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Purpose When handling small-sized shafts and holes, achieving optimal safety, size compatibility and shape adaptability using rigid grippers presents significant problems. Recent advancements have introduced soft end-effectors that offer enhanced safety and adaptability for gripping parts. However, these soft end-effectors often struggle to maintain the necessary gripping positional accuracy. The purpose of this paper is to design a soft end-effector specifically engineered to address these problems, combining precise gripping capabilities with improved safety, positional accuracy and adaptability to the size and shape of fragile, small-sized components. Design/methodology/approach A soft finger with multilayer decreasing drive air chambers is designed to achieve the finger bending increasing from the root to the tip of the finger to improve the flexibility of the fingertip. Additionally, a three-finger self-centering configuration is employed, coupled with an expandable structure to increase the gripping range. Furthermore, a theoretical mathematical model of the finger is established. The physical prototype is manufactured and subjected to experimental testing, including gripping tests on small-sized, fragile shaft holes, to validate its operational performance. Findings The grasping experiments confirm that the designed end-effector can maintain coaxial positioning and meet adaptability requirements when handling fragile components with small-sized shaft holes. Furthermore, the addition of expanding palm structure increases the gripping attitude and enriches the application scene and gripping space. Originality/value The design of multilayer decreasing air chamber structure to solve the problem of poor gripping stability and low positional accuracy of soft manipulator; the expandable palm design is introduced to enhance gripping space; and solved the problem of gripping accuracy in the assembly of fragile parts with small-size shafts and holes.

In this paper, the flow characteristics of an air chamber inside a tunnel when subjected to train-nose-entry wavefronts were analyzed using numerical simulation. The results demonstrate that there exists a specific range of connection sizes for a fixed volume of air chamber, which imparts an under-damped characteristic to the chamber. Additionally, the pressure distribution within the air chamber and tunnel exhibits a noticeable three-dimensional effect as a consequence of the non-uniform flow field at the connection of the air chamber. The difference in the numerical results of the maximum pressure gradient is primarily observed at the air chamber connection when comparing the axisymmetric model to the one-dimensional model. However, this difference gradually diminishes to approximately 1% after the wavefronts have traversed through the air chamber for a distance of approximately 5 m. Furthermore, a scaled experimental setup was constructed to compare the obtained numerical results with the experimental data, successfully validating the accuracy of the numerical method.

The sound amplification ratios of sealed air chambers with different shapes were quantitatively compared to design a body-conduction microphone to measure animal scratching sounds. Recently, quantitative monitoring of scratching intensity in dogs has been required. We have already developed a collar with a body-conduction microphone to measure body-conducted scratching sounds. However, the air chamber, one of the components of the body-conduction microphone, has not been appropriately designed. This study compared the amplification ratios of air chambers with different shapes through numerical analysis and experiments. According to the results, the horn-shaped air chamber achieved the highest amplification performance, at least for sound frequencies below 3 kHz. The simulated amplification ratio of the horn-shaped air chamber with a 1 mm height and a 15 mm diameter was 52.5 dB. The deformation of the bottom of the air chamber affected the amplification ratio. Adjusting the margin of the margined horn shape could maintain its amplification ratio at any pressing force. The simulated and experimental amplification ratios of the margined horn-shaped air chamber were 53.4 dB and 19.4 dB, respectively.

To achieve the goal of carbon neutrality, China has been expanding wind and solar energies rapidly for decades. To cope with their inherent intermittency and randomness, modern power systems demand a large number of storage facilities. Compressed air energy storage (CAES) is a promising technology that is capable of undertaking the rule of large-scale renewable energy integration. However, conventional CAES systems suffer from low energy storage density and unstable turbine operating pressure. To solve the problems, a new type of isobaric CAES system linked with a reservoir by pipeline was proposed. Its core innovation lies in using the constant hydrostatic pressure formed by the upstream reservoir to act on the air chamber, aiming to achieve the basic stability of the working pressure throughout the working process. In this paper, the main working principle of the system is firstly introduced. Secondly, the 3D CFD simulation method for high pressure air-water flow is verified by bench mark problems. Thirdly, the flow and temperature patterns during working processes in a practical energy storage chamber are simulated and analysed. Fourthly, the sudden trip transient conditions are discussed to assess the operational safety of the system. The results indicate that the high-pressure air in the chamber was maintained within the range of 5.8MPa±5% during the working processes, which are significantly better than the pressure fluctuations of the traditional CAES. During charging, gas pressure, density, and temperature increase linearly, while during discharging, they decrease linearly. This study confirms that the air and water have clear interface because large chamber and slow interface change, and the system remains operationally safe even in the extreme transient conditions.

Air-chambers are mechanical devices capable of decreasing positive and increasing negative water-hammer pressures in pumping pipelines; however, large size air-chambers might increase the costs substantially. Also, air-inlet valves are powerful devices which can efficiently control negative pressures. Obtaining the best protection scheme where transient pressures are maintained in a safe bound while minimizing the protection cost is an optimization problem. In this research, a single objective optimization model is introduced in which the types and locations of air-inlet valves and the size of air-chamber are determined such that the total cost is minimized while all pressures along the pipeline are in the allowable range. Maximum and minimum transient pressures are considered as constraints in the optimization analysis using penalty functions. A self-adaptive real genetic algorithm is used to solve the problem. The model is applied to a real transmission pipeline with 4 m 3 /s flow capacity. The results indicate that the proposed model is capable to determine proper number of air-inlet valves, their locations and types so that the air-chamber size and the total cost are substantially reduced.

