Ejemplo n.º 1
0
class ZumyROS:
    def __init__(self):
        self.zumy = Zumy()
        rospy.init_node('zumy_ros')
        self.cmd = (0, 0)
        rospy.Subscriber('cmd_vel', Twist, self.cmd_callback, queue_size=1)
        rospy.Subscriber('enable', Bool, self.enable_callback, queue_size=1)
        rospy.Subscriber(
            '/base_computer', String, self.watchdog_callback, queue_size=1
        )  #/base_computer topic, the global watchdog.  May want to investigate what happens when there moer than one computer and more than one zumy

        self.lock = Condition()
        self.rate = rospy.Rate(30.0)
        self.name = socket.gethostname()

        if rospy.has_param("~timeout"):
            self.timeout = rospy.get_param('~timeout')  #private value
        else:
            self.timeout = 2  #Length of watchdog timer in seconds, defaults to 2 sec.

        #publishers
        self.status_pub = rospy.Publisher("Status", ZumyStatus, queue_size=5)
        self.imu_pub = rospy.Publisher('imu', Imu, queue_size=1)
        self.r_enc_pub = rospy.Publisher('r_enc', Float32, queue_size=5)
        self.l_enc_pub = rospy.Publisher('l_enc', Float32, queue_size=5)
        self.r_vel_pub = rospy.Publisher('r_vel', Float32, queue_size=5)
        self.l_vel_pub = rospy.Publisher('l_vel', Float32, queue_size=5)

        self.imu_count = 0

        self.batt_pub = rospy.Publisher('Batt', Float32, queue_size=5)

        self.last_message_at = time.time()
        self.watchdog = True

        #an array of times, which will be updated, and used to figure out how fast the while loop is going.
        self.laptimes = np.ones(6) * time.time()

        # NEW!
        self.IR_ai_side_pub = rospy.Publisher('/' + self.name + '/IR_ai_side',
                                              Float32,
                                              queue_size=1)
        self.IR_ai_front_pub = rospy.Publisher("/" + self.name +
                                               "/IR_ai_front",
                                               Float32,
                                               queue_size=1)
        self.IR_ai_top_pub = rospy.Publisher('/' + self.name + '/IR_ai_top',
                                             Float32,
                                             queue_size=1)
        self.IR_ai_bottom_pub = rospy.Publisher("/" + self.name +
                                                "/IR_ai_bottom",
                                                Float32,
                                                queue_size=1)
        # Publish twists to /cmd_vel in order to drive the Zumy.

    def cmd_callback(self, msg):
        self.lock.acquire()
        self.cmd = twist_to_speeds(
            msg
        )  #update the commanded speed, the next time the main loop in run comes through, it'll be update on the zumy.
        self.lock.release()

    def enable_callback(self, msg):
        #enable or disable myself based on the content of the message.
        if msg.data and self.watchdog:
            self.zumy.enable()
        else:
            self.zumy.disable()
            self.cmd = (0, 0)  #turn the motors off
        #do NOT update the watchdog, since the watchdog should do it itself.
        #If i'm told to go but the host's watchdog is down, something's very wrong, and i won't be doing much

    def watchdog_callback(self, msg):
        #update the last time i got a messag!
        self.last_message_at = time.time()
        self.watchdog = True

    def run(self):

        while not rospy.is_shutdown():
            self.lock.acquire()
            self.zumy.cmd(*self.cmd)

            try:
                imu_data = self.zumy.read_imu()
                imu_msg = Imu()
                imu_msg.header = Header(self.imu_count, rospy.Time.now(),
                                        self.name)
                imu_msg.linear_acceleration.x = 9.81 * imu_data[0]
                imu_msg.linear_acceleration.y = 9.81 * imu_data[1]
                imu_msg.linear_acceleration.z = 9.81 * imu_data[2]
                imu_msg.angular_velocity.x = 3.14 / 180.0 * imu_data[3]
                imu_msg.angular_velocity.y = 3.14 / 180.0 * imu_data[4]
                imu_msg.angular_velocity.z = 3.14 / 180.0 * imu_data[5]
                self.imu_pub.publish(imu_msg)
            except ValueError:
                pass

            try:
                enc_data = self.zumy.enc_pos()
                enc_msg = Float32()
                enc_msg.data = enc_data[0]
                self.r_enc_pub.publish(enc_msg)
                enc_msg.data = enc_data[1]
                self.l_enc_pub.publish(enc_msg)
            except ValueError:
                pass

