxwell, the standard-solid, and the Hunt-Crossley, are considered. Measurements of the transient variations of the cylinders operating pressures and both pistons strokes, at different loading conditions, are conducted. A comprehensive dynamic model of the studied system, considering the four models, is deduced. The Kelvin-Voigt model produced tensile forces by the end of the contact period and it resulted in discontinuities in the contact force during its steady state period. Both results are physically impossible in rigid bodies impacting. In the Maxwell model, large amount of discontinuities appeared in the contact force, which causes the piston to make an infinite number of rebounds during the contact period. In the standard-solid model, the discontinuities in the contact force were found to be much less than those of the Maxwell model. As a result, when the impact occurs, the cylinder pressure gets an overshoot accompanied with large oscillations when the Maxwell model is applied, however, these oscillations do not approximately appear when the standard-solid model is applied. The simulation results showed also that the Hunt-Crossley nonlinear model presented very high penetration depth, which is certainly unrealistic in rigid bodies impacting. The validation of the proposed dynamic models showed that the standard-solid is the most suitable model that may represent the impact in the studied cylinders.

Impact dynamics modelling of viscoelastic materials

The aim of this paper is modelling and simulation of nonlinear impact system of viscoelastic bodies. Linear impact model was developed based on Kelvin-Voigt, and nonlinear modelling was based on Hunt-Crossley model. Two approaches were used in the nonlinear modelling; one is based on standard parameters of stiffness/damping coefficients, and the other approach is based on calibrated coefficients of stiffness/damping terms.A multi velocity values are considered to be 10.00 m/s, 20.00 m/s and 30.00 m/s to evaluate the dynamic response of the viscoelastic impact model. This study concentrated on various high velocity impact to enhance a modeling process where coding solve type and Matlab Simulink environment is utilized.In addition, higher order ODE fitted data model has been used to improve the dynamic response of the viscoelastic body by optimizing fundamental impact model parameters, i.e. stiffness and damping terms based on deflection-time experimental data. The nonlinear body response and the contact force are analyzed and the results showed the linear model has been corrected by 96.39% from experimental one, while the fitted data model corrected by 96.72%.

Fundamental Contact Dynamics Model of a Crawler-Type Vehicle Simulation

In this paper, I established a single crawler model with a dynamic contact force considered. I modeled each crawler track using dynamic contact model. By modeling each crawler track, I hope to be able to analyze trafficability of a crawler type vehicle in various road surfaces. First, I think that I established a single crawler model. I modeled a single crawler using Hunt-Crossley model and Coulomb model that handle a nonlinear contact force model. And also, I built a prototype single crawler for comparing the experimental examination with the simulation examination. In advance, the running over limit of the prototype single crawler was analyzed geometrically, and I bore out that it could run over to 163 mm. Therefore, I conducted the experiment examination with step height of 160 mm and 165 mm and obtained trajectory data that were allowed to run over and were not allowed to run over. From the result of both the experimental examination and the simulation examination, I bore out the validity of our single crawler model. I described about our single crawler model, the simulation examination and the experimental examination in this paper.

Modeling of impact of the poppet element on its seat body in pressure relief valves

This article deals with modeling of the impact between the moving elements and their seats bodies in pressure relief valves. Four different impact models, such as the Kelvin–Voigt, the Maxwell, the standard-solid and the Hunt–Crossley models, are considered. A comprehensive dynamic model of the studied valve, considering the four models, is deduced. The simulation results show that the Kelvin–Voigt model cannot be used to represent the impact in pressure relief valves because, by the end of impact period, the model results in a tensile force, which is physically impossible in rigid bodies impacting. In the Maxwell model, a considerable number of discontinuities appeared in the impact force, which causes the poppet element to make a number of rebounds with the seat body during the impact period. However, in the standard-solid model, the poppet element barely rebounds. In the Hunt–Crossley nonlinear model, a certain penetration distance between the poppet element and the seat body occurs, which is certainly unrealistic in rigid bodies impacting. The validation of the impact models showed that the Maxwell model is the suitable impact model that can be used to represent the impact in pressure relief valves. However, the validation of the proposed dynamic model proved that the impact has no significant effect on the dynamic performance of pressure relief valves. The main reason behind this is that the impact occurs when the operating pressure has fallen down (the valve is out of operation).

Research of Contact Response of an Elastic Sphere Impacting a Rigid Plate Based on the Mass-Spring-Damped Oscillator Model and Dimensionless Parameter \omega_\Omega

The contact theory, such as the Hertz theory and Hunt-Crossley model can just solve the contact response when the sphere goes to the maximum compression but can't solve the contact process. In traditional research the impact process is considered as a single degree of freedom dynamical spring-damping system, however, the calculated contact force is much greater than the actual one. Based on the shortage of the conducted studies, a new dimensionless parameter Omega is proposed in this paper, the mass-spring-damped oscillator model (MSDOM) and the new contact theory with the consideration of the sphere mass and Omega are established. The correctness of the theoretical model is verified by 3D simulation, and the optimal contact force model is obtained. Furthermore, influence rules of material properties and contact parameters on contact response were studied. The results show that the contact deformation, velocity, piecewise nonlinear contact force and acceleration based on MSDOM and Omega are effective to calculate the contact response. The contact stiffness, damping, material properties of sphere and elastic modulus of the plate have different influence on the contact response while the Poisson's ratio nu_2 has little effect on it.

