Abstract:This paper presents a novel method for nonprehensile manipulation of parts on a circularly oscillating platform when the effective coefficient of dry friction between the part and the platform is being dynamically controlled. Theoretical and experimental analyses have been performed to validate the proposed method and to determine the control parameters that define the characteristics of the part’s motion. A mathematical model of the manipulation process with dynamic dry friction control was developed and solv… Show more
“…The shape of the trajectory of the particle depends mainly on λ ( Figure 5 a). In a symmetric system (when λ = 0), the particle can travel some distance from the starting point in an undulating or spiral trajectory, but then it starts to circle around the point of equilibrium [ 51 , 52 ]. As a result of the asymmetry created by dynamic dry friction control, the particle can be moved in a preferred direction.…”
Currently used planar manipulation methods that utilize oscillating surfaces are usually based on asymmetries of time, kinematic, wave, or power types. This paper proposes a method for omnidirectional manipulation of microparticles on a platform subjected to circular motion, where the motion of the particle is achieved and controlled through the asymmetry created by dynamic friction control. The range of angles at which microparticles can be directed, and the average velocity were considered figures of merit. To determine the intrinsic parameters of the system that define the direction and velocity of the particles, a nondimensional mathematical model of the proposed method was developed, and modeling of the manipulation process was carried out. The modeling has shown that it is possible to direct the particle omnidirectionally at any angle over the full 2π range by changing the phase shift between the function governing the circular motion and the dry friction control function. The shape of the trajectory and the average velocity of the particle depend mainly on the width of the dry friction control function. An experimental investigation of omnidirectional manipulation was carried out by implementing the method of dynamic dry friction control. The experiments verified that the asymmetry created by dynamic dry friction control is technically feasible and can be applied for the omnidirectional manipulation of microparticles. The experimental results were consistent with the modeling results and qualitatively confirmed the influence of the control parameters on the motion characteristics predicted by the modeling. The study enriches the classical theories of particle motion on oscillating rigid plates, and it is relevant for the industries that implement various tasks related to assembling, handling, feeding, transporting, or manipulating microparticles.
“…The shape of the trajectory of the particle depends mainly on λ ( Figure 5 a). In a symmetric system (when λ = 0), the particle can travel some distance from the starting point in an undulating or spiral trajectory, but then it starts to circle around the point of equilibrium [ 51 , 52 ]. As a result of the asymmetry created by dynamic dry friction control, the particle can be moved in a preferred direction.…”
Currently used planar manipulation methods that utilize oscillating surfaces are usually based on asymmetries of time, kinematic, wave, or power types. This paper proposes a method for omnidirectional manipulation of microparticles on a platform subjected to circular motion, where the motion of the particle is achieved and controlled through the asymmetry created by dynamic friction control. The range of angles at which microparticles can be directed, and the average velocity were considered figures of merit. To determine the intrinsic parameters of the system that define the direction and velocity of the particles, a nondimensional mathematical model of the proposed method was developed, and modeling of the manipulation process was carried out. The modeling has shown that it is possible to direct the particle omnidirectionally at any angle over the full 2π range by changing the phase shift between the function governing the circular motion and the dry friction control function. The shape of the trajectory and the average velocity of the particle depend mainly on the width of the dry friction control function. An experimental investigation of omnidirectional manipulation was carried out by implementing the method of dynamic dry friction control. The experiments verified that the asymmetry created by dynamic dry friction control is technically feasible and can be applied for the omnidirectional manipulation of microparticles. The experimental results were consistent with the modeling results and qualitatively confirmed the influence of the control parameters on the motion characteristics predicted by the modeling. The study enriches the classical theories of particle motion on oscillating rigid plates, and it is relevant for the industries that implement various tasks related to assembling, handling, feeding, transporting, or manipulating microparticles.
“…Recently, a novel approach for omnidirectional vibrational transportation has been proposed [21,22]. The omnidirectional motion of an object on a horizontal platform subjected to harmonic circular motion was achieved and controlled through an asymmetry induced by periodic dynamic dry friction control between the object and the platform.…”
A transportation system requires an asymmetry to achieve objects’ motion on an oscillating surface. Transportation methods based on vibrational techniques usually employ different types of asymmetries, such as temporal (time) asymmetry, kinematic asymmetry, wave asymmetry or power asymmetry. However, transporting an object on an inclined angle requires a relatively high net frictional force over each period of vibrational cycles due to the gravitational potential energy exerted on the object. This paper investigates the transportation of an object upward on an inclined plane that harmonically oscillates in its longitudinal direction. The novelty of this research is attributed to the upward motion of the object on the inclined plane, which is achieved by creating an additional asymmetry of the system through dry friction dynamic manipulations. For this reason, periodic dynamic dry friction manipulations have been employed to create the asymmetry of frictional conditions, resulting in a net frictional force that outweighs the gravitational force. A mathematical model has been developed using the Lagrange method, which describes the moving object’s motion. Moreover, the theoretical findings and results confirmed that the object’s velocity and direction can be controlled by dynamic dry friction manipulations. To demonstrate the technical feasibility of the proposed method, an experimental investigation was carried out where the results demonstrated that the control parameters significantly influence the characteristics of the directional motion of the moving object. This transportation method is beneficial for various modern industries engaged in transportation and manipulation tasks with objects spanning a broad range of sizes, including those operating at small scales for applications in lab-on-a-chip technology, micro-assembly lines, micro-feeder systems and other delicate component manipulation systems. The presented research advances the classical theories of vibrational transportation on inclined surfaces.
“…A nonprehensile manipulation technique was proposed where the required dynamic directionality was achieved via a system asymmetry that was induced by periodic alteration of the effective coefficient of dry friction between the part and the manipulation platform in [17][18][19].…”
This paper presents a novel method for convey-ing of miniature and microparts on a subjected to sinusoi-dal displacement cycles in the horizontal direction when the effective coefficient of dry friction between the part and the platform is periodically being controlled. Hereby, the required dynamic directionality is achieved via the system asymmetry created by periodic alteration of the effective coefficient of dry friction between the micropart and the platform. A mathematical model of conveying process is developed and solved numerically to determine the influence of frictional properties, friction control and sinusoidal excitation parameters on the conveying process characteristics. It was found that the velocity and direction of conveying can be easily controlled in a wide range by changing the phase shift between the function of the ef-fective dry friction coefficient and the function of horizon-tal sinusoidal displacement cycles as well as the duration of effective dry friction coefficient reduction. To test the theoretical findings in practise, an experimental setup for micropart conveying with controlled dry friction was cre-ated and build. The experimental results revealed the func-tional capabilities of the proposed method for micropart conveying by demonstrating how the velocity, direction and step size are controlled by regulating the parameters of friction control and sinusoidal excitation.The proposed method can be practically used in conveying, feeding, manipulation and assembly systems for miniature and microparts in the mechatronics, elec-tronic and other industries.
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