A new generation of pneumatic servos for industrial robots

Pu, Junsheng; Weston, Richard

doi:10.1017/s0263574700004999

Cited by 20 publications

(8 citation statements)

References 4 publications

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“…In order to deal with the uncertainties and the highly nonlinear behavior of pneumatic systems, a number of approaches have also been developed that incorporate some form of learning. Pu and Weston [5] describe an algorithm which is trained to provide feed-forward signals to optimize various point to point motions. McDonell and Bobrow [6] use a real time identification scheme to identify a locally linear time-varying model for the system about arbitrary reference trajectories.…”

Section: Introductionmentioning

confidence: 99%

Modeling, identification, and control of a pneumatically actuated, force controllable robot

Bobrow

McDonell²

1998

IEEE Trans. Robot. Automat.

160

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This research focuses on modeling and control of a lightweight and inexpensive pneumatic robot that can be used for position tracking and for end-effector force control. Unlike many previous controllers, our approach more fully accounts for the nonlinear dynamic properties of pneumatic systems such as servovalve flow characteristics and the thermodynamic properties of air compressed in a cylinder. We show with theory and experiments that pneumatic actuators can rival the performance of more common electric actuators. Our pneumatic robot is controlled by extending existing manipulator control algorithms to handle the nonlinear flow and compressibility of air. The control approach uses the triangular form of the coupled rigid body and air flow dynamics to establish path tracking. In addition to the trajectory tracking control law, a hybrid position/force control algorithm is developed. The experimental results indicate that the tip forces on the robot can be controlled without the need for an expensive force/torque sensor usually required by electric motor driven systems.

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Section: Introductionmentioning

confidence: 99%

Modeling, identification, and control of a pneumatically actuated, force controllable robot

Bobrow

McDonell²

1998

IEEE Trans. Robot. Automat.

160

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“…Spool-type servo valves can directly control flow rate. Because their exhaust flow rates are smaller than those of nozzle-flapper type valves, spool-type servo valves are widely used in pneumatically driven robot systems [8][9][10]. However, spool-type valves still experience air leakage owing to the presence of a gap between the spool and the sleeve.…”

Section: Introductionmentioning

confidence: 99%

Development of a Poppet-Type Pneumatic Servo Valve

et al. 2018

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In pneumatic positioning and force-control systems, spool-type servo valves are widely used for obtaining quick responses and precise control. However, air leakage from these valves results in increased energy consumption. To address this problem, we developed a three-port poppet-type servo valve to reduce air leakage. The developed valve consists of a camshaft, two orifices, two metal balls, and a housing with two flow channels. The metal ball is pushed by fluid, and spring force closes the orifice. The port opens when the cam rotates and pushes the ball. The cam shape and orifice size were designed to provide the desired flow rate. The specifications of the DC motor for rotating the camshaft were determined considering the fluid force on the ball. Static and dynamic characteristics of the valve were measured. We experimentally confirmed that air leakage was 0.1 L/min or less. The ratio of air leakage to maximum flow rate was only 0.37%. Dynamic characteristic measurements showed that the valve had a bandwidth of 30 Hz. The effectiveness of the valve was demonstrated through experiments involving pressure and position control.

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“…Another key element is the pneumatic servo valve. Its structure and parameters are important in order to achieve good performance [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Trajectory control of pneumatic servo table with air bearing

Kawashima

Kagawa

et al. 2011

Proceedings of 2011 International Conference on Fluid Power and Mechatronics

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In this paper, the trajectory control design of the pneumatic servo table considering the dynamics of pipelines and servo valve is proposed. The table is mainly composed by a pneumatic actuator, the high-performance pneumatic servo valve and pipelines. The pneumatic actuator utilizes a pneumatic cylinder with air bearings. This servo valve, with high dynamics up to 300Hz, is connected with the pneumatic actuator by pipelines. The whole system is pneumatically driven, it has advantages like low heat generation and non-magnetic, which are suitable for precise positioning. A linear model considering the dynamics of pipelines and the servo valve is designed to simulate the system. Compared with experimental results, it is found that with 7 th order linear control model, the discrepancy between experimental and simulation results became much smaller than the 3 rd order model was used. However, a low dimensional model is necessary for practical use. Since there are two poles which are much further from imaginary axis compared with other five poles in the pole loci of the 7 th order model, the model's order can be reduced into 5 th . By comparing simulation with experimental results, we found that the 5 th order model can also match with the real system well. Based on this result, a 5 th order feed forward has been designed. When a curve which can derivate by five times is inputted, the experimental results show that the maximum trajectory has been minimized by 20μm.

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A new generation of pneumatic servos for industrial robots

Cited by 20 publications

References 4 publications

Modeling, identification, and control of a pneumatically actuated, force controllable robot

Modeling, identification, and control of a pneumatically actuated, force controllable robot

Development of a Poppet-Type Pneumatic Servo Valve

Trajectory control of pneumatic servo table with air bearing

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