            try:
                vel_data = self.zumy.enc_vel()
                vel_msg = Float32()
                vel_msg.data = vel_data[0]
                self.l_vel_pub.publish(vel_msg)
                vel_msg.data = vel_data[1]
                self.r_vel_pub.publish(vel_msg)
            except ValueError:
                pass

            try:
                v_bat = self.zumy.read_voltage()
                self.batt_pub.publish(v_bat)
            except ValueError:
                pass

            try:
                IR_ai_front_data = self.zumy.read_IR_ai_front()
                scaled_front_data = IR_ai_front_data * 3.3
                self.IR_ai_front_pub.publish(scaled_front_data)
            except ValueError:
                self.IR_ai_front_pub.publish(19)
                pass

            try:
                IR_ai_side_data = self.zumy.read_IR_ai_side()
                scaled_side_data = IR_ai_side_data * 3.3
                self.IR_ai_side_pub.publish(scaled_side_data)
            except ValueError:
                self.IR_ai_side_pub.publish(17)
                pass

            try:
                IR_ai_top_data = self.zumy.read_IR_ai_top()
                scaled_top_data = IR_ai_top_data * 3.3
                self.IR_ai_top_pub.publish(scaled_top_data)
            except ValueError:
                self.IR_ai_top_pub.publish(16)
                pass

            try:
                IR_ai_bottom_data = self.zumy.read_IR_ai_bottom()
                scaled_bottom_data = IR_ai_bottom_data * 3.3
                self.IR_ai_bottom_pub.publish(scaled_bottom_data)
            except ValueError:
                self.IR_ai_bottom_pub.publish(18)
                pass

            #END NEW

            if time.time() > (
                    self.last_message_at + self.timeout
            ):  #i've gone too long without seeing the watchdog.
                self.watchdog = False
                self.zumy.disable()
            self.zumy.battery_protection(
            )  # a function that needs to be called with some regularity.

            #handle the robot status message
            status_msg = ZumyStatus()
            status_msg.enabled_status = self.zumy.enabled
            status_msg.battery_unsafe = self.zumy.battery_unsafe()
            #update the looptimes, which will get published in status_msg
            self.laptimes = np.delete(self.laptimes, 0)
            self.laptimes = np.append(self.laptimes, time.time())
            #take average over the difference of the times... and then invert.  That will give you average freq.
            status_msg.loop_freq = 1 / float(np.mean(np.diff(self.laptimes)))

            self.status_pub.publish(status_msg)
            self.lock.release()  #must be last command involving the zumy.

            self.rate.sleep()
            self.first_move = False

        # If shutdown, turn off motors & disable anything else.
        self.zumy.disable()
Ejemplo n.º 2
0
class ZumyROS:	
  def __init__(self):
    self.zumy = Zumy()
    rospy.init_node('zumy_ros')
    self.cmd = (0,0)
    rospy.Subscriber('cmd_vel', Twist, self.cmd_callback,queue_size=1)
    rospy.Subscriber('cmd_left', Float32, self.cmd_callback_left, queue_size=1)
    rospy.Subscriber('cmd_right', Float32, self.cmd_callback_right, queue_size=1)
    self.lock = Condition()
    self.rate = rospy.Rate(30.0)
    self.name = socket.gethostname()
    
    #publishers
    self.heartBeat = rospy.Publisher('heartBeat', String, queue_size=5)
    self.imu_pub = rospy.Publisher('imu', Imu, queue_size = 1)
    self.r_enc_pub = rospy.Publisher('r_enc', Int32, queue_size = 5)
    self.l_enc_pub = rospy.Publisher('l_enc', Int32, queue_size = 5)
    self.imu_count = 0

    self.batt_pub = rospy.Publisher('Batt',Float32,queue_size = 5)

  def cmd_callback(self, msg):
    lv = 0.6
    la = 0.4
    v = msg.linear.x
    a = msg.angular.z
    r = lv*v + la*a
    l = lv*v - la*a
    self.lock.acquire()
    self.cmd = (l,r)
    self.lock.release()

  def cmd_callback_left(self, msg):
    self.lock.acquire()
    self.cmd = (0.6*msg.data, self.cmd[1])
    self.lock.release()

