Igor Zeidis

Modelling of locomotion systems using deformable magnetizable media

This paper deals with the modelling and the realization of active and passive locomotion systems using the effects of the deformation of a magnetizable elastic material and the deformation of the surface of a membrane filled with a ferrofluid under the influence of a magnetic field. Prototypes implementing these principles have been constructed and proved positive. Theoretically (analytically and numerically) calculated results of the velocity of the mobile system are compared with the experimental data. Artificial worms based on these principles could be autonomous systems, and could be useful in medicine and in inspection technology.

Mathematical Model of Worm-like Motion Systems with Finite and Infinite Degree of Freedom

This paper presents some theoretical and practical investigations of worm-like motion systems that have the earthworm as live prototype. In the first part of the paper these systems are modeled in form of straight chains of n ≥ 1 interconnected mass points. The ground contact can be described either by non-symmetric dry friction or by unilateral differential constraints. The second part the paper deals with the peristaltic movement of a body due to a wavelike disturbance of the boundary surface. The investigations concentrate on motion in a tube or channel, and on motion on a horizontal plane as well. In both cases the body is modeled as a viscous Newton fluid. The dependence of the massflow through a cross section on disturbance and material data (viscosity, dimensions) is discussed. The paper presents first prototypes of technically implemented artificial worms.

Waves on the surface of a magnetic fluid layer in a traveling magnetic field

The plane flow of a layer of incompressible viscous magnetic fluid with constant magnetic permeability under the action of a traveling magnetic field is analyzed. The strength of the magnetic field producing a sinusoidal traveling small-amplitude wave on the surface of a magnetic fluid is found. This flow can be used in designing mobile robots.

Vibration-driven mobile robots based on magneto-sensitive elastomers

This paper describes a new concept for locomotion of miniature robots based on periodic electromagnetic actuation of magneto-sensitive elastomer bodies. The morphology of the robots relies on the dynamics of resonance for locomotion. Based on the described principle two prototypes are presented. The first prototype incorporates an inelastic polymeric frame with an integrated micro-coil and an attached magnetosensitive elastomeric body. The movement of the robot without moving parts exposed to the environment is bidirectional, the locomotion direction is frequency-controlled. The second prototype consists of only a symmetric magnetosensitive elastomeric body with 6 embedded micro-coils and is an example for compliant planar locomotion systems using the introduced actuating mechanism. The working principle of both prototypes is discussed with the help of transient dynamic analyses and verified with experimental tests.

Single Piezo Actuator Driven Micro Robot for 2-Dimensional Locomotion

We analyse two micro robots for 2-dimensional locomotion on a flat surface. Forced bending vibrations of continua are used by both systems which are excited by piezoelectric bending actuators. These vibrations are transformed by non classical legs to complex trajectories at the contact points between robot and environment. The locomotion direction of the system can be controlled by the excitation frequencies of the actuation element. Models are developed and investigated to describe important motion effects of the robots. Furthermore some experimental results are presented.

Analysis of the Vibrissa Parametric Resonance Causing a Signal Amplification during Whisking Behaviour

The paper deals with the mechanical vibrational motion of vibrissae during natural exploratory behaviour of mammals. The theoretical analysis is based on a mechanical model of a cylindrical beam with circular natural configuration under an applied periodic force at the tip, which corresponds to the surface roughness of an investigated object. The equation of motion of the beam is studied using the Euler-Bernoulli beam theory and asymptotic methods of mechanics. It is shown that from the mechanical point of view the phenomenon of parametric resonance of the vibrissa is possible. It means that the amplitude of forced vibrations of a vibrissa increases exponentially with time, if it is stimulated within a specific resonance frequency range, which depends on biomechanical parameters of the vibrissa. The most intense parametric resonance occurs, when the excitation frequency is close to the doubled natural frequency of free vibrations. Thus, it may be used to distinguish and amplify specific periodic components of a complex roughness profile during texture discrimination.

Worm-like Locomotion Systems (WLLS) - Theory, Control and Prototypes

Most of biologically inspired locomotion systems are dominated by walking machines pedal locomotion. A lot of biological models (bipedal up to octopedal) are studied in the literature and their constructions were transferred by engineers in different forms of realization. Non-pedal forms of locomotion show their advantages in inspection techniques or in applications to medical technology for diagnostic systems and minimally invasive surgery (endoscopy). These areas of application were considered by (Choi et al., 2002), (Mangan et al., 2002), (Menciassi & Dario, 2003). Hence, this type of locomotion and its drive mechanisms are current topics of main focus. In this chapter we discuss the problem of developing worm-like locomotion systems, which have the earthworm as a living prototype, from two points of view: • modelling and controlling in various levels of abstraction, • designing of prototypes with classical and non-classical forms of drive.

Ferrofluid-based Flow Manipulation and Locomotion Systems

The article demonstrates some examples of locomotion systems with bifluidic flow control using ferrofluid. By controlling the change of shape, position, and pressure of the ferrofluid in a secondary low viscous fluid by magnetic fields locomotion of objects or the ferrofluid itself can be realized. The locomotion of an object is caused, in the first example, by a ferrofluid generated flow of the secondary fluid and in the second and third case by the direct alteration of the ferrofluid position.

Dynamics of Mechanical Systems with Mecanum Wheels

The kinematics and dynamics of a mechanical system with mecanum wheels is studied. A mecanum wheel is a wheel with rollers attached to its circumference. Each roller rotates about an axis that forms an angle with the plane of the disk (for the omni-wheels, the axes of the rollers lie in the plane of the wheel and in an ideal case are tangent to the outer circumference of the wheel). Such a design provides additional kinematic advantages for the mecanum wheels in comparison with the conventional wheels. Within the framework of non-holonomic mechanics, the equations of motion are derived for the case of an arbitrary angle at which the rollers are attached (usually, this angle is assumed to be equal to 45°). In robotics, a simplified approach, in which the equations of non-holonomic kinematic constraints are solved approximately by means of a pseudo-inverse matrix, is frequently applied. Such an approximate approach leads to “holonomization” of the system and allows Lagrange’s equations of the second kind to be used. In the present paper, the equations of motion obtained on the basis of the principles of non-holonomic mechanics are compared with the approximate equations. It is shown that for translational motions and for the rotation of the system about its center of mass, both these approaches lead to the same result.

Dynamics and Control of a Two-Module Mobile Robot on a Rough Surface

A two-module (two-body) locomotion system moving along a straight line on a rough horizontal plane is considered. The motion of the system is excited by a periodic change in the distance between the bodies. Friction between the bodies and the plane obeys Coulomb’s law. The conditions for the system to be able to start moving from a state of rest and the steady-state motion are studied. The friction force acting on the system is assumed to be small as compared with the excitation force, and the method of averaging is applied to the equation of motion of the system’s center of mass. On the basis of the averaged equation, necessary and sufficient conditions subject to which the system can start moving from a state of rest in a dry friction environment are obtained. The excitation law that implies a piecewise quadratic time history of the distance between the bodies is considered. For this excitation law, the system can start moving from a state of rest if the bodies have different masses and the times of increase and decrease of the distance between them do not coincide. Closed-form expressions for the steady-state velocity of the system’s center of mass are obtained and investigated as a function of the parameters of the system and the excitation law. The maximum magnitudes of the steady-state velocities and the respective values of the parameters are found. An experimental prototype of the robot under consideration was built. The experimental results demonstrate qualitative agreement with the theoretical predictions.