Sensory feedback system for electroactive polymer based transducers

Abstract

A system for obtaining inline sensory feedback from an electroactive polymer based transducer for use in feedback control applications is disclosed. Specifically a method of obtaining sensory feedback from an electroactive polymer based transducer includes the steps of: receiving a user input in a control system, combining it with a control system feedback signal from a sensory feedback circuitry and producing a control signal; receiving the control signal in an amplifier and sensory tone generator, combining it with an amplifier feedback signal from the sensory feedback circuitry and producing a power signal; receiving the power signal and an environmental disturbance in an electroactive polymer transducer and sensory circuitry and responsive to the user input producing a sensory signal; receiving the sensory signal in the sensory feedback circuitry and producing the control system feedback signal and the amplifier feedback signal; and producing a data output in the control system.

Description

FIELD OF INVENTION [0001] The present invention relates generally to an electroactive polymer based transducers and in particular electroactive polymer based transducers for use in inline sensory feedback and control system applications. BACKGROUND OF THE INVENTION [0002] Position and force feedback are crucial requirements for high performance industrial and consumer based control applications. Such applications Include micro and nano positioning, human interactive robotics, multi-agent robotics, toys, soft tissue handling and animatronics. [0003] Traditional transducers include AC and DC motors, pneumatic, solenoid and hydraulic actuators. Sensory feedback from traditional transducers is commonly provided by additional components such as strain gages, accelerometers, laser interferometers, encoders, potentiometers, LVDTs, pressure sensors, load cells, and additional electroactive sensors. Each of these components requires extra power and signal recovery circuitry. Furthermore, in ...

AI Technical Summary

Benefits of technology

[0006] The present invention relates to a system for obtaining inline sensory feedback from an electroactive polymer based transducer for use in feedback control applications. The system infers strain, pressure and health of an electroactive polymer based transducer from real-time measurements of the electrical property changes.

[0007] In one embodiment, during operation of the transducer, the inherent electrical properties of the electroactive polymer transducer are monitored with sensory signals to determine information regarding the state of the transducer. These measurements may be made with and without the presence of the potentially high voltage control signal used to power the transducer. These measurements alone may be used to infer strain from the transducer in real-time position control applications.

[0008] In another embodiment, during operation of the transducer, both the high voltage signal applied to the transducer and the sensory signal may be measured and combined to infer both the strain state of the transducer and the electrostatic stress applied to the transducer in real-time. These measurements are then useful as feedback for real-time impedance control applications.

[0009] In an additional embodiment, the combined measurement of the sensory signal and the control signal may be further manipulated with a microprocessor to determine the external disturbances that may be applied to the transducer. This information may then be employed for real-time disturbance rejection or vibration suppression type control applications.

[0010] Furthermore, the sensory feedback system may be responsible for monitoring the health condition of the electroactive polymer transducer. In this case, in addition to the aforementioned measurements, the sensory system may monitor the power delivery to the electroactive polymer transducer. These measurements may be used to prevent dielectric breakdown of the transducer or to cease power delivery to the transducer In the event of dielectric breakdown or mechanical failure of the device. In this case, the sensory feedback system acts as a watchdog to ensure safe operation of the transducer.

[0011] The system responsible for making the foregoing measurements from an electroactive polymer transducer is comprised of an amplifying stage, a sensory feedback stage and a control stage. The amplifying stage includes a means by which to add the sensory signal to the control signal and provides power to the electroactive polymer transducer during operation. It also includes provision for an internal feedback control loop to improve the performance of the amplifying stage in supplying energy to the electroactive polymer transducer. The sensory feedback stage includes circuitry for obtaining the feedback signals from the electroactive polymer transducer with and without the presence of the control signal. It also comprises signal conditioning circuitry, control / sensory signal separation circuitry, electrical property message extraction circuitry, and transient surge protection circuitry. The control stage comprises a computer, microcontroller or programmable logic circuit capable of extracting the strain state information from the sensory feedback system with the assistance of a predetermined algorithm. Finally, the control stage also generates suitable control signals from the sensory signals obtained by the sensory stage with provision for user defined or pre-programmed commands.

Problems solved by technology

Furthermore, in space critical applications, the additional components commonly used to provide sensory feedback can interfere with the motion of the transducer and inhibit adequate operation of the device.

In applications involving electroactive polymer transducers, the traditional approach to obtaining sensory feedback by addition of sensory components is cumbersome and with large strain transducers some methods of obtaining feedback are seemingly impossible to implement.

Furthermore, the addition of sensory elements to the transducer compromises the compact quality of electroactive polymer based devices that primarily attracts designers to these materials.

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