  def cmd_callback_right(self, msg):
    self.lock.acquire()
    self.cmd = (self.cmd[0], 0.6*msg.data)
    self.lock.release()

  def run(self):
    while not rospy.is_shutdown():
      self.lock.acquire()
      self.zumy.cmd(*self.cmd)
      imu_data = self.zumy.read_imu()
      enc_data = self.zumy.read_enc()
      self.lock.release()
      
      imu_msg = Imu()
      imu_msg.header = Header(self.imu_count,rospy.Time.now(),self.name)
      imu_msg.linear_acceleration.x = 9.81 * imu_data[0]
      imu_msg.linear_acceleration.y = 9.81 * imu_data[1]
      imu_msg.linear_acceleration.z = 9.81 * imu_data[2]
      imu_msg.angular_velocity.x = 3.14 / 180.0 * imu_data[3]
      imu_msg.angular_velocity.y = 3.14 / 180.0 * imu_data[4]
      imu_msg.angular_velocity.z = 3.14 / 180.0 * imu_data[5]
      self.imu_pub.publish(imu_msg)
      
      enc_msg = Int32()
      enc_msg.data = enc_data[0]
      self.r_enc_pub.publish(enc_msg)
      enc_msg.data = enc_data[1]
      self.l_enc_pub.publish(enc_msg)

      v_bat = self.zumy.read_voltage()
      self.batt_pub.publish(v_bat)
      self.heartBeat.publish("I am alive")
      self.rate.sleep()

    # If shutdown, turn off motors
    self.zumy.cmd(0,0)
class ZumyROS:
    def __init__(self):
        self.zumy = Zumy()
        rospy.init_node('zumy_ros')
        self.cmd = (0, 0)
        rospy.Subscriber('cmd_vel', Twist, self.cmd_callback, queue_size=1)
        rospy.Subscriber('enable', Bool, self.enable_callback, queue_size=1)
        rospy.Subscriber(
            '/base_computer', String, self.watchdog_callback, queue_size=1
        )  #/base_computer topic, the global watchdog.  May want to investigate what happens when there moer than one computer and more than one zumy

        self.lock = Condition()
        self.rate = rospy.Rate(30.0)
        self.name = socket.gethostname()

        if rospy.has_param("~timeout"):
            self.timeout = rospy.get_param('~timeout')  #private value
        else:
            self.timeout = 2  #Length of watchdog timer in seconds, defaults to 2 sec.

        #publishers
        self.status_pub = rospy.Publisher("Status", ZumyStatus, queue_size=5)
        self.imu_pub = rospy.Publisher('imu', Imu, queue_size=1)
        self.r_enc_pub = rospy.Publisher('r_enc', Float32, queue_size=5)
        self.l_enc_pub = rospy.Publisher('l_enc', Float32, queue_size=5)
        self.r_vel_pub = rospy.Publisher('r_vel', Float32, queue_size=5)
        self.l_vel_pub = rospy.Publisher('l_vel', Float32, queue_size=5)

        self.imu_count = 0

        self.batt_pub = rospy.Publisher('Batt', Float32, queue_size=5)

        self.last_message_at = time.time()
        self.watchdog = True

        #an array of times, which will be updated, and used to figure out how fast the while loop is going.
        self.laptimes = np.ones(6) * time.time()

        # NEW!
        self.is_turning = False
        self.IR_ai_side_pub = rospy.Publisher('/' + self.name + '/IR_ai_side',
                                              Float32,
                                              queue_size=1)
        self.IR_ai_front_pub = rospy.Publisher("/" + self.name +
                                               "/IR_ai_front",
                                               Float32,
                                               queue_size=1)
        self.directions = {
            "F": 0.,
            "L": 90.,
            "R": -90.,
            "B": 180.
        }  # (CCW, 0 is N) the direction that the the zumy will face
        # Publish twists to /cmd_vel in order to drive the Zumy.
        self.zumy_vel_pub = rospy.Publisher('/' + self.name + '/cmd_vel',
                                            Twist,
                                            queue_size=2)

    def cmd_callback(self, msg):
        self.lock.acquire()
        self.cmd = twist_to_speeds(
            msg
        )  #update the commanded speed, the next time the main loop in run comes through, it'll be update on the zumy.
        self.lock.release()

    def enable_callback(self, msg):
        #enable or disable myself based on the content of the message.
        if msg.data and self.watchdog:
            self.zumy.enable()
        else:
            self.zumy.disable()
            self.cmd = (0, 0)  #turn the motors off
        #do NOT update the watchdog, since the watchdog should do it itself.
        #If i'm told to go but the host's watchdog is down, something's very wrong, and i won't be doing much

    def watchdog_callback(self, msg):
        #update the last time i got a messag!
        self.last_message_at = time.time()
        self.watchdog = True

