Force Of Cylinder Research Articles

PID electro-hydraulic cylinder force tracking system with friction compensation

Friction can be found in all mechanical systems, and is the cause of control tracking error. In this article, LuGre friction model for symmetric hydraulic cylinder was studied and obtained experimentally. The estimated friction force was applied for reference force compensation. Force tracking performances of PID force control systems with and without friction compensation were tested and compared. Control system with friction compensation outperformed one without in all cases of tracking tests. The best result was found in the square force tracking tests, with an average error at maximum compression force of 86.105 N in the case of with friction compensation compared with error of 511.996 N in the case without. However, the estimated friction achieved in the study was noisy. This is due to the use of noisy numerically differentiated velocity signal in the friction estimation procedure.

Pneumatic Automation Tools: Pneumatic Muscle

The traditional actuating motor for pneumatic drives is a differential double-acting pneumatic cylinder used to create a pushing force that is significantly larger than the pulling force. The pneumatic muscle is a single-acting operating motor to be used for creating a pulling force. The pneumatic muscle is based on a cylindrical bladder (a thin two-dimensional elastic structure) property to change its shape or size upon applying overpressure of actuating medium to it.The paper objective is to present this new type of the actuating motor to a wide range of specialists in pneumatic automation. Using a bladder structure of the pneumatic muscle of the MAS family, company "FESTO" as an example, the paper considers a physical nature of its operation and defines a dependence of the force, developed by a pneumatic muscle in its internal cavity, on the overpressure value and the value of contraction. Describes an experimental setup to study static and dynamic characteristics of the pneumatic muscle, as well as a design of the loading and measuring device.The experimental study allowed us to obtain static and dynamic characteristics of the pneumatic muscle MAS 10-300: dependencies "force - contraction", "force - overpressure", and “contraction -overpressure". The averaged predicted value of the braid angle of impulsion of the cord thread for three sizes of the MAS family pneumatic muscle is determined according to German FESTO Product Catalogue to be 23 ... 25.5°.It is shown that the force curve of the pneumatic muscle is essentially nonlinear: the curve linearity is evident only when the pneumatic muscle contractions are, at most, 2% of its original length. Dynamic properties of the pneumatic muscle loaded with a constant force were evaluated through analysis of frequency characteristics: the operating frequency of the pneumatic muscle was f = 3 ... 6 Hz.The paper presents the reproducibility data of the force characteristic of a pneumatic muscle during its cyclic constant-value over-pressurisation p = 4 bar with a frequency f = 0.5 Hz.The researches have shown that with the cyclic over-pressurisation of the pneumatic muscle the force-value deviations from its averaged value are of systematic nature, depend on the number of loads, and so cannot be estimated by statistical characteristics. The paper considers an operating mode of the pneumatic muscle, as an extension spring, which is appropriate to the external force application to the pneumatic muscle to ensure return of the pneumatic muscle to the initial position after its contraction under over-pressurisation. An average value of the pneumatic spring stiffness is obtained from the force characteristic of the pneumatic muscle through its piecewise-linear approximation within the specified range of change in the contraction value. A comparative estimate of the forces developed by pneumatic muscles and pneumatic cylinders with equal working areas is given. It has been found that the pneumatic muscle contraction force exceeds the pulling force of the pneumatic cylinder, on average, 12 ... 14 times, but this advantage comes out only when the contractions of a pneumatic muscle are small. The usability of a short pneumatic muscle, as a control and loading device for the gates of hydraulic and pneumatic valve-type automation devices, has been investigated.

