Continuum robots are inspired by biological trunks, snakes and tentacles. Unlike conventional robot manipulators, there are no rigid structures or joints. Advantageous is the ease of miniaturization combined with high dexterity, since limiting components such as bearings or gears can be omitted. Most currently used actuation elements in continuum robots require a large drive unit with electric motors or similar mechanisms. Contrarily, shape memory alloys (SMAs) can be integrated into the actual robot. The actuation is realized by applying current to the wires, which eliminates the need of an additional outside drive unit. In the presented study, SMA actuator wires are used in variously scaled continuum robots. Diameters vary from 1 to 60 mm and the lengths of the SMA driven tentacles range from 75 to 220 mm. The SMAs are arranged on an annulus in a defined distance to the neutral fiber, whereby the used cores vary from superelastic NiTi rods to complex structures and also function as restoring unit. After outlining the theoretical basics for the design of an SMA actuated continuum robot, the design process is demonstrated exemplarily using a guidewire for cardiac catheterizations. Results regarding dynamics and bending angle are shown for the presented guidewire.

Due to their unique manipulation capabilities, continuum robots find applications in a variety of different areas, such as medical technology or maintenance and repair. When working with continuum robots, it is often necessary to bend the structure according to complex shapes. This is commonly achieved by arranging several individual modules in series. In this paper, a novel continuum robot concept is presented based on a serial arrangement of SMA (Shape Memory Alloy) wires actuated modules. The key advantage of the described modular continuum robot is the number of connection wires required to control the SMA wires, which is also independent of the number of modules. This feature makes it possible to virtually connect a very large number of serial modules, thus enabling to design continuum robots with arbitrary complexity. After outlining the concept, the mechanical and electrical components required to build one module of such an SMA driven continuum robot are introduced.

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To determine the lifespan of a system, the lifespan of all parts as well as the interaction of the parts as a system must be known. Accordingly, in systems where shape memory alloy (SMA) wires are used as actuator elements, their lifespan must be determined as well. Therefore, a test bench to determine the lifespan of SMA wires is needed. Since the requirements of actuator systems differ for example in stroke, response time or force, the test bench will be designed in an as modular way as possible. This allows for testing different actuator configurations as for example single wires or wire bundles of different diameters. This work outlines the development of the test bench, discusses first measurements of a 3D printed validation setup and concludes with a summary and an outlook on the optimization steps as well as the tests to be performed.

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