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Bento Arm Hardware

The Bento Arm is an anthropometric robotic arm designed specifically for robotic prosthesis training and research applications. The Bento Arm includes 5 degrees of freedom (shoulder rotation, elbow flexion, wrist rotation, wrist flexion, hand open/close). The arm was designed to be 1:1 scale with anatomical proportions and uses the MX-series of Dynamixel actuators which include integrated position and velocity joint feedback and control. The Bento Arm is ideally suited for machine learning and sensory feedback research, but can also be used in general purpose robotics applications.

Build your own Bento Arm

The Bento Arm consists of off-the-shelf MX-series Dynamixel actuators and brackets, metric fasteners, and custom 3D printed parts. Instructions for building the arm and setting up the actuators can be found in 'Bento Arm - Assembly Guide.doc'. The assembly guide will be your main goto document while printing and building the arm and includes references to the other files in the repository:

  • Bill of Materials: A detailed list of the off-the-shelf materials and parts required to build the Bento Arm. Note: We have listed the distributors that we have used in the past as a point of reference, but be aware that there are multiple distributor options for each part and that we do not endorse the listed distributors in any way.
  • 3D Printing Guide: The printing guide includes a list of the 3D prints and print settings (Table 1) and how they relate to the parts in the main Solidworks assembly (Table 2).
  • 3D Print Files: The folder that contains the raw STL files as well as the .THING and .x3g files for 3D printing on a Makerbot Replicator 2. NOTE: The STL files have been adjusted to print with proper tolerances in the PLA material.
  • Electronics Wiring Diagram: The wiring diagram for building a cable to connect the actuators to power and control signals.
  • Solidworks Files: The folder that contains the Solidworks part and assembly files. The main assembly file for the entire arm is called 'main_assembly_OS_rev3.sldasm'. The parts and assemblies were modelled in Solidworks 2014 SP 5 and the part files are currently set to their PLA configurations.
  • STEP Files: This folder contains the STEP file for the main assembly and should be importable into most alternate 3D CAD softwares.


You can share your experience, new design, ideas, feature requests, or questions on the Bento Arm project forum.

If you would like to contribute to future official releases of the Bento Arm hardware we recommend contacting us on the forums to coordinate with our development team. To get started you will need to fork this repo and once your modification or enhancement is complete submit a pull request.


The Bento Arm hardware is released under the Creative Commons BY-SA 4.0 license. A local copy of the license that was forked from is available in the repository.


The 3d files and documentation for building the Bento Arm







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