Open Source RoboticsRobots, software & learning

Dual Purpose Acrobot & Pendubot Platform

Robot / hardware build

Two-joint underactuated control testbench with two T-Motor actuators and selectable active/passive joint configurations. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

Build & first use →Official websiteUpstream build guideBill of materials

For
Researchers and educators familiar with dynamics, metal fabrication and CAN motor control [1]
Cost
No current cost yet. Upstream bill of materials [10]
Source rights
Named licenses are documented by part. Review licenses
Unknowns
host computer, tools, operating system not fully established. Review gaps

Source researched · Not tested by us
Sources checked · Research details

Licenses & related hardware

Requirements · Research details and dates

On this page

Overview

The Dual Purpose Acrobot & Pendubot Platform is a two-joint underactuated control testbench, not a general-purpose robot arm. Its T-Motor parts list specifies two AK80-6 actuators; Acrobot uses a passive shoulder and active elbow, while Pendubot uses an active shoulder and passive elbow. Use that named configuration when matching the mechanism, motor setup and controller rather than treating every alternative in the repository as one interchangeable build. [1] [10]

Is this for you?

Known limitations
  • Full mjbots hardware documentation is explicitly unfinished in this snapshot; not equivalent to the T-Motor setup.
  • STEP assembly is an exchange snapshot, not native parametric design or verified fit; design_A/C and BOM geometry must be matched.
  • Two-motor power/CAN/stop requirements need configuration-specific review; no current complete delivered build budget.

Editorial source-scope assessment; no execution, fit or compatibility test.

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] · Editorial assessment

What you need

Dependencies
  • Python>=3.8 recommended
  • Ubuntu20/22 dependency routes; make install or environment.yaml via mamba
  • Optional C++/iLQR, Acados and other controller extras are separate

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

Hardware & parts

Upstream bill of materials [10]

Hardware configuration

Two-joint underactuated control testbench with two T-Motor actuators and selectable active/passive joint configurations.

Editorial source-scope assessment; no execution, fit or compatibility test.

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] · Editorial assessment

Actuators
  • Two T-Motor AK80-6 units; chosen Acrobot/Pendubot mode activates one joint and leaves the other passive

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

Assembly & first use

Open the upstream getting-started guide [1]

  • Inspect the T-Motor Acrobot/Pendubot configuration and initial simulation route before choosing fabrication and motor-control hardware.
  • Follow the selected source installation/configuration route only after reconciling the stated version, hardware and dependency gaps.

Editorial source-scope assessment