intravehicular communication - uavcan · 2019. 6. 25. · iot, general robotics, industrial...

Intravehicular communication

IoT,general robotics, industrial automation

Constrained, cheap toverify & validate

Flexible, hard toverify & validate

High-level,abstract

Low-level,high coupling

Legacy Non-viable options

Modernsoftware-defined

vehicles




High-level,abstract

Low-level,high couplingRC PWM...

DDS

Legacy Non-viable options


vehicles




High-level,abstract


CANopen,CANaerospace

MQTT

Legacy

ARINC 429

Non-viable options


vehicles

DDS


vehicles




High-level,abstract



MQTT

Legacy

ARINC 429

Non-viable options

AFDX

DDS


vehicles




High-level,abstract



MQTT

Legacy

ARINC 429

TCPI2C

Non-viable options

AFDX

DDS



vehiclesConstrained, cheap toverify & validate


High-level,abstract


AFDX


UAVCAN MQTT

Legacy

ARINC 429

TCPI2C

Non-viable options

DDS

Core design goals● Real-time● Viable for safety-critical systems● Low memory footprint● Low overhead● Simple

Real-time● Deterministic transport● Constant-complexity algorithms● Bounded data structures

High latency, worseLow latency, better

UAVCAN over C

AN FD

DShot15

0

UAVCAN over C

AN 2.0

Onesh

ot125

Multish

ot, O

nesh

ot42,

DShot60

0, etc

.

RC PW

M

(terrib

le)

ca. 150 𝜇sca. 100 𝜇s ca. 1500 𝜇s

Real-time

Safety-critical● Fully decentralized, democratic● No shared state● Power-up-and-go● Redundant transports● About 1000 SLoC (libcanard)

Safety-criticalDesign trade-offs:

● Robust transport assumed● Static architecture● No arbitrary-size data objects: uint8[<=256] data

NXP LPC11C24ARM Cortex M050 MHz8K RAM32K ROMno RTOS

Low memory footprint

STM32F302ARM Cortex M4F72 MHz16K RAM64K ROMno RTOS


Protocol RAM ROMUAVCAN 8 K 32 KCANaerospace 4 K 8 K

DDS/XRCE 32 K 250 K

DDS/RTPS 100 K ≫250 K


Simple● Complexity comparable to CANaerospace● Detailed specification under 80 pages + standard data types● About 1 man/month to implement from scratch (excl. DSDL)● Robust reference implementations in C, C++, Python, Rust (WIP)

Simple

SimpleFamiliar communication abstractions:

● Stateless publish-subscribe● Simple request-response (RPC)● Very low semantic overhead

Brief history of UAVCAN

Micro-satellitesUAV Manned

aircraftRobotic systems Light EV

Common high-level communication requirements

CAN 2.0 CAN FD Ethernet IEEE 802.15.4

Other transports

Scope ofUAVCAN v0





Other transports

Scope of UAVCAN v1

MY STANDARD DATA TYPES





Other transports

Scope of UAVCAN v1

Dronecodeprofile

Integrating UAVCAN

Open● MIT licensed● Github hosted reference implementations● Open specification (no membership required)

Useful● Tools● Documentation● Reference Implementations● Communication● Validation Suites

Forward Looking● Not encumbered with legacy and bloat● Designed with new technology in mind● Lowers the chance of getting locked-in to a bus technology

DSDL in Practice● Enables good system design by defining interfaces between sub-systems● Similar to ROS, sub-systems are decoupled and can be developed in parallel● Versioning allows a vehicle system to evolve over time● As an IDL it avoids technology lock-in● Certifiable generators could be produced

Core Application Functions● Heartbeat/status● GetInfo● Diagnostics, data flow, registers● Plug-and-play● Node software update and ExecuteCommand

What changed?

WHAT DID I DO?!?

(When you realize you need to change the dsdl type you just manufactured into to 3 million devices)

WHAT DID I DO?!?

https://forum.uavcan.org/t/simpler-and-better-dsdl-versioning/280

Kjetil Kjeka

https://forum.uavcan.org/t/simpler-and-better-dsdl-versioning/280

Migration to UAVCAN v1

UAVCAN v1 reference implementations

Implementation Language Transports Status

Libcanard C99 CAN (FD) Usable

PyUAVCAN Python CAN (FD), UDP/IP, serial, … Usable

Libuavcan C++11 CAN (FD) ETA Aug 2019

uavcan.rs Rust CAN (FD) TBA

v1v0 discussion & feedback transition

Migration proposal

Vendo

rs no

tified

of

impe

nding

brea

kage

The P

X4 midd

leware

migrate

d to v

1 (bre

aking

)

Now PX4 v1.11March 2020

EOL ofPX4 v1.10

EOL of th

e las

t PX4

supp

orting

v0

Migration proposalHR resources secured

How do I build stuff with UAVCAN v1?

https://new.uavcan.org

Future of UAVCAN

Remaining Work● Finish the reference implementations● Finish the new tools (Yukon)● Define and deploy a type management process● Lowering the entry barrier

Broad strokes● New transports: UDP/IP, serial, wireless● Lowering the entry barrier● Maintaining the high software quality standards● Deploy in two vehicle systems● Formal standardization

Project Health● Higher (lower?) bus factor is needed● More representation is needed by vendors and manufacturers● A PX4 integration expert/maintainer is needed

Conclusion● UAVCAN v1 is the recommended choice for new projects● Legacy systems based on UAVCAN v0 will be supported until 2021 at least● Ongoing research on heterogeneous UDP, serial, and wireless transports

https://forum.uavcan.org/t/alternative-transport-protocols/324

Resources● Dev call every Wednesday 18:00 UTC; see bit.ly/2MVdPBx● Forum: https://forum.uavcan.org● Specification: https://new.uavcan.org (soon to be https://uavcan.org)● Github: https://github.com/UAVCAN

○ Python: https://github.com/UAVCAN/pyuavcan/tree/uavcan-v1.0 ○ C: https://github.com/UAVCAN/libcanard/tree/uavcan-v1.0 ○ C++: https://github.com/UAVCAN/libuavcan/tree/uavcan-v1.0○ Stand-alone DSDL to code generator: https://github.com/UAVCAN/nunavut

https://bit.ly/2MVdPBx

https://forum.uavcan.org/

https://new.uavcan.org/

https://uavcan.org

https://github.com/UAVCAN

https://github.com/UAVCAN/pyuavcan/tree/uavcan-v1.0

https://github.com/UAVCAN/libcanard/tree/uavcan-v1.0

https://github.com/UAVCAN/libuavcan/tree/uavcan-v1.0

https://github.com/UAVCAN/nunavut

UncomplicatedApplication-levelVehicularCommunicationAndNetworking

Intravehicular communication

intravehicular communication - uavcan · 2019. 6. 25. · iot, general robotics, industrial...

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