battery_monitor.py

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#!/usr/bin/python
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##\author Kevin Watts
##\brief Monitors battery status, and send high/low power status messages

from __future__ import with_statement

PKG = 'continuous_ops_executive'
import roslib; roslib.load_manifest(PKG)
import rospy

import threading

from pr2_msgs.msg import PowerState
from continuous_ops_msgs.msg import ChargeStatus

from collections import deque

CHARGE_LEVEL = 95
DISCHARGE_LEVEL = 40

BUFFER_SIZE = 10

# Return true if we are fully charged
# True if we have 5 consecutive messages above charge level
# And last message shows we're still charging
def _check_stuffed(msgs):
    if not len(msgs) >= 5:
        return False

    for i in range(0, 5):
        m = msgs[-1 * i]
        if not m.relative_capacity > CHARGE_LEVEL:
            return False
        
    if msgs[-1].AC_present == 0:
        return False
    
    return True

class BatteryMonitor(object):
    def __init__(self):
        self._mutex = threading.Lock()
        self._state_pub = rospy.Publisher('charge_status', ChargeStatus, latch=True)
        self._msgs = deque()
        self._power_sub = rospy.Subscriber('power_state', PowerState, self._power_cb)

    def _power_cb(self, msg):
        with self._mutex:
            self._msgs.append(msg)
            
            # Clip deque to max length
            while len(self._msgs) > BUFFER_SIZE:
                self._msgs.popleft()

    def update(self):
        with self._mutex:
            if not self._msgs:
                return

            out = ChargeStatus()
            out.charge_status = ChargeStatus.UNPLUGGED
            out.battery_status = ChargeStatus.HAPPY

            last = self._msgs[-1]

            if last.AC_present > 0:
                out.charge_status = ChargeStatus.CHARGING

            # Hungry if we're not charging and below the minimum level
            if last.AC_present == 0 and last.relative_capacity < DISCHARGE_LEVEL:
                out.battery_status = ChargeStatus.HUNGRY
                
            # Check if we should be stuffed
            if _check_stuffed(self._msgs):
                out.battery_status = ChargeStatus.STUFFED

            self._state_pub.publish(out)


if __name__ == '__main__':
    rospy.init_node('battery_monitor')
    bm = BatteryMonitor()

    try:
        my_rate = rospy.Rate(1.0)
        while not rospy.is_shutdown():
            bm.update()
            my_rate.sleep()
    except KeyboardInterrupt, e:
        pass
    except Exception, e:
        import traceback
        traceback.print_exc()