NexArm

NexArm is a desktop robotic arm sold by Hiwonder, a Shenzhen-based maker of educational robotics kits, for imitation-learning, teleoperation and embodied-AI coursework. Hiwonder markets it as an open-source "6-axis" arm with an all-metal body, serial-bus servos with magnetic encoders, and compatibility with the Hugging Face LeRobot framework.^[1][2] It is sold in several configurations: an ESP32-based arm with an optional K230 vision module, a leader-and-follower "Imitation Learning" pairing, and a "NexArm ROS" version that adds a Raspberry Pi or NVIDIA Jetson controller and a depth camera.^[1][2][3]

The arm is a vendor product with vendor documentation. Almost every figure in this article is a Hiwonder statement; the exceptions are noted. No independent measurement of its payload, reach or repeatability was located for this article, and the only third-party coverage found is a short blog post.^[9]

Vendor and product line

Hiwonder is the brand of Shenzhen Hiwonder Technology Co., Ltd., which describes itself as founded in 2015 and gives an address in the Bao'an District of Shenzhen, China. The company sells STEAM-education robots, robotic arms and servos, and says its products are used in more than 80 countries.^[8] Its GitHub documentation account, Hiwonder-docs, created a NexArm repository on April 2, 2026, and its storefront published three NexArm product listings during 2026.^[1][2][3][7]

Prices are the store's list prices on the date given and change without notice.

According to the ESP32-version documentation, the Starter Kit ships assembled with the arm, a 12 V adapter, cables and a screwdriver; the Standard Kit adds a base plate, screws and G-clamps; the Advanced Kit adds the K230 vision module with its bracket, a speaker and a card reader; and the Ultimate Kit adds a second power adapter and base plate, a NexArm leader arm, a PS3 wireless controller, 0.3-megapixel and 2-megapixel wide-angle cameras with wrist and external mounts, and a USB hub.^[5]

Hardware

Hiwonder's product pages give the following specifications for the ESP32 version. They are vendor figures and no test method is published for them.^[1][2]

The "6-axis" label counts the gripper. Hiwonder's LeRobot integration lists six joints named shoulder_pan, shoulder_lift, elbow_flex, wrist_flex, wrist_roll and gripper, and its imitation-learning tutorial assigns these names to servo IDs 6 down to 1.^[4][6] The arm therefore has five arm joints plus a gripper, the same layout as the SO-101, rather than six arm joints as in the reBot Arm B601 or seven as in OpenArm. In degrees of freedom terms it is a 5-DOF arm with an actuated gripper.

Hiwonder's own materials disagree about the servos. The product pages list a mix of HX-12H, HX-30HM and HX-65HM servos on the follower and HX-10HM and HX-12H servos on the leader, while the README of Hiwonder's LeRobot fork says both arms use six HX-30HM servos and elsewhere refers to "65 kg cm magnetic encoder servos".^[1][2][4] The fork's README also describes the HX-30HM as a 12-bit (0 to 4095) serial-bus servo communicating at 1 Mbps.^[4] Which description matches shipping units cannot be settled from the published material.

The NexArm ROS version is a different assembly: 245 x 131 x 617 mm, 1.3 kg, an ESP-WROOM ESP32 board for the servos plus a Raspberry Pi 5 or Jetson Nano, Orin Nano or Orin NX as the ROS computer, a 3D structured-light depth camera, an OLED status display, a 64 GB microSD card (Raspberry Pi 5 and Jetson Nano) or 128 GB SSD (Orin models), and Ubuntu 22.04 with ROS 2 Humble. Its servo list is given only as "HX-12H / HX-30HM / HX-65HM".^[3]

