Underwater Servo SER-202X Brushless, Multi-turn

Reliable, affordable, compact underwater servos with brushless motors and multi-turn capability! With a machined acetal upper and lower case, these waterproof servos are rated to 200 meters. Or choose the anodized aluminum lower case option and you can operate at 400 meters!

• SER-2020: Features the Hitec HSR-M9382TH R/C servo with a PWM interface. This servo produces 3.3 Nm of torque and offers an extended travel range (up to ± 3.5 full turns of rotation with position control or continuous rotation with speed control). It uses a brushless motor and magnetic encoder, eliminating the most common causes of servo failure. Rated to 200m.
• SER-2021: same as SER-2020 but with anodized aluminum lower case, rated to 400m.

Output shaft is a 6-mm titanium D-shaft. Titanium Servo Hub available separately.

You will need a regular Cobalt 3-pin cable (NOT a 3-pin Power cable) to connect to these servos.

WARNING: These servos do not have internal protection against overheating or overvoltage. They can be damaged or destroyed by:

• driving the servo against a hard stop for more than 5-10 seconds
• running the servo at high torque continuously
• applying more than the recommended voltage to the servo

Users should design their electrical and mechanical systems to avoid these scenarios.

These servos have the following programmable features:

• Rotation: The endpoints can be adjusted to increase (or decrease) the amount of rotation available. The max achievable is +/- 3.5 turns.
• Continuous Mode: If your project requires multi-turns without position feedback, toggle to continuous rotation mode and the servo will spin in either direction at a speed proportional to the PWM pulse width.
• Speed: The speed of the servo can be adjusted. Max speed is the default, but speed can be reduced.
• Fail-Safe: This allows you to set a position that the servo will go to in the event of a signal loss between the servo controller and the servo.
• Direction: This servo, like any, is bidirectional but you can program the direction it moves when increasing (or decreasing) the PWM signal.
• Deadband Width: This setting refers to the position accuracy of the servo. The default setting is 1, which is the most precise. In some cases, such as when running multiple servos on one channel, a wider deadband is preferred so that the servos can work in unison.
• Soft Start: If you want the ramp-up from idle to max speed to be slightly lessened, you can adjust the Soft Start from 20% (default) up to 100%.

All of the above features can be accessed using the Hitec DPC-11 servo programmer. The programmer will plug into a PC using a USB to mini USB cable. It requires a 6V battery and the BLDC_HSR User interface_Ver 3.1 (see Downloads tab). You cannot program the servo using the default Ver 2.9 software that the DPC-11 ships with.

If you are not familiar with how servos work, we highly recommend doing a web search on "servo tutorial" and reading several of the results.

SKUs: SER-2020 SER-2021

Blue Trail Engineering’s Underwater Servos are compact, robust actuators for small marine robotic applications at depths of up to 400 meters. They consist of an off-the-shelf R/C servo installed in a machined enclosure with a titanium output shaft and waterproof connector. This architecture leverages decades of servo development in the R/C industry to provide extremely high reliability as well as almost limitless options for speed, torque, travel distance, and other features, all at a fraction of the cost of other subsea actuators.

• SER-2020: Features the Hitec HSR-M9382TH R/C servo with a PWM interface. This servo produces 3.3 Nm of torque and offers an extended travel range (up to ± 3.5 full turns of rotation with position control or continuous rotation with speed control). It uses a brushless motor and magnetic encoder, eliminating the most common causes of servo failure. Rated to 200m.
• SER-2021: same as SER-2020 but with anodized aluminum lower case, rated to 400m.

All of our servos are fully assembled and pressure-tested before shipping.

The servo output shaft is a 6-mm titanium D-shaft. Titanium Servo Hub available separately.

You will need a regular Cobalt 3-pin cable (NOT a 3-pin Power cable) or Cobalt 4-pin cable (depending on the servo model) to connect to these servos.

WARNING: These servos do not have internal protection against overheating or overvoltage. They can be damaged or destroyed by:

• driving the servo against a hard stop for more than 5-10 seconds
• running the servo at high torque continuously
• applying more than the recommended voltage to the servo

Users should design their electrical and mechanical systems to avoid these scenarios.

These servos have the following programmable features:

• Rotation: The endpoints can be adjusted to increase (or decrease) the amount of rotation available. The max achievable is +/- 3.5 turns.
• Continuous Mode: If your project requires multi-turns without position feedback, toggle to continuous rotation mode and the servo will spin in either direction at a speed proportional to the PWM pulse width.
• Speed: The speed of the servo can be adjusted. Max speed is the default, but speed can be reduced.
• Fail-Safe: This allows you to set a position that the servo will go to in the event of a signal loss between the servo controller and the servo.
• Direction: This servo, like any, is bidirectional but you can program the direction it moves when increasing (or decreasing) the PWM signal.
• Deadband Width: This setting refers to the position accuracy of the servo. The default setting is 1, which is the most precise. In some cases, such as when running multiple servos on one channel, a wider deadband is preferred so that the servos can work in unison.
• Soft Start: If you want the ramp-up from idle to max speed to be slightly lessened, you can adjust the Soft Start from 20% (default) up to 100%.

All of the above features can be accessed using the Hitec DPC-11 servo programmer. The programmer will plug into a PC using a USB to mini USB cable. It requires a 6V battery and the BLDC_HSR User interface_Ver 3.1 (see Downloads tab). You cannot program the servo using the default Ver 2.9 software that the DPC-11 ships with.

If you prefer not to program the servo yourself, we will happily program the servo per your specifications for free. Simply email sales@bluetrailengineering.com after placing your order.

FAQ

Q: What is the difference between the SER-2XXX servos and the older SER-110X and SER-120X?

A: The main differences are:

• The enclosure walls are thicker, making the unit more durable and giving an increased depth rating of 200 or 400 meters.
• The surface finish is smoother and tolerances are tighter, making the O-ring seals more reliable.
• The external surfaces are flat for easier mounting from either the side or the top.
• It uses a 6-mm "D-shaft" output shaft instead of a square shaft, making it easier to attach to your device using a simple set screw.
• There is an available kit option, made possible by an easier assembly process.

Q: What kind of fasteners are needed to mount the servo?

A: The holes in the top face of the housing are 16 mm deep and are intended to be used with #6 or M3.5 self-tapping screws like these. The screws should have between 12 and 16 mm of engagement in the plastic. The holes in the sides of the servo go all the way through the servo and are 3.2 mm in diameter, so use M3 screws longer than the width of the servo (which is 32 mm) to mount in this direction.

Q: How do I mount things to the output shaft?

A: The best way is to use our Titanium Servo Hub. Or you can use any type of 6-mm set-screw shaft coupling (including a homemade one), but be aware that the output shaft is titanium and you will get some amount of galvanic corrosion if you put a different type of metal in contact with it. You can also use a hub like these from ServoCity, but again, be sure that the materials are suitable for your application (putting aluminum in contact with titanium in seawater for an extended period of time is not a good idea).

SER-2XXX Datasheet

BLDC_HSR User interface_Ver 3.1 software for DPC-11 programmer.

Need CAD files? Please see the Resources page.