diff --git a/stretch_core/nodes/command_groups.py b/stretch_core/nodes/command_groups.py
index 202d581..8d44642 100644
--- a/stretch_core/nodes/command_groups.py
+++ b/stretch_core/nodes/command_groups.py
@@ -7,62 +7,162 @@ from hello_helpers.gripper_conversion import GripperConversion
 
 
 class SimpleCommandGroup:
-    def __init__(self, joint_name, acceptable_joint_error=0.015, clip_ros_tolerance=0.001):
+    def __init__(self, joint_name, joint_range, acceptable_joint_error=0.015, clip_ros_tolerance=0.001):
+        """Simple command group to extend
+
+        Attributes
+        ----------
+        name: str
+            joint name
+        range: tuple(float)
+            acceptable joint bounds
+        active: bool
+            whether joint is active
+        index: int
+            index of joint's goal in point
+        goal: dict
+            components of the goal
+        error: float
+            the error between actual and desired
+        acceptable_joint_error: float
+            how close to zero the error must reach
+        clip_ros_tolerance: float
+            the clip ros tolerance
+        """
+        self.name = joint_name
+        self.range = joint_range
+        self.active = False
+        self.index = None
+        self.goal = {"position": None}
+        self.error = None
         self.clip_ros_tolerance = clip_ros_tolerance
         self.acceptable_joint_error = acceptable_joint_error
-        self.joint_name = joint_name
-
-    def update(self, joint_names, invalid_joints_error_func, **kwargs):
-        self.use_joint = False
-        if self.joint_name in joint_names:
-            self.joint_index = joint_names.index(self.joint_name)
-            self.use_joint = True
-        return True
 
     def get_num_valid_commands(self):
-        if self.use_joint:
+        """Returns number of active joints in the group
+
+        Returns
+        -------
+        int
+            the number of active joints within this group
+        """
+        if self.active:
             return 1
+
         return 0
 
-    def set_goal(self, point, invalid_goal_error_func, **kwargs):
-        self.joint_goal = False
-        self.goal_joint_ros = None
-        self.goal_joint_hello = None
-        if self.use_joint:
-            self.goal_joint_ros = point.positions[self.joint_index]
-            self.goal_joint_hello = self.ros_to_mechaduino(self.goal_joint_ros)
-            self.joint_goal = True
-        if self.joint_goal and (self.goal_joint_hello is None):
-            error_string = 'received goal point that is out of bounds. The first error that was caught is that the {0} goal is invalid ({1} = {2}).'.format(self.joint_name, self.joint_name, self.goal_joint_ros)
-            invalid_goal_error_func(error_string)
-            return False
+    def update(self, commanded_joint_names, invalid_joints_callback, **kwargs):
+        """Activates joints in the group
+
+        Checks commanded joints to activate the command
+        group and validates joints used correctly.
+
+        Parameters
+        ----------
+        commanded_joints_names: list(str)
+            list of commanded joints in the trajectory
+        invalid_joints_callback: func
+            error callback for misuse of joints in trajectory
+
+        Returns
+        -------
+        bool
+            False if commanded joints invalid, else True
+        """
+        self.active = False
+        self.index = None
+        if self.name in commanded_joint_names:
+            self.index = commanded_joint_names.index(self.name)
+            self.active = True
+
         return True
 
-    def ros_to_mechaduino(self, joint_ros):
-        return joint_ros
+    def set_goal(self, point, invalid_goal_callback, **kwargs):
+        """Sets goal for the joint group
+
+        Sets and validates the goal point for the joints
+        in this command group.
+
+        Parameters
+        ----------
+        point: trajectory_msgs.JointTrajectoryPoint
+            the target point for all joints
+        invalid_goal_callback: func
+            error callback for invalid goal
+
+        Returns
+        -------
+        bool
+            False if commanded goal invalid, else True
+        """
+        # TODO: validate commanded_joint_names and all arrays in JointTrajectoryPoint (positions/velocities/etc) are same size
+        self.goal = {"position": None}
+        if self.active:
+            self.goal['position'] = point.positions[self.index]
+            if self.goal['position'] is None:
+                err_str = 'Received goal point that is out of bounds. The first error that was caught is that the {0} goal is invalid ({1} = {2}).'.format(self.name, self.name, self.goal['position'])
+                invalid_goal_callback(err_str)
+                return False
+
+        return True
 
     def init_execution(self, robot, robot_status, **kwargs):
-        pass
+        """Starts execution of the point
+
+        Uses Stretch's Python API to begin moving to the
+        target point.
+
+        Parameters
+        ----------
+        robot: stretch_body.robot.Robot
+            top-level interface to Python API
+        robot_status: dict
+            robot's current status
+        """
+        raise NotImplementedError
 
     def update_execution(self, robot_status, **kwargs):
-        # This method needs to be implemented. It also needs to set self.joint_error.
-        return None
+        """Monitors progress of joint group
+
+        Checks against robot's status to track progress
+        towards the target point.
+
+        This method must set self.error.
+
+        Parameters
+        ----------
+        robot_status: dict
+            robot's current status
+
+        Returns
+        -------
+        float/None
+            error value if group active, else None
+        """
+        raise NotImplementedError
 
     def goal_reached(self):
-        if self.joint_goal:
-            return (abs(self.joint_error) < self.acceptable_joint_error)
-        else:
-            return True
+        """Returns whether reached target point
+
+        Returns
+        -------
+        bool
+            if active, whether reached target point, else True
+        """
+        if self.active:
+            return (abs(self.error) < self.acceptable_joint_error)
+
+        return True
 
