Oracle3 – User Documentation

Observations

the node contains up to 30 precomputed hints, see in the code: erl3::ErlOracle oracle_msgs[30]; sometimes in the space, the robot could find a ID greater than 30: it must be discarded.
the array int markerID[30]; contains the ID associated to the respective message into erl3::ErlOracle oracle_msgs[30];. For instance, the id of the i-th hint oracle_msgs[i] is markerID[i]
in particular, winID is the ID of the solution of the case
there are two types of ID: there’s the one in the message Marker which is an index of the array of hints; and there’s the ID of the other message ErlOracle that is an identifier of a hypothesis of the case.
each hypothesis identifier goes from 0 up to 5

SCHEMA – node simulation.cpp

Note

run the node referring to it with final_oracle
the node name at runtime is assignment3
the source file is called simulation3.cpp

service erl2::Oracle

this service is used to check the validity of a solution in “solve” phase. it returns the winner ID choosed at the beginning of the game by the Oracle.

the system should check wether the ID of the solution is equal to the one returned by this service. the returned value is never corrupted concerning this particular type of message.

---
int32 ID

note: in the actual implementation, the ID goes from 0 included to 5 included.

message erl2::ErlOracle

this message is sent every time the cluedo_link is at a distance up to 0.25m.

int32 ID
string key
string value

the message could be corrupted in many ways:

empty field(s)
one or more fields could be “-1”
the field “key” could contain a string different from the allowed ones: who, where, and what

so, remember to check the validity of the message.

HOW TO receive a hint

the robot goes around in search of a ArUco code containing the ID of the hint. When it finds one hint, it makes a service request to the Oracle through /oracle_hint service, declaring the found hint. This request is of type exp_assignment3/Marker, made as follows:

int32 markerId

---

erl2/ErlOracle oracle_hint

the field of type erl2/ErlOracle has these fields:

int32 ID
string key
string value

HOW TO check the solution

to check whether a specific ID is the solution of the mystery, call the service /oracle_solution of type erl2/Oracle. Here’s the prototype of the service:

---
int32 ID

Code Reference

Functions

bool oracleService(erl2::Oracle::Request &req, erl2::Oracle::Response &res)

bool oracleCallback(exp_assignment3::Marker::Request &req, exp_assignment3::Marker::Response &res)

int main(int argc, char **argv)

Variables

ros::Publisher oracle_pub

double markx[4]

double marky[4]

double markz[4]

double lastmarkx = 0.0

double lastmarky = 0.0

const std::string key[3] = {"who", "what", "where"}

const std::string person[6] = {"MissScarlett", "ColonelMustard", "MrsWhite", "MrGreen", "MrsPeacock", "ProfPlum"}

const std::string object[6] = {"candlestick", "dagger", "leadPipe", "revolver", "rope", "spanner"}

const std::string place[9] = {"conservatory", "lounge", "kitchen", "library", "hall", "study", "bathroom", "diningRoom", "billiardRoom"}

int uIDs[3] = {-1, -1}

int winID = -1

int markerID[30]

erl2::ErlOracle oracle_msgs[30]