diff --git a/subt/main.py b/subt/main.py
index a4d09e332..2a656c32d 100644
--- a/subt/main.py
+++ b/subt/main.py
@@ -10,6 +10,7 @@
 from datetime import timedelta
 from collections import defaultdict
 from io import StringIO
+from random import Random
 
 import numpy as np
 
@@ -146,6 +147,7 @@ class SubTChallenge:
     def __init__(self, config, bus):
         self.bus = bus
         bus.register("desired_speed", "pose2d", "artf_xyz", "pose3d", "stdout", "request_origin")
+        self.random = Random(0)
         self.start_pose = None
         self.traveled_dist = 0.0
         self.time = None
diff --git a/subt/monitors.py b/subt/monitors.py
new file mode 100644
index 000000000..a93387c61
--- /dev/null
+++ b/subt/monitors.py
@@ -0,0 +1,96 @@
+import logging
+
+g_logger = logging.getLogger(__name__)
+
+
+class TimeoutReached(Exception):
+    pass
+
+
+class TimeoutMonitor:
+    def __init__(self, robot, timeout):
+        self.robot = robot
+        self.timeout = timeout
+        self.fired = False
+
+    def update(self):
+        if (self.robot.time - self.start_time) > self.timeout:
+            raise TimeoutReached(self)
+
+    def __enter__(self):
+        self.start_time = self.robot.time
+        self.fired = False
+        self.handle = self.robot.register(self.update)
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.robot.unregister(self.handle)
+        if exc_val is not None and isinstance(exc_val, TimeoutReached):
+            if exc_val.args[0] == self:
+                self.fired = True
+                g_logger.info("Timeout {self.timeout} reached.")
+                return True  # don't reraise
+
+    def __bool__(self):
+        return self.fired
+
+
+class PitchError(Exception):
+    pass
+
+
+class RollError(Exception):
+    pass
+
+
+class PitchMonitor:
+    def __init__(self, robot, pitch_limit):
+        self.robot = robot
+        self.pitch_limit = pitch_limit
+        self.fired = False
+
+    def update(self):
+        if self.pitch_limit is not None and self.robot.pitch is not None:
+            if abs(self.robot.pitch) > self.pitch_limit:
+                raise PitchError(self)
+
+    def __enter__(self):
+        self.fired = False
+        self.handle = self.robot.register(self.update)
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.robot.unregister(self.handle)
+        if exc_val is not None and isinstance(exc_val, PitchError):
+            if exc_val.args[0] == self:
+                self.fired = True
+                g_logger.info("Pitch limit {math.degrees(self.pitch_limit)} reached.")
+                return True  # don't reraise
+
+    def __bool__(self):
+        return self.fired
+
+
+class RollMonitor:
+    def __init__(self, robot, roll_limit):
+        self.robot = robot
+        self.roll_limit = roll_limit
+        self.fired = False
+
+    def update(self):
+        if self.roll_limit is not None and self.robot.roll is not None:
+            if abs(self.robot.roll) > self.roll_limit:
+                raise RollError(self)
+
+    def __enter__(self):
+        self.fired = False
+        self.handle = self.robot.register(self.update)
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.robot.unregister(self.handle)
+        if exc_val is not None and isinstance(exc_val, RollError):
+            if exc_val.args[0] == self:
+                self.fired = True
+                g_logger.info("Pitch limit {math.degrees(self.roll_limit)} reached.")
+                return True  # don't reraise
+
+    def __bool__(self):
+        return self.fired
diff --git a/subt/test_monitors.py b/subt/test_monitors.py
new file mode 100644
index 000000000..bdbb8e395
--- /dev/null
+++ b/subt/test_monitors.py
@@ -0,0 +1,110 @@
+import unittest
+import math
+from unittest import mock
+from datetime import timedelta
+from subt import monitors
+
+class Robot:
+
+    def __init__(self):
+        self.callbacks = []
+        self.time = timedelta()
+        self.pitch = 0
+        self.roll = 0
+
+    def update(self, dt=timedelta(milliseconds=101)):
+        self.time += dt
+        self.pitch += 0.1
+        self.roll += 0.15
+        for f in self.callbacks:
+            f()
+
+    def register(self, callback):
+        self.callbacks.append(callback)
+        return callback
+
+    def unregister(self, handle):
+        assert handle in self.callbacks
+        self.callbacks.remove(handle)
+
+
+class TimeoutTest(unittest.TestCase):
+
+    def test_timeout(self):
+        robot = Robot()
+        timeout = monitors.TimeoutMonitor(robot, timedelta(seconds=1))
+        with timeout:
+            for _ in range(100):
+                robot.update()
+            else:
+                self.assertTrue(False)
+        self.assertGreater(robot.time, timedelta(seconds=1))
+        self.assertTrue(timeout)
+
+    def test_stacked_timeout(self):
+        robot = Robot()
+        timeout_outside = monitors.TimeoutMonitor(robot, timedelta(seconds=1))
+        timeout_inside = monitors.TimeoutMonitor(robot, timedelta(seconds=0.5))
+        with timeout_outside:
+            with timeout_inside:
+                for _ in range(100):
+                    robot.update()
+            self.assertGreater(robot.time, timedelta(seconds=0.5))
+            self.assertLess(robot.time, timedelta(seconds=1))
+            self.assertTrue(timeout_inside)
+            self.assertFalse(timeout_outside)
+            for _ in range(100):
+                robot.update()
+        self.assertGreater(robot.time, timedelta(seconds=1))
+        self.assertTrue(timeout_outside)
+
+
+class PitchRollTest(unittest.TestCase):
+
+    def test_pitch(self):
+        robot = Robot()
+        pitch_limit = monitors.PitchMonitor(robot, math.radians(80))
+        with pitch_limit:
+            for _ in range(100):
+                robot.update()
+            else:
+                self.assertTrue(False)
+        self.assertTrue(pitch_limit)
+
+    def test_roll(self):
+        robot = Robot()
+        roll_limit = monitors.RollMonitor(robot, math.radians(80))
+        with roll_limit:
+            for _ in range(100):
+                robot.update()
+            else:
+                self.assertTrue(False)
+        self.assertTrue(roll_limit)
+
+    def test_stacked_roll(self):
+        robot = Robot()
+        max_roll_limit = monitors.RollMonitor(robot, math.radians(80))
+        with max_roll_limit:
+            mid_roll_limit = monitors.RollMonitor(robot, math.radians(20))
+            with mid_roll_limit:
+                for _ in range(100):
+                    robot.update()
+                else:
+                    self.assertTrue(False)
+            self.assertTrue(mid_roll_limit)
+            self.assertFalse(max_roll_limit)
+            for _ in range(100):
+                robot.update()
+            else:
+                self.assertTrue(False)
+            self.assertTrue(mid_roll_limit)
+            self.assertTrue(max_roll_limit)
+
+    def test_roll_logging(self):
+        with mock.patch("subt.monitors.g_logger") as logger:
+            robot = Robot()
+            roll = monitors.RollMonitor(robot, math.radians(20))
+            with roll:
+                robot.roll = 2
+                robot.update()
+            self.assertTrue(logger.info.called)