Payload Software Interface

To log payload data and debug payload issues, payloads developed for the Spot platform should observe the following guidelines:

  • Payloads gather and generate their own log data.

  • Payloads generate and send their own text annotations to mark robot logs for preservation.

  • Each payload component provides access to its own debug data.

  • Logic on the payload determines what data to log and when to log it.

Payload API services

The API provides two services for managing and registering payloads and payload services:

  • PayloadService

  • PayloadRegistrationService

Robot directory services are used to register services that a payload might offer so that they can be exposed on the robot.

  • DirectoryService

  • DirectoryRegistrationService

Service and Payload Faults

The Fault Service enables external clients to raise service faults, which can be read by external clients via the robot state and are automatically displayed in the tablet. Service faults are a type of fault that can originate from both on the robot and external clients. Each service fault is associated with a service, a payload, or both.

Service faults enable services and payloads to easily display information about current systems health to operators. The faults should assist operators in effective debugging and resolution of any off-robot issues that arise during operation.

The Fault documentation provides more context on the different types of faults that may be used with Spot.

DirectoryService RPCs

RPC Description
GetServiceEntry Get information about a specific service.
ListServiceEntries List all known services at the time of the request.

DirectoryRegistrationService RPCs

RPC Description
RegisterService Called by a system to announce, via the robot directory, a new service it is hosting.
UnregisterService Called by a system to deregister a service from the robot directory.
UpdateService Update the ServiceEntry for a system hosting a service.

PayloadService RPCs

RPC Description
ListPayloads Query the robot for a list of currently-registered payloads.

PayloadRegistrationService RPCs

RPC Description
RegisterPayload Register a new payload with the robot.
GetPayloadAuthToken Get an auth token to enable the payload.

Registering payloads

This code snippet example uses the API to communicate payload configuration settings to Spot. The example first registers a payload then lists all payloads on the robot, including the newly registered payload.

...
# Authenticate robot before being able to use it
robot.authenticate(config.username, config.password)

# Create a payload registration client
payload_registration_client = robot.ensure_client(
PayloadRegistrationClient.default_service_name)

# Create a payload
payload = payload_protos.Payload()
payload.GUID = '78b076a2-b4ba-491d-a099-738928c4410c'
payload.name = 'Client Registered Payload Ex'
payload.description = 'This payload was created and registered by the register_payload.py client example.'
payload.label_prefix.append("test_payload")
payload.is_authorized = False
payload.is_enabled = False
payload.is_noncompute_payload = False

# Register the payload
payload_registration_client.register_payload(payload)

# Create a payload client
payload_client = robot.ensure_client(PayloadClient.default_service_name)

# List all payloads
payloads = payload_client.list_payloads()
print(payloads)
...

Refer to the Python payload registration code example in the Spot SDK for details.

Payload self-registration

The Payload Registration API gives developers the ability to deploy payloads that register themselves with the robot when they power on without the need to store user credentials on the payload.

The payload registration process completes after an admin operator accepts the payload using the robot’s admin console. If the payload has registered itself, it should appear in the Payload section of the admin console.

  • Payloads can register API services. Example: A LIDAR payload registers RemoteService callbacks to trigger scans during robot missions.

  • Payload and service registration do not require robot user credentials.

Once a payload has been authorized, its unique GUID and secret combination can be used as credentials to request a limited-access user token that will grant permission to the auth, directory, robot-state, and directory-registration services. The granted user token will be valid for 12 hours.

Registration examples

The Spot SDK Python code examples includes payload registration and service registration examples that provide sample scripts, protos, and a list of dependencies: Self-registration Python code examples in the Spot SDK.

Configuring and authorizing payloads

A payload, like any software client, can access the API by using login credentials. However, for self-registration, payloads can complete basic registration and get access to host services without needing to pass hardcoded user credentials.

