This paper proposes a variation on a sliding mode control approach that provides significant energy savings for the control of pneumatic servo systems. The control methodology is formulated by first decoupling the standard four-way spool valve used for pneumatic servo control into two three-way valves, then using the resulting two control degrees of freedom to simultaneously satisfy both the sl...

Pneumatic control valves are still the most used in process industries due to their low cost and simplicity. This paper presents a design procedure of a PID controller for a pneumatic control valve. For comparison, P and PI controllers are also utilized for the control valve. The bond graph method is used to model the control valve, in order to compare the response characteristics of the valve....

2 Abstract Pneumatic actuators have several advantages such as light weight, safety, low cost and high compliance. However, many pneumatic actuators have complicated systems that include a compressor, air tubes, and pneumatic valves with electrical wires. This research proposes a new control method for a multiplex pneumatic transmission constructed with special resonant valves and air tubes wit...

Pneumatic servo systems are applied in several industrial applications and have also been studied extensively for the purposes of compensating the nonlinearity of pneumatic servo systems and improving the controllability with robust control. In their control system design, the transfer function of a pneumatic servo system has been a third-order time lag system, based on the assumption that serv...

This paper proposes a structure and control approach for the energy saving servo control of a pneumatic servo system. The energy saving approach is enabled by supplementing a standard four-way spool valve controlled pneumatic actuator with an additional two-way valve that enables flow between the cylinder chambers. The “crossflow” valve enables recirculation of pressurized air, and thus enables...

Pressure control of a pneumatic actuator using fast switching On/Off valves continues to remain a major challenge for researchers. This article proposes a novel pulse width modulation–sliding mode controller that improves pressure tracking of pneumatic actuators. First, a comprehensive mathematical model of the pneumatic system was developed that consists of several submodels. The model compris...

The dynamic breakup of emulsion droplets was demonstrated in double-layered microfluidic devices equipped with designed pneumatic actuators. Uniform emulsion droplets, produced by shearing at a T-junction, were broken into smaller droplets when they passed downstream through constrictions formed by a pneumatically actuated valve in the upper control layer. The valve-assisted droplet breakup was...

This paper proposes a control approach that can provide significant energy savings for the control of pneumatic servo systems. The control methodology is formulated by decoupling the standard four-way spool valve used for pneumatic servo control into two threeway valves, then using the resulting two control degrees of freedom to simultaneously satisfy a performance constraint (which for this pa...

Novel latching microfluidic valve structures are developed, characterized, and controlled independently using an on-chip pneumatic demultiplexer. These structures are based on pneumatic monolithic membrane valves and depend upon their normally-closed nature. Latching valves consisting of both three- and four-valve circuits are demonstrated. Vacuum or pressure pulses as short as 120 ms are adequ...

Pneumatic actuators are attractive for robotic rehabilitation applications because they are lightweight, powerful, and compliant, but their control has historically been difficult, limiting their use. In this paper we present the pneumatic control system developed for Pneu-WREX: a pneumatically actuated, upper extremity orthosis for rehabilitation after stroke. The developed pneumatic control s...