Shape Memory Alloy Actuator for Long-Stroke, Fast Response Control

The patent divides the actuation mechanism into separate functional components: a first shape memory alloy line for driving the swing arm, and a second shape memory alloy line for controlling the braking arm. This segmentation allows each line to be optimized for its specific function rather than requiring a single long line to achieve both stroke and control, thereby reducing overall structural complexity while maintaining actuation stroke.

The patent introduces a braking arm as an intermediary component between the second shape memory alloy line and the swing arm. The braking arm, controlled by the second SMA line, applies braking force to the swing arm through a braking portion, enabling precise control of the actuation stroke without requiring the driving SMA line to be excessively long.

By segmenting the control function into a separate second shape memory alloy line that controls the braking arm, the patent reduces the effective length of the driving path for the first SMA line. This allows the first SMA line to maintain a shorter, more responsive configuration while still achieving the required actuation stroke through the mechanical advantage provided by the braking arm mechanism.

The patent employs dynamic control where the braking arm can be actuated independently to apply braking force at different stages of the swing arm's motion. This dynamic braking control allows the system to maintain fast response speeds by preventing excessive motion early in the actuation cycle, rather than relying on a long SMA line to naturally limit stroke through its physical length.

The patent separates the spring function from the driving function by using a dedicated elastic member instead of making the SMA line itself a spring. The elastic member provides the necessary spring force and stroke, while the first shape memory alloy line maintains its primary function of providing high driving force through controlled phase transformation, thus avoiding the trade-off between stroke and force.

The elastic member acts as an intermediary energy storage and release mechanism between the power source and the swing arm. It stores elastic potential energy during compression and releases it to drive the swing arm, providing both the required actuation stroke and maintaining high driving force values without compromising either parameter.

The patent segments the spring function (performed by the elastic member) from the driving function (performed by the first shape memory alloy line). The elastic member provides the compliant spring action for stroke extension, while the SMA line maintains high stiffness during actuation through its phase transformation characteristics, thereby preserving response speed while achieving increased stroke.

The system employs dynamic stiffening where the first shape memory alloy line exhibits high stiffness during its phase transformation actuation phase, while the elastic member provides compliant spring action during the recovery phase. This dynamic differentiation allows the system to maintain high response speed during actuation while achieving extended stroke during recovery, without compromising either performance.

The patent implements periodic action by using the elastic member to maintain the actuation stroke passively after initial actuation. The elastic member stores energy during compression and releases it periodically to maintain the swing arm's position, eliminating the need for continuous energy input from the shape memory alloy line and significantly reducing overall energy consumption.

The elastic member provides self-service energy storage and release functionality that automatically maintains the actuation stroke without requiring continuous external energy input. The system leverages the elastic member's inherent energy storage capacity to sustain the stroke, reducing dependence on continuous SMA line energization and lowering energy consumption.