Active closed-loop vortex-induced vibration control of an elastically mounted circular cylinder at low Reynolds number using feedback rotary oscillations

An active rotary oscillation feedback control methodology is adopted to suppress the flow-induced transverse vibration (VIV) of an elastically supported impenetrable circular cylinder in a uniform low Reynolds number flow (\(\textit{Re} = 100\)). The coupled fluid–structure interaction is replicated by applying the moving mesh technique via a user-defined function (UDF) in the main code of a commercial CFD solver. The closed-loop VIV control action is realized by active forced rotational oscillations of the circular cylinder about its axis based on the feedback signal of the lift coefficient. This prevents the occurrence of resonance by shifting the vortex shedding frequency away from the natural oscillator frequency. Three different active closed-loop proportional controllers are implemented, and their superior performance in cylinder VIV suppression is demonstrated against that of a representative open-loop control system with pre-specified rotational oscillations. It is shown that, in comparison with the open-loop system, the selected closed-loop controller achieves a better cylinder VIV response suppression with a much lower control effort along with considerable reductions in the associated lift/drag coefficients. Furthermore, the closed-loop controller is very effective in a wide range of reduced velocities and does not need to find the “lock-on” forcing frequency for proper de-synchronization. Moreover, the imposed feedback cylinder rotary oscillation is found to considerably affect the spatial characteristics of the wake flow structure by changing the 2S-Coalescent wake pattern (C-2S-mode) of an uncontrolled cylinder into the classical von Karman vortex street (2S-mode), very similar to that of a stationary obstacle. Lastly, when the system is in the fully developed condition, the proportional controller can be complemented by a fuzzy logic inference system for intelligent tuning of gain parameter in order to suppress the impulsive upsurge observed in the cylinder force coefficients of the proportional controller at the start of the control action.

Predicting modal characteristics of a cluster of cylinders in axial flow: From potential flow solutions to coupled CFD–CSM calculations

External fluid flow has a number of effects on the dynamics of a submersed structure: e.g., a solitary cylinder exposed to an external flow experiences added mass and damping due to the presence of the surrounding fluid. At high axial flow velocities relative to the stiffness of the cylinder, coupled instabilities such as flutter and divergence occur. Compared to a solitary cylinder, a cluster of cylinders also experiences inter-cylinder coupling: pressure perturbations in the fluid due to the movement or acceleration of one cylinder force another cylinder to move. Consequently, the different cylinders can move in organized patterns.In this contribution, modal characteristics of a 7-rod bundle will be predicted by linear theory as well as by coupled CFD–CSM (Computational Fluid Dynamics — Computational Structure Mechanics) calculations. In the first part, fluid forces which lead to coupling of motion are computed with classical potential flow theory and URANS (Unsteady Reynolds-Averaged Navier–Stokes). Those forces are divided in a contribution in phase with the acceleration and a contribution in phase with the velocity of a cylinder. In the second part, modal characteristics of a 7 cylinder bundle are computed with coupled CFD–CSM simulations. The initial perturbations, which are required for the time-domain simulations come from a simplified structural model, with potential flow coupling between cylinders. The results are compared to linear theory. In the final part, approximations are proposed to predict upper and lower bounds of eigenfrequencies and damping, using calculations with only one cylinder.

Axial acoustic radiation force on a rigid cylinder near an impedance boundary for on-axis Gaussian beam

This work presents a theoretical model to calculate the acoustic radiation force on a rigid cylindrical particle immersed in an ideal fluid near a boundary for an on-axis Gaussian beam. An exact solution of the axial acoustic radiation force function is derived for a cylindrical particle by applying the translation addition theorem of cylindrical Bessel function. We analyzed the effects of the impedance boundary on acoustic radiation force of a rigid cylinder immersed in water near an impedance boundary with particular emphasis on the radius of the rigid cylinder and the distance from the cylinder center to impedance boundary. Simulation results reveal that the existence of particle trapping behavior depends on the choice of nondimensional frequency as well as the offset distance from the impedance boundary. The value of the radiation force function varies when the cylinder lies at the different position of the on-axis Gaussian beam. For the particle with different radius, the acoustic radiation force functions vary significantly with frequency. This study provides a theoretical basis for acoustic manipulation, which may benefit to the improvement and development of the acoustic control technology.

Acoustic radiation force on a fluid cylindrical particle immersed in water near an impedance boundary.

