Slider Crank Research Articles

Adaptive self-recurrent wavelet neural network and sliding mode controller/observer for a slider crank mechanism

Adaptive self-recurrent wavelet neural network and sliding mode controller/observer for a slider crank mechanism

Adaptive self-recurrent wavelet neural network and sliding mode controller/observer for a slider crank mechanism

In this paper, a novel control strategy based on an adaptive Self-Recurrent Wavelet Neural Network (SRWNN) and a sliding mode controller/observer for a slider crank mechanism is proposed. The aim is to reduce the tracking error of the linear displacement of this mechanism while following a specified trajectory. The controller design consists of two parts. The first one is a sliding mode control strategy and the second part is an SRWNN controller. This controller is trained offline first, and then the SRWNN weights are updated online by the adaptive control law. Apart from the hybrid control strategy proposed in this paper, a velocity observer is implemented to replace the use of velocity sensors. The outcomes obtained in the numerical experiment section prove that the smallest tracking error is obtained for the linear and angular displacements in comparison with other strategies found in literature due to the uncertainty and disturbance rejection properties of the sliding mode and the self-recurrent wavelet neural network controllers.

Piezoelectric energy harvester under parametric excitation: A theoretical and experimental investigation

In the present work, both theoretical and experimental investigation of a vertical cantilever beam–based piezoelectric energy harvester are carried out under principal parametric resonance condition. A piezoelectric patch is attached near the fixed end of the cantilever beam along with an attached mass positioned at an arbitrary location. The extended Hamilton’s principle is used to derive the spatio-temporal equation of motion, and generalized Galerkin’s approximation is used to obtain the temporal nonlinear electromechanical governing equation of motion. The method of multiple scales is used to find the reduced modulation equations. Due to large transverse deflection and effect of rotary inertia of the attached mass, the system exhibits cubic and inertial nonlinearities. An experimental setup with slider crank mechanism–based shaker and a harvester consisting of a cantilever beam with piezoelectric patch and attached mass is designed and developed. The challenges posed by parametric resonance in crack development in the PZT and in the beam are reported. The theoretical and experimental output voltage and the power obtained are found to be in good agreement. Furthermore, a qualitative and quantitative comparative study of 17 energy harvesters has been carried out, and the normalized power densities have been compared.

Performance study of the hypocycloid gear mechanism for internal combustion engine applications

Fuel conversion efficiency is one of the main concerns in the field of internal combustion engine systems. Although the Otto cycle delivers the maximum efficiency possible in theory, the kinematics of the slider–crank mechanism of the conventional internal combustion engines makes it difficult to reach this level of efficiency in practice. This study proposes using the unique hypocycloid gear mechanism instead of the conventional slider–crank mechanism for the internal combustion engines to increase engine efficiency and minimize frictional power losses. The hypocycloid gear mechanism engine’s kinematics provides the means for the piston-rod assembly to reciprocate in a straight-line motion along the cylinder axis besides achieving a nonlinear rate of piston movement. As a result, this characteristic allows for a true constant-volume combustion, which in turn would lead to higher work output. An in-cylinder gas volume change model of the hypocycloid gear mechanism engine was developed and incorporated into the thermodynamic model for the internal combustion engine cycle. The thermodynamic model of the hypocycloid gear mechanism engine was developed and simulated using MATLAB/Simulink software. A comparison between the conventional engine and the hypocycloid gear mechanism engine in terms of engine performance characteristics showed the enhancements achieved using hypocycloid gear mechanism for internal combustion engine applications. The hypocycloid gear mechanism engine analysis results indicated higher engine efficiency approaching that of the Otto cycle.

A 5-Degrees-of-Freedom Lightweight Elbow-Wrist Exoskeleton for Forearm Fine-Motion Rehabilitation

Exoskeleton robots have been demonstrated to effectively assist the rehabilitation of patients with upper or lower limb disabilities. To make exoskeletons more accessible to patients, they need to be lightweight and compact without major performance tradeoffs. Existing upper limb exoskeletons focus on assistance with coarse motion of the upper arm, whereas forearm fine-motion rehabilitation is often ignored. This paper presents an elbow-wrist exoskeleton with five degrees of freedom (DoFs). Using geared bearings, slider crank mechanisms, and a spherical mechanism for the wrist and elbow modules, this exoskeleton can provide 5-DoF rotary motion forearm assistance. The optimized exoskeleton dimensions allow sufficient rotation output while the motors are placed parallel to the forearm and elbow joint. Thus, compactness and less inertia loading can be achieved. Linear and rotary series elastic actuators with high torque-to-weight ratios are proposed to accurately measure and control interaction force and impedance between exoskeleton and forearm. The resulting 3-kg exoskeleton can be used alone or easily in combination with other exoskeleton robots to provide various robot-aided upper limb rehabilitation.

