Dimensionless Analysis on the Characteristics of Pneumatic Booster Valve with Energy Recovery

Factories are increasingly reducing their air supply pressures in order to save energy. Hence, there is a growing demand for pneumatic booster valves to overcome the local pressure deficits in modern pneumatic systems. To further improve energy efficiency, a new type of booster valve with energy recovery (BVER) is proposed. The BVER principle is presented in detail, and a dimensionless mathematical model is established based on flow rate, gas state, and energy conservation. The mathematics model was transformed into a dimensionless model by accurately selecting the reference values. Subsequently the dimensionless characteristics of BVER were found. BVER energy efficiency is calculated based on air power. The boost ratio is found to be mainly affected by the operational parameters. Among the structural ones, the recovery/boost chamber area ratio and the sonic conductance of the chambers are the most influential. The boost ratio improves by 15%–25% compared to that of a booster valve without an energy recovery chamber. The efficiency increases by 5%–10% depending on the supply pressure. A mathematical model is validated by experiment, and this research provides a reference for booster valve optimisation and energy saving

Development of a Pneumatically-Driven Robotic Forceps with a Flexible Wrist Joint

AbstractThe present paper describes a pneumatically-driven forceps manipulator for minimally-invasive robot surgery that has a simplified flexible wrist joint for easy fabrication, cost reduction and future miniaturization. The joint structure consists only of a machined spring, and four NiTi super-elastic wires fixed to the joint-end are actuated by pneumatic cylinders in push-pull motions. This mechanism realizes two degrees-of-freedom bending motions of the wrist joint and provides higher manipulation stiffness than other flexible joint mechanisms. Theoretical models of the proposed mechanism are developed; kinematic relation between joint positions and actuator displacements is described as a simple ideal continuum model, and dynamic model of the manipulator is described considering frictional and elastic forces of the joint mechanism. The joint position control system employs a cascade structure: the outer loop of the position control with dynamics compensation and the inner loop of the pneumatic force control. Performances of the joint position control are evaluated through elementary experiments, and effectiveness of the proposed joint mechanism is demonstrated

Development of a Wearable Haptic Glove Presenting Haptic Sensation by Electrical Stimulation

Most haptic devices generate haptic sensation using mechanical actuators. However, the workload and limited workspace handicap the operator from operating freely. Electrical stimulation is an alternative approach to generate haptic sensations without using mechanical actuators. The light weight of the electrodes adhering to the body brings no limitations to free motion. Because a real haptic sensation consists of feelings from several areas, mounting the electrodes to several different body areas can make the sensations more realistic. However, simultaneously stimulating multiple electrodes may result in “noise” sensations. Moreover, the operators may feel tingling because of unstable stimulus signals when using the dry electrodes to help develop an easily mounted haptic device using electrical stimulation. In this study, we first determine the appropriate stimulation areas and stimulus signals to generate a real touch sensation on the forearm. Then, we propose a circuit design guideline for generating stable electrical stimulus signals using a voltage divider resistor. Finally, based on the aforementioned results, we develop a wearable haptic glove prototype. This haptic glove allows the user to experience the haptic sensations of touching objects with five different degrees of stiffness

Analysis of the Energy Efficiency of a Pneumatic Booster Regulator with Energy Recovery

Pneumatic booster regulators (PBR) are in great demand in modern pneumatic systems for their energy-saving abilities. A new booster regulator with energy recovery (VBA-R) was proposed, and its energy efficiency was investigated by introducing the concept of air power. On the basis of quality-alterable gas thermodynamics, an energy efficiency assessment and pressure response model for VBA-R was proposed. First, a model was solved using MATLAB/Simulink software, and an alternative experiment was designed to verify the mathematical model and performance improvement. The results showed that the simulation was consistent with the experiment. We also can conclude that, first of all, the energy efficiency decreases with the increasing of supply pressure and flow-rate consumption; a VBA-R has the highest efficiency when its diameter ratio is closest to 1.3. Finally, a recovery chamber helped to improve the performance of the VBA-R, which included a boost ratio improvement of 15–25% and an efficiency improvement of 5–10% compared with a conventional VBA booster regulator. This research lays the foundation for optimism regarding the proposed booster regulator