 
 class HeadPanCommandGroup(SimpleCommandGroup):
     def __init__(self, head_pan_calibrated_offset, head_pan_calibrated_looked_left_offset):
-        SimpleCommandGroup.__init__(self, 'joint_head_pan', acceptable_joint_error=0.15, clip_ros_tolerance=0.001)
+        SimpleCommandGroup.__init__(self, 'joint_head_pan', (0, 0), acceptable_joint_error=0.15)
         self.head_pan_calibrated_offset = head_pan_calibrated_offset
         self.head_pan_calibrated_looked_left_offset = head_pan_calibrated_looked_left_offset
 
     def init_execution(self, robot, robot_status, **kwargs):
-        if self.joint_goal:
+        if self.active:
             pan_error = self.update_execution(robot_status, backlash_state=kwargs['backlash_state'])
             robot.head.move_by('head_pan', pan_error)
             if pan_error > 0.0:
@@ -71,29 +171,32 @@ class HeadPanCommandGroup(SimpleCommandGroup):
                 kwargs['backlash_state']['head_pan_looked_left'] = False
 
     def update_execution(self, robot_status, **kwargs):
+        self.error = None
         backlash_state = kwargs['backlash_state']
-        if self.joint_goal:
+        if self.active:
             if backlash_state['head_pan_looked_left']:
                 pan_backlash_correction = self.head_pan_calibrated_looked_left_offset
             else:
                 pan_backlash_correction = 0.0
-            self.current_joint_hello = robot_status['head']['head_pan']['pos'] + self.head_pan_calibrated_offset + pan_backlash_correction
-            self.joint_error = self.goal_joint_hello - self.current_joint_hello
-            self.joint_target = self.goal_joint_hello
-            return self.joint_error
-        else:
-            return None
+            pan_current = robot_status['head']['head_pan']['pos'] + \
+                          self.head_pan_calibrated_offset + pan_backlash_correction
+            self.error = self.goal['position'] - pan_current
+            return self.error
+
+        return None
 
 
 class HeadTiltCommandGroup(SimpleCommandGroup):
-    def __init__(self, head_tilt_calibrated_offset, head_tilt_calibrated_looking_up_offset, head_tilt_backlash_transition_angle):
-        SimpleCommandGroup.__init__(self, 'joint_head_tilt', acceptable_joint_error=0.52, clip_ros_tolerance=0.001)
+    def __init__(self, head_tilt_calibrated_offset,
+                 head_tilt_calibrated_looking_up_offset,
+                 head_tilt_backlash_transition_angle):
+        SimpleCommandGroup.__init__(self, 'joint_head_tilt', (0, 0), acceptable_joint_error=0.52)
         self.head_tilt_calibrated_offset = head_tilt_calibrated_offset
         self.head_tilt_calibrated_looking_up_offset = head_tilt_calibrated_looking_up_offset
         self.head_tilt_backlash_transition_angle = head_tilt_backlash_transition_angle
 
     def init_execution(self, robot, robot_status, **kwargs):
-        if self.joint_goal:
+        if self.active:
             tilt_error = self.update_execution(robot_status, backlash_state=kwargs['backlash_state'])
             robot.head.move_by('head_tilt', tilt_error)
             if tilt_error > (self.head_tilt_backlash_transition_angle + self.head_tilt_calibrated_offset):
@@ -102,36 +205,36 @@ class HeadTiltCommandGroup(SimpleCommandGroup):
                 kwargs['backlash_state']['head_tilt_looking_up'] = False
 
     def update_execution(self, robot_status, **kwargs):
+        self.error = None
         backlash_state = kwargs['backlash_state']
-        if self.joint_goal:
+        if self.active:
             if backlash_state['head_tilt_looking_up']:
                 tilt_backlash_correction = self.head_tilt_calibrated_looking_up_offset
             else:
                 tilt_backlash_correction = 0.0
-            self.current_joint_hello = robot_status['head']['head_tilt']['pos'] + self.head_tilt_calibrated_offset + tilt_backlash_correction
-            self.joint_error = self.goal_joint_hello - self.current_joint_hello
-            self.joint_target = self.goal_joint_hello
-            return self.joint_error
-        else:
-            return None
+            tilt_current = robot_status['head']['head_tilt']['pos'] + \
+                           self.head_tilt_calibrated_offset + tilt_backlash_correction
+            self.error = self.goal['position'] - tilt_current
+            return self.error
+
+        return None
 
 
 class WristYawCommandGroup(SimpleCommandGroup):
     def __init__(self):
-        SimpleCommandGroup.__init__(self, 'joint_wrist_yaw', acceptable_joint_error=0.015, clip_ros_tolerance=0.001)
+        SimpleCommandGroup.__init__(self, 'joint_wrist_yaw', (0, 0))
 
     def init_execution(self, robot, robot_status, **kwargs):
-        if self.joint_goal:
+        if self.active:
             robot.end_of_arm.move_by('wrist_yaw', self.update_execution(robot_status))
 
     def update_execution(self, robot_status, **kwargs):
-        if self.joint_goal:
-            self.current_joint_hello = robot_status['end_of_arm']['wrist_yaw']['pos']
-            self.joint_error = self.goal_joint_hello - self.current_joint_hello
-            self.joint_target = self.goal_joint_hello
-            return self.joint_error
-        else:
-            return None
+        self.error = None
+        if self.active:
+            self.error = self.goal['position'] - robot_status['end_of_arm']['wrist_yaw']['pos']
+            return self.error
+
+        return None
 
 
 class GripperCommandGroup: