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Navigation State Machine Library

After using Smach as the library for defining and running our navigation state machine last year, a number of issues with smach motivated the ideation and implementation of a new state machine library built specifically to address Smach’s shortcomings with a focus on reducing potential runtime errors and cleaning up cluttered code.

Problems in Smach

Section titled “Problems in Smach”

Separation of transitions and states

Section titled “Separation of transitions and states”

Representation of transitions and states with strings

Section titled “Representation of transitions and states with strings”

Persistent State Objects

Section titled “Persistent State Objects”

No direct control over entry and exit behavior

Section titled “No direct control over entry and exit behavior”

Feature bloat

Section titled “Feature bloat”

Key Design Points of the new library

Section titled “Key Design Points of the new library”

States return the next state as an object (no strings)

Section titled “States return the next state as an object (no strings)”

States are not persistent

Section titled “States are not persistent”

onEnter(), onLoop(), onExit() interface

Section titled “onEnter(), onLoop(), onExit() interface”

How it works

Section titled “How it works”

How to use it

Section titled “How to use it”

Create a State

Section titled “Create a State”

Create a State Machine

Section titled “Create a State Machine”

Run the State Machine

Section titled “Run the State Machine”

Introspection Messages

Section titled “Introspection Messages”

Log Level

Section titled “Log Level”