Dynamic analysis of slider-crank mechanism with clearance fault

In this paper, the dynamic behavior of the slider-crank mechanism with clearance fault is investigated. The revolute joint with clearance is equivalent to a virtual massless rod, and then the dynamic equation of the crank slider mechanism with clearance is established by the Lagrangian method. In addition, a three-dimensional dynamic model of the crank slider mechanism with clearance is also established by ADAMS. The numerical results show that the clearance affects the displacement and velocity response of the crank-slider mechanism in a weak way, but influences the acceleration response of the mechanism in a significant manner. Due to the existence of the clearance, the revolute joint of the mechanism produces a rub-impact phenomenon, and the larger the clearance, the greater the impact strength. During the rub-impact process, there are three kinds of motion states of separation, collision and contact occur.

Automating the Derivation of the Equations of Motion of a Multibody Dynamic System With Uncertainty Using Polynomial Chaos Theory and Variational Work

Abstract Understanding how variation impacts a multibody dynamic (MBD) system's response is important to ensure the robustness of a system. However, how the variation propagates into the MBD system is complicated because MBD systems are typically governed by a system of large differential algebraic equations. This paper presents a novel process, variational work, along with the polynomial chaos multibody dynamics (PCMBoD) automation process for utilizing polynomial chaos theory (PCT) in the analysis of uncertainties in an MBD system. Variational work allows the complexity of the traditional PCT approach to be reduced. With variational work and the constrained Lagrangian formulation, the equations of motion of an MBD PCT system can be constructed using the PCMBoD automated process. To demonstrate the PCMBoD process, two examples, a mass-spring-damper and a two link slider–crank mechanism, are shown.

Modeling and Analysis of Spatial Flexible Mechanical Systems With a Spherical Clearance Joint Based on the LuGre Friction Model

Abstract A computational methodology for modeling spatial flexible mechanical systems with stick-slip friction in a spherical clearance joint is presented. A modified three-dimensional (3D) absolute nodal coordinate formulation based shear deformable beam element with two nodes is proposed and employed to discretize the flexible components. To avoid locking problems, we employed an enhanced continuum mechanics approach to evaluate the beam element elastic forces. The strain components εyz, εyy, and εzz are approximated using linear interpolation to improve the computational efficiency while the loss of accuracy is acceptable. The contact and friction forces in a spherical clearance joint were evaluated by the hybrid contact and LuGre friction models, respectively. Three numerical examples are presented and discussed. A simple pendulum was utilized to prove the correctness of the modified beam element. A classical slider–crank mechanism was employed to validate the computational methodology. A spatial rigid–flexible slider–crank mechanism with a spherical clearance joint was used to investigate the effect of link flexibility and joint clearance on the dynamic behavior of mechanical systems. Using the LuGre friction model, we reproduced the Stribeck effect as it is expected in real world settings. The components with appropriate stiffness play the role of suspension for spatial mechanical systems with imperfect joints. The vibrations of the flexible components play an active role of intensifying the collision in kinematic joint with clearance.

Effect of changes in the crank radius on the kinematics of the pumping unit when regulating the dynamic level of the fluid in the well

The article deals with the effect of changes in the crank radius on the kinematics of the pumping unit when regulating the dynamic level of the fluid between the tubing strings and the casing in order to increase the well production rate or reduce the accident rate. To improve the quality of prediction, the movement of a polished rod over time is calculated using the Fourier variable separation method: the product of the rocker head of a pumping unit determined as movement of a slider crank mechanism along the straight line (as a circle chord), and the difference of this chord with a length of the circumference equivalent to the movement of the swivel joint of the balancer with a connecting rod. As a result, the accuracy of calculations is increased and the solution of the problem is simplified.

