# I cannot manually set the depth of the ROV **URL:** \ **Category:** ArduSub\ **Tags:** pymavlink\ **Created:** [May 2, 2022, 10:12am UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065 "2022-05-02T10:12:34Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![robotmark](https://avatars.discourse-cdn.com/v4/letter/r/f4b2a3/32.png) [@robotmark](https://discuss.bluerobotics.com/u/robotmark)\ **Post date:** [May 2, 2022, 10:12am UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/1 "2022-05-02T10:12:34Z")
Hi, I want to set depth for ROV. I use the link [set-target-depth-attitude](https://www.ardusub.com/developers/pymavlink.html#set-target-depthattitude) in the code to set the depth, I found that no matter what number I set in the set\_target\_depth() function, the ROV was never able to reach my preset depth. ROV always maintains depth at a depth of about 15cm from the surface of the water. Why is this? Looking forward to your reply. ```auto """ Example of how to set target depth in depth hold mode with pymavlink """ import time import math # Import mavutil from pymavlink import mavutil # Imports for attitude from pymavlink.quaternion import QuaternionBase def set_target_depth(depth): """ Sets the target depth while in depth-hold mode. Uses https://mavlink.io/en/messages/common.html#SET_POSITION_TARGET_GLOBAL_INT 'depth' is technically an altitude, so set as negative meters below the surface -> set_target_depth(-1.5) # sets target to 1.5m below the water surface. """ master.mav.set_position_target_global_int_send( int(1e3 * (time.time() - boot_time)), # ms since boot master.target_system, master.target_component, coordinate_frame=mavutil.mavlink.MAV_FRAME_GLOBAL_INT, type_mask=( # ignore everything except z position mavutil.mavlink.POSITION_TARGET_TYPEMASK_X_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_Y_IGNORE | # DON'T mavutil.mavlink.POSITION_TARGET_TYPEMASK_Z_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_VX_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_VY_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_VZ_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_AX_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_AY_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_AZ_IGNORE | # DON'T mavutil.mavlink.POSITION_TARGET_TYPEMASK_FORCE_SET | mavutil.mavlink.POSITION_TARGET_TYPEMASK_YAW_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_YAW_RATE_IGNORE ), lat_int=0, lon_int=0, alt=depth, # (x, y WGS84 frame pos - not used), z [m] vx=0, vy=0, vz=0, # velocities in NED frame [m/s] (not used) afx=0, afy=0, afz=0, yaw=0, yaw_rate=0 # accelerations in NED frame [N], yaw, yaw_rate # (all not supported yet, ignored in GCS Mavlink) ) def set_target_attitude(roll, pitch, yaw): """ Sets the target attitude while in depth-hold mode. 'roll', 'pitch', and 'yaw' are angles in degrees. """ master.mav.set_attitude_target_send( int(1e3 * (time.time() - boot_time)), # ms since boot master.target_system, master.target_component, # allow throttle to be controlled by depth_hold mode mavutil.mavlink.ATTITUDE_TARGET_TYPEMASK_THROTTLE_IGNORE, # -> attitude quaternion (w, x, y, z | zero-rotation is 1, 0, 0, 0) QuaternionBase([math.radians(angle) for angle in (roll, pitch, yaw)]), 0, 0, 0, 0 # roll rate, pitch rate, yaw rate, thrust ) # Create the connection master = mavutil.mavlink_connection('udpin:0.0.0.0:14550') boot_time = time.time() # Wait a heartbeat before sending commands master.wait_heartbeat() # arm ArduSub autopilot and wait until confirmed master.arducopter_arm() master.motors_armed_wait() # set the desired operating mode DEPTH_HOLD = 'ALT_HOLD' DEPTH_HOLD_MODE = master.mode_mapping()[DEPTH_HOLD] while not master.wait_heartbeat().custom_mode == DEPTH_HOLD_MODE: master.set_mode(DEPTH_HOLD) # set a depth target set_target_depth(-0.5) time.sleep(10) # clean up (disarm) at the end master.arducopter_disarm() master.motors_disarmed_wait() ``` ---
**Author:** ![clyde](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/clyde/32/8563_2.png) [@clyde](https://discuss.bluerobotics.com/u/clyde)\ **Post date:** [May 2, 2022, 10:10pm UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/2 "2022-05-02T22:10:05Z")
Try commenting out the `X_IGNORE` and `Y_IGNORE` lines as well, see this example: [Don't ignore position · clydemcqueen/ardusub-gitbook@6b26cd3 · GitHub](https://github.com/clydemcqueen/ardusub-gitbook/commit/6b26cd3bdd5140ec9b0286fb161e311cc5b2a329) ArduSub will ignore the x and y in ALT\_HOLD mode – only the z will be used, see: [ardupilot/GCS\_Mavlink.cpp at master · ArduPilot/ardupilot · GitHub](https://github.com/ArduPilot/ardupilot/blob/master/ArduSub/GCS_Mavlink.cpp#L674) I hope this helps. /Clyde ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [May 3, 2022, 12:22am UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/3 "2022-05-03T00:22:23Z")
Hi @clyde, thanks for picking up on this - that’s a bug, so I’ve raised an issue for it [here](https://github.com/ArduPilot/ardupilot/issues/20680) 🙂 @robotmark in the meantime Clyde’s suggested workaround of not setting the ignore flags of X and Y position should avoid the issue, although maybe put a note in any code that does that that it will need to be modified once you’re using a newer version of ArduSub that has the fix included. ---
