# Knowledge Base **URL:** https://forum.hello-robot.com/c/knowledge-base/13.md [Latest](https://forum.hello-robot.com/latest.md) · [Categories](https://forum.hello-robot.com/categories.md) --- ## [About the Knowledge Base category](https://forum.hello-robot.com/t/about-the-knowledge-base-category/612)
**Author:** [@aedsinger](https://forum.hello-robot.com/u/aedsinger)\ **Replies:** 0
Check here for snippets, workarounds, and other practical information to productively work with Stretch. Note that more complete instruction for using Stretch can still be found in Stretch Docs and its tutorials. --- ## [Lightweight Stretch 3 Data Recorder for Dex Teleop](https://forum.hello-robot.com/t/lightweight-stretch-3-data-recorder-for-dex-teleop/1523)
**Author:** [@Jason\_Koubi](https://forum.hello-robot.com/u/Jason_Koubi)\ **Replies:** 0\ **Last updated:** [August 11, 2026, 5:07pm UTC](https://forum.hello-robot.com/t/lightweight-stretch-3-data-recorder-for-dex-teleop/1523 "2026-08-11T17:07:36Z")
We’ve been working on a lightweight Stretch 3 data collection workflow for imitation learning built directly on top of standalone Stretch Dex Teleop. The recorder runs without ROS 2 and keeps dependencies on the robot m… --- ## [The position or the shape of the object](https://forum.hello-robot.com/t/the-position-or-the-shape-of-the-object/1489)
**Author:** [@Mallak\_Alqaisi](https://forum.hello-robot.com/u/Mallak_Alqaisi)\ **Replies:** 3\ **Last updated:** [April 21, 2026, 6:45pm UTC](https://forum.hello-robot.com/t/the-position-or-the-shape-of-the-object/1489 "2026-04-21T18:45:23Z")
Hello, Does the shape or position of an object affect the execution of a task? For instance, when running the command python -m stretch.app.ai\_pickup --use\_llm to pick up a book, I notice that the gripper fails to grasp… --- ## [How to extend battery life with portable battery?](https://forum.hello-robot.com/t/how-to-extend-battery-life-with-portable-battery/433)
**Author:** [@Theophile\_Gervet](https://forum.hello-robot.com/u/Theophile_Gervet)\ **Replies:** 5\ **Last updated:** [August 11, 2025, 8:58am UTC](https://forum.hello-robot.com/t/how-to-extend-battery-life-with-portable-battery/433 "2025-08-11T08:58:00Z")
Hey Hello Robot team and community! We want to use Stretch for experiments that take more than 2 consecutive hours (up to 8-10 hours in a day) and thus need longer battery life on the robot. What’s the best way to acco… --- ## [Calibrate Dynamic Limits for Reliable Trajectory Tracking](https://forum.hello-robot.com/t/calibrate-dynamic-limits-for-reliable-trajectory-tracking/1342)
**Author:** [@shehab](https://forum.hello-robot.com/u/shehab)\ **Replies:** 0\ **Last updated:** [June 3, 2025, 10:56pm UTC](https://forum.hello-robot.com/t/calibrate-dynamic-limits-for-reliable-trajectory-tracking/1342 "2025-06-03T22:56:34Z")
Calibrate Dynamic Limits for Reliable Trajectory Tracking Both the Stretch Python API and the stretch\_ros2 package offer the ability to have Stretch track spline trajectories defined by joint waypoints. This can be valua… --- ## [Remote Connection to StretchWebTeleop using ngrok: DEBUGGING](https://forum.hello-robot.com/t/remote-connection-to-stretchwebteleop-using-ngrok-debugging/1280)
**Author:** [@keshavshankar](https://forum.hello-robot.com/u/keshavshankar)\ **Replies:** 4\ **Last updated:** [March 21, 2025, 8:03pm UTC](https://forum.hello-robot.com/t/remote-connection-to-stretchwebteleop-using-ngrok-debugging/1280 "2025-03-21T20:03:46Z")
Recently, I achieved remote control of the stretch\_web\_teleop using these instructions, and some additional debugging, so I thought I would post them in hopes of helping others with similar issues. This will allow you t… --- ## [Generating URDFs On-the-Fly](https://forum.hello-robot.com/t/generating-urdfs-on-the-fly/1215)