Neural Network Augmented Physics Models for Systems With Partially Unknown Dynamics: Application to Slider–Crank Mechanism

Dynamic models of mechatronic systems are abundantly used in the context of motion control and design of complex servo applications. In practice, these systems are often plagued by unknown interactions, which make the physics-based relations of the system dynamics only partially known. This article presents a neural network augmented physics (NNAP) model as a combination of physics-inspired and neural layers. The neural layers are inserted in the model to compensate for the unmodeled interactions, without requiring direct measurements of these unknown phenomena. In contrast to traditional approaches, both the neural network and physical parameters are simultaneously optimized, solely by using state and control input measurements. The methodology is applied on experimental data of a slider–crank setup, for which the state-dependent load interactions are unknown. The NNAP model proves to be a stable and accurate modeling formalism for dynamic systems that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ab initio</i> can only be partially described by physical laws. Moreover, the results show that a recurrent implementation of the NNAP model enables improved robustness and accuracy of the system state predictions, compared to its feedforward counterpart. Besides capturing the system dynamics, the NNAP model provides a means to gain new insights by extracting the neural network from the converged NNAP model. In this way, we discovered accurate representations of the unknown spring force interaction and friction phenomena acting on the slider mechanism.

Newtonian approach towards mathematical modelling and tuning of a Continuously Variable Transmission

Mathematical modelling of a Push - Belt Continuously Variable Transmission (CVT) has been done previously using energy-based methods. However, this paper presents a force based (Newtonian) approach as it eliminates the process of solving differential equations and hence, increases computational speed while eliminating the errors arising out of numerical solutions. The methodology for obtaining the engine rpm for optimum power is elucidated. An offset slider crank model has been used for conversion of rotary motion of flyweights to linear motion, in order to compress the pressure spring in the driving pulley. Mass of flyweights and stiffness values of pressure springs in driving and driven pulley are set as parameters which govern the constant engine rpm. The plot of engine rpm against vehicle speed is observed to be a saturating curve which gives the constant engine rpm obtained by CVT action.

Comparative study on the performance of different drive mechanisms used in a beta type Stirling engine through thermodynamic analysis

In this study, thermodynamic and kinematic analyses of bell crank, slider crank, rhombic and scotch yoke drive mechanisms were performed for a beta type Stirling engine with a swept volume of 365 cm3. The kinematic analyses of Stirling engines with these different drive mechanisms were investigated by using the MSC Adams program, and the pressure-volume variations depending on the crankshaft angle were determined by using the isothermal analysis method. It was determined that compression and expansion volume values of rhombic drive mechanism were close to each other, while compression volume value was extremely higher than expansion volume value in other drive mechanisms. For this reason, in this research conducted with working fluid of equal amount (m=0.000716 kg), for all of drive mechanisms, it was determined that engine with rhombic drive mechanism generates 19.2% net work more than the other drive mechanism. The masses of working fluid used in 1 bar charge pressure from engines with bell crank, slider crank, rhombic and scotch yoke drive mechanism were 0.000716 kg, 0.000737 kg, 0.000536 kg and 0.000724 kg, respectively. The net work amounts obtained as a result of the thermodynamic analyses made for the 1 bar charge pressure value in bell crank, slider crank, rhombic and scotch yoke drive mechanisms are 12.85 J, 12.44 J, 11.61 J and 13.05 J, respectively. In this research conducted with working fluid in the same charge pressure, it was determined that 10.8% less net work was obtained from engine with rhombic drive mechanism. Since all the changes of the volume in the bell crank, slider crank and scotch yoke drive mechanisms are very close to each other, the net work performance values obtained with the equal amount of working fluid and the same charge pressure values are also very close to each other.

Flexible slider crank mechanism synthesis using meta-heuristic optimization techniques: a new designer tool assistance for a compliant mechanism synthesis

This work bespeaks an insight into a real imperfect multibody systems synthesis, wherein the flexible behaviour of its components is considered. Based on the end-effector mechanism velocity, acceleration and defined transversal deflection for a flexible component, the mechanism optimal design variables have been investigated. Subsequently, the three aforementioned responses have been involved simultaneously for a combined optimization process. To this end, an Assistance Tool Design, subsuming several meta-heuristic optimization techniques such as Genetic Algorithm (GA), Imperialist Competitive Algorithm (ICA), Artificial Bee Colony (ABC), Ant Colony (AC), Differential Evolution (DE) and Simulating Annealing (SA) techniques, has been developed under MATLAB software. The Assistance Tool Design enables designers to carry out the synthesis of mechanisms by means of one or many optimization techniques mentioned above. It has been proven that AC and DE outperform the other optimization techniques. Nevertheless, awkwardness has been bearded for the mechanism synthesis using only a single response, mainly the flexible connecting rod mid-point transversal deflection. The combined synthesis subsuming simultaneously the three responses discussed above settles a perfect trade-off for all the optimization techniques.