A damped bipedal inverted pendulum for human–structure interaction analysis

The bipedal inverted pendulum with damping has been adopted to simulate human–structure interaction recently. However, the lack of analysis and verification has provided motivation for further investigation. Leg damping and energy compensation strategy are required for the bipedal inverted pendulum to regulate gait patterns on vibrating structures. In this paper, the Hunt–Crossley model is adopted to get zeros contact force at touch down, while energy compensation is achieved by adjusting the stiffness and rest length of the legs. The damped bipedal inverted pendulum can achieve stable periodic gait with a lower energy input and flatter attack angle so that more gaits are available, compared to the template, referred to as spring-load inverted pendulum. The measured and simulated vertical ground reaction force-time histories are in good agreement. In addition, the dynamic load factors are also within a reasonable range. Parametric analysis shows that the damped bipedal inverted pendulum can achieve stable gaits of 1.6 to 2.4 Hz with a reasonable first harmonic dynamic load factor, which covers the normal walking step frequency. The proposed model in this paper can be applied to human–structure interaction analysis.

Real-Time Nonlinear Characterization of Soft Tissue Mechanical Properties

Online soft tissue characterization is important for robotic-assisted minimally invasive surgery to achieve precise and stable robotic control with haptic feedback. This paper presents a new nonlinear recursive adaptive filtering methodology for online nonlinear soft tissue characterization. An adaptive unscented Kalman filter is developed based on the Hunt-Crossley model by windowing approximation to online estimate system and measurement noise covariances. To improve the accuracy of noise covariance estimations, a recursive formulation is subsequently developed for estimation of system and measurement noise covariances by introducing a weighting factor. This weighting factor is further modified to accommodate noise statistics of large variation which could be caused by rupture events and geometric discontinuities in robotic-assisted surgery. Simulations, experiments, and comparison analyses demonstrate that the proposed nonlinear recursive adaptive filtering methodology can characterize soft tissue parameters in the presence of system or measurement noise statistics in both small and large variations for robotic-assisted surgery. The proposed methodology can effectively estimate soft tissue parameters under system and measurement noises in both small and large variations, leading to improved filtering accuracy and robustness in comparison with UKF.

Precision Motion Control using Nonlinear Contact Force Model in a Surgical Device.

Otitis media with effusion (OME) is a common middle ear disease in children. The Ventilation Tube Applicator is an ear surgical device to treat OME by inserting a grommet into tympanic membrane (TM). This grommet insertion process requires very delicate control to minimise trauma to the TM and to ensure that the grommet is successfully inserted. This paper introduces a precision motion controller using Hunt-Crossley contact force model to provide a good prediction of the force on the TM during the insertion process. This predicted force was used to reject the disturbance in the motion control scheme and resulted in tremendous improvement in precision and accuracy. The maximum absolute tracking error of the motion controller was reduced by up to 29%, and the root mean square error was reduced by up to 43%. This novel use of a nonlinear contact force model has been proven to work well and can be considered for other robotic surgeries that involves contact and requires placement accuracy.

가압 플랫폼의 PD 힘 제어와 헌트-크로슬리 모델을 이용한 안정성 증명

가압 플랫폼의 PD 힘 제어와 헌트-크로슬리 모델을 이용한 안정성 증명

In vivo and in vitro comparative assessment of the log-linearized Hunt–Crossley model for impact-contact modeling in physical human–robot interactions

In physical human–robot interactions, making the robot perceive in real time the mechanical contact impedance is critical for interactions safety, robot control and haptic rendering for robot teleoperation and can be achieved through online parametric model identification. Probing the viscoelastic properties of tissues is also a medical concern. For soft viscoelastic biological tissues, the Hunt–Crossley model is a contact force model computationally inexpensive while being accurate. As this model is non-linear, a log linear approximation has been proposed to achieve a fast and real-time identification using a recursive least squares approach. In this article, we want to regard the log-linearized expression of the Hunt–Crossley model no more as an approximation, but rather as a valuable empirical mechanical model of soft biological tissues. We show through experimental data fit and sophisticated statistical analysis that the log-linearized Hunt–Crossley model performs always closely to the Hunt–Crossley model and is even often slightly better. The experimental conditions investigated are related to impact and contact interactions, relevant in the context of Cobotics.

Gain determination of feedback force for an ultrasound scanning robot using genetic algorithm.

The remote medical diagnosis system (RMDS) is for providing medical diagnosis to the patients located in remote sites. To apply to RMDS and medical automation, many master-slave type ultrasound scanning robots are being developed and researched. One of the important research issue of the master-slave type ultrasound scanning robot is to determine the gains of the feedback force. Therefore, in this study, we suggest a gain determination method of feedback force for a master-slave type ultrasound thyroid scanning robot using a genetic algorithm. A master-slave type ultrasound thyroid scanning robot (NCCMSU) was constructed, and the optimal y and z direction feedback force gains were calculated for NCCMSU with genetic algorithm. The Hunt-Crossley model is used to model the elastic behavior of the thyroid phantom and the thyroid scanning procedure is embedded in genetic algorithm by modeling the procedure mathematically. The genetic algorithm solves the average feedback force-overall procedure time optimization problem to seek optimal y, z direction feedback gains candidates. The rating results show that although there are some deviations among the subjective ratings, the feedback force with the determined gain setting is within the appropriate range. By analyzing the subjective rating test, the optimal y, z direction feedback force gains were determined. The optimal gains were verified by thyroid phantom scanning test and the scanned ultrasound image analysis. With the proposed method, the y, z direction optimal feedback force gains of the master-slave type ultrasound scanning robots can be determined. The proposed methods were verified by thyroid phantom scanning test.