This work presents a theoretical model to calculate the acoustic radiation force of a fluid cylindrical particle immersed in water near a boundary. A solution of the acoustic radiation force function, which is the radiation force per unit energy density and unit cross-sectional surface area, is derived for a cylinder near a boundary in normal incident plane wave by applying the translation addition theorem of cylindrical function. The effects of impedance boundary on acoustic radiation force of a fluid oleic acid cylinder and a mixture fluid cylinder immersed in water are analyzed with particular emphasis on the radius of fluid cylinder and the distance from its center to the impedance boundary. The results reveal that the existence of particle trapping behavior depends on the choice of the nondimensional frequency ka as well as the offset distance from the impedance boundary. This study provides a theoretical basis for acoustic manipulation, which may be of benefit to the improvement and development of the acoustic control technology.

Dynamic Simulation of the Harvester Boom Cylinder

Based on the complete dynamic calculation method, the layout, force, and strength of harvester boom cylinders were designed and calculated. Closed simulations for the determination of the dynamic responses of the harvester boom during luffing motion considering the cylinder drive system and luffing angle position control have been realized. Using the ADAMS mechanical system dynamics analysis software, six different arm poses were selected and simulated based on the cylinder as the analysis object. A flexible model of the harvester boom luffing motion has been established. The movement of the oil cylinder under different conditions were analyzed, and the main operation dimensions of the harvester boom and the force condition of the oil cylinder were obtained. The calculation results show that the dynamic responses of the boom are more sensitive to the luffing acceleration, in comparison with the luffing velocity. It is seen that this method is very effective and convenient for boom luffing simulation. It is also reasonable to see that the extension of the distance of the bottom of the boom is shortened by adjusting the initial state of the boom in the working process, which can also effectively reduce the workload of the boom—thus improving the mechanical efficiency.

Force Control for Active Chassis Balancing

This paper presents the realization of the worldwide first automated walking excavator chassis. To this end, the authors build a new generation of high-performance hydraulic valves with integrated pressure feedback to achieve fast and accurate cylinder force tracking. This allows automatically adapting the legs to uneven terrains and optimally shaping the ground reaction forces in order to change the orientation and height of the cabin. Due to the contact redundancy, automated balancing is implemented as a contact force optimization problem, including constraints on contact forces and joint torques. The corresponding prioritized optimization problem can be simplified by using a quasi-static approximation of the system dynamics and a complexity reduction due to the kinematic structure of the legs. Our approach considers the unknown configuration and load of the cabin, arm, and bucket as system disturbances, whereby gravitational effects are approximated as well as possible. It is tested in a Gazebo simulation and validated in different experiments by using a prototype walking excavator machine. The proposed method revolutionizes operator control of these versatile but complex multipurpose vehicles: Instead of manual and coordinatively very demanding cylinder position adjustment, the operator can command simple high-level commands like a cabin pose. Furthermore, it significantly reduces peak forces in the cylinders and at the contact points, which causes less damage to the mechanics and the ground.

The Movement Analysis of Hydraulic Robotic Arms

The robotic arm drived by hydraulic are widely applied in most kinds of large engineering equipments, such as concrete pump truck, bridge monitor truck, crane etc. In this paper, the movement of hydraulic robotic arms and hydraulic cylinders are separately analyzed with multi-body dynamics. And the dynamic differential equation is built with the driving force of the hydraulic cylinder as the main force. The equation is based on the theory of multi-body dynamics, building the coupled model of robotic arm system and hydraulic-driving system to study the relation between the end-position, angle and the hydraulic system.

Concept Design of Movable Beam of Hydraulic Press

The hydraulic press movable beam is one of the key components of the hydraulic press; its design quality impacts the accuracy of the workpiece that the press suppressed. In this paper, first, with maximum deflection and material strength as constraints, mechanical model of the movable beam is established; next, the concept design model of the moveable beam structure is established; the relationship among the force of the side cylinder, the thickness of the inclined plate, outer plate is established also. Taking movable beam of the 100MN type THP10-10000 isothermal forging hydraulic press as an example, the conceptual design result is given. This concept design method mentoned in the paper has general meaning and can apply to other similar product design.

