> For the complete documentation index, see [llms.txt](https://docs.hello-robot.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hello-robot.com/stretch4_docs/guides/hardware-guide.md).
# Hardware Guide
This manual provides the engineering data and user guidance for working with the Hello Robot Stretch 4 hardware .
## Disclaimer
{% hint style="warning" %}
The Hello Robot Stretch is intended for use in the research of mobile manipulation applications by users experienced in the use and programming of research robots. This product is not intended for general use in the home by consumers, and lacks the required certifications for such use. Please see the section on Regulatory Compliance for further details.
{% endhint %}
## Functional Specification
Full system datasheet [available here](https://drive.google.com/file/d/1lyNPdvGHvn5w1UVGlV-HEfL53Mco89LW/view?usp=sharing).
## Body Plan
## Hardware Architecture
## Robot Subsystems
### Base
The base is a 3-omniwheel holonomic drive. It includes 6 Laser Line Sensors to allow detection of stairs, thresholds, etc. Charging region and I/O ports are located in the "trunk" on one side of the base.
| | |
| ---------------------------------- | ---------------------------------------------------------------------------------------------- |
| Item | Notes |
| Holonomic Drive | 3X 8" diameter Omniwheels. |
| Line Sensor Array | 6X Pixart Laser Line Sensors for cliff and hazard monitoring. |
| Removable Shell for Battery Access | Please refer to the Battery Swap section. |
| Docking Region | Spring-loaded contacts mating with the Docking Station for wireless charging. |
| Charge Port |
Barrel Jack Connector. !! Only use the Official Hello Robot 36V Charger!!
|
| ON/SLEEP/OFF |
ON/OFF Button. ON : Green solid LED. SLEEP : Red blinking LED. OFF : No LED.
|
| ETH/USB/HDMI Ports |
ETH : 1X RJ45 Port. USB : 2X USB-A 2.0 & 1X USB-A 3.0 Ports. HDMI : 4K HDMI Port.
|
### Battery Swap
Stretch 4 features a removable battery that can be accessed by removing the top shell of the base.
| | | |
| ------ | ------------------------------------------------------ | ------------------------------------------------------------------------------- |
| Step 1 | Turn off robot. | Hold the power button for \~6 seconds until the LED turns off. |
| Step 2 | Remove base top shell. | Shell has magnets that keep it in place. No tool required. |
| Step 3 | Unplug the cable from the battery. | Press the latch and pull the cable. |
| Step 4 | Unlatch the battery from the top plate. | Flip both draw latches to release the battery from the strike plates. |
| Step 5 | Remove / Swap battery. | Be mindful when manipulating the battery: **it weighs 30lbs**!! |
| Step 6 | Secure the battery on the top plate with both latches. | Make sure the battery is securely held in place before moving to the next step. |
| Step 7 | Plug the cable to the battery. | Make sure the cable is latched to the battery before closing the robot. |
| Step 8 | Install top shell and turn the robot on. | That's it :) |
{% hint style="danger" %}
DO NOT charge the battery with any other charger that is not an official Hello Robot charger.
{% endhint %}
{% hint style="warning" %}
Replacing Stretch 4's battery is NOT a "hot swap". The robot will cut power during the swap.
{% endhint %}
Battery removal tutorial:
{% embed url="" %}
Battery installation tutorial:
{% embed url="" %}
{% hint style="warning" %}
**When lifting the robot (with or without the shipping box), please remove the battery.** The robot weighs \~60lbs without the battery, making it more comfortable to transport.
{% endhint %}
### Head
The head includes a high definition sensor suite with 2 Hemispherical LiDARs and 3 RGB Cameras. It also has a runstop, battery level indicators and a developer interface to allow for additional user hardware. The eye rings can be used for animations.
| | |
| ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Item | Notes |
| Hemispherical LiDAR (2X) | Dual Hemispherical 3D LiDAR (360° x 189°) provide a depth map of the world around the robot at all times with over 2,000,000 measurements per second. |
| Fisheye Camera (2X) |
Dual Global Shutter RGB Cameras (2.3MP) provide wide FOV; calibrated to LiDARs provide RGBD data all around the body. Eye LEDs for animation.
|
| Teleoperation Camera | High-Res RGB Camera (12MP) for remote teleoperation. |
| Runstop | The runstop allows the user to pause the motion of the four primary DOF (base, lift, and arm) by tapping the illuminated button on the head. When the runstop is enabled, these DOF are in a ‘Safety Mode’ that inhibits the motion controller at the firmware level. Disabling the runstop allows normal operation to resume. |
| State of Charge LEDs | 8X Discrete LEDs that indicate the battery State of Charge. |
| Speaker | Noise reduction microphone and speaker. |
| USB Hub | 1X USB-A 3.2 & 1X USB-C 3.2 Ports. |
#### Mounting Points
The top of the head includes 3x M4 threaded and 4x M5 threaded mounting points as shown below:
### Lift
The lift degree of freedom provides vertical translation of the arm. It is driven by a closed loop stepper motor, providing smooth and precise motion through a low gear-ratio belt drive. The brake release button allows the motion of the arm when the robot is off.
### Telescopic Arm
The arm comprises 5 telescoping aluminum links set on rollers. Its proprietary drive train is driven by a stepper motor with closed loop control and current sensing, allowing contact sensitivity during motion.
The retracted arm and wrist combined are designed to fit within the footprint of the base. The arm is designed to have:
* Reach: 0.55m
* Max payload (Retracted) : 4kg
* Max payload (Extended) : 2.5kg
### Dexterous Wrist
The Stretch 4 dexterous wrist is 3 DOF (Yaw, Pitch, Roll) fully internally cabled system with an OAK-D SR camera at the roll joint for precise grasping and servoing.