An efficient formulation for flexible multibody dynamics using a condensation of deformation coordinates

This paper introduces a more efficient formulation for flexible multibody dynamics based on the floating frame of reference formulation (FFRF). A two-step condensation method is proposed. The first condensation involves coordinate reduction using a modal transformation, from nodal coordinates to modal coordinates, in the context of model order reduction (MOR). The second condensation involves re-fabrication of the equations of motion using a dynamic condensation of the deformation modal coordinates obtained from the first condensation. In the first condensation, constraint modes are corrected by condensation of the truncated modes that represent the effects of residual flexibility. As a result, the first condensation offers a more accurate deformation field in the reduced order model, which consequently leads to a more accurate flexible multibody simulation. In the second condensation, the equations of motion of a flexible multibody are once more reduced to the equations of motion in terms of absolute coordinates for the body reference frames. In this way, the proposed method deals with smaller sized equations of motion than in the conventional FFRF, where they are represented in terms of both absolute coordinates and deformation modal coordinates. The effect of the first condensation was verified using a benchmark example of a slider–crank mechanism with a flexible connecting rod. The efficiency of the proposed condensation method was also investigated using a computational complexity analysis with an $n$ -flexible body pendulum.

An improved model of contact collision investigation on multi-body systems with revolute clearance joints

An improved contact collision model for the impact analysis of a slider–crank mechanism with revolute clearance joints is presented and discussed in this paper. Clearances in revolute joints are inevitable due to wear, machining tolerance, and local deformations. In view of the energy loss and the stiffness changes during collision, which modifies the coulomb friction force, an improved contact collision force model is established. The influence of clearance size, speed, and friction on the acceleration of slider is analyzed, and the simulation results are compared with the experimental data. The results demonstrate that the parameters of clearance joints have obvious effects on dynamic characteristics, and the improved model can accurately describe the dynamic characteristics of joints with clearance.

A thermodynamic comparison of rhombic-drive and slider–crank mechanisms for a two-stroke SI engine

ABSTRACT In this study, mathematical models of a novel mechanism, rhombic-drive, for a two-stroke, spark ignition (SI) engine, and a two-stroke SI engine with a conventional slider–crank mechanism were performed in MATLAB software. Their performances were compared with kinematic and thermodynamic analyses. Mathematical model was conducted according to real cycle approach and some of the operating parameters such as compression ratio, swept volume, heat release time, and lambda were kept identical for both engines. Pressure, volume, temperature, heat release, heat transfer coefficient, work, piston speed, and acceleration changes were examined. Maximum in-cylinder pressure was taken at 222°CA with 4,188 kPa for rhombic-drive engine while 190°CA with 4,003 kPa for slider–crank mechanism engine and maximum temperature was only 39 K higher for rhombic-drive mechanism engine. Theoretical thermal efficiencies of rhombic-drive and slider–crank mechanism were 31.14% and 31.87%, respectively. Effective power of rhombic-drive mechanism engine was 2.12 kW, whereas slider–crank mechanism engine was 2.17 kW. Mechanical efficiency of rhombic-drive engine was obtained 85.89%, while this was only 86.21% for slider–crank mechanism engine.

Energy harvesting of a frequency up-conversion piezoelectric harvester with controlled impact

Frequency up-conversion is an effective approach to increase the output power of a piezoelectric energy harvester (PEH). In this work, we studied a piezoelectric energy harvesting system, which converts low-frequency vibration from ambient sources to the resonant vibration of the PEH to improve the energy harvesting efficiency. The PEH includes two beams, a pair of rack and pinions, and a slider crank mechanism to retrieve energy from ambient low-frequency vibrations through impacts. The soft driving beam is subjected to a sinusoidal base excitation along the transverse direction. The piezoelectric bimorph undergoes both slow longitudinal motion as well as transverse vibrations. The transverse vibration of the bimorph is induced by impacts which is the vibration source to generate output power. The longitudinal motion of the bimorph is used to control the impact with the soft driving beam, which guarantees the harvester to pump in more kinetic energy from the driving beam. Using the discontinuous dynamic theory, the energy harvesting performance of the impact-controlled system was studied in period one and period two motions. The stability of periodic solutions was investigated and bifurcation diagrams of impact velocities, times and displacements were obtained. The harvested power of the piezoelectric beam versus the based excitation frequency was also obtained, and the results were compared to the power generation of a piezoelectric beam directly subjected to the base excitation along the transverse direction.

