Previously authors established the simulation method of a pneumatic drive system, where one solenoid valve drives one pneumatic cylinder. Nowadays, a computer simulation is available to choose pneumatic devices when designing a pneumatic drive system, and we can choose optima devices and get easily a desired response of a cylinder without technical knowledge. On the other hands, sometimes one solenoid valve drives some cylinders in a press machine or a lifting and lowering device. Then branches and junctions of pipe are necessary in a pneumatic drive system. However, not only influence of branches and junctions of pipe on a cylinder response, but also a method to build them to the simulation of a pneumatic cylinder drive system are not clear, though many researches on flow of a branch and a junction of pipe and its pressure loss coefficient have been conducted.
In this paper, the simulation method where one solenoid valve drives a number of cylinders at a time is developed. It is found that the influence of branches and junctions of pipe on a cylinder response is little except pipe length is very short by the developed simulation. The simulation results are in close agreement with the experimental results, and we show that developed simulation method is effective.
PID control schemes have been widely used in most industrial systems due to its simplicity and ease of implementation. In this paper, we propose a novel method for proportional-integral-derivative （PID） controller tuning directly using the closed-loop test data without parametric model of plant. The extended fictitious reference iterative tuning （E-FRIT） algorithm does not require any parameters of the plant model but only experimental data collected from the closed-loop system. By using an E-FRIT, which is one of the PID controller parameters tuning that enables us to obtain the ideal parameters with only one-shot experiment, this paper constructs a fictitious reference signal for the pneumatic servo system such that we can tune the PID controller parameters for desired control performance. A simple optimization problem is formulated to determine an appropriate reference model for the controlled process, and we use the particle swarm optimization （PSO） as the optimization method. The effectiveness of the proposed method is evaluated by an experimental result of a force control of the pneumatic servo system.
Accumulator is an important component for oil-hydraulic circuits. It is used for storing energy, absorbing pulsation flow, and suppressing surge pressure. For predicting accumulator performance, mathematical models of the accumulator have been investigated by many researchers. In the mathematical models of accumulator, an equation of state of gas, thermodynamics, and heat transfer have been considered. The aim of this paper is to propose a mathematical model of bladder-type accumulator considering heat conduction effect inside rubber membrane. Experiments were carried out using a bladder-type accumulator which was connected to a piston-type accumulator. The bladder-type accumulator was prefilled first and then discharged, the piston-type accumulator was charged by the oil discharged from the bladder-type accumulator. Discharging process of the bladder-type accumulator and charging process of the piston-type accumulator were measured simultaneously. The accumulator model proposed was validated by measured date of the experiments.
In recent years, 3D printer technology has brought many projects on the myoelectric hand to provide lightweight and inexpensive ones. However, the use of many mechanical and electronic components still limits the reduction of the total weight and cost. It also causes inevitable battery life problem. Therefore the authors propose a novel self-powered pneumatic prosthetic hand with which no electricity is required. The hand can grasp physical objects flexibly and quickly enough and is superior in portability because no external facilities like tank and compressor are needed in contrast to the traditional pneumatic devices. Driven by the supination motion of the arm, it does not have the restriction of the posture when the user wants to grasp. In addition, the hand is equipped with a tactile feedback system to realize a soft grasping.