Ultra Motion’s linear servo actuators provide reliable, high-performance motion control for the most demanding applications, engineered to withstand the harsh oscillatory loads typical in swashplate systems. In the Phenix UAS Ultra 2XL rotorcraft, six AM Servo Cylinders control the two swashplates, delivering the precision and rapid response critical for optimal flight control throughout the required flight envelope.

Ultra Motion’s suite of servo actuators provides environmentally hardened, reliable, and power-dense actuation options that meet the demands of the defense industry. All of our servo actuators utilize our patented Phase Index® absolute position feedback and include built-in brushless DC control electronics. Communication protocols like RS-485 and CAN 2.0B allow for complete control over the actuator while enabling detailed telemetry for health monitoring and preventative maintenance.

Design features include:

• D38999 connectors
  • Custom options include alternative keying arrangements, finishes, and connectors.
• Saltwater resistance for marine and shipboard applications.
• Preloaded actuators for zero backlash, increased stiffness, and maximum control authority.
• Pressure-compensated oil-filled designs for submerged operation to depths exceeding 6000 meters.
• Dual redundant actuators with redundant motors, controllers, and triplicated absolute position feedback when single electrical fault tolerance is required.

Typical defense applications include:

• Vehicle Control
  • Fixed-wing surfaces, swashplate and tail-rotor, fins, subsea rudder/fin, hydrofoils, landing gear, etc.
• Utility Actuation
  • Hatches, pin release, sensor deployment
• Sensor leveling platforms
• Valves

The Servo Cylinder is a popular choice for high reliability UAV control surface and utility linear actuator applications. The A-Series Servo Cylinder uses a brushless DC motor and contactless absolute position feedback to reduce wear and provide superior performance when compared to potentiometers and brushed DC solutions. The built-in control electronics offer a variety of communication interfaces including CAN 2.0B, RS-422/485 serial, RC PWM, 4-20 mA in/out, etc.

The Ultra Motion AM Servo Cylinder is designed to excel in harsh shock/vibe environments with IP65 dynamic and IP67 static ingress protection ratings. The D38999 receptacles provide military standard connections, and the on-board temperature, current, voltage, and humidity sensors allow for constant health monitoring of the servo actuator. Custom heater firmware is available that maintains a configurable controller temperature even in ambient environments < -40°C. The Servo Cylinder has an 8 to 36 VDC operating bus voltage, which is compliant with the majority of UAV power busses and will survive at >51 VDC.

The Servo Cylinder offers forces up to 530 lbf, strokes up to 7.75 inches, and speeds up to 14 in/s, allowing for high bandwidth control >15 Hz at small position amplitudes.

The Servo Cylinder uses a helically skewed BLDC motor to eliminate detent torque which allows for smooth backdriving at low forces (~10 lbf) when unpowered or commanded to zero phase current. This allows for the possibility of eliminating bulky and costly magnetic clutch assemblies from the actuator in optionally piloted vehicle (OPV) applications.

Conversions of control surfaces from rotary actuators to linear actuators can lead to increased power density, increased control authority due to higher resolution position control and significantly reduced backlash, and decreased cost/mass. Contact Ultra Motion Engineering to discuss your unmanned vehicle actuator requirements in detail. View Servo Cylinder performance and dimensions by using our online configurator here.

All of the dynamic shaft seal design efforts taken by Ultra Motion will minimize the amount of liquid ingress into the actuator enclosure, but 100% moisture exclusion is not feasible. For this reason, the A2 and AM Servo Cylinders include a custom injection molded desiccant block in close proximity to the control electronics and BLDC stator to adsorb moisture over long periods of time. The desiccant block is a molecular sieve that traps moisture molecules as they migrate through the semi-solid component.

Compared to typical silica-gel desiccants, the high-performance injection molded desiccant used in the Servo Cylinder slowly adsorbs moisture over years, does not release moisture at high temperatures, and is structurally robust. This small component would normally go unnoticed, but it plays an important role in making the Servo Cylinder extremely reliable in harsh marine environments.

Our custom engineered desiccant block is also paired with a precision humidity sensor that continuously monitors relative humidity inside of the actuator’s sealed housing. This allows users to assess the functionality of the actuator’s seals and determine if the desiccant block requires service long before an unexpected problem occurs.

Dragonfly is a rotorcraft lander being designed by the Johns Hopkins Applied Physics Laboratory in support of NASA’s New Frontiers program. The Dragonfly dual-quadcopter will be sent to explore Saturn’s moon, Titan, and to take a variety of in-flight atmospheric and surface measurements. Titan’s dense atmosphere and low gravity make it an ideal candidate for an aerial exploration vehicle making it able to cover tens of miles of Saturn’s moon in under an hour.

In order to acquire surface samples, Honeybee Robotics has been contracted to design a pneumatic transfer subsystem called DrACO – Drill for Acquisition of Complex Organics. DrACO acts similarly to an everyday vacuum cleaner, using a high-speed pump and the external atmosphere to acquire, store, and analyze samples of loose particles on Titan’s surface.

A high-fidelity DrACO prototype has been successfully tested in a state-of-the-art “Titan Pressure Environment Chamber (TPEC)” that was custom built for this mission by Johns Hopkins APL. This chamber mimics Titan’s 1.5 atm and -181 °C atmosphere and puts the equipment to the test. An Ultra Motion Servo Cylinder was used to move a pneumatic suction tube up and down to the imitation Titan surface within the TPEC, emulating what Honeybee Robotic’s drill will do on Titan. The Servo Cylinder was insulated in order to maintain an acceptable temperature for operation while exposed to the -181 °C temperature. The Servo Cylinder has built-in temperature feedback and a special heating firmware that makes use of non-torque generating phase currents to turn the motor into a heater for extremely cold ambient environment applications.

Read more about the Dragonfly mission here