Design of Vehicle Track Adjustment Mechanism Based on Synchronous Valve

Track adjustment mechanism of high frame vehicle is designed in order to meet the agronomic requirements of maize field management. track adjustment mechanism is designed using parallel four links, in which a rotating plate acting as connecting rod is hinged with hydraulic pushing rod, and wheel track is adjusted by stretching of the hydraulic pushing rod. In the adjustment process, synchronization of wheel track adjustment on both sides is ensured by hydraulic synchronization valve. The mechanics analysis method is used to analyze force of the wheel track adjusting mechanism, and the force of hydraulic cylinder is determined. Model of the track adjusting system is established by AMESim and dynamic simulation is carried out. Changes of pressure, flow and displacement of two hydraulic adjusting cylinders are analyzed. The simulation results show that pressure of two hydraulic cylinders appears small pulsates before t=3.45 s, it rises to the maximum of 20MPa at t=3.55 s and then stabilizes at 20MPa. Flow rate of the two hydraulic cylinders jumps up and down around 32.5 L / min before t = 3.45 s, the jump amplitude of hydraulic cylinder 1 is 10.7 L/min, the jump amplitude of hydraulic cylinder 2 is 3.0 L/min. Displacement of two hydraulic cylinders gradually increase before t=3.55 s, they reach the maximum value of 0.6 m at t=3.55 s and then stabilizes at 0.6 m. Displacement difference of two cylinders appears pulsation before t=3.55 s, it reaches 8.5×10-3 m at t = 0.21 s and stable in the vicinity of 0 m. The change of pressure, flow and displacement of hydraulic cylinders accord with design requirement, and the maximum displacement difference value of 8.5×10-3m can meet the agronomic requirement of high-stalk crops field management.

Modeling and Analysis of Truck Mounted Concrete Pump Boom by Virtual Prototyping

By far there is lack of research on different working conditions between rigid and flexible dynamics of truck mounted concrete pump booms. First a 3D model has been established by using virtual prototyping technology of a 37 m long boom in Pro/Engineering software. Then the rigid body simulation model has been built. Next modal superimposition method is adopted to change the 4 rigid body booms into flexible ones. Kinematics law and dynamic characteristics of 4 common working conditions had been studied then. Next tip displacement and the first boom hydraulic cylinder force of the 4 working conditions between rigid and flexible models have been researched. Furthermore the first natural frequencies of the structure have been calculated. The results show that the frequency of the horizontal condition has the lowest of all and the roof condition has the largest of all. Besides the cylinder forces of the flexible model are larger than the corresponding rigid ones because of the flexible boom vibration. Finally an experiment has been done on a boom test rig which proved that the established simulation model is reasonable and the frequency results are correct. All of these provide design reference to mechanical manipulator as well as reducing product development cost of such mechanism.

Features of flow past square cylinder with a perforated plate

A numerical investigation was performed on the reduction of the fluid forces acting on the square cylinder in the laminar flow regime with a perforated plate. The effects of geometric parameters such as the distance between the square cylinder and the perforated plate on the wake of the square cylinder were discussed. Furthermore, the flow characteristics such as the drag coefficient, lift coefficient, Strouhal number and flow pattern were obtained. It can be concluded that the drag force of the square cylinder reduces to some extent due to the addition of the perforated plate. The flow structure varies when the perforated plate is located behind the square cylinder. Moreover, the recirculation zone augments with the increase of L/D, and the vortex trace on the upper and lower surface of the square cylinder moves gradually backwards until a stable recirculation zone formed between the square cylinder and the perforated plate.