Dynamic computation for rigid–flexible multibody systems with hybrid uncertainty of randomness and interval

Considering the unavoidable uncertainty of material properties, geometry, and external loads existing in rigid–flexible multibody systems, a new hybrid uncertain computational method is proposed. Two evaluation indexes, namely interval mean and interval error bar, are presented to quantify the system response. The dynamic model of a rigid–flexible multibody system is built by using the absolute node coordinate formula (ANCF). The geometry size and external loads of rigid components are considered as interval variables, while the Young’s modulus and Poisson’s ratio of flexible components are expressed by a random field. The continuous random field is discretized to Gaussian random variables by using the expansion optimal linear estimation (EOLE) method. This paper proposes an orthogonal series expansion method, termed as improved Polynomial-Chaos-Chebyshev-Interval (PCCI) method, which solves the random and interval uncertainty under one integral framework. The improved PCCI method has some sampling points located on the bounds of interval variables, which lead to a higher accuracy in estimating the bounds of multibody systems’ response compared to the PCCI method. A rigid–flexible slider–crank mechanism is used as a numerical example, which demonstrates that the improved PCCI method has a higher accuracy than the PCCI method.

Design and Development of Fertilizer Spraying Machine

In agricultural sector, generally farmer uses the traditional way of carrying a spray tank on his back and spray onto the crop. This is time consuming, costly and fatigue is also a major concern. These problems can be overcome by using a reciprocating multi sprayer. It facilitates uniform spread pesticides or insecticides. Precision made nozzle tip is used for adjustable stream capable of throwing foggy spray depending on the requirement. we use a slider crank mechanism to convert rotary motion into reciprocating motion to operate the pump. The pesticide is spread through the nozzle giving a continuous flow of pesticide at the required pressure. A special arrangement adjusts the pressure from low to high. We also use a weed cuter for removing the unwanted weeds. By using this agricultural sprayer, spraying time, weeding time and human efforts are reduced and resulting in cost reduction. Aim of the project is that the farmer need not carry the entire pesticide sprayer pump on his shoulders, but just pull/push the mechanism mounted on the trolley to operate the pump to spray.This makes the farmer feel more comfortable, relaxed and less tiresome by reducing human efforts due to the constant pumping action.

KINEMATIC SYNTHESIS OF CRANK-SLIDER MECHANISM OF THE GRIPPING DEVICE BASED ON THE POWER TRANSMISSION INDEX

Purpose. The main purpose of the work is to carry out a kinematic synthesis of a crank-slider gripping device in accordance to the criterion of the constancy of the drive power of the mechanism with restrictions on permissible pressure angles in kinematic pairs. Methodology. Achieving this purpose is carried out by means of the theory of mechanisms and machines using the analytical method of the Ozols triangles of kinematics of plane rod mechanisms and mathematical modeling of the movement of links. Findings. The ten-bar mechanism of the gripping device is built on the basis of a paired parallelogram of a crank-slider mechanism with a leading slider. For gripping device, which is built on the basis of the rod scheme, it is advisable optimal design using the criteria for the transfer of motion or transmission indices. The criterion of optimization is the ratio of the speed of the leading link to the projection of the velocity vector of the driven point on the direction of the clamping force vector (power transmission index). The lowest energy costs can be achieved, provided that this ratio is equal to one. Analytical dependences are obtained for determining the velocity function of the central and de-axial crank-slider gripping device, which are convenient for analysis and modeling. On their basis, an energy synthesis of the geometrical parameters of the mechanism of the gripping device in accordance with the criterion of the smallest deviation from the unit ofpower transmission index is performed. The possibilities of the gripping device are enhanced by using it in a de-axial crank-slider mechanism, and the best results can be obtained in a scheme where the de-axial value is larger than the crank length. It is determined the specific values of the relative parameters of the lengths of the links and the ranges of rotation of the crank of the central and de-axial crank-slider of the grippingdevice, which best meet the optimization criterion and satisfy the pressure angle constraints. Originality. For the first time, a new criterion for the transmission of motion was introduced –power transmission index. According to this criteria, a kinematic synthesis of the gripping device built on the basis of a paired crank slider mechanism was carried out. Practical value. Practical recommendations are proposed on the size and location of the links of the mechanism for the central and de-axial crank-slider mechanism, which satisfy the requirements of the optimization criterion and implement restrictions on permissible pressure angles.