The quick connect interface at the roll joint gives freedom to the user to use different end effector tools.
A USB-A 2.0 Port for accessory mounting can be found at the top of the yaw joint shell.
Each joint is powered by a FeeTech SM80BL. The range of motion of each joint 310°.
{% embed url="" %}
#### Quick Connect Interface
Pressing the pink button next to the OAK-D SR Camera allows the tool to be removed.
If you would like to use your own end-effector tool with the quick connect interface, please contact for CAD and hardware support.
{% embed url="" %}
### Stretch Compliant Gripper
The Stretch Compliant Gripper utilizes a FeeTech SM80BL servo to drive the spring grasper mechanism.
It also includes Aruco tags to enable precise visual servoing, as well as mounting points to enable ‘Puppet’ based on-device data collection.
## Robot Accessories
### Parallel Jaw Gripper
The Parallel Jaw Gripper utilizes a FeeTech SM80BL servo to drive the linkage mechanism.
The fingers can be changed to a design of your choice. It comes standard with the ‘Aloha’ style fingers that have shown success in Physical AI for precise, dexterous manipulation.
It also includes Aruco tags to enable precise visual servoing, as well as mounting points to enable ‘Puppet’ based on-device data collection.
### Puppet Teleop Pistol Accessory
Stretch 4 comes with an accessory that attaches to the bottom of the Stretch Compliant Gripper or the Parallel Jaw Gripper. It can be used for data collection and remote control of a second Stretch 4 robot.
### NVIDIA Jetson Orin NX
The NVIDIA Jetson Orin NX comes installed within the Stretch base and is ready for development.
It includes 128GB NVME and 16GB memory. It has its own WiFi as well as Ethernet networking to the main compute.
### Docking Station
The docking station sits on a flat floor against a wall, allowing Stretch to autonomously dock itself and begin charging. It includes 3X reflective Aruco tags, enabling Stretch to detect the station in low-light or dark environment using its LiDARs.
## Robot Care
### Transporting the Robot
Stretch was designed to be transported in the back of a car, up a staircase, or around a building.
For short trips, the robot can be simply rolled around by grabbing its mast.
{% hint style="warning" %}
**For safety, please use two people to lift the robot.**
{% endhint %}
{% hint style="warning" %}
**When lifting the robot (with or without the shipping box), please remove the battery.** The robot weighs \~60lbs without the battery, making it more comfortable to transport.
{% endhint %}
{% hint style="warning" %}
In a car or in any other means of transportation, it is heavily recommended to transport Stretch 4 in its shipping box to not damage the robot or alter the calibration of the system.
{% endhint %}
{% hint style="info" %}
It may be picked up by its mast and carried up stairs as well. You can use the eye hook located on the top plate to attach a handle. You can also use the handle located on the bottom of the robot for a better grasp.
{% endhint %}
### Belt Tension
A neoprene timing belt drives the arm up and down the lift. It may loosen over long periods of time if it experiences sustained loading. In this case, slack will become visually apparent in the belt as the lift moves.
The belt is very straightforward to re-tension. Please contact for tensioning instructions.
### Keeping the Robot Clean
The robot surfaces can be wiped down with an alcohol wipe or a moist rag from time to time in order to remove any debris or oils that accumulate on the shells or mast.
The drive wheels can accumulate dust over time and begin to lose traction. They should be periodically wiped down as well.
If the robot cameras or LiDARs requires cleaning, use appropriate lens cleaning fluid and a microfiber cloth.
Fan filters at the bottom of the robot can accumulate dust over time and cause overheating in the base. Removing the dust with a soft brush will help keep thermals inside the base normal.
### Keeping the Robot Calibrated
The robot comes pre-calibrated with a robot-specific URDF. This calibration allows the LiDARs and cameras to accurately estimate its environment and own body.
The robot may become slightly uncalibrated over time for a variety of reasons, including normal wear and tear and loosening of robot joints, or accidental collisions or falls leading to high loads on the robot joints.
The calibration accuracy can be checked using the provided ROS tools. If necessary, the user can recalibrate the robot. See the [Stretch URDF Calibration Guide](https://github.com/hello-robot/stretch_ros2/tree/humble/stretch_calibration#overview) for more information.
### System Check
It is useful to periodically run stretch\_system\_check.py. This will check that the robot's hardware devices are present and within normal operating conditions.
## Regulatory Compliance
Stretch is not certified for use as a consumer device in the U.S., EU, or elsewhere.
Unless stated otherwise, Stretch is not subjected to compliance testing nor certified to meet any requirements, such as requirements for EMI, EMC, or ESD.
Per [FCC 47 CFR, Part 15, Subpart B, section 15.103(c)](https://www.law.cornell.edu/cfr/text/47/15.103), we claim Stretch as an exempted device, since it is a digital device used exclusively as industrial, commercial, or medical test equipment, where test equipment is equipment intended primarily for purposes of performing scientific investigations.
[OET BULLETIN NO. 62](https://transition.fcc.gov/bureaus/oet/info/documents/bulletins/oet62/oet62rev.pdf), titled "UNDERSTANDING THE FCC REGULATIONS FOR COMPUTERS AND OTHER DIGITAL DEVICES" from December 1993 provides further clarification of the Section 15.103(c) exemption: “*Test equipment* includes devices used for maintenance, research, evaluation, simulation and other analytical or scientific applications in areas such as industrial plants, public utilities, hospitals, universities, laboratories, automotive service centers and electronic repair shops.”
***
All materials are Copyright 2026 by Hello Robot Inc. Hello Robot and Stretch are registered trademarks.
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://docs.hello-robot.com/stretch4_docs/guides/hardware-guide.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.