Current Issue : July-September Volume : 2024 Issue Number : 3 Articles : 5 Articles
This work presents a novel electromagnetic clutch installed on the crankshaft pulley to decouple the internal combustion engine from the front-end accessory drive of a P0 hybrid electric vehicle. The objective is to supply the air conditioning compressor directly with the belt starter– generator electric machine without dragging the inertia of the engine during engine fuel cut-off phases. This operation yields an improved vehicle energetic efficiency and allows for uninterrupted air conditioning also when the start–stop function is activated. This paper focuses on the mechanical assembly and electromagnetic behavior of the device. Furthermore, two position-sensorless techniques are proposed to estimate the clutch state. The effectiveness of the proposed solution is experimentally validated on a dedicated test bench. Experimental tests demonstrated that the opening and closing phases required 50 and 25 ms, respectively, thereby satisfying the time constraints for switching different operating modes in a vehicle (∼100 ms)....
A soft robot is composed of soft materials, which exhibit continuous deformation and driving structure integration and can arbitrarily change shapes and sizes over wide ranges. It shows strong adaptability to unstructured environments and has broad application prospects in military reconnaissance, medical rescues, agricultural production, etc. Soft robots based on ionic electroactive polymers (EAPs) have low-driving voltages, large-actuation displacements, fast responses, light weights, and low powers and have become a hot research field of bionic robots. Ionic liquid gels (ILGs) are new ionic EAPs. In this study, a new soft actuator was designed based on an ILG, and the electromechanical coupling model of an ILG soft actuator was studied in detail. Based on the system transfer function method, a mechatronic coupling model for the soft actuator was developed. According to the material characteristics and current response law of the ILG-containing EAP, an equivalent circuit model was used to describe transfer of the output current and input voltage. Based on the equivalent transformer model for ionic polymer–metal composite (IPMC) actuators proposed by Claudia Bonomo, the electromechanical coupling equation and a driving equation of the ILG soft actuator were established. The least-squares method was used with the couplingmodel of an ILG soft actuator to identify the systemparameters for the model, and the effects of the structural parameters on the end displacement and driving force of the soft actuator were analyzed....
In this contribution, the development of a 3D-printed soft actuator integrated with shape memory alloys (SMA) wires capable of bending in two directions is presented. This work discusses the design, manufacturing, modeling, simulation, and feedback control of the actuator. The SMA wires are encased in Polytetrafluoroethylene (PTFE) tubes and then integrated into the 3D-printed matrix made of thermoplastic polyurethane (TPU). To measure and control the deformation angle of the soft actuator, a computer vision system was implemented. Based on the experimental results, a mathematical model was developed using the system identification method and simulated to describe the dynamics of the actuator, contributing to the design of a controller. However, achieving precise control of the deformation angle in systems actuated by SMA wires is challenging due to their inherent nonlinearities and hysteretic behavior. A proportional-integral (PI) controller was designed to address this challenge, and its effectiveness was validated through real experiments....
Polypodium aureum, a fern, possesses a specialized spore-releasing mechanism like a catapult induced by the quick expansion of vaporized bubbles. This study introduces lipid-coated perfluorocarbon droplets to enable repeatable vaporization–condensation cycles, inspired by the repeatable vaporization of Polypodium aureum. Lipid-perfluorocarbon droplets have been considered not to exhibit repeatable oscillations due to bubble collapse of the low surface tension of lipid layers. However, a single lipid-dodecafluoropentane droplet with a diameter of 9.17 μm shows expansion–contraction oscillations over 4000 cycles by changing lipid composition and applying a low-power 1.7 MHz ultrasound to induce the partial vaporization of the droplets. The optimal combinations of shell composition, droplet fabrication, and acoustic conditions can minimize the damage on shell structure and promote a quick recovery of damaged shell layers. The highly expanding oscillatory microbubbles provide a new direction for fuel-free micro- or nanobots, as well as biomedical applications of contrast agents and drug delivery....
The electro-hydrostatic actuator (EHA) is a new type of high-performance servo actuator that originated in the field of aerospace, and it is gradually becoming a common basic component for various types of large equipment. A miniature EHA, mainly composed of a micro two-dimensional (2D) piston pump and a brushless DC motor, is designed in this article by simplifying the system structure. This paper analyzes the structure and working principle of this EHA and establishes the mathematical models of the brushless DC motor, micro two-dimensional pump, and hydraulic cylinder. Field-oriented control (FOC) is used to drive the brushless DC motor, and the models of the controller are established in Simulink. Furthermore, the models of the mechanical and hydraulic systems of the miniature EHA are established in AMESim. In addition to this, a prototype of this miniature EHA was fabricated in this paper and an experimental platform was built for experiments. In the joint simulation environment, the rise time of the EHA system at 6000 r/min is 0.158 s and the frequency response amplitude attenuation to −3 dB has a bandwidth of 20 Hz. On the other hand, the constructed miniature EHA prototype was dynamically characterized to obtain a rise time of 0.242 s at 6000 r/min and a bandwidth of 13 Hz. In this paper, the feasibility of the design scheme of the miniature EHA system is verified, and its excellent dynamic properties are verified with simulation and experiment....
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