brake_thrash.py

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#!/usr/bin/env python

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# Copyright (c) 2014-2018, Dataspeed Inc.
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import rospy
from std_msgs.msg import Bool
from dbw_mkz_msgs.msg import BrakeCmd
from dbw_mkz_msgs.msg import GearReport, SteeringReport

class BrakeThrash:
    def __init__(self):
        rospy.init_node('brake_thrash')

        # Shutdown
        self.shutdown = False

        # Received messages
        self.dbw_enabled = False
        self.msg_steering_report_ready = False
        self.msg_gear_report = GearReport()
        self.msg_gear_report_ready = False
        self.msg_steering_report = SteeringReport()
        self.msg_steering_report_ready = False

        # Parameters
        self.started = False
        rospy.loginfo('Preparing to thrash the brake pedal command to try and induce a fault...')
        rospy.loginfo('Validating that vehicle is parked...')
        
        # Publishers and subscribers
        self.pub = rospy.Publisher('/vehicle/brake_cmd', BrakeCmd, queue_size=10)
        rospy.Subscriber('/vehicle/dbw_enabled', Bool, self.recv_enabled)
        rospy.Subscriber('/vehicle/gear_report', GearReport, self.recv_gear)
        rospy.Subscriber('/vehicle/steering_report', SteeringReport, self.recv_steering)
        rospy.Timer(rospy.Duration(0.2), self.timer_process)

    def timer_process(self, event):
        # Check for safe conditions
        if not self.msg_steering_report_ready:
            self.shutdown = True
            rospy.logerr('Speed check failed. No messages on topic \'/vehicle/steering_report\'')
        elif not self.msg_steering_report.speed == 0.0:
            self.shutdown = True
            rospy.logerr('Speed check failed. Vehicle speed is not zero.')
        if not self.msg_gear_report_ready:
            self.shutdown = True
            rospy.logerr('Gear check failed. No messages on topic \'/vehicle/gear_report\'')
        elif not self.msg_gear_report.state.gear == self.msg_gear_report.state.PARK:
            self.shutdown = True
            rospy.logerr('Gear check failed. Vehicle not in park.')

        # Check if enabled
        if self.shutdown:
            rospy.signal_shutdown('')
            return

        # Check if enabled
        if not self.dbw_enabled:
            rospy.logwarn('Drive-by-wire not enabled!')

        # Start command timers
        if not self.started:
            self.started = True
            rospy.Timer(rospy.Duration(0.01000), self.timer_cmd_0)
            rospy.Timer(rospy.Duration(0.01001), self.timer_cmd_1)
            rospy.loginfo('Started thrashing the brake pedal command to try and induce a fault.')
        
        # Prepare for next iteration
        self.msg_gear_report_ready = False
        self.msg_steering_report_ready = False

    def timer_cmd_0(self, event):
        if not self.shutdown:
            msg = BrakeCmd()
            msg.enable = True
            msg.pedal_cmd_type = BrakeCmd.CMD_PEDAL
            msg.pedal_cmd = 0.0
            self.pub.publish(msg)

    def timer_cmd_1(self, event):
        if not self.shutdown:
            msg = BrakeCmd()
            msg.enable = True
            msg.pedal_cmd_type = BrakeCmd.CMD_PEDAL
            msg.pedal_cmd = 1.0
            self.pub.publish(msg)

    def recv_enabled(self, msg):
        self.dbw_enabled = msg.data

    def recv_gear(self, msg):
        self.msg_gear_report = msg
        self.msg_gear_report_ready = True

    def recv_steering(self, msg):
        self.msg_steering_report = msg
        self.msg_steering_report_ready = True

    def shutdown_handler(self):
        pass

if __name__ == '__main__':
    try:
        node = BrakeThrash()
        rospy.on_shutdown(node.shutdown_handler)
        rospy.spin()
    except rospy.ROSInterruptException:
        pass