Only released in EOL distros:
Package Summary
appl
- Author: petercai
- License: BSD
- Source: git https://github.com/petercaiyoyo/appl.git (branch: master)
Overview
APPL is a C implementation of the SARSOP algorithm for solving discrete POMDPs. Details of this algorithm can be found at appl homepage. This package is a C ROS wrapper of the appl software。The package works as a ROS server to give feedback to the ROS client about the current optimal action according to the generated POMDP policy. In this way the ROS user can develop independently instead of compiling together with the APPL code and also can avoid potential library conflicts between them.
Before compiling the node
In this simple guide, we assume you have background knowledge of POMDP planning.
1. At the very first stage, you need to write a POMDPX model description file. Information can be found at the above website.
2. After you have the POMDPX file, you need to solve it with APPL to generate the corresponding PolicyX file. The basic way of doing it is to go to ~/appl/src folder and type: ./pomdpsol ../examples/POMDPX/Tiger.pomdpx (we have an example pomdpx file in the above indicated position). The generated policy is written to out.policy by default. The pomdpsol executable has already been compiled and placed in the src folder. You don't need to recompile again.
3. After you have the PolicyX file, you can use rosmake to compile the node.
Node
Service
appl_request
- Call this service to send the observation and get the action
Parameters
~appl_problem_name(string)
- the position of the PomdpX file
~appl_policy_name(string)
- the position of the PolicyX file
Service Description
A typical POMDP control cycle is : robot executes an action and receives an observation. Here the robot controller needs to send the received observation the service node to get the feedback action. The message format is:
int64 cmd --> command type string obs --> observation string xstate -->fully observable states --- int64 action -->the action you should execute given by the service node
1. cmd=0 test command.
2.cmd=1 initialization. You need to specify the initial fully observable states in xstate(if you have) you are in
3. cmd=2 actual communication. You need to specify the obs and xstate(if you have).
For obs , if there's only one observable variable, you just copy the enumerable value of the variable as specified in the PomdpX file. If there are more than one variable, you need to first concatenate those values together in the ascending order of the variable names.
The rule of xstate is the same as obs.
For example, in the below PomdpX variable declaration script, it has 3 fully observable variables: RobPos,RobVel,PedPose.It has only one observation variable oPed. A valid assignment to xstate can be "sx00y00sR00sV0". And a valid assignment to obs can be "ox00y00".
<Variable> <StateVar vnamePrev="RobPose_0" vnameCurr="RobPose_1" fullyObs="true"> <ValueEnum> sR00 sR01 sR02 sR03 sR04 sR05 sR06 sR07 sR08 sR09 strRob </ValueEnum> </StateVar> <StateVar vnamePrev="RobVel_0" vnameCurr="RobVel_1" fullyObs="true"> <ValueEnum> sV0 sV1 sV2 </ValueEnum> </StateVar> <StateVar vnamePrev="PedPose_0" vnameCurr="PedPose_1" fullyObs="true"> <ValueEnum> sx00y00 sx00y01 sx00y02 sx00y03 sx00y04 sx00y05 sx00y06 sx00y07 sx00y08 sx00y09 sx01y00 sx01y01 sx01y02 sx01y03 sx01y04 sx01y05 sx01y06 sx01y07 sx01y08 sx01y09 sx02y00 sx02y01 sx02y02 sx02y03 sx02y04 sx02y05 sx02y06 sx02y07 sx02y08 sx02y09 sx03y00 sx03y01 sx03y02 sx03y03 sx03y04 sx03y05 sx03y06 sx03y07 sx03y08 sx03y09 str </ValueEnum> </StateVar> <StateVar vnamePrev="PedGoal_0" vnameCurr="PedGoal_1" fullyObs="false"> <ValueEnum> G0 G1 G2 G3 </ValueEnum> </StateVar> <ObsVar vname="oPed"> <ValueEnum> ox00y00 ox00y01 ox00y02 ox00y03 ox00y04 ox00y05 ox00y06 ox00y07 ox00y08 ox00y09 ox01y00 ox01y01 ox01y02 ox01y03 ox01y04 ox01y05 ox01y06 ox01y07 ox01y08 ox01y09 ox02y00 ox02y01 ox02y02 ox02y03 ox02y04 ox02y05 ox02y06 ox02y07 ox02y08 ox02y09 ox03y00 ox03y01 ox03y02 ox03y03 ox03y04 ox03y05 ox03y06 ox03y07 ox03y08 ox03y09 ostr </ValueEnum> </ObsVar> <ActionVar vname="action_robot"> <ValueEnum> aCru aAcc aDec </ValueEnum> </ActionVar> <RewardVar vname="reward_robot"/> </Variable>
Example
We provided a tigertest.cpp file in the root of the package, but you need to copy it to a seperate node to run it as a client. Also you need the Tiger.pomdpx and Tiger.policy in the examples/POMDPX folder.