936 research outputs found
Observer-based tuning of two-inertia servo-drive systems with integrated SAW torque transducers
This paper proposes controller design and tuning
methodologies that facilitate the rejection of periodic load-side disturbances applied to a torsional mechanical system while simultaneously compensating for the observerâs inherent phase delay. This facilitates the use of lower-bandwidth practically realizable disturbance observers. The merits of implementing full- and reduced-order observers are investigated, with the latter being implemented with a new low-cost servo-machine-integrated highband width
torque-sensing device based on surface acoustic wave
(SAW) technology. Specifically, the authorsâ previous work based on proportionalâintegralâderivative (PID) and resonance ratio control (RRC) controllers (IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1226â1237, Aug. 2006) is augmented with observer disturbance feedback. It is shown that higher-bandwidth disturbance observers are required to maximize disturbance attenuation over the low-frequency band (as well as the desired rejection frequency), thereby attenuating a wide range of possible frequencies. In such cases, therefore, it is shown that the RRC controller is
the preferred solution since it can employ significantly higher observer bandwidth, when compared to PID counterparts, by virtue of reduced noise sensitivity. Furthermore, it is demonstrated that the prototype servo-machine-integrated 20-N · mSAWtorque transducer is not unduly affected by machine-generated electromagnetic
noise and exhibits similar dynamic behavior as a
conventional instrument inline torque transducer
Improved performance of motor-drive systems by SAW shaft torque feedback
The paper describes the application of a non-contact, high bandwidth, low cost, SAW-based torque
measuring system for improving the dynamic performance
of industrial process motor-drive systems. Background to
the SAW technology and its motor integration is discussed
and a resonance ratio control (RRC) technique for the
coordinated motion control of multi-inertia mechanical
systems, based on the measurement of shaft torque via a
SAW-based torque sensor is proposed. Furthermore, a
new controller structure, RRC plus disturbance feedback
is proposed, which enables the controller to be designed to
independently satisfy tracking and regulation
performance. A tuning method for the RRC structure is
given based on the ITAE index, normalized as a function of
the mechanical parameters enabling a direct performance
comparison between a basic proportional and integral (PI)
controller. The use of a reduced-order state observer is
presented to provide a dynamic estimate of the load-side
disturbance torque for a multi-inertia mechanical system,
with an appraisal of the composite closed-loop dynamics.
The control structures are experimentally validated and
demonstrate significant improvement in dynamic tracking
performance, whilst additionally rejecting periodic load
side disturbances, a feature previously unrealisable except
by other, high-gain control schemes that impose small
stability margins
SAW torque transducers for disturbance rejection and tracking control of multi-inertia servo-drive systems
The paper proposes a resonance ratio control (RRC) technique for the coordinated motion control of multi-inertia mechanical systems, based on the measurement of shaft torque via a SAW-based torque sensor. Furthermore, a new controller structure, RRC plus disturbance feedback is proposed, which enables the controller to be designed to independently satisfy tracking and regulation performance. A tuning method for the RRC structure is given based on the ITAE index, normalized as a function of the mechanical parameters enabling a direct performance comparison between a basic proportional and integral (PI) controller. The use of a reduced-order state observer is presented to provide a dynamic estimate of the load-side disturbance torque for a multi-inertia mechanical system, with an appraisal of the composite closed-loop dynamics. It is shown that the integrated formulation of the tuning criteria enables lower bandwidth observers to be implemented with a corresponding reduction in noise and computational load. The control structures are experimentally validated via a purpose designed test facility and demonstrate significant improvement in dynamic tracking performance, whilst additionally rejecting periodic load side disturbances, a feature previously unrealisable except by other, high-gain control schemes that impose small stability margins
High-performance control of dual-inertia servo-drive systems using low-cost integrated SAW torque transducers
AbstractâThis paper provides a systematic comparative
study of compensation schemes for the coordinated motion
control of two-inertia mechanical systems. Specifically, classical proportionalâintegral (PI), proportionalâintegralâderivative (PID), and resonance ratio control (RRC) are considered, with an enhanced structure based on RRC, termed RRC+, being proposed. Motor-side and load-side dynamics for each control structure are identified, with the âintegral of time multiplied by absolute
errorâ performance index being employed as a benchmark metric. PID and RRC control schemes are shown to be identical from a closed-loop perspective, albeit employing different feedback sensing mechanisms. A qualitative study of the practical effects of employing each methodology shows that RRC-type structures