Instead, a payload is manually authorized by an operator on the admin console Payloads page. To ensure that the payload authorization is not used by malicious payloads, each payload must provide a unique GUID and secret (password) at registration time. The GUID and secret can then be used to request a user token that grants access to the basic components of the API (directory, directory registration, robot-state).

Payload device network configuration

The robot’s default private IP address is 192.168.80.3. Users can configure these properties via the robot’s admin console. Use the network settings to change the robot’s network configuration from WiFi AP to WiFi client.

The robot’s rear ethernet port can be configured to a user desired IP address via the web interface. By default, its IP is set to 10.0.0.3.

Payload devices should use the following network configuration:

  • IP v4 host address 192.168.50.5 or 192.168.50.6 for either front or rear payload port

  • Do not use the same IP address for both front and rear payload port

  • Netmask 255.255.255.0

  • Default gateway gateway will be set to 192.168.50.3

Devices on the payload network can reach the robot at 192.168.50.3 via port 443. Devices on the robot network can reach payload services as follows:

  1. TCP traffic sent to the robot’s IP address on ports 20022, 20080, or 20443 will be forwarded to 192.168.50.5 on ports 22, 80, or 443.

  2. TCP/UDP traffic sent to the robot’s IP address on ports 21000-22000 will be forwarded to 192.168.50.5 on that same port.

  3. TCP traffic sent to the robot’s IP address on ports 30022, 30080, or 30443 will be forwarded to 192.168.50.6 on ports 22, 80, or 443.

  4. TCP/UDP traffic sent to the robot on ports 31000-32000 will be forwarded to 192.168.50.6.

Payload port forwarding table

Description Robot port Target Protocol
Standard Forwards 1 20000 + [22, 80, 443] 192.168.50.5:[22, 80, 443] TCP
Fixed Forwards 1 21000-22000 192.158.50.5:21000-22000 TCP/UDP
Standard Forwards 2 30000 + [22, 80, 443] 192.168.50.6:[22, 80, 443] TCP
Fixed Forwards 2 31000-32000 192.158.50.6:31000-32000 TCP/UDP

Robot port forwards for ports 20443, 20022, 30443, and 30022 now masquerade. They should allow the payload to respond to forwarded traffic to the robot on any of the robot’s ports.

All other forwarded ports are purely port forwarded, meaning that packets received by the payload still have the original address of the sender. These port forwards will only connect for hosts on one of the LANs attached to the robot OR for hosts located on the default route as configured in the robot network page.

Configuring payload mass properties

In order to locomote properly, the robot needs to know the physical properties of any payload it is carrying. This includes the center of mass location relative to the base link of the robot, moments of inertia, and other values.

A payload self-registration service is available as part of the Spot 2.0 SDK.

The following payload configuration table shows configuration values for the Spot CORE payload as they would appear in the robot’s admin console GUI.

This table provides a reference when developing a client application using the the RegisterPayload RPC to register a Spot payload.

Position (m)

Item Value Units
X -0.16 m
Y 0 m
Z 0 m

Orientation (radians)

Item Value Units
Yaw 0 rad.
Roll 0 rad.
Pitch 0 rad.

Total mass (kg)

Item Value Units
  2.0 kg

Position of Center of Mass (m)

Item Value Units
X -0.13 m
Y 0 m
Z 0.045 m

Moment of inertia tensor (kg-m2)

Item Value Units
XX 0.00675 kg-m2
XY 0 kg-m2
XZ 0 kg-m2
YY 0.0126167 kg-m2
YZ 0 kg-m2
ZZ 0.0166667 kg-m2

Bounding boxes: Center (m)

Item Value Units
X -0.13m m
Y 0 m
Z 0.045 m

Bounding boxes: Orientation (radians) ZXY

Item Value Units
Yaw 0 rad.
Roll 0 rad.
Pitch 0 rad.

Bounding boxes: XYZ extent (m)

Item Value Units
X 0.13 m
Y 0.095 m
Z 0.045 m

The payload.proto file in the Spot SDK provides details about fields and data types.