Navigate with a Rover Base

One key feature of Viam is the navigation service, the stateful definition of Viam’s motion service.

Using Navigation, you can queue up user-defined waypoints and your robot will move to them in the order that you specify. You can also add obstacles or set linear and angular velocity targets in your navigation service config. Viam’s motion planner will plan routes that avoid those obstacles and attempt to keep the robot at your specified velocity.

To try it out yourself, you need a mobile base and a movement sensor that can track the robot’s GPS coordinates and angular and linear velocity. Follow this tutorial to get started using Viam’s Navigation service to help your wheeled base navigate across space with our recommended stack.

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Requirements

A base
We used a LEO rover, configured as a wheeled base, but you can use whatever model of rover base you have on hand:
A movement sensor with GPS position, compass heading, and angular and linear velocity readings
We used three movement sensors to satisfy these requirements:
1. A SparkFun GPS-RTK-SMA Breakout movement sensor configured as a gps-nmea-rtk-serial model, providing GPS position and compass heading measurements.
2. A wheeled-odometry model gathering angular and linear velocity information from the encoders wired to our base’s motors.
3. A merged model aggregating the readings together for the navigation service to consume.
You can use any combo of movement sensors you want as long as you are getting all the types of measurements required. See the navigation service for more info on movement sensor requirements.

Tip

If you are using different hardware, the navigation setup process will be mostly the same, but you will need to substitute your robot’s components.

Before you start, make sure to create a robot in the Viam app and install viam-server on your robot.

Configure the components you need

First, configure the components of your robot.

Info

If you are using different hardware, configure them according to the instructions for each component.

Click to see how we configured our LEO rover

Config Builder
Raw JSON

Configure a board with `"digital_interrupts"`

First, configure the board local to your rover. Follow these instructions to configure your board model. We used a jetson board, but you can use any model of board you have on hand, as the resource’s API is hardware agnostic.

Configure a board named local as shown below:

Configuration of a jetson board with digital interrupts in the Viam app config builder.

Configure digital interrupts on your board to signal precise GPIO state changes to the encoders on your rover base. Copy and paste the following into your board’s Attributes to add digital interrupts on pins 31, 29, 23, and 21:

{
  "digital_interrupts": [
    {
      "name": "ra",
      "pin": "31"
    },
    {
      "pin": "29",
      "name": "rb"
    },
    {
      "pin": "23",
      "name": "lb"
    },
    {
      "name": "la",
      "pin": "21"
    }
  ]
}

Save your config.

Configure a rover base with encoded motors

Configure your rover base to act as the moving platform of the navigating robot. Start by configuring the encoders and motors of your encoded motor.

Follow these instructions to configure the left and right encoders of the wheeled base. We configured ours as incremental encoders, as shown below:

Assign the pins as the digital interrupts you configured for the board, and wire the encoders accordingly to pins numbered 31, 29, 23, and 21 on your local board. Refer to the incremental encoder documentation for attribute information.
Next, follow these instructions to configure the left and right motors of the wheeled base. We configured ours as gpio motors, as shown below:
Wire the motors accordingly to the GPIO pins numbered 35, 35, 15, 38, 40, and 33 on your local board. Refer to the gpio motor documentation for attribute information.
Finally, configure whatever rover you have as a wheeled model of base, bringing the motion produced by these motors together on one platform:
- Make sure to select each of your right and left motors as Right Motors and Left Motors and set the wheel circumference and width of each of the wheels the motors are attached to.
- Configure the frame system for this wheeled base so that the navigation service knows where it is in relation to the movement sensor.
  - Click on Add frame on the Config tab, and, if your movement sensor is mounted on top of the rover like ours is, set Orientation’s Z to 1 and Th to 90.
  - Select the world as the parent frame.
Refer to the wheeled base configuration instructions for attribute information.

Tip

Be sure to wire the board to the encoders and motors on your base matching this configuration. If you choose to wire your components differently, adjust your pin assignment configuration from these instructions according to your wiring.