A new regime of multiple states in free vibration of a cylinder at low Re

The existence of multiple response in vortex-induced vibration of a circular cylinder is explored in the laminar flow regime by carrying out computations with different initial conditions for several mass ratios. In addition to primary and secondary hystereses near the ends of the lock-in regime, multiple states of the fluid-structure system exist in the middle of the lock-in regime as well. One of the two states is associated with large amplitude of cylinder oscillation. The response of the cylinder, for this state, lies on the classically known lower branch. In the other state, the cylinder exhibits low oscillation amplitude. Depending on the mass ratio and reduced speed this state may either be synchronized or desynchronized with the wake. A new branch of cylinder response has been identified for the lock-in state in this regime. The time histories of cylinder displacement and force coefficients on this branch are similar to that observed on the initial branch. In view of this, the new branch is referred to as initial branch (II). The variation of frequency of cylinder oscillation and phase between cylinder displacement and lift coefficient along IB(II) is studied.

Force Control for Active Chassis Balancing

This paper presents the realization of the worldwide first automated walking excavator chassis. To this end, the authors build a new generation of high-performance hydraulic valves with integrated pressure feedback to achieve fast and accurate cylinder force tracking. This allows automatically adapting the legs to uneven terrains and optimally shaping the ground reaction forces in order to change the orientation and height of the cabin. Due to the contact redundancy, automated balancing is implemented as a contact force optimization problem, including constraints on contact forces and joint torques. The corresponding prioritized optimization problem can be simplified by using a quasi-static approximation of the system dynamics and a complexity reduction due to the kinematic structure of the legs. Our approach considers the unknown configuration and load of the cabin, arm, and bucket as system disturbances, whereby gravitational effects are approximated as well as possible. It is tested in a Gazebo simulation and validated in different experiments by using a prototype walking excavator machine. The proposed method revolutionizes operator control of these versatile but complex multipurpose vehicles: Instead of manual and coordinatively very demanding cylinder position adjustment, the operator can command simple high-level commands like a cabin pose. Furthermore, it significantly reduces peak forces in the cylinders and at the contact points, which causes less damage to the mechanics and the ground.

Aerodynamics of a cylinder in the wake of a V-shaped object

The interaction between two different shaped structures is very important to be understood. Fluid-structure interactions and aerodynamics of a circular cylinder in the wake of a V-shaped cylinder are examined experimentally, including forces, shedding frequencies, lock-in process, etc., with the V-shaped cylinder width d varying from d/D = 0.6 to 2, where D is the circular cylinder diameter. While the streamwise separation between the circular cylinder and V-shaped cylinder was 10D fixed, the transverse distance T between them was varied from T/D = 0 to 1.5. While fluid force and shedding frequency of the circular cylinder were measured using a load cell installed in the circular cylinder, measurement of shedding frequency of the V-shaped cylinder was done by a hotwire. The major findings are: (i) a larger d begets a larger velocity deficit in the wake; (ii) with increase in d/D, the lock-in between the shedding from the two cylinders is centered at d/D = 1.1, occurring at d/D 0.95-1.35 depending on T/D; (iii) at a given T/D, when d/D is increased, the fluctuating lift grows and reaches a maximum before decaying; the d/D corresponding to the maximum fluctuating lift is dependent on T/D, and the relationship between them is linear, expressed as ; that is, a larger d/D corresponds to a greater T/D for the maximum fluctuating lift.

Drag force and transport property of a small cylinder in free molecule flow: A gas-kinetic theory analysis.

Analytical expressions are derived for aerodynamic drag force on small cylinders in the free molecule flow using the gas-kinetic theory. The derivation considers the effect of intermolecular interactions between the cylinder and gas media. Two limiting collision models, specular and diffuse scattering, are investigated in two limiting cylinder orientations with respect to the drift velocity. The earlier solution of Dahneke [B. E. Dahneke, J. Aerosol Sci. 4, 147 (1973)10.1016/0021-8502(73)90066-9] is shown to be a special case of the current expressions in the rigid-body limit of collision. Drag force expressions are obtained for cylinders that undergo Brownian rotation and for those that align with the drift velocity. The validity of the theoretical expressions is tested against experimental mobility data available for carbon nanotubes.

