Servo Component

The servo component supports “RC” or “hobby” servo motors. These are small motors with built-in potentiometer position sensors, enabling you to control the angular position of the servo precisely.

As servos can use a lot of power, drawing voltage away from a board, you should power your servo with its own power supply in most cases. The following shows an example wiring diagram for a hobby servo wired to a pi board:

The colors of the servo wires in this diagram may not match your servo. Refer to your servo’s data sheet for wiring specifications.

Most robots with a servo need at least the following hardware:

• A board component that can run viam-server
• A servo
• A power supply for the board
• A power supply for the servo

Related Services

Frame System

Data Management

Supported Models

To use your servo with Viam, check whether one of the following built-in models supports your servo.

Built-in models

For configuration information, click on the model name:

If none of these models fit your use case, you can create a modular resource to add support for it.

Control your servo with Viam’s client SDK libraries

To get started using Viam’s SDKs to connect to and control your robot, go to your robot’s page on the Viam app, navigate to the Code sample tab, select your preferred programming language, and copy the sample code generated.

When executed, this sample code will create a connection to your robot as a client. Then control your robot programmatically by adding API method calls as shown in the following examples.

These examples assume you have a servo called "my_servo" configured as a component of your robot. If your servo has a different name, change the name in the code.

Be sure to import the servo package for the SDK you are using:

from viam.components.servo import Servo

import (
  "go.viam.com/rdk/components/servo"
)

API

The servo component supports the following methods:

Move

Move the servo to the desired angle in degrees.

my_servo = Servo.from_robot(robot=robot, name="my_servo")

# Move the servo from its origin to the desired angle of 10 degrees.
await my_servo.move(10)

# Move the servo from its origin to the desired angle of 90 degrees.
await my_servo.move(90)

myServo, err := servo.FromRobot(robot, "my_servo")

// Move the servo from its origin to the desired angle of 10 degrees.
myServo.Move(context.Background(), 10, nil)

// Move the servo from its origin to the desired angle of 90 degrees.
myServo.Move(context.Background(), 90, nil)

GetPosition

Get the current set angle of the servo in degrees.

my_servo = Servo.from_robot(robot=robot, name="my_servo")

# Move the servo from its origin to the desired angle of 10 degrees.
await my_servo.move(10)

# Get the current set angle of the servo.
pos1 = await my_servo.get_position()

# Move the servo from its origin to the desired angle of 20 degrees.
await my_servo.move(20)

# Get the current set angle of the servo.
pos2 = await my_servo.get_position()

myServo, err := servo.FromRobot(robot, "my_servo")

// Move the servo from its origin to the desired angle of 10 degrees.
myServo.Move(context.Background(), 10, nil)

// Get the current set angle of the servo.
pos1, err = myServo.Position(context.Background(), nil)

// Move the servo from its origin to the desired angle of 20 degrees.
myServo.Move(context.Background(), 20, nil)

// Get the current set angle of the servo.
pos2, err = myServo.Position(context.Background(), nil)

Stop

Stop the servo from moving.

my_servo = Servo.from_robot(robot=robot, name="my_servo")

# Move the servo from its origin to the desired angle of 10 degrees.
await my_servo.move(10)

# Stop the servo. It is assumed that the servo stops moving immediately.
await my_servo.stop()

myServo, err := servo.FromRobot(robot, "my_servo")

// Move the servo from its origin to the desired angle of 10 degrees.
myServo.Move(context.Background(), 10, nil)

// Stop the servo. It is assumed that the servo stops moving immediately.
myServo.Stop(context.Background(), nil)

GetGeometries

Get all the geometries associated with the servo in its current configuration, in the frame of the servo. The motion and navigation services use the relative position of inherent geometries to configured geometries representing obstacles for collision detection and obstacle avoidance while motion planning.

my_servo = Servo.from_robot(robot=robot, name="my_servo")

geometries = await my_servo.get_geometries()

if geometries:
    # Get the center of the first geometry
    print(f"Pose of the first geometry's centerpoint: {geometries[0].center}")

DoCommand

Execute model-specific commands that are not otherwise defined by the component API. For built-in models, model-specific commands are covered with each model’s documentation. If you are implementing your own servo and add features that have no built-in API method, you can access them with DoCommand.

my_servo = Servo.from_robot(robot, "my_servo")

command = {"cmd": "test", "data1": 500}
result = my_servo.do(command)

myServo, err := servo.FromRobot(robot, "my_servo")

command := map[string]interface{}{"cmd": "test", "data1": 500}
result, err := myServo.DoCommand(context.Background(), command)

Close

Safely shut down the resource and prevent further use.

my_servo = Servo.from_robot(robot, "my_servo")

await my_servo.close()

myServo, err := servo.FromRobot(robot, "my_servo")

err := myServo.Close(ctx)

Troubleshooting

You can find additional assistance in the Troubleshooting section.

You can also ask questions in the Community Discord and we will be happy to help.

Next Steps

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