This study investigates the performance of a pumped discharge line with joint use of protective devices against water hammer expected to occur due to sudden stoppage of pumps. To this end, a pumped discharge line planned to be constructed is considered for hydraulic transients generated subsequent to pump trips. The unprotected form of the system is found to experience very low pressures below the vapor pressure of the liquid. Then single and combined application of flywheel, air chamber and in-line check valves are proposed and checked for their effectiveness in protecting the system. Single use of those devices is found to be insufficient and expensive, whereas the joint application of the in-line check valves and the air chamber are shown to be economical and successful in protecting the pipeline. Combined use of in-line check valves and air chamber is found to reduce the volume of the chamber by 65%, which also reduces the total cost of the protective measure by approximately 50%.

Foam-based soft actuators are lightweight and highly compressible, which make them an attractive option for soft robotics. A negative pressure drive would complement the advantages of foam actuators and improve the durability of the soft robotic system. In this study, a foam actuator was designed with a negative pressure pneumatic drive comprising bellows air chambers, a polyurethane foam body, and sealing layers at the head and tail. Experiments were performed to test the bending and contraction performances of the actuator with the foaming multiplier and air chamber length as variables. At air pressures of 0–90 kPa, the bending angle and contraction of the actuator increased with the foaming multiplier and number of air chamber sections. The designed actuator achieved a bending angle of 56.2° and contraction distance of 34 mm (47.9% of the total length) at 90 kPa, and the bending and contraction output forces were 3.5 and 7.2 N, respectively. A control system was built, and four soft robots were constructed with different numbers of actuators. In experiments, the robots successfully completed operations such as lifting, gripping, walking, and gesturing. The designed actuator is potentially applicable to debris capture, field rescue, and teaching in classrooms.

The traditional belt conveyor faces challenges such as equipment wear and unstable operation due to friction. This study proposes an air-suspended belt conveyor system supported by an air film to address these issues. An experimental platform was designed and constructed, including a 10-meter-long conveyor with optimized air chamber structure, centrifugal fan, PLC-based control system, and electronic belt scale. Hardware selection and software design were completed, integrating manual and automatic operation modes. Preliminary experiments verified the feasibility of the platform, showing that the fan speed control error was less than 10 r/min under static conditions. This work lays the foundation for adaptive power matching control in air-suspended belt conveyors.

The rapid and accurate control of air chamber pressure in slurry pressure balance (SPB) shield tunneling machines is crucial for establishing the balance between slurry pressure and soil and water pressure, ensuring the stability of the support face. A novel air chamber pressure control method based on nonlinear adaptive robust control (ARC) and using a pneumatic proportional three-way pressure-reducing valve is proposed in this paper. Firstly, an electric proportional control system for the air chamber pressure is developed. Secondly, a nonlinear state space model for the air chamber pressure regulation process is established. Utilizing experimental data from the SPB shield tunneling machine test bench, nonlinear adaptive identification is conducted through the nonlinear recursive least square algorithm. The results demonstrate the model’s effectiveness and accuracy. Then, a nonlinear ARC for air chamber pressure is designed based on the backstepping method, and its Lyapunov stability is proved. Finally, the feasibility and effectiveness of the controller designed in this paper is verified through simulation and experiments. The results demonstrate that the developed control system can compensate for the nonlinearity and disturbance in the air chamber pressure regulation process. It can achieve good transient and steady-state performance and has good robustness against uncertainty.

It is known that the deformities that affect the lower limbs are multiple in terms of location and severity of the injury. These deformities are treated with the use of orthosis, which varies depending on the type of deformity and the area of ​​injury. The principle on which the orthosis depends on the treatment of deformities is applying three-point pressures. These pressures are applied during the manufacturing process of the orthosis but with the time when the deformation response to treatment by corrected forces these mean the value and location of these corrective forces will change and this requires the manufacturing of a new orthosis. This requires costs in money and time to re-correct these forces. In this study, a force correction system was suggested that could change the value and location of corrective forces without need to manufacture a new orthosis and within a few minutes by placing an air chamber on the side of the orthosis. When increasing or withdrawing the amount of air inside the air chamber, the magnitudes of corrected force change according to the required value, this process providing comfort to the patient and reducing the effort of the professional staff supervisor (orthotist) to correct the deformity. The result showed that a method of correction forces applied by using the air chamber to correct deformities was successful when applied to a patient with varus foot deformity where the pressure generated from the air chamber on the leg was measured by using the F-Socket devise at the lateral side recorded a higher interface pressure (140Kpa) than the others sides due to pump the air to push the ankle joint for correction deformity without needing to manufacture of a new orthosis to change the values of correction forces thus reducing the cost and time to treat deformity, also the result showed improvement of the gait cycle, the value of ground reaction force on the body and footprint of the patient when comparing the results before and after the use of the orthosis by the patient.