**Author:** [@bshah](https://forum.hello-robot.com/u/bshah)\ **Replies:** 0\ **Last updated:** [January 31, 2025, 4:18am UTC](https://forum.hello-robot.com/t/generating-urdfs-on-the-fly/1215 "2025-01-31T04:18:36Z")
If you’re writing a library or app for Stretch that uses the robot’s URDF to do FK, IK, motion planning, perception, etc., consider switching to using the Stretch URDF library to generate URDFs on-the-fly: import stretc… --- ## [Aloha 2 Gripper on Stretch 3](https://forum.hello-robot.com/t/aloha-2-gripper-on-stretch-3/960)
**Author:** [@Mohamed\_Fazil](https://forum.hello-robot.com/u/Mohamed_Fazil)\ **Replies:** 2\ **Last updated:** [August 26, 2024, 6:11pm UTC](https://forum.hello-robot.com/t/aloha-2-gripper-on-stretch-3/960 "2024-08-26T18:11:43Z")
Hi all, we have an experimental implementation of the Aloha 2 Gripper installed on Stretch 3, and we were also able to do Dex teleop with it. Here are the hardware and software instructions for installing and using the A… --- ## [QT applications error out due to conflict with cv2 (Could not load the Qt platform plugin "xcb")](https://forum.hello-robot.com/t/qt-applications-error-out-due-to-conflict-with-cv2-could-not-load-the-qt-platform-plugin-xcb/1047)
**Author:** [@Mohamed\_Fazil](https://forum.hello-robot.com/u/Mohamed_Fazil)\ **Replies:** 0\ **Last updated:** [July 22, 2024, 6:42pm UTC](https://forum.hello-robot.com/t/qt-applications-error-out-due-to-conflict-with-cv2-could-not-load-the-qt-platform-plugin-xcb/1047 "2024-07-22T18:42:08Z")
We would like to address an existing bug that will likely occur using Python scripts that import the cv2 library and have a component that uses the linux apt installed QT platform to run a GUI. The error output would loo… --- ## [Use Gamepad controller to teleop robot remotely when connected to same wifi](https://forum.hello-robot.com/t/use-gamepad-controller-to-teleop-robot-remotely-when-connected-to-same-wifi/1005)
**Author:** [@vipul](https://forum.hello-robot.com/u/vipul)\ **Replies:** 5\ **Last updated:** [June 7, 2024, 9:06pm UTC](https://forum.hello-robot.com/t/use-gamepad-controller-to-teleop-robot-remotely-when-connected-to-same-wifi/1005 "2024-06-07T21:06:06Z")
Hii- I have a use case where i want to operate the robot remotely situated at a different location using gamepad controller and view the camera feed on the screen remotely. Stretch3 has a web browser to where we can vi… --- ## [ToolNone workaround for Trajectories](https://forum.hello-robot.com/t/toolnone-workaround-for-trajectories/945)
**Author:** [@byrnete](https://forum.hello-robot.com/u/byrnete)\ **Replies:** 1\ **Last updated:** [March 27, 2024, 2:45am UTC](https://forum.hello-robot.com/t/toolnone-workaround-for-trajectories/945 "2024-03-27T02:45:33Z")
Not sure if this has been posted yet, but I couldn’t find anything and other’s might be having this issue. I’ve been working with a Stretch RE1, and took off the Stretch Gripper it came with. After doing this, I followe… --- ## [Full Body Inverse Kinematics via Optimization](https://forum.hello-robot.com/t/full-body-inverse-kinematics-via-optimization/839)
