inFuse

h1. 03/09 : PoM/Prism Discussion

*Participants :* 

Simon, Ellon, Quentin, Pierre

*Goal of the meeting :* Discuss the PoM/Prism architecture (previously InSitu). Prism is the sub-task of PoM which handle the internal transform tree of a robot (RobotBaseFrame to SensorFrame(s)).

*Note :* PoM is divided in two part : Prism which handles the pose of sensors relative to the robot and (name undefined, default = MightyLocalizer) MightyLocalizer which handles the pose of the robot frame relative to the World Frame. The meeting is only about Prism.

h2. Features of Prism

* *Load and maintain the RobotBaseFrame to SensorFrame(s) tree of the robot up to date :* URDF configuration file for initialization. Is a client of moving sensor mounts (arms, platforms...) to update internal transform tree. No memory. Handles transform uncertainty.

* *Sensor pose service :* A sensor acquiring data must ask Prism for a time stamp and a sensor pose(= current transform RobotBaseFrame to SensorFrame + uncertainty). The pose and the time are stored by the sensor node alongside the sensor data (this pose will be of use only with this data. Hence no memory is need in Prism).

* *Send time stamp to mighty-localizer for saving*

h2. Details

h3. Loading and maintaining internal tree

* *Internal Tree :* all SensorFrames connected to a single RobotBaseFrame through one or several edges. Two types of edges : fixed or moving.

(insert diagram)

* *Initialization :* Internal tree building form URDF file. Default values for moving edges to define ?

* *Maintaining the tree :* Prism receives poses form all moving sensor mounts. Movable edges in the internal tree are updated right away (no memory). To define : communication between joints and Prism (identification of joints etc...).

h3. Sensor pose service

Acquired sensor data has be associated with a pose of the sensor and a time stamp.

* *Pose of the sensor relative to the world :* Divided into two parts

(insert diagram)

The SensorFrame to RobotBaseFrame transform (furnished by Prism) is measured at the time of the acquisition and will NOT be modified later. Hence, no memory is needed in Prism and the SensorFrame to RobotFrame transform is recorded alongside the data outside of Prism. (the RobotBaseFrame to WorldFrame recorded at the time of acquisition will however be modified later by MightyLocalizer).

* *Workflow :*

* * 1) Data acquisition by sensor