|
The ArMem memory system is distributed: It consists of several memory servers storing data in a hierarchical structure. A memory server can be defined in any ArmarX package and defines which kind of data it stores (e.g. robot state, object classes and instances, visual data, speech, ...). As a memory server knows which data it stores, it can provide special behaviour, such as custom visualization, aggregation, interpolation or prediction. As each server is a separate component describing its own structure, it is simple to add new memory servers containing special data types, which are defined in ArmarX packages further down in the dependency chain.
All memory servers follow the same hierarchical data structure and self-describing data format. The data structure consists of several levels, storing histories/timelines of different entities stored in different segments (see "Memory Levels" below). The common data format is ArmarX Object Notation (ARON) / Interpretable Data Format (IDF), which is a self-describing, hierarchical data format, allowing extensive introspection as well as general storage. Each item in the memory (i.e. entries in all levels) can be identified with a Memory ID, which contains the keys of each (specified) level. For example, a core segment ID specifies the memory name and core segment name, while an entity instance ID specifies the whole path to the leaf of the data structure.
Technically, each memory server is one ArmarX component implementing the armarx::armem::server::MemoryInterface
(comprising a armarx::armem::server::ReadingMemoryInterface
and a armarx::armem::server::WritingMemoryInterface
). Memory servers register themselves in the Memory Name System (MNS), where they can be found by their (semantic) memory name (which is usually a short, human-readable name such as "Robot", "Object" or "Vision"). Memory servers receive data via commits (via the armarx::armem::server::WritingMemoryInterface
), and return data according to queries (via the armarx::armem::server::ReadingMemoryInterface
).
A memory server stores data in a hierarchical structure consisting of several levels:
Level | Key | Description | Examples | Implementation |
---|---|---|---|---|
Memory | Name (String) | Semantic grouping of one or more core segments. Corresponds to one memory server. | Robot, Object, Vision | armarx::armem::wm::Memory |
Core Segment | Name (String) | Building block of a memory containing homogeneous data of a specific (ARON) type. Specifies a Core Segment Type which all provided data must comply to. | (Robot) Proprioception, (Object) Classes, Known (Object) Instances, ImageRGB | armarx::armem::wm::CoreSegment |
Provider Segment | Name (String) | Sub-segment of a core segment which contains the data from a single source (e.g. a camera, a method, a component). Can define a Provider Segment Type which extends the Core Segment Type. | Primesense, MyObjectLocalizer, MyGraspPlanner | armarx::armem::wm::ProviderSegment |
Entity | Name (String) | A single thing or concept whose properties change over time. An entity has a history / timeline, i.e. a sequence of snapshots storing the entity's properties at a specific point in time. | image , some_object , some_object_grasps | armarx::armem::wm::Entity |
Entity Snapshot | Timestamp (armarx::armem::Time aka armarx::DateTime ) | An entry of an entity's history, i.e. the state of an entity at a specific point in time. Can contain multiple (entitiy) instances. | Image, object instance, grasp hypotheses at a time t | armarx::armem::wm::EntitySnapshot |
Entity Instance | Index (int) | One instance of the segment's ARON type. | left/right stereo image (at time t), object (at time t), grasp hypothesis (one of many at time t) | armarx::armem::wm::EntityInstance |
Entity Instance Metadata | – | Metadata stored alongside the instance's data. | Further timesteps, confidence | armarx::armem::wm::EntityInstanceMetadata |
This is a list of existing memory servers, their core segments and their ARON data types.
RobotStateMemory
(RobotAPI)Core Segment Name | Type | Description | Example Entities |
---|---|---|---|
Description | RobotDescription | Robot description (e.g. link to XML or URDF file) | Description of ARMAR-6 |
Proprioception | Proprioception | Robot configuration and internal sensor values. | Proprioception of ARMAR-6 |
Localization | Transform | Transformations between frames {world,map,robot} to retrieve global robot pose. | Transfrom from robot root frame to map frame |
Missing:
Description
core segmentObjectMemory
(RobotAPI)Core Segment Name | Type | Description | Example Entities |
---|---|---|---|
Class | ObjectClass | Static description of a known object class. Entity names are (ArmarXObjects) object IDs. | KIT/CoffeeFilters , YCB/001_chips_can |
Instance | ObjectInstance | Localized object instance. Entity names are (ArmarXObjects) object IDs. | KIT/CoffeeFilters , YCB/001_chips_can/instance_1 |
Attachments | ObjectAttachment and ArticulatedObjectAttachment |
ArMemVisionMemory
(VisionX)Core Segment Name | Type | Description | Example Entities |
---|---|---|---|
ImageRGB | ImageRGB | RGB images (mono and stereo) of a camera | image |
ImageDepth | ImageDepth | Depth images of an RGB-D or stereo camera | image |
SpeechMemory
(SpeechX)Core Segment Name | Type | Description | Example Entities |
---|---|---|---|
Command | SpeechCommand | Language commands from speech (topic Speech_Commands ). | command |
TextListenerInterface | Text | Data from TextListenerInterface topics. (TextToSpeech , RobotAction ) | text |
...
SkillsMemory
(RobotAPI)Core Segment Name | Type | Description | Example Entities |
---|---|---|---|
Statechart | Transition | Transitions in ArmarX state charts. | tbd |
An example memory server (alongside a matching client) showing how to implement a standard memory server and test the framework during development.
ExampleMemory
(RobotAPI)Core Segment Name | Type | Description | Example Entities |
---|---|---|---|
ExampleData | ExampleData | Some example data. | example |
This memory is meant to allow for a quick-and-dirty integration of your data type in the memory framework. When your development finishes a stable state, consider creating moving the core segment(s) to an existing memory server or creating a new dedicated memory server.
GeneralPurposeMemory
(RobotAPI)Core Segment Name | Type | Description | Example Entities |
---|---|---|---|
None. You can add segments on the fly. |