Method for overload protection of SMA device

摘要

A method for detecting a mechanical overload condition of an energized linear actuator to prevent commanding an activation signal to the linear actuator that may mechanically overload the linear actuator includes monitoring feedback variation of a movable element associated with the linear actuator including monitoring a present feedback signal of the movable element, monitoring a previous feedback signal of the movable element, comparing the present feedback signal and the previous feedback signal and determining the feedback variation based on the comparing. The feedback variation is compared to a feedback variation threshold. An input signal associated with the activation signal for controlling the linear actuator is monitored and the input signal compared to an input signal threshold. The electrical overload condition is detected when the feedback variation is less than the feedback variation threshold and the input signal is greater than the input signal threshold.

主权项

1. Method for detecting a mechanical overload condition of an energized linear actuator and providing a mechanical overload protection scheme to prevent commanding an activation signal to the linear actuator that may mechanically overload the linear actuator when the mechanical overload condition is detected, comprising:
monitoring feedback variation of a movable element associated with the linear actuator comprising monitoring a present feedback signal indicating a present position of the movable element during a present activation cycle of the linear actuator, monitoring a previous feedback signal indicating a previous position of the movable element immediately before the present activation cycle is initiated whilst the linear actuator is deactivated, comparing the present feedback signal and the previous feedback signal and determining the feedback variation based on a difference between the present position and the previous position of the movable element; comparing the feedback variation to a feedback variation threshold; and one of if the feedback variation is greater than the feedback variation threshold, determining the mechanical overload condition does not exist and the mechanical overload protection scheme will not be provided; only if the feedback variation is less than the feedback variation threshold: monitoring an input signal associated with the activation signal for controlling the linear actuator, comparing the input signal to an input signal threshold, and detecting the mechanical overload condition and providing the mechanical overload protection scheme when the feedback variation is less than the feedback variation threshold and the input signal is greater than the input signal threshold.