**Author:** [@Michal](https://forum.hello-robot.com/u/Michal)\ **Replies:** 0\ **Last updated:** [November 7, 2023, 12:54pm UTC](https://forum.hello-robot.com/t/full-body-inverse-kinematics-via-optimization/839 "2023-11-07T12:54:49Z")
In the past there was a method proposed and a discussion about inverse kinematics on the stretch. In short this method works by simplifying the base of the robot to a prismatic joint in the forward/backward direction of … --- ## [Occupancy Grids vs Max Height Images](https://forum.hello-robot.com/t/occupancy-grids-vs-max-height-images/834)
**Author:** [@mlalji](https://forum.hello-robot.com/u/mlalji)\ **Replies:** 2\ **Last updated:** [November 2, 2023, 2:30pm UTC](https://forum.hello-robot.com/t/occupancy-grids-vs-max-height-images/834 "2023-11-02T14:30:23Z")
I am attempting to use the stretch\_navigation ros package to autonomusly map my current environment. I am using explore\_lite, a ros package that sends goals to move\_base which allows it to explore what they call “frontie… --- ## [My experience porting FUNMAP to ROS 2](https://forum.hello-robot.com/t/my-experience-porting-funmap-to-ros-2/799)
**Author:** [@Atharva\_Pusalkar](https://forum.hello-robot.com/u/Atharva_Pusalkar)\ **Replies:** 0\ **Last updated:** [September 4, 2023, 4:13am UTC](https://forum.hello-robot.com/t/my-experience-porting-funmap-to-ros-2/799 "2023-09-04T04:13:18Z")
Hello Stretch Community! I am Atharva Pusalkar, a graduate student at the Carnegie Mellon Robotics Institute (CMU RI), advised by Prof. Yonatan Bisk and Prof. Zackory Erickson. I joined Hello Robot as an intern this sum… --- ## [Physical aspects of the Robot for Simulation](https://forum.hello-robot.com/t/physical-aspects-of-the-robot-for-simulation/792)
**Author:** [@Mohamed\_Fazil](https://forum.hello-robot.com/u/Mohamed_Fazil)\ **Replies:** 0\ **Last updated:** [August 24, 2023, 1:02am UTC](https://forum.hello-robot.com/t/physical-aspects-of-the-robot-for-simulation/792 "2023-08-24T01:02:23Z")
Hi Stretch Community, We have been working towards supporting research works that use Stretch in a simulation environment and groups trying to achieve close-to-real dynamics of the real robot. Therefore, we have gathere… --- ## [URDF Mass Parameters](https://forum.hello-robot.com/t/urdf-mass-parameters/789)
**Author:** [@aedsinger](https://forum.hello-robot.com/u/aedsinger)\ **Replies:** 0\ **Last updated:** [August 21, 2023, 11:42pm UTC](https://forum.hello-robot.com/t/urdf-mass-parameters/789 "2023-08-21T23:42:29Z")
Greetings! We’ve recently updated the Stretch URDF data to include accurate mass and inertial data. As you can see in this PR, the updated URDFs include new inertial data. The process we used to generate this data is: … --- ## [Braking at Hardstops during Velocity Control](https://forum.hello-robot.com/t/braking-at-hardstops-during-velocity-control/785)
**Author:** [@Mohamed\_Fazil](https://forum.hello-robot.com/u/Mohamed_Fazil)\ **Replies:** 0\ **Last updated:** [August 17, 2023, 6:59pm UTC](https://forum.hello-robot.com/t/braking-at-hardstops-during-velocity-control/785 "2023-08-17T18:59:47Z")
With Stretch Body v0.5.3, we have introduced a safety braking mechanism during velocity control for all the joints. When a joint travels too near and towards the hardstops, the braking mechanism automatically dampens the… --- ## [Calibrating zeros for the Dex Wrist roll/pitch/yaw joints](https://forum.hello-robot.com/t/calibrating-zeros-for-the-dex-wrist-roll-pitch-yaw-joints/768)