Software and documentation

The ESP32 version is programmed from the Arduino IDE. Hiwonder's documentation for it, hosted on a Sphinx documentation site and mirrored in the Hiwonder-docs/NexArm repository, has eight chapters: getting started; ESP32 development basics (single and multi-servo control, buttons, buzzer, OLED); motion control, including the forward and inverse kinematics derivation used by the firmware and the host-to-device serial protocol; AI vision features; "WonderMK" large-AI-model features; external controller integration; peripheral control; and an imitation-learning tutorial.^[5][6][7] The repository's main branch holds only a stub that tells readers to pick the "Esp32-Version" documentation, and states that the ROS version's documentation "will be released soon"; the ROSVersion branch contained an 11-byte placeholder on September 16, 2026.^[7]

Out of the box, the arm can be driven from Hiwonder's Wonderbot phone app over Bluetooth (slider control per servo, or Cartesian control through inverse kinematics with roll, pitch and gripper sliders), from a Windows PC application that also edits and downloads action groups, or from a PS3 wireless controller; a leader arm can drive a follower wirelessly using ESP-NOW.^[5] Factory firmware, the PC software, the Android APK and assembly videos are distributed through Google Drive folders linked from the documentation rather than from the repository.^[5]

The K230 vision module, included in the Advanced and Ultimate kits, is described by Hiwonder as a 6 TOPS device with more than 30 built-in vision functions, including colour, face and gesture recognition, YOLO-based detection, and multimodal large-model interaction; the product page lists demonstrations such as waste-card sorting, object tracking and voice-directed pick-and-place.^[1] The ROS version's page additionally advertises multimodal large-model integration and "OpenClaw" agents, a Hiwonder term whose implementation is not described on the page.^[3]

LeRobot integration

Hiwonder supports imitation learning through its own fork of LeRobot, Hiwonder-official/lerobot-nexarm, created on July 8, 2026 under the Apache 2.0 licence inherited from the upstream project. The fork adds a nexarm_follower robot class, examples/nexarm configuration files, and a README describing the setup: the leader arm is an ESP32 board reading its servos, the follower arm is an ESP32 with an AT32F421 co-processor, and both connect to the host by USB serial. Two USB cameras (a top-down "front" view and a "wrist" view, 640 x 480 at 30 frames per second) supply the visual observations.^[4] The README documents a simple frame-based serial protocol with commands to set speed and acceleration, enter a "LeRobot bridge mode" on the follower, read or write six servo positions, and toggle torque.^[4]

The documentation's imitation-learning chapter walks through installing Miniconda and Hiwonder's LeRobot environment, finding the serial ports and cameras, teleoperating, recording a dataset (its example uses 50 episodes), training an ACT policy with policy.type=act for 100,000 steps, and running inference on the arm.^[6] Hiwonder's product page says the arm can run policies such as ACT, diffusion policy and Pi0, but neither it, the tutorial nor the fork's README publishes success rates or other results for any trained policy.^[2][4][6]

As of September 16, 2026, the upstream huggingface/lerobot repository's robots directory listed SO-100/101, Koch, LeKiwi, OpenArm, reBot B601 and several other platforms but no NexArm entry, so NexArm users depend on Hiwonder's fork.^[10]

Openness

Hiwonder calls NexArm open source and the fork's README says that "all schematics, firmware, and code are open source".^[4] What is actually published is narrower than that sentence suggests. The documentation repository carries no licence file, the firmware and host software are distributed as downloads from Google Drive rather than as versioned source in a public repository, and the product pages and getting-started documentation reviewed for this article link no CAD files.^{[1][2][3][5][7]} The LeRobot fork is the one component with a clear licence, Apache 2.0.^[4] Readers who need a licence for the mechanical design or firmware should confirm it with Hiwonder; the OSHWA-certified, CERN-OHL-licensed reBot Arm and the Apache-licensed SO-101 files are the relevant points of comparison.

Reception

Robotic Gizmos, a hobbyist robotics blog, ran a short item on NexArm on July 29, 2026, summarising the vendor's description (ESP32 plus AT32 architecture, metal body, LeRobot compatibility, K230 vision module).^[9] The Hiwonder fork had three GitHub stars and one fork on September 16, 2026, and the documentation repository had none.^[4][7] No peer-reviewed paper, benchmark result or independent teardown of NexArm was found in the sources consulted for this article.