    # NEW!
    def turn_zumy(self, direction):
        # angle in degrees
        # returns a Twist that is published and turns zumy
        omega = np.array([0, 0, 1])  # rotate about z
        translation = np.array([0, 0, 0])
        angle = self.directions[direction]
        theta = deg2rad(angle)
        omega = omega * theta
        rbt = create_rbt(omega, theta, translation)
        v = find_v(omega, theta, translation)
        linear = Vector3(v[0] / 5, v[1] / 5, v[2] / 5)
        angular = Vector3(omega[0], omega[1], omega[2] / 3)
        twist = Twist(linear, angular)
        self.zumy_vel_pub.publish(twist)
        while True:
            if time.time() > start + 3:
                self.stop()
                break
        # self.is_turning = True
        return twist

    # NEW!
    def stop(self):
        linear = Vector3(0, 0, 0)
        angular = Vector3(0, 0, 0)
        stop_twist = Twist(linear, angular)
        self.zumy_vel_pub.publish(stop_twist)
        # self.is_turning = False

    def run(self):

        while not rospy.is_shutdown():
            self.lock.acquire()
            self.zumy.cmd(*self.cmd)

            # self.is_turning = False

            try:
                imu_data = self.zumy.read_imu()
                imu_msg = Imu()
                imu_msg.header = Header(self.imu_count, rospy.Time.now(),
                                        self.name)
                imu_msg.linear_acceleration.x = 9.81 * imu_data[0]
                imu_msg.linear_acceleration.y = 9.81 * imu_data[1]
                imu_msg.linear_acceleration.z = 9.81 * imu_data[2]
                imu_msg.angular_velocity.x = 3.14 / 180.0 * imu_data[3]
                imu_msg.angular_velocity.y = 3.14 / 180.0 * imu_data[4]
                imu_msg.angular_velocity.z = 3.14 / 180.0 * imu_data[5]
                self.imu_pub.publish(imu_msg)
            except ValueError:
                pass

            try:
                enc_data = self.zumy.enc_pos()
                enc_msg = Float32()
                enc_msg.data = enc_data[0]
                self.r_enc_pub.publish(enc_msg)
                enc_msg.data = enc_data[1]
                self.l_enc_pub.publish(enc_msg)
            except ValueError:
                pass

            try:
                vel_data = self.zumy.enc_vel()
                vel_msg = Float32()
                vel_msg.data = vel_data[0]
                self.l_vel_pub.publish(vel_msg)
                vel_msg.data = vel_data[1]
                self.r_vel_pub.publish(vel_msg)
            except ValueError:
                pass

            try:
                v_bat = self.zumy.read_voltage()
                self.batt_pub.publish(v_bat)
            except ValueError:
                pass

            # NEW!
            # Note: zumy code MUST be between acquire/release calls!
            # Note: read must be in a try-catch block!
            try:
                # self.zumy_vel_pub.publish(move_zumy_forward())
                # side port is p16
                IR_ai_side_data = self.zumy.read_IR_ai_side()
                scaled_side_data = IR_ai_side_data * 3.3
                self.IR_ai_side_pub.publish(scaled_side_data)
                '''
        if IR_ai_data < 0.5:
          twist = turn_zumy(self.directions['L'])
          self.zumy_vel_pub.publish(twist)
        else:
          twist = turn_zumy(self.directions['R'])
          self.zumy_vel_pub.publish(twist)
        '''
            except ValueError:
                self.IR_ai_side_pub.publish(33)
                pass
            try:

                # NEW!
                # checks if acceleration about z axis is below a certain level.
                if imu_msg.angular_velocity.z < .05:

                    IR_ai_front_data = self.zumy.read_IR_ai_front()
                    scaled_front_data = IR_ai_front_data * 3.3
                    self.IR_ai_front_pub.publish(scaled_front_data)

                    if scaled_front_data > 2.0:
                        self.IR_ai_front_pub.publish(9999)
                        self.turn_zumy('L')

                        # self.is_turning = True

            except ValueError:
                self.IR_ai_front_pub.publish(36)
                pass

            #END NEW

            if time.time() > (
                    self.last_message_at + self.timeout
            ):  #i've gone too long without seeing the watchdog.
                self.watchdog = False
                self.zumy.disable()
            self.zumy.battery_protection(
            )  # a function that needs to be called with some regularity.