**Author:** [@Anant\_Rai](https://forum.hello-robot.com/u/Anant_Rai)\ **Replies:** 2\ **Last updated:** [August 15, 2023, 2:51am UTC](https://forum.hello-robot.com/t/calibrating-zeros-for-the-dex-wrist-roll-pitch-yaw-joints/768 "2023-08-15T02:51:33Z")
Hi, I have a hello robot whose 0, 0, 0 rpy doesn’t seem aligned with gravity. I feel this could be cause of overuse but not sure. Wanted to know how can we calibrate the dexterous wrist manually so as to fix this misal… --- ## [Location of the robot](https://forum.hello-robot.com/t/location-of-the-robot/771)
**Author:** [@Humberto\_Andres\_Hida](https://forum.hello-robot.com/u/Humberto_Andres_Hida)\ **Replies:** 4\ **Last updated:** [July 20, 2023, 5:26pm UTC](https://forum.hello-robot.com/t/location-of-the-robot/771 "2023-07-20T17:26:01Z")
Hi I want to ask if there is any topic, which i can subscribe to know the coordinates of the robot based on the global coordinates o a map, or other to know that. --- ## [Inverse Kinematics Tutorial & Workshop Recording](https://forum.hello-robot.com/t/inverse-kinematics-tutorial-workshop-recording/639)
**Author:** [@bshah](https://forum.hello-robot.com/u/bshah)\ **Replies:** 17\ **Last updated:** [July 14, 2023, 8:23am UTC](https://forum.hello-robot.com/t/inverse-kinematics-tutorial-workshop-recording/639 "2023-07-14T08:23:51Z")
New tutorial for inverse kinematics on Stretch has been released on Github! You can preview the tutorial on Github, and instructions to run it are within the notebook itself. Additionally, I’m hosting a workshop in 2 … --- ## [Stretch Expected Run Time](https://forum.hello-robot.com/t/stretch-expected-run-time/710)
**Author:** [@Visaacan\_Rathiraj](https://forum.hello-robot.com/u/Visaacan_Rathiraj)\ **Replies:** 2\ **Last updated:** [June 21, 2023, 5:00pm UTC](https://forum.hello-robot.com/t/stretch-expected-run-time/710 "2023-06-21T17:00:31Z")
We have ran some tests with different robots and battery configurations to understand the continuous run time given a specific compute load. All tests were run using this command below roslaunch Stretch\_navigation mappi… --- ## [Using the Wacc expansion header for a UART device](https://forum.hello-robot.com/t/using-the-wacc-expansion-header-for-a-uart-device/167)
**Author:** [@Lionel\_Zhang](https://forum.hello-robot.com/u/Lionel_Zhang)\ **Replies:** 9\ **Last updated:** [June 1, 2023, 3:06am UTC](https://forum.hello-robot.com/t/using-the-wacc-expansion-header-for-a-uart-device/167 "2023-06-01T03:06:17Z")
Hello! We are planning to swap our the Stretch gripper for a prosthetic hand that communicates using UART. For our initial testing, we have been using a UART to USB adapter that connects to the hand with TX, RX, GND. Af… --- ## [Navigation with ArUco Tags](https://forum.hello-robot.com/t/navigation-with-aruco-tags/483)
**Author:** [@hello-garv](https://forum.hello-robot.com/u/hello-garv)\ **Replies:** 3\ **Last updated:** [May 26, 2023, 5:24am UTC](https://forum.hello-robot.com/t/navigation-with-aruco-tags/483 "2023-05-26T05:24:42Z")
Hello Stretch Community! I am a masters student with Northwestern’s MS in Robotics program, and this summer, I have been interning with the fantastic Hello Robot crew. I was brought on to help develop for Stretch specif… --- ## [How to avoid Stretch RE1 battery problems](https://forum.hello-robot.com/t/how-to-avoid-stretch-re1-battery-problems/109)
**Author:** [@aedsinger](https://forum.hello-robot.com/u/aedsinger)\ **Replies:** 2\ **Last updated:** [May 19, 2023, 4:40am UTC](https://forum.hello-robot.com/t/how-to-avoid-stretch-re1-battery-problems/109 "2023-05-19T04:40:00Z")
Some of the Stretch units have experienced difficulty maintaining their battery charge, or difficulty recovering from a deep discharge. By adopting our recommended best practices you should be able to avoid problems. We… --- ## [Improving Battery Run Times](https://forum.hello-robot.com/t/improving-battery-run-times/726)
