Brief instructions to install and run symbolicPerseus ----------------------------------------------------- Author: Pascal Poupart (ppoupart@cs.uwaterloo.ca) Reference: Chapter 5 of Poupart's PhD thesis (http://www.cs.uwaterloo.ca/~ppoupart/publications/ut-thesis/ut-thesis.pdf) Sections: --------- * Installation * Lauching Matlab * Solving POMDPs * Evaluating a policy * Tracing/executing a policy * POMDP problems Installation: ------------- 1) Untar and unzip symbolicPerseus.tgz >> tar -xvzf symbolicPerseus.tgz 2) Compile the java code with Sun's java SDK. Use the same version as Matlab's java virtual machine. To check the java version used by matlab, type "version -java" at the Matlab prompt. The java code has been compiled with java 1.5.0 without any problem. >> cd symbolicPerseus/javaClasses >> javac *.java Launching Matlab: ----------------- Launch matlab in the symbolicPerseus directory. This is critical since matlab will automatically read the files startup.m and java.opts which tell Matlab's java virtual machine where to find the java classes (startup.m) and how much memory to allocate (java.opts). >> cd symbolicPerseus >> matlab N.B. Do not launch matlab with the -nojvm option because that will prevent the java virtual machine from starting up. The code has been tested with Matlab 7.3. Solving POMDPs: --------------- Run the "solvePOMDP" function by typing >> [valueFunction,policy] = solvePOMDP('problems/coffee/coffee3po.txt'); It first parses the POMDP 'coffee3po.txt' encoded in SPUDD format. Then some reachable belief states are sampled by following a some initial policy (default policy is QMDP with look ahead depth of 1). This may take a few minutes. Then the POMDP is solved by running the boundedPerseus.m function. Again, this may take a few minutes per iteration. The value function and policies are automatically saved in the file 'problems/coffee/coffee3po_Lbel_Miter_Nsize.mat' indicating that L belief states were sampled, M Perseus iterations were performed and at most N alpha vectors were computed at each iteration. There are several parameters that can be passed to the "solvePOMDP" function to fine tune the computation. Type "help solvePOMDP" for a summary of these parameters and their default values. Evaluating a policy: -------------------- To evaluate a policy, run one of the evalPOMDPpolicy functions by typing >> avRew = evalPOMDPpolicyGraph('problems/coffee/coffee3po.txt', 'problems/coffee/coffee3po_Lbel_Miter_Nsize.mat') or >> avRew = evalPOMDPpolicyStationary('problems/coffee/coffee3po.txt', 'problems/coffee/coffee3po_Lbel_Miter_Nsize.mat') or >> avRew = evalPOMDPpolicyNonStationary('problems/coffee/coffee3po.txt', 'problems/coffee/coffee3po_Lbel_Miter_Nsize.mat') It averages the total discounted reward earned over 500 runs of 50 steps each. The average of the runs performed so far is reported after each run. Note that evalPOMDPpolicyGraph is the fastest function. It selects actions based on the policy graph that is computed by symbolic perseus. The value of the initial belief state reported by symbolic perseus is an estimate of the policy graph. evalPOMDPpolicyNonStationary requires a lot of memory but executes a policy that is strictly better than the policy graph. Actions are selected by finding the best alpha vector computed at each iteration of symbolic perseus. evalPOMDPpolicyStationary selects actions by finding the best alpha vector of the last iteration of symbolic perseus. Hence only the value function of the last iteration needs to be loaded in memory, which reduces memory requirements. However, the policy may have a value arbitrarily lower than that of the non-stationary policy or the policy graph. Tracing/executing a policy: --------------------------- To trace a policy by manually choosing the observations, type: >> tracePOMDPpolicyGraph('problems/coffee/coffee3po.txt', 'problems/coffee/coffee3po_Lbel_Miter_Nsize.mat'); or >> tracePOMDPpolicyStationary('problems/coffee/coffee3po.txt', 'problems/coffee/coffee3po_Lbel_Miter_Nsize.mat'); or >> tracePOMDPpolicyNonStationary('problems/coffee/coffee3po.txt', 'problems/coffee/coffee3po_Lbel_Miter_Nsize.mat'); At each step, the action chosen by the policy willl be displayed. Then the user will be asked to manually enter the observation. To execute a policy where the observations are provided by some sensors (i.e., real hardware), you need to write a function to replace "queryObservation". The queryObservation function queries a user for observations that are entered manually. The replacing function should have the same signature as queryObservation, but the sensors are queried instead of a user to obtain the next observation. The observation must be encoded in an "obsConfig", which is a 2xN matrix such that the first row lists the ids of the observation variables and the second row lists the values of the observation variables. For example [4,5;1,2] indicates that observation variable 4 has value 1 and observation variable 5 has value 2. Note that the ids of the observation variables should be those of the "primed" version (i.e., ids of the variables at the next time step). You can find out the ids of the observation variables by typing: >> [ddPOMDP.obsVars.id] and the primed observation variables by typing: >> [ddPOMDP.obsVars.id] + ddPOMDP.nVars POMDP problems: --------------- See the file problems/README for an overview of the POMDP problems included with this release.