Control components

Read sensor data and send commands to motors, arms, grippers, and other actuators from your app. Each component type has its own SDK client with methods specific to that type. This page shows the pattern for getting a component client and calling its methods.

For the full list of component types and their methods, see the SDK reference for your language: TypeScript, Python, Flutter, Go, or C++.

Prerequisites

• A project with an active machine connection (see Connect to a machine)
• At least one component configured on the machine (sensor, motor, camera, arm, or any other type). If you do not have physical hardware, add a fake component in the Viam app’s CONFIGURE tab (fake:sensor, fake:motor, and so on).

Get a component client

Every component type follows the same pattern: you get a typed client from the connected machine by name, then call methods on that client.

import * as VIAM from "@viamrobotics/sdk";

const sensor = new VIAM.SensorClient(machine, "my_sensor");
const motor = new VIAM.MotorClient(machine, "my_motor");

import 'package:viam_sdk/viam_sdk.dart';

final sensor = Sensor.fromRobot(robot, 'my_sensor');
final motor = Motor.fromRobot(robot, 'my_motor');

from viam.components.sensor import Sensor
from viam.components.motor import Motor

sensor = Sensor.from_robot(robot=machine, name="my_sensor")
motor = Motor.from_robot(robot=machine, name="my_motor")

import (
    "go.viam.com/rdk/components/sensor"
    "go.viam.com/rdk/components/motor"
)

mySensor, err := sensor.FromProvider(machine, "my_sensor")
if err != nil {
    logger.Fatal(err)
}

myMotor, err := motor.FromProvider(machine, "my_motor")
if err != nil {
    logger.Fatal(err)
}

The string "my_sensor" or "my_motor" is the name you gave the component in your machine configuration. If you named it something different, change the string to match.

Read from a sensor

const readings = await sensor.getReadings();
console.log(readings);
// Example output: { temperature: 22.5, humidity: 45.2 }

final readings = await sensor.readings();
print(readings);
// Example output: {temperature: 22.5, humidity: 45.2}

readings = await sensor.get_readings()
print(readings)
# Example output: {'temperature': 22.5, 'humidity': 45.2}

readings, err := mySensor.Readings(context.Background(), nil)
if err != nil {
    logger.Fatal(err)
}
fmt.Println(readings)
// Example output: map[temperature:22.5 humidity:45.2]

The readings map contains whatever key-value pairs the sensor returns. The keys and types depend on the sensor model. For fake:sensor, the readings are generated test values.

Control a motor

// Set power (range: -1 to 1)
await motor.setPower(0.5);

// Stop
await motor.stop();

// Check if moving
const moving = await motor.isMoving();
console.log(`Motor is moving: ${moving}`);

// Set power (range: -1 to 1)
await motor.setPower(0.5);

// Stop
await motor.stop();

// Check if moving
final moving = await motor.isMoving();
print('Motor is moving: $moving');

# Set power (range: -1 to 1)
await motor.set_power(power=0.5)

# Stop
await motor.stop()

# Check if moving
moving = await motor.is_moving()
print(f"Motor is moving: {moving}")

// Set power (range: -1 to 1)
err = myMotor.SetPower(context.Background(), 0.5, nil)
if err != nil {
    logger.Fatal(err)
}

// Stop
err = myMotor.Stop(context.Background(), nil)
if err != nil {
    logger.Fatal(err)
}

// Check if moving
moving, err := myMotor.IsMoving(context.Background())
if err != nil {
    logger.Fatal(err)
}
fmt.Printf("Motor is moving: %v\n", moving)

setPower takes a value from -1 (full reverse) to 1 (full forward). 0 is stopped. For fake:motor, the state changes are tracked internally but nothing physical moves. You can verify the state change by opening the Viam app’s CONTROL tab for the same machine.

Other component types

The pattern is the same for every component type. Get a typed client by name, then call that type’s methods:

The method names follow the same naming convention in each language: Python uses snake_case, Go uses CamelCase, TypeScript uses camelCase, Flutter uses camelCase. See your SDK’s reference for the exact signatures.

Next

• Stream video for displaying camera feeds (TypeScript and Flutter WebRTC streaming, or get_images polling for Python and Go)
• Handle disconnection and reconnection for reconnection behavior when controlling actuators
• Connect to a machine if you have not set up a connection yet