**Author:** [@Visaacan\_Rathiraj](https://forum.hello-robot.com/u/Visaacan_Rathiraj)\ **Replies:** 0\ **Last updated:** [May 19, 2023, 2:46am UTC](https://forum.hello-robot.com/t/improving-battery-run-times/726 "2023-05-19T02:46:01Z")
TLDR: If you are experiencing unexpected shutdowns of Stretch due to reduced battery runtime then this post can help you diagnose and fix the issue. Battery maintenance is a complex subject. The Battery Maintenance Guid… --- ## [Using the Battery Health Tool](https://forum.hello-robot.com/t/using-the-battery-health-tool/714)
**Author:** [@Visaacan\_Rathiraj](https://forum.hello-robot.com/u/Visaacan_Rathiraj)\ **Replies:** 0\ **Last updated:** [May 19, 2023, 1:29am UTC](https://forum.hello-robot.com/t/using-the-battery-health-tool/714 "2023-05-19T01:29:55Z")
Note: This tool can show false readings if users do not follow the procedure below The Battery Health Tool, allows users to get some insight on the current state of health of the Stretch’s battery. For accurate results … --- ## [Repairing Unhealthy Batteries](https://forum.hello-robot.com/t/repairing-unhealthy-batteries/713)
**Author:** [@Visaacan\_Rathiraj](https://forum.hello-robot.com/u/Visaacan_Rathiraj)\ **Replies:** 0\ **Last updated:** [May 19, 2023, 1:27am UTC](https://forum.hello-robot.com/t/repairing-unhealthy-batteries/713 "2023-05-19T01:27:03Z")
Please follow the Repair Battery Section in The Battery Maintenance Guides (Stretch RE1 and Stretch 2) for proper battery repair procedure Expected improvement of repair cycle: You should expect a minimum of 24% improv… --- ## [Working with Stretch - monitors, rolling tables, tethers, and more](https://forum.hello-robot.com/t/working-with-stretch-monitors-rolling-tables-tethers-and-more/53)
**Author:** [@hello-ck](https://forum.hello-robot.com/u/hello-ck)\ **Replies:** 4\ **Last updated:** [May 11, 2023, 11:16am UTC](https://forum.hello-robot.com/t/working-with-stretch-monitors-rolling-tables-tethers-and-more/53 "2023-05-11T11:16:17Z")
Hello everyone, I thought it would be helpful to start a discussion about how people work with Stretch. Even at Hello Robot, people have different styles. Below, I provide details about my personal development setup and… --- ## [Creating smooth motion using trajectories](https://forum.hello-robot.com/t/creating-smooth-motion-using-trajectories/671)
**Author:** [@bshah](https://forum.hello-robot.com/u/bshah)\ **Replies:** 5\ **Last updated:** [May 5, 2023, 7:34am UTC](https://forum.hello-robot.com/t/creating-smooth-motion-using-trajectories/671 "2023-05-05T07:34:58Z")
Suppose you wanted to program Stretch to draw a perfect circle. Like this: You might put Stretch in front of a whiteboard and hand it a marker. You need some points on a circle, and fortunately, numpy makes this … --- ## [Using the Robot Trace tool to debug Stretch Body](https://forum.hello-robot.com/t/using-the-robot-trace-tool-to-debug-stretch-body/629)
**Author:** [@aedsinger](https://forum.hello-robot.com/u/aedsinger)\ **Replies:** 0\ **Last updated:** [March 8, 2023, 6:28pm UTC](https://forum.hello-robot.com/t/using-the-robot-trace-tool-to-debug-stretch-body/629 "2023-03-08T18:28:52Z")
Starting with Stretch Body 0.4.26 and Stretch Factory v0.3.15 we have introduced a new debugging tool for Stretch Body called Robot Trace. Note: This tool is recommended for advanced users only The Robot Trace tool p… [Next page](https://forum.hello-robot.com/c/knowledge-base/13.md?page=1)