V. Böhm

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.

Compliant Gripper Based on a Multistable Tensegrity Structure

This paper describes a new design approach of compliant grippers based on tensegrity structures with multiple states of self-equilibrium. As an example a planar tensegrity structure with two stable equilibrium states is considered and its potential use in a two-finger-gripper is discussed. The form finding and the influence of the segment parameters on global structural properties (e.g. mechanical compliance, static stability) are considered, with the help of static geometric nonlinear analyses, based on the Finite Element Method. The working principle is verified for a selected prototype.

A Novel Gripper Based on a Compliant Multistable Tensegrity Mechanism

Within this paper a novel gripper is introduced. The gripper is based on a tensegrity mechanism with multiple states of self-equilibrium. These tensegrity mechanism is built upon a mechanical compliant tensegrity structure, consisting of tensile and compressive members. The existence, shape and stability of the different states of self-equilibrium depend on the parameters of the members. After investigating this dependency with a form-finding algorithm the structure is extended with additional members to obtain a two-finger-gripper. The equilibrium configurations represent the opened and the closed state of the gripper. Due to the several equilibrium configurations, the control of the gripper can be realised easily and is discussed with theoretical analyses. The working principle of the gripper and the mechanical compliance is verified by a prototype. In addition, as an outlook for further works, a miniaturised prototype of the tensegrity mechanism with two stable states of self-equilibrium has been built.

On the Mechanical Compliance of Technical Systems

In the safe physical human-machine interaction the compliance of technical systems is an elementary requirement. The physical compliance of technical systems can be provided either by control functions implementation and/or intrinsic by structural configuration and material properties optimization. The latter is advantageous because of higher reliability as well as general simplicity of the design and production technologies. In the paper we focus on mechanical systems with intrinsic mechanical compliance. In general the deformability of structures is primarly characterised by their stiffness. Compliant mechanisms are mechanisms, whose functionality is based on its deformability. The goal of each engineer is by the design of mechanisms the setting of compliance depending upon the purpose of its application. It should be considered, that the compliance is dependent on a variety of parameters. The optimal design of these mechanisms can be realized only with precise knowledge of the influence parameters and possible types of compliance.