Model-based force and position tracking control of an asymmetric cylinder with a digital hydraulic valve

AbstractThis paper presents a model-based control solution for large inertia systems controlled by a fast digital hydraulic valve. The solution is based on model-based force control and it is shown that the cylinder chamber pressures have first order dynamics with the proper parameter selection. The robust stability is analyzed under unknown load mass, bulk modulus, and delay, and it is shown that a simple cascaded P + PID controller results in good control performance and robustness. The simulated results show smooth and stable response with good tracking performance despite large variations in the load mass and bulk modulus.

Flow characteristics and drag force of a square cylinder in crossflow modulated by a slot jet injected from upstream surface

The flow characteristics and drag force of a square cylinder with a front jet injection were experimentally investigated in a wind tunnel. The evolution process of the characteristic flow patterns was recorded by the laser-assisted smoke flow visualization method. The time-averaged velocity fields measured by particle image velocimetry (PIV) were applied to analyze the velocity vectors, streamline patterns, vorticity contours, velocity distributions, and time histories of instantaneous velocities around the upstream region of the square cylinder. The drag force experienced by the square cylinder was obtained by measuring the surface pressures on the front and rear faces. The results show that the jet emitted from the upstream surface of the square cylinder periodically swings left-and-right in the experimental range of injection ratio ⩽0.9. In the time-averaged velocity field, the jet flow impinges the freestream at a four-way saddle and subsequently bifurcates into two streams; one stream goes toward the left edge of the upstream surface, while the other stream directs toward the right edge of the upstream surface. Two recirculation regions formed above the upstream surface of the square cylinder are enclosed by those two streams. The vorticity contours around the upstream surface of the square cylinder are characterized by two adjacent vorticity-concentrated areas of opposite signs. The time histories of the instantaneous velocities around the four-way saddle, jet exit, and shear layer of the swinging jet represent periodic oscillation. This characteristic oscillation frequency is dominated by the wake instability. The recirculation regions formed above the cylinder’s upstream surface prevent impingement from the freestream. Consequently, the surface pressure coefficients on the upstream surface of the square cylinder are reduced. This reduction in the surface pressure coefficient decreases the drag force acting on the square cylinder.

PERANCANGAN MESIN PEMOTONGAN BAHAN BAKU GENTENG DENGAN SISTEM KENDALI PLC LOGIC SMART RELAY(SR3B101FU)

Genting raw materials cutting machine is cutting processing tool with the mechanical system work. Working system for each element of machine motion in this study using apneumatic control based mover. One important aspect of the method and manufacturing series systems through the use of automation technology is a programmable logic control (PLC) as the control system. One of the main problems in this research activity is the use of automation technology which can produce products quickly, accurately and efficiently. However, before doing it all, need to understand the operational characteristics of the machine it self, so in the design, manufacture and operation will be easier and get the results as expected. Through this study, the authors tried methods of improvements to the system control processing equipment raw materials, PLC is used as an interface to drive the motion of elements in Pneumatic pump for each motion element. This study focused on the design and construction of the driving element processing tool. The control system of cutting genting raw material is used SR3B101FU PLC (AC 220V) with a pneumatic drive system on the cutting element and pushing motion. The research methodology used in this study is divided into 3 parts, first control system design such as electricity, wiring and PLC programming, second are construction system design such as mechaninal contruction of cutting process and third analysis of control system such as pneumatic cylinder pressures and forces acting genting to determine capability of machine raw materials cutting and pushing process. Forces acting on the double acting cylinder is equal to 1252.86 N its mean cutting machines and encouragement to work at maximum mass of 127.71 kg , while the mass of critical raw materials amounted to only 0.149 kg so that the machine has the capability to perform the cutting of raw materials and promoting material cutting results. Keyword : PLC, Pneumatik, Genting