摘要:
A system for and method of reducing the effects of preheat period variation in shape memory alloy actuation, include sensing the removal of motion delay due to slack, backlash, and/or compliance in the actuator and drive-train of the system, and determining actuator activation, as a result thereof.
摘要:
A method of controlling and/or predicting the remaining useful life of an active material actuator, such as a shape memory alloy wire, includes obtaining historical actuation data of an inherent system variable, such as electrical resistance, over a secondary variable, such as time, determining a normal operating envelope having upper and lower bounds based on the data, determining a current profile for a given actuation cycle, and comparing the shape of the current profile to the envelope to determine an out-of-bounds event.
摘要:
A method of controlling and/or predicting the remaining useful life of an active material actuator, such as a shape memory alloy wire, includes obtaining historical actuation data of an inherent system variable, such as electrical resistance, over a secondary variable, such as time, determining a normal operating envelope having upper and lower bounds based on the data, determining a current profile for a given actuation cycle, and comparing the shape of the current profile to the envelope to determine an out-of-bounds event.
摘要:
A method of sensing an ambient heat transfer condition surrounding a shape memory alloy element includes heating the shape memory alloy element, sensing the resistance of the shape memory alloy element, and measuring the period of time taken to heat the shape memory alloy element to a pre-determined level of a resistance characteristic. The ambient heat transfer condition surrounding the shape memory alloy element is calculated by referencing a relationship between the period of time taken to heat the shape memory alloy to the pre-determined level of the resistance characteristic and the ambient heat transfer condition.
摘要:
Shape memory alloy (SMA) actuating elements are commonly simpler and of lower mass than alternative actuator designs and may find particular application in the transportation industry. Such SMA-powered devices are usually reliable and long-lived but the phase transformations which occur in the SMA alloy and are responsible for its utility are not totally reversible. This irreversibility, a consequence of irrecoverable strain, may progressively degrade the long-term actuator performance as the irrecoverable strain accumulates over many operating cycles. Methods and devices for compensating for these effects and extending the useful cycle life of SMA actuators are described.
摘要:
An actuator includes a thermally activated active material member, and an external element configured to selectively engage the member and presenting a predetermined rate of thermal conductivity configured to transfer heat energy to and/or from the member, so as to reduce the actuation period or rate of cooling after actuation, when engaged.
摘要:
An overheating protection system adapted for use with a shape memory alloy actuator element, includes at least one switching shape memory alloy element presenting a slower activation period than that of the actuator element, and configured to selectively prevent activation of the actuator element, when the actuator element is actually or predicted to be experiencing overheating; and a circuit comprising the system, wherein the switching element and/or a circuit implement functions to modify activation of the actuator element.
摘要:
An actuator includes a thermally activated active material member, and an external element configured to selectively engage the member and presenting a predetermined rate of thermal conductivity configured to transfer heat energy to and/or from the member, so as to reduce the actuation period or rate of cooling after actuation, when engaged.
摘要:
Shape memory alloy (SMA) actuating elements are commonly simpler and of lower mass than alternative actuator designs and may find particular application in the transportation industry. Such SMA-powered devices are usually reliable and long-lived but the phase transformations which occur in the SMA alloy and are responsible for its utility are not totally reversible. This irreversibility, a consequence of irrecoverable strain, may progressively degrade the long-term actuator performance as the irrecoverable strain accumulates over many operating cycles. Methods and devices for compensating for these effects and extending the useful cycle life of SMA actuators are described.
摘要:
A method of controlling a shape memory alloy actuator utilizing the change in resistance exhibited by the actuator over an actuation cycle, and more preferably, a derivative thereof, to identify at least one event, and generating a response based upon the event.