Actuador miniatura de 1150gr de fuerza con Alambres Musculares®

Features

 Stroke: 0.375 inches (9.5mm)

 Output Force: constant 2.5 lb-f (11 N), peak 5.0 lb-f (22 N)

 Actuation Time: 50 ms to position hold (depends on input voltage or PWM)

 Actuation Speed: up to 200 mm/s

 Weight (as shown): 0.45 ounces (12.8 grams)

 Dimensions: 2.8” x 1.3” x 0.098” (71 x 33 x 2.5mm)

 Mounting Holes: 1.125” x 2.675” thru pattern for #2 SHCS

 Vertical Height from 0.063” FR-4 PCB Surface: 0.059” (1.5mm)

 Operating Temperature Range: -20°F to 140°F (-29°C to 60°C)

The operating principles of the MP1150GB  actuators are relatively simple: SMA wire segments form a series-resistive electrical circuit within the MP1150GB MiniPistonactuator.

Input current ohmically heats the SMA wire elements, which begin to contract when they reach a temperature of roughly 75°C (167°F). The wires are fully contracted at ~110°C (230°F) and should not be heated above 150°C (302°F)

When power is removed, the SMA wire must cool below ~60°C (140°F) to return fully to the un-powered position. The actuator does not need to fully return to the un-powered position to actuate again, however. In fact, using control methods described below, the actuators could maintain any position along the design stroke (though we do not recommend this type of operation except by experienced users).

The MP1150GB MiniPistonprovides force only in the powered direction, returning to the unpowered position if un-constrained. The MP1150GB MiniPistonmust be allowed to return to the un-powered position under it’s built-in restoring force (bias-spring) after actuation, or the SMA wires will ‘bulge’ outward, and may become caught on other structural elements of the actuator.

The MP1150GB MiniPistonMotor Body is designed for mounting on a flat plane, and is not designed to support the weight of other objects, or to be torqued or compressed other than at the mounting holes.

MP1150GB MiniPistondevices have not been tested extensively for side loading. However, they are very robust devices, and qualitative testing indicates that they perform well under all conditions at the rated loads.

The MP1150GB MiniPistonhas a 2.5 lb.-f (11 N) force rating. Under higher load conditions (beyond the design rating), the actuator may not reach the end of stroke. Note that the actuation time is slightly longer for an actuator under load, than for an un-loaded actuator.

The maximum ambient operating temperature for the MP1150GBactuator is 60°C (140°F); while the minimum tested operating temperature is -30°C (-22°F). Long-term exposure to ambient temperatures above 75°C will result in passive (un-powered) actuation of the actuator. To avoid damaging the SMA wire, the wire temperature should never exceed 150°C (302°F).

The stainless steel output shaft of the MP1150GBis connected electrically to the “GND” terminal, intended for use as power supply ‘ground’. To avoid electrical shock or shorts, do not connect the “GND” to live power. Future models of our actuators will have electrically insulated output shafts.

The actuation time of the MP1150GB MiniPistondepends on the input power, from ~50 ms to ‘position-hold’. The actuation time also changes slightly with load and/or ambient temperature. For a given input power, actuation time increases for higher loads.

Actuation time also increases for lower ambient temperatures, since additional power is required simply to raise the wire to room temperature.

If actuated rapidly, the SMA wire passes through the transition temperature range very quickly, and can become overheated if power is not removed quickly when the actuator reaches the end of stroke (and the output shaft shorts to the “SW” pin (center pin of 3-pin connector). Use of the Miga MOSFET Analog Switching Circuit prevents overheating by removing power the moment the end-switch is reached.

The repetition rate of the MP1150GB MiniPistonis governed by the time required to cool and return to the un-powered position. Unconstrained, the MP1150GB MiniPistonreturns fully to the unpowered position in ~5 seconds, depending on ambient conditions and the SMA wire diameter. Forced cooling can increase the repetition rate by up to 100x if high rate operation is a requirement.

To safely explore the optimal input power for the MP1150GB MiniPistonactuator and your application, connect a battery or power supply capable of supplying several amps between the actuator ground (“GND” or black wire) and power (“+V” or red wire).

Voltages above +12V are capable of damaging (overheating) the wire, so pulse timing or other power control circuitry must be used. For safest operation, note the one-second rule below. Once initial power levels are determined, increase the load on the actuator, further incrementing the input power to accommodate the higher loads and your desired actuation time.

If too little power is applied to an actuator (or if it is applied too slowly), the wire loses heat to the environment more quickly than it is provided by the power source. The actuator will not function if too little power is applied, and may not achieve full stroke (full phase transition).

The so-called “one-second” rule applies for all MP1150GB MiniPistonactuators, and safely assumes that, for an un-constrained actuator, the voltage and current settings that result in actuation time of one-second will not damage (overheat) the SMA wire elements, even if power is left on continuously. That is, at this power level, you cannot overheat the wire by leaving the power ON for too long (although we do not recommend this mode of operation). The safest way to determine these settings is to begin with very low voltage, and increase it slowly until full actuation occurs in one second. The following approximate values apply for the MP1150GBactuators:

SMA wire: 5 segments, 10.75” Active Length

Resistance: 3.7 ohms *

10V actuation: ~2.7 amps, 0.5s *

Mounting Holes: 4x 2-56 screws on 1.125” x 2.675” pattern

Pulse Width Modulated power can be used to optimize actuator power consumption for battery operation, or to control the relative position along the design stroke. After actuating, an SMA wire requires time to cool before returning to the un-powered position. If power is removed at mid-stroke, for instance, and re-applied when the wire first begins to cool, a PWM control loop can safely maintain a load at any position along the stroke.

MP1150GBSeries SMA actuators do have their limitations, and it is important to understand these limitations in order to utilize them to their fullest potential.

1) The optimal uses for the MP1150GB MiniPiston Series are those involving powered motion in one direction only: powering OFF the actuator the moment the end of stroke is reached.

The ideal example is a latch-release mechanism, whereby a spring-loaded cabinet door is released using a MP1150GB MiniPiston actuator.

2) While it is possible to do very high precision operations with MP1150GB MiniPistonactuators (using various position encoders, for instance), SMA wires stretch or “creep” slightly with age. This may mean that periodic adjustment would be required for high accuracy positioning tasks.

3) MP1150GB MiniPiston actuators have not been designed for “continuous” operation, holding a load in place for extended periods. This type of operation is possible, but not without paying careful attention to the temperature environment. The maximum “duty cycle” depends upon ambient temperature conditions and load.

4) MP1150GB MiniPiston actuators have a built in spring to return an un-powered actuator to the rest position if unconstrained. If constrained by a load or other friction or drag, however, the wires will elongate when cool, and ‘bulging’ outwards, may become trapped by other elements of the actuator. For optimal use, the actuator should be allowed to return unrestrained when power is removed.

Code: MP1150GK price: $60