Comparison with the SO-101

Hiwonder positions NexArm one step above its own SO-ARM101 kit. Its fork README claims 500 g payload against 200 g, ±2 mm against ±3 mm repeatability, a 0.5 m against 0.4 m workspace, dual-output-shaft servos against single-shaft, and a metal body against printed PLA.^[4] The SO-101 figures in that comparison are Hiwonder's; the SO-101 project's README and bill of materials publish no payload, reach or repeatability specification.^[11] The two arms share the same five-joint-plus-gripper layout, and the SO-101 follower likewise uses 1/345-geared servos, though its leader mixes 1/147, 1/191 and 1/345 gearing where Hiwonder cites a single 1:147 ratio for the NexArm leader.^[2][11]

References

1. ^1 ^2 ^3 ^4 ^5 ^6 ^7 ^8Hiwonder. "Hiwonder NexArm Open-Source VLA Embodied AI Robotic Arm with ESP32 & AT32 Dual-Chip Design, AI Vision, Large AI Model, and K230 Vision Module," product page (specification table; variants and prices; store metadata gives a publication date of April 30, 2026). Accessed September 16, 2026. hiwonder.com/...nexarm
2. ^1 ^2 ^3 ^4 ^5 ^6 ^7 ^8 ^9Hiwonder. "Hiwonder NexArm LeRobot VLA Open-Source 6-Axis Robotic Arm for Embodied AI, Imitation Learning, and ESP32 Development," product page (500 mm reach, 500 g payload, ±2 mm repeatability; 1:147 and 1:345 gear ratios; prices; published May 14, 2026). Accessed September 16, 2026. hiwonder.com/...nexarm6-axis
3. ^1 ^2 ^3 ^4 ^5 ^6Hiwonder. "Hiwonder NexArm Open-Source ROS Robotic Arm VLA Embodied AI Kit," product page (ROS-version specification table; controller variants and prices; published July 6, 2026). Accessed September 16, 2026. hiwonder.com/...nexarm-ros
4. ^1 ^2 ^3 ^4 ^5 ^6 ^7 ^8 ^9 ^10Hiwonder. "Hiwonder-official/lerobot-nexarm," fork of huggingface/lerobot (README: hardware overview, joint layout, serial protocol, comparison with SO-ARM101; repository created July 8, 2026; Apache-2.0). Accessed September 16, 2026. github.com/...lerobot-nexarm
5. ^1 ^2 ^3 ^4 ^5Hiwonder. "1. Getting Started," NexArm documentation, ESP32 version (kit contents, app and PC software control, firmware downloads). Accessed September 16, 2026. wiki.hiwonder.com/...1_Getting_Started_NexArm
6. ^1 ^2 ^3 ^4Hiwonder. "8. Imitation Learning Tutorial," NexArm documentation, ESP32 version (servo naming, data collection, ACT training, inference). Accessed September 16, 2026. wiki.hiwonder.com/...8_Imitation_Learning_Tutorial
7. ^1 ^2 ^3 ^4 ^5Hiwonder. "Hiwonder-docs/NexArm," documentation source repository (created April 2, 2026; branches main, ESPVersion, ROSVersion, LearningVersion; no licence file). Accessed September 16, 2026. github.com/...NexArm
8. ^Hiwonder. "About," company page (Shenzhen Hiwonder Technology Co., Ltd.; founded 2015; Shenzhen address). Accessed September 16, 2026. hiwonder.com/...about
9. ^1 ^2Robotic Gizmos. "Hiwonder NexArm Open Source Robotic Arm with Vision AI." July 29, 2026. roboticgizmos.com/hiwonder-nexarm
10. ^Hugging Face. "huggingface/lerobot," `src/lerobot/robots` directory listing. Accessed September 16, 2026. github.com/...robots
11. ^1 ^2TheRobotStudio. "Standard Open SO-100 & SO-101 Arms," README and bill of materials. Accessed September 16, 2026. github.com/...SO-ARM100