            #handle the robot status message
            status_msg = ZumyStatus()
            status_msg.enabled_status = self.zumy.enabled
            status_msg.battery_unsafe = self.zumy.battery_unsafe()
            #update the looptimes, which will get published in status_msg
            self.laptimes = np.delete(self.laptimes, 0)
            self.laptimes = np.append(self.laptimes, time.time())
            #take average over the difference of the times... and then invert.  That will give you average freq.
            status_msg.loop_freq = 1 / float(np.mean(np.diff(self.laptimes)))

            self.status_pub.publish(status_msg)
            self.lock.release()  #must be last command involving the zumy.

            self.rate.sleep()

        # If shutdown, turn off motors & disable anything else.
        self.zumy.disable()
Ejemplo n.º 4
0
class ZumyROS:
    def __init__(self):
        self.zumy = Zumy()
        rospy.init_node('zumy_ros')
        self.cmd = (0, 0)
        rospy.Subscriber('cmd_vel', Twist, self.cmd_callback, queue_size=1)
        self.lock = Condition()
        self.rate = rospy.Rate(30.0)
        self.name = socket.gethostname()

        #publishers
        self.heartBeat = rospy.Publisher('heartBeat', String, queue_size=5)
        self.imu_pub = rospy.Publisher('imu', Imu, queue_size=1)
        self.r_enc_pub = rospy.Publisher('r_enc', Int32, queue_size=5)
        self.l_enc_pub = rospy.Publisher('l_enc', Int32, queue_size=5)
        self.imu_count = 0

        self.batt_pub = rospy.Publisher('Batt', Float32, queue_size=5)

    def cmd_callback(self, msg):
        lv = 0.6
        la = 0.4
        v = msg.linear.x
        a = msg.angular.z
        r = lv * v + la * a
        l = lv * v - la * a
        self.lock.acquire()
        self.cmd = (l, r)
        self.lock.release()

    def run(self):
        while not rospy.is_shutdown():
            self.lock.acquire()
            self.zumy.cmd(*self.cmd)
            imu_data = self.zumy.read_imu()
            enc_data = self.zumy.read_enc()
            self.lock.release()

            imu_msg = Imu()
            imu_msg.header = Header(self.imu_count, rospy.Time.now(),
                                    self.name)
            imu_msg.linear_acceleration.x = 9.81 * imu_data[0]
            imu_msg.linear_acceleration.y = 9.81 * imu_data[1]
            imu_msg.linear_acceleration.z = 9.81 * imu_data[2]
            imu_msg.angular_velocity.x = 3.14 / 180.0 * imu_data[3]
            imu_msg.angular_velocity.y = 3.14 / 180.0 * imu_data[4]
            imu_msg.angular_velocity.z = 3.14 / 180.0 * imu_data[5]
            self.imu_pub.publish(imu_msg)

            enc_msg = Int32()
            enc_msg.data = enc_data[0]
            self.r_enc_pub.publish(enc_msg)
            enc_msg.data = enc_data[1]
            self.l_enc_pub.publish(enc_msg)

            v_bat = self.zumy.read_voltage()
            self.batt_pub.publish(v_bat)
            self.heartBeat.publish("I am alive")
            self.rate.sleep()

        # If shutdown, turn off motors
        self.zumy.cmd(0, 0)
class ZumyROS:	
  def __init__(self):
    self.zumy = Zumy()
    rospy.init_node('zumy_ros')
    self.cmd = (0,0)
    rospy.Subscriber('cmd_vel', Twist, self.cmd_callback,queue_size=1)
    rospy.Subscriber('enable', Bool, self.enable_callback,queue_size=1)

    rospy.Subscriber('/base_computer',String,self.watchdog_callback,queue_size=1) #/base_computer topic, the global watchdog.  May want to investigate what happens when there moer than one computer and more than one zumy

    self.lock = Condition()
    self.rate = rospy.Rate(30.0)
    self.name = socket.gethostname()


    if rospy.has_param("~timeout"):
        self.timeout = rospy.get_param('~timeout') #private value
    else:
      self.timeout = 2 #Length of watchdog timer in seconds, defaults to 2 sec.
    