**Author:** ![robotmark](https://avatars.discourse-cdn.com/v4/letter/r/f4b2a3/32.png) [@robotmark](https://discuss.bluerobotics.com/u/robotmark)\ **Post date:** [May 6, 2022, 5:21am UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/4 "2022-05-06T05:21:19Z")
Thank you ! ---
**Author:** ![robotmark](https://avatars.discourse-cdn.com/v4/letter/r/f4b2a3/32.png) [@robotmark](https://discuss.bluerobotics.com/u/robotmark)\ **Post date:** [May 6, 2022, 5:21am UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/5 "2022-05-06T05:21:54Z")
Thank you very much ! ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [June 12, 2025, 3:09am UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/6 "2025-06-12T03:09:21Z")
For posterity, [the fix for this](https://github.com/ArduPilot/ardupilot/pull/20682) was merged into master at the time, and not backported to older releases, so requires ArduSub \>= 4.5. ---
**Author:** ![shefali](https://avatars.discourse-cdn.com/v4/letter/s/90db22/32.png) [@shefali](https://discuss.bluerobotics.com/u/shefali)\ **Post date:** [June 10, 2025, 7:51pm UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/7 "2025-06-10T19:51:41Z")
Hi, I am trying to send my BlueROV2 running a navigator board a Z value. There is no GPS attached so I’ve specified to ignore x y values. I would like this to work in a local frame, and not require any sort of global positioning. I’ve tried to execute this command in both ALT\_HOLD and MANUAL mode, but it doesn’t work. I’ve also tried to manually assign it an x.y position which didn’t seem to work (not shown in the code below but I can attach if it’s helpful). Is there a way to work around not having a GPS and still sending it depth in this way? Thanks in advance. I’ve pasted the code which doesn’t work below. ```auto import time # Import mavutil from pymavlink import mavutil import sys import os sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname( __file__ ), '..'))) import utils.bluerov_utils as utils def set_target_depth(depth): """ Sets the target depth while in depth-hold mode. 'depth' is technically an altitude, so set as negative meters below the surface -> set_target_depth(-1.5) # sets target to 1.5m below the water surface. """ master.mav.set_position_target_local_ned_send( int(1e3 * (time.time() - boot_time)), # ms since boot master.target_system, master.target_component, coordinate_frame=mavutil.mavlink.MAV_FRAME_LOCAL_NED, type_mask=( # ignore everything except z position mavutil.mavlink.POSITION_TARGET_TYPEMASK_X_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_Y_IGNORE | # DON'T mavutil.mavlink.POSITION_TARGET_TYPEMASK_Z_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_VX_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_VY_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_VZ_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_AX_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_AY_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_AZ_IGNORE | # DON'T mavutil.mavlink.POSITION_TARGET_TYPEMASK_FORCE_SET | mavutil.mavlink.POSITION_TARGET_TYPEMASK_YAW_IGNORE | mavutil.mavlink.POSITION_TARGET_TYPEMASK_YAW_RATE_IGNORE ), x=0, y=0, z=depth, vx=0, vy=0, vz=0, # velocities in NED frame [m/s] (not used) afx=0, afy=0, afz=0, yaw=0, yaw_rate=0 # accelerations in NED frame [N], yaw, yaw_rate # (all not supported yet, ignored in GCS Mavlink) ) # Create the connection master, armed = utils.arm() # set the desired operating mode # this doesn't work in manual mode either, or stabilize DEPTH_HOLD = 'ALT_HOLD' mapping = master.mode_mapping() DEPTH_HOLD_MODE = mapping[DEPTH_HOLD] for m in mapping: print(f"{m}: {mapping[m]}") while not master.wait_heartbeat().custom_mode == DEPTH_HOLD_MODE: master.set_mode(DEPTH_HOLD) boot_time = time.time() # set a depth target of 0.5 meters below the surface set_target_depth(-.5) # wait for a while at the target depth (adjust time as needed) time.sleep(10) # Wait for 30 seconds at the target depth master = utils.disarm(master) ``` ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [June 12, 2025, 10:16am UTC](https://discuss.bluerobotics.com/t/i-cannot-manually-set-the-depth-of-the-rov/12065/8 "2025-06-12T10:16:26Z")
Hi @shefali, welcome to the forum 🙂 I’ve moved your post here because it’s seemingly on the same topic. As specified in the solution above, setting just the Z position bit for depth control should work in ArduSub \>= 4.5 (which is the current stable). If you want to use it with an older version you’ll need to also comment out the X and Y position ignore bits because they’re treated as a group. If that doesn’t resolve your issue then there may be other issues with your code. In particular I’d suggest making sure you’re 1. [Waiting specifically for an _autopilot_ heartbeat](https://discuss.bluerobotics.com/t/controlling-pwm-values-with-python/12529/5) 2. Avoiding (or disabling) [relevant failsafes](https://discuss.bluerobotics.com/t/pymavlink-send-rc-issue/11302/2)