In the Raw JSON mode in your robot’s Config tab, add the following JSON objects to the "components" array:

    {
      "depends_on": [],
      "model": "jetson",
      "name": "local",
      "type": "board",
      "attributes": {
        "digital_interrupts": [
          {
            "name": "ra",
            "pin": "31"
          },
          {
            "pin": "29",
            "name": "rb"
          },
          {
            "pin": "23",
            "name": "lb"
          },
          {
            "name": "la",
            "pin": "21"
          }
        ]
      }
    },
    {
      "attributes": {
        "width_mm": 350,
        "left": [
          "left-motor"
        ],
        "right": [
          "right-motor"
        ],
        "wheel_circumference_mm": 400
      },
      "depends_on": [
        "left-motor",
        "right-motor"
      ],
      "frame": {
        "translation": {
          "y": 0,
          "z": 0,
          "x": 0
        },
        "orientation": {
          "value": {
            "y": 0,
            "z": 1,
            "th": 90,
            "x": 0
          },
          "type": "ov_degrees"
        },
        "parent": "world"
      },
      "model": "wheeled",
      "name": "base",
      "type": "base"
    },
    {
      "model": "gpio",
      "name": "left-motor",
      "type": "motor",
      "attributes": {
        "ticks_per_rotation": 420,
        "board": "local",
        "max_rpm": 50,
        "pins": {
          "pwm": "33",
          "a": "38",
          "b": "40"
        },
        "encoder": "l-encoder"
      },
      "depends_on": []
    },
    {
      "model": "gpio",
      "name": "right-motor",
      "type": "motor",
      "attributes": {
        "encoder": "r-encoder",
        "ticks_per_rotation": 425,
        "max_rpm": 50,
        "pins": {
          "a": "35",
          "b": "36",
          "pwm": "15"
        },
        "board": "local"
      },
      "depends_on": []
    },
    {
      "attributes": {
        "board": "local",
        "pins": {
          "b": "lb",
          "a": "la"
        }
      },
      "depends_on": [],
      "name": "l-encoder",
      "type": "encoder",
      "model": "incremental"
    },
    {
      "model": "incremental",
      "type": "encoder",
      "namespace": "rdk",
      "attributes": {
        "board": "local",
        "pins": {
          "b": "rb",
          "a": "ra"
        }
      },
      "depends_on": [],
      "name": "r-encoder"
    }

Configure a GPS movement sensor so the robot knows where it is while navigating. We configured ours as a gps-nmea-rtk-serial movement sensor:
We named ours gps. Refer to the gps-nmea-rtk-serial movement sensor documentation for attribute information.
Configure a wheeled odometry movement sensor to provide angular and linear velocity measurements from the encoded motors on our base.
We named ours enc-linear. Refer to the wheeled-odometry movement sensor documentation for attribute information.
Now that you’ve got movement sensors which can give you GPS position and linear and angular velocity readings, configure a merged movement sensor to aggregate the readings from our other movement sensors into a singular sensor:
We named ours merged. Refer to the merged movement sensor documentation for attribute information.
- Make sure your merged movement sensor is configured to gather "position" readings from the gps movement sensor.
- Configure the frame system for this movement sensor so that the navigation service knows where it is in relation to the base. Click on Add frame on the Config tab, and, if your movement sensor is mounted on top of the rover like ours is, set Orientation’s Z to 1. Select the base as the parent frame.

In the Raw JSON mode in your robot’s Config tab, add the following JSON objects to the "components" array:

    {
      "name": "gps",
      "type": "movement_sensor",
      "attributes": {
        "ntrip_password": "yourpassword",
        "ntrip_url": "http://your.url:8082",
        "ntrip_username": "yourusername",
        "serial_baud_rate": 115200,
        "serial_path": "/dev/serial/by-id/usb-u-blox_AG_-_www.u-blox.com_u-blox_GNSS_receiver-if00",
        "ntrip_connect_attempts": 10,
        "ntrip_mountpoint": "NJI2"
      },
      "depends_on": [],
      "model": "gps-nmea-rtk-serial"
    },
    {
      "name": "merged",
      "type": "movement_sensor",
      "attributes": {
        "angular_velocity": [
          "enc-linear"
        ],
        "compass_heading": [
          "gps"
        ],
        "orientation": [
          "enc-linear"
        ],
        "position": [
          "gps"
        ]
      },
      "depends_on": [],
      "frame": {
        "orientation": {
          "value": {
            "z": 1,
            "th": 0,
            "x": 0,
            "y": 0
          },
          "type": "ov_degrees"
        },
        "parent": "base",
        "translation": {
          "y": 0,
          "z": 0,
          "x": 0
        }
      },
      "model": "merged"
    },
    {
      "model": "wheeled-odometry",
      "type": "movement_sensor",
      "namespace": "rdk",
      "attributes": {
        "base": "base",
        "left_motors": [
          "left-motor"
        ],
        "right_motors": [
          "right-motor"
        ]
      },
      "depends_on": [],
      "name": "enc-linear"
    }

Config Builder
Raw JSON

Add the navigation service so that your wheeled base can navigate between waypoints and avoid obstacles. To add the navigation service to your robot, do the following:

On your robot’s Config page, navigate to the Services tab.
At the bottom of the page, create a service. Choose Navigation as the type.
Then click Create Service.

Select Raw JSON mode. Copy and paste the following into your new service’s "attributes":

{
  "base": "base",
  "movement_sensor": "merged",
  "obstacles": [],
  "store": {
    "type": "memory"
  },
  "position_polling_frequency": 2,
  "meters_per_sec": 1.2,
  "degs_per_sec": 90,
  "plan_deviation_m": 0.25
}

Edit the attributes as applicable. Attribute information is available in the navigation service documentation.

Click Save Config at the bottom of the window.

Your navigation service should now appear in your robot’s Config tab as a card with a map like the following:

Navigation Card

For more detailed information see the navigation service.

In the Raw JSON mode in your robot’s Config tab, add the following JSON object to the "services" array:

"services": [
  {
    "name": "nav",
    "type": "navigation",
    "attributes": {
    "base": "base",
    "movement_sensor": "merged",
    "obstacles": [],
    "store": {
        "type": "memory"
    },
    "position_polling_frequency": 2,
    "meters_per_sec": 1.2,
    "degs_per_sec": 90,
    "plan_deviation_m": 0.25
    }
  }
]

Click Save Config at the bottom of the window.

Now that you have configured your navigation service, add waypoints to your navigation service. You can add waypoints from the Control tab or programmatically.

Control tab method

Go to the Control tab of your robot in the Viam app, and open the navigation card. From there, ensure that Navigation mode is selected as Manual, so your robot will not begin navigation while you add waypoints.

Add waypoints

Select Waypoints on the upper-left corner menu of the navigation card. Zoom in on your current location and click on the map to add a waypoint.

Waypoint 0 being added in the Viam app config builder on a New York City street

Add as many waypoints as you desire. Hover over a waypoint in the left-hand menu and click the trash icon to delete a waypoint.

Waypoint 1 being added in the Viam app config builder, further down the street

(Optional) Add obstacles

If you want your robot to avoid certain obstacles in its path while navigating, you can also add obstacles. Select Obstacles on the upper-left corner menu of the navigation card. Zoom in on your current location and click on the map to add an obstacle. Add as many obstacles as you desire. Hover over an obstacle in the left-hand menu and click the trash icon to delete an obstacle.

Toggle Navigation mode to Waypoint. Your rover will begin navigating between waypoints.

There should have been a video here but your browser does not seem to support it.

Programmatic method

If you want to do add waypoints programmatically, use the service’s API method AddWaypoint():

Add waypoints

Go
Python

myNav, err := navigation.FromRobot(robot, "my_nav_service")

// Create a new waypoint at the specified latitude and longitude
location = geo.NewPoint(40.76275, -73.96)

// Add your waypoint to the service's data storage
err := myNav.AddWaypoint(context.Background(), location, nil)

my_nav = NavigationClient.from_robot(robot=robot, name="my_nav_service")

# Create a new waypoint at the specified latitude and longitude
location = GeoPoint(latitude=40.76275, longitude=-73.96)

# Add your waypoint to the service's data storage
await my_nav.add_waypoint(point=location)

To start navigating, set your service to MODE_WAYPOINT with the service’s API method SetMode():

Go
Python

myNav, err := navigation.FromRobot(robot, "my_nav_service")

// Set the Mode the service is operating in to MODE_WAYPOINT and begin navigation
mode, err := myNav.SetMode(context.Background(), Mode.MODE_WAYPOINT, nil)

my_nav = NavigationClient.from_robot(robot=robot, name="my_nav_service")

# Set the Mode the service is operating in to MODE_WAYPOINT and begin
# navigation
await my_nav.set_mode(Mode.ValueType.MODE_WAYPOINT)

Next steps: automate obstacle detection

In this tutorial, you have learned how to use Navigation to navigate across waypoints. Now, you can make navigation even better with automated obstacle detection.

