hokuyo_listener.py

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#!/usr/bin/env python
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##\author Kevin Watts
##\brief Listens to diagnostics from hokuyo_node and reports OK/FAIL

PKG = 'pr2_hardware_test_monitor'

import roslib
roslib.load_manifest(PKG)

from diagnostic_msgs.msg import DiagnosticArray, DiagnosticStatus, KeyValue
from std_srvs.srv import *

import rospy

import threading

from pr2_hw_listener import PR2HWListenerBase

class HokuyoListener(PR2HWListenerBase):
    """
    Listens to diagnostics from a Hokuyo laser scanner with the given namespace.
    """
    def __init__(self):
        self._diag_sub = rospy.Subscriber('/diagnostics', DiagnosticArray, self._diag_callback)
        self._mutex = threading.Lock()

        self._ok = True
        self._update_time = 0
        self.name = 'tilt_hokuyo_node'

    def create(self, params):
        """
        params must have the value "name", which is the namespace of the Hokuyo to listen to.

        \param params { } : ROS Parameters in namespace
        \return bool : True if created OK
        """
        if not params.has_key('name'):
            rospy.logerr('Hokuyo Listener was not given param "name"')
            return False
        self.name = params['name']
        
        return True

    def _diag_callback(self, msg):
        self._mutex.acquire()
        for stat in msg.status:
            if stat.name.find(self.name) >= 0:
                self._ok = (stat.level == 0)
                self._update_time = rospy.get_time()
                if not self._ok:
                    break

        self._mutex.release()
    
    def check_ok(self):
        self._mutex.acquire()
        msg = ''
        stat = 0
        if not self._ok:
            stat = 2
            msg = 'Hokuyo Error'

        if rospy.get_time() - self._update_time > 3:
            stat = 3
            msg = 'Hokuyo Stale'
            if self._update_time == 0:
                msg = 'No Hokuyo Data'
        
        self._mutex.release()
        return stat, msg, None