Design of a bistable electromagnetic coupling mechanism for underactuated manipulators

Abstract

Electromagnetic clutches have been widely used in underactuated lightweight manipulator designs as a coupling mechanism due to their advantages of fast activation and electrical controllability. However, an electromagnetic clutch consumes electrical energy continuously during its operation. Furthermore, conventional electromagnetic clutches are not fail-safe in unexpected power failure conditions. These factors have a significant impact on the energy efficiency and the safety of the design, and these are vital aspects for underactuated lightweight manipulators. This paper introduces a bistable electromagnetic coupling mechanism design, with reduced energy consumption and with a fail-safe mechanism. The concept of a bistable electromagnetic mechanism consists of an electromagnet with two permanent magnets. The design has the capability to maintain stable mechanism states, either engaged or disengaged, without a continuous electrical power supply, thus enhancing fail-safety and efficiency. Moreover, the design incorporates the advantages of conventional electromagnetic clutches such as rapid activation and electrical controllability. The experimental results highlight the effectiveness of the proposed mechanism in reducing electric energy consumption. Besides this, a theoretical model is developed and a good correlation is achieved between the theoretical and experimental results. The reduced electric energy consumption and fail-safe design make the bistable electromagnetic mechanism a promising concept for underactuated lightweight manipulators.

A Kinematic Coupling Mechanism With Binary Electromagnetic Actuators for High-Precision Positioning

“…Other technologies, such as bistable compliant mechanisms, were also proposed for specific application, such as the monolithic design in [18]. Overall, research trends have shown that DEAs and electromagnetic actuators are favoured in tasks that require accurate positioning but struggle with high payloads [19][20][21][22][23][24]. Conversely, pneumatics and SMAs are able to withstand higher forces, but at the cost of lower accuracy and efficiency, and increased size.…”

“…Given the similar performance of the Three-Groove and Kelvin Clamp couplings, the first [32] has been selected for the mechanisms in Section III because of its symmetrical layout. Any Manipulation [8] Any Manipulation [9][10][11] DEA a Biomedical [12] Electromagnets Biomedical [13] SMA b Space [14][15] SMA b Grasping [16] SMA Manipulation [17] Pneumatics Manipulation [18] Compliance Space [19] Electromagnets Tooling [20][21] Electromagnets Flytrap [22][23] Electromagnets Manipulation [24] Electromagnets Origami robots a DEA: Dielectric Elastomer Actuation b SMA: Shape Memory Alloy However, the constructive solutions shown in this paper are only two examples of implementation of the proposed concept, which can be realized with a wide variety of geometries.…”

“…Thanks to their unique features, binary-actuated systems are suitable for deployment tasks that require a rapid and/or accurate positioning of sensors and tools, with applications that range from space exploration to surgical robotics. These fields require simple, robust, and reliable mechanisms, and binary devices have often been proposed to meet this need [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”