Magnetorheological fluids (MRFs) are suspensions of micron-sized ferrous particles in oil that exhibit a rapid and reversible transition from a liquid state to a near-solid state when an external magnetic field is applied. They revealed to be particularly suitable for a wide range of electromagnetic applications because of their yield stress range, response time, and simplicity of their excitation system. For example, they can be effectively used in the design of haptic interfaces and actuators with variable compliance. The Haptic Black Box-with Permanent Magnet device (HBB-PM) shown in Figure 1a comprises 400 permanent magnets (PMs) arranged in a 20x20 array that formed the excitation system [1]. These were placed underneath a 200 mm x 200 mm square plexiglass chamber containing the MRF. The NdFeB magnets have a remanence of about 1.4 T. The dimensions of each magnet are 10x10x10 mm, and the distance between two adjacent PMs is 3 mm. It is possible to control the magnetic field within the fluid using an actuation system, which consists of 400 PM stepping motors, that move the magnets in the vertical direction. By controlling the field delivered to the chamber, virtual objects could be created within the fluid with a given shape and compliance. ASFER (Figure 1b) is a spherical magnetorheological/electromagnetic actuator with 3 DoF. It consists of a partially laminated stator and a concentric double-layer hollow-rotor composed of ferromagnetic and conductive materials [2]. The stator is equipped with coils fed by AC voltage (motion coils), while the hollow-rotor is a spherical ferromagnetic solid core on which a spherical conductive shell is placed. A handle installed on the rotor transmits the rotating and tilting movements with a spherical joint in the internal hollow. The MRF fills the joint’s space between the ball and the socket, and the DC coils (excitation coils) arranged in two levels produce the magnetic field that excites the MRF. In this way, it is possible to transmit a suitable and controllable passive torque.
Use of magnetorheological fluids for electromagnetic applications
Claudia Simonelli
;Antonino Musolino;Rocco Rizzo;Luca Sani;Nicolò Gori
2023-01-01
Abstract
Magnetorheological fluids (MRFs) are suspensions of micron-sized ferrous particles in oil that exhibit a rapid and reversible transition from a liquid state to a near-solid state when an external magnetic field is applied. They revealed to be particularly suitable for a wide range of electromagnetic applications because of their yield stress range, response time, and simplicity of their excitation system. For example, they can be effectively used in the design of haptic interfaces and actuators with variable compliance. The Haptic Black Box-with Permanent Magnet device (HBB-PM) shown in Figure 1a comprises 400 permanent magnets (PMs) arranged in a 20x20 array that formed the excitation system [1]. These were placed underneath a 200 mm x 200 mm square plexiglass chamber containing the MRF. The NdFeB magnets have a remanence of about 1.4 T. The dimensions of each magnet are 10x10x10 mm, and the distance between two adjacent PMs is 3 mm. It is possible to control the magnetic field within the fluid using an actuation system, which consists of 400 PM stepping motors, that move the magnets in the vertical direction. By controlling the field delivered to the chamber, virtual objects could be created within the fluid with a given shape and compliance. ASFER (Figure 1b) is a spherical magnetorheological/electromagnetic actuator with 3 DoF. It consists of a partially laminated stator and a concentric double-layer hollow-rotor composed of ferromagnetic and conductive materials [2]. The stator is equipped with coils fed by AC voltage (motion coils), while the hollow-rotor is a spherical ferromagnetic solid core on which a spherical conductive shell is placed. A handle installed on the rotor transmits the rotating and tilting movements with a spherical joint in the internal hollow. The MRF fills the joint’s space between the ball and the socket, and the DC coils (excitation coils) arranged in two levels produce the magnetic field that excites the MRF. In this way, it is possible to transmit a suitable and controllable passive torque.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