provide preferred solutions if low-cost high-performance torque transducers can be employed, for instance, those based on surface acoustic wave tecnologies. Moreover, the extra degree of freedom afforded by both PID and RRC, as compared with the basic PI, is shown to be sufficient to simultaneously induce optimal closed-loop performance and independent selection of virtual inertia ratio. Furthermore, the proposed RRC+ scheme is subsequently
shown to additionally facilitate independent assignment
of closed-loop bandwidth. Summary attributes of the investigation are validated by both simulation studies and by realization of the methodologies for control of a custom-designed two-inertia system
Observer based tuning techniques and integrated SAW torque transducers for two-inertia servo-drive systems
A controller design and tuning methodology is proposed that facilitates the rejection of periodic load-side disturbances applied to a torsional mechanical system, whilst simultaneously compensating for the disturbance observer's inherent phase delay, thereby facilitating the used of lower bandwidth, practically realisable, disturbance observers. The merits of implementing both a full- and reduced order observer, is investigated, with the latter being implemented with a new low-cost, high-bandwidth torque sensing device based on surface acoustic wave technolog
Influence of control structures and load parameters on performance of a pseudo direct drive
The paper describes an in-depth and systematic analysis of a pseudo direct drive permanent magnet machine in closed loop control. Due to the torque being transmitted from the high-speed rotor (HSR) to the low-speed rotor (LSR), through a relatively low stiffness magnetic gear with non-linear characteristics, speed oscillations appear in the drive output with a conventional proportional integral (PI) controller. Therefore two candidate controllers have been proposed as an alternative to the PI control and all controllers have been optimally tuned with a genetic algorithm against a defined criterion. Furthermore, closed loop models are established in the complex frequency domain to determine the system damping and the cause of the oscillations. Consequently, the best controller structure that improves the dynamic behaviour of the system in terms of speed tracking and disturbance rejection could be identified, based on the frequency domain analysis. Experimental results are presented to validate the analysis and the proposed control technique
Application of higher harmonic blade feathering on the OH-6A helicopter for vibration reduction
The design, implementation, and flight test results of higher harmonic blade feathering for vibration reduction on the OH-6A helicopter are described. The higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate. These inputs are transformed into 3P, 4P and 5P blade feathering angles. This results in modified blade loads and reduced fuselage vibrations. The primary elements of this adaptive vibration suppression system are: (1) acceleration transducers sensing the vibratory response of the fuselage; (2) a higher harmonic blade pitch actuator system; (3) a flightworthy microcomputer, incorporating the algorithm for reducing vibrations, and (4) a signal conditioning system, interfacing between the sensors, the microcomputer and the HHC actuators. The program consisted of three distinct phases. First, the HHC system was designed and implemented on the MDHC OH-6A helicopter. Then, the open loop, or manual controlled, flight tests were performed, and finally, the closed loop adaptive control system was tested. In 1983, one portion of the closed loop testing was performed, and in 1984, additional closed loop tests were conducted with improved software. With the HHC system engaged, the 4P pilot seat vibration levels were significantly lower than the baseline ON-6A levels. Moreover, the system did not adversely affect blade loads or helicopter performance. In conclusion, this successful proof of concept project demonstrated HHC to be a viable vibration suppression mechanism
Automation Systems Design and Laboratory Prototyping Aimed at Mature Petroleum Drilling Rig Retrofitting
This paper presents a control system design methodology for the drill-string rotary drive and draw-works hoist system aimed at mature drilling rig retrofitting. The rotary drive is equipped with an active damping speed control system featuring a proportional-integral speed controller readily available within modern controlled electrical drives, extended with drill-string back-spinning prevention scheme for the case of stuck tool. The draw-works hoist system features a tool normal force (Weight-on-Bit) controller with tool longitudinal speed (Rate-of-Penetration) limiting functionality. The design of proposed control systems has been based on suitable control-oriented process models and damping optimum criterion which guarantees a desired level of closed-loop system damping. The proposed drilling control systems have been verified on a downscaled laboratory experimental setup, which represents a necessary pre-requirement before these systems are tested in the field
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