    #publishers
    self.status_pub = rospy.Publisher("Status",ZumyStatus, queue_size=5)
    self.imu_pub = rospy.Publisher('imu', Imu, queue_size = 1)
    self.r_enc_pub = rospy.Publisher('r_enc',Float32, queue_size = 5)
    self.l_enc_pub = rospy.Publisher('l_enc',Float32, queue_size = 5)
    self.r_vel_pub = rospy.Publisher('r_vel',Float32,queue_size = 5)
    self.l_vel_pub = rospy.Publisher('l_vel',Float32,queue_size = 5)
    
    self.imu_count = 0

    self.batt_pub = rospy.Publisher('Batt',Float32,queue_size = 5)

    self.last_message_at = time.time()
    self.watchdog = True 

    #an array of times, which will be updated, and used to figure out how fast the while loop is going.
    self.laptimes = np.ones(6)*time.time()





  def cmd_callback(self, msg):
    self.lock.acquire()
    self.cmd = twist_to_speeds(msg) #update the commanded speed, the next time the main loop in run comes through, it'll be update on the zumy.
    self.lock.release()

  def enable_callback(self,msg):
    #enable or disable myself based on the content of the message.   
    if msg.data and self.watchdog:
      self.zumy.enable()
    else:
      self.zumy.disable()
      self.cmd = (0,0) #turn the motors off
    #do NOT update the watchdog, since the watchdog should do it itself.
    #If i'm told to go but the host's watchdog is down, something's very wrong, and i won't be doing much

  def watchdog_callback(self,msg):
    #update the last time i got a messag!
    self.last_message_at = time.time()
    self.watchdog = True



  def run(self):
    while not rospy.is_shutdown():
      self.lock.acquire()
      self.zumy.cmd(*self.cmd)
      try:
        imu_data = self.zumy.read_imu()
        imu_msg = Imu()
        imu_msg.header = Header(self.imu_count,rospy.Time.now(),self.name)
        imu_msg.linear_acceleration.x = 9.81 * imu_data[0]
        imu_msg.linear_acceleration.y = 9.81 * imu_data[1]
        imu_msg.linear_acceleration.z = 9.81 * imu_data[2]
        imu_msg.angular_velocity.x = 3.14 / 180.0 * imu_data[3]
        imu_msg.angular_velocity.y = 3.14 / 180.0 * imu_data[4]
        imu_msg.angular_velocity.z = 3.14 / 180.0 * imu_data[5]
        self.imu_pub.publish(imu_msg)
      except ValueError:
        pass

      try:
        enc_data = self.zumy.enc_pos()
        enc_msg = Float32()
        enc_msg.data = enc_data[0]
        self.r_enc_pub.publish(enc_msg)
        enc_msg.data = enc_data[1]
        self.l_enc_pub.publish(enc_msg)
      except ValueError:
        pass

      try:
        vel_data = self.zumy.enc_vel()
        vel_msg = Float32()
        vel_msg.data = vel_data[0]
        self.l_vel_pub.publish(vel_msg)
        vel_msg.data = vel_data[1]
        self.r_vel_pub.publish(vel_msg)
      except ValueError:
        pass
        
      try:
        v_bat = self.zumy.read_voltage()
        self.batt_pub.publish(v_bat)
      except ValueError:
        pass
      
      if time.time() > (self.last_message_at + self.timeout): #i've gone too long without seeing the watchdog.
        self.watchdog = False
        self.zumy.disable()
      self.zumy.battery_protection() # a function that needs to be called with some regularity.


      #handle the robot status message
      status_msg = ZumyStatus()
      status_msg.enabled_status = self.zumy.enabled
      status_msg.battery_unsafe = self.zumy.battery_unsafe()
      #update the looptimes, which will get published in status_msg
      self.laptimes = np.delete(self.laptimes,0)
      self.laptimes = np.append(self.laptimes,time.time())
      #take average over the difference of the times... and then invert.  That will give you average freq.
      status_msg.loop_freq = 1/float(np.mean(np.diff(self.laptimes)))

      self.status_pub.publish(status_msg)




      self.lock.release() #must be last command involving the zumy.
     

      self.rate.sleep()

      


    # If shutdown, turn off motors & disable anything else.
    self.zumy.disable()