First, configure a depth camera that your robot can sense how far away it is from obstacles.

We configured ours as an Intel RealSense Camera, which is available as a modular resource in the Viam registry:

An example configuration for an Intel RealSense camera in the Viam app Config Builder.

Tip

You can alternatively use an ultrasonic sensor configured as a camera. Attribute information for an ultrasonic camera is the same as for a sensor.

If you want the robot to be able to automatically detect obstacles in front of it, configure a Vision service segmenter. For example, configure the Vision service model obstacles_depth to detect obstacles in front of the robot. Then, use one of Viam’s client SDKs to automate obstacle avoidance with the navigation service like in the following Python program:

Click to view full example of automated obstacle avoidance with the Python SDK

import asyncio
import time
from viam.robot.client import RobotClient
from viam.rpc.dial import Credentials, DialOptions
from viam.components.base import Base
from viam.services.vision import VisionClient
from viam.proto.common import GeoPoint
from viam.services.navigation import NavigationClient

MANUAL_MODE = 1
DRIVE_MODE = 2
SECONDS_TO_RUN = 60 * 15


async def connect():
    opts = RobotClient.Options.with_api_key(
        # Replace "<API-KEY>" (including brackets) with your robot's api key
        api_key='<API-KEY>',
        # Replace "<API-KEY-ID>" (including brackets) with your robot's api key
        # id
        api_key_id='<API-KEY-ID>'
    )
    return await RobotClient.at_address('<INSERT REMOTE ADDRESS>', opts)


async def nav_avoid_obstacles(
    base: Base,
    nav_service: NavigationClient,
    obstacle_detection_service: VisionClient
):
    while True:
        obstacle = await obstacle_detection_service.get_object_point_clouds(
          "myRealSense"
        )
        print("obstacle: ", obstacle)
        z = obstacle[0].geometries.geometries[0].center.z
        print(z)
        r = await nav_service.get_mode()
        if z < 1000:
            if r != MANUAL_MODE:
                await nav_service.set_mode(MANUAL_MODE)
        else:
            if r != DRIVE_MODE:
                await nav_service.set_mode(DRIVE_MODE)


async def main():
    robot = await connect()

    # Get base component and services from the robot
    base = Base.from_robot(robot, "base")
    obstacle_detection_service = VisionClient.from_robot(robot, "myObsDepth")
    nav_service = NavigationClient.from_robot(robot, "nav")

    # Get waypoints and add a new waypoint
    waypoints = await nav_service.get_waypoints()
    assert (len(waypoints) == 0)
    await nav_service.add_waypoint(GeoPoint(latitude=0.00006, longitude=0))

    # Get waypoints again, check to see that one has been added
    waypoints = await nav_service.get_waypoints()
    assert (len(waypoints) == 1)

    # Avoid obstacles
    await nav_avoid_obstacles(base, nav_service, obstacle_detection_service)

if __name__ == '__main__':
    asyncio.run(main())

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Navigate with a Rover Base

Requirements

Tip

Configure the components you need

Info

Configure a board with `"digital_interrupts"`

Configure a rover base with encoded motors

Tip

Configure movement sensors

Configure a Navigation service

Start navigating with the Navigation service

Control tab method

Add waypoints

(Optional) Add obstacles

Begin navigation

Programmatic method

Add waypoints

Begin navigation

Next steps: automate obstacle detection

Tip

Navigate with a Rover Base

Requirements

Tip

Configure the components you need

Info

Configure a board with "digital_interrupts"

Configure a rover base with encoded motors

Tip

Configure movement sensors

Configure a Navigation service

Start navigating with the Navigation service

Control tab method

Add waypoints

(Optional) Add obstacles

Begin navigation

Programmatic method

Add waypoints

Begin navigation

Next steps: automate obstacle detection

Tip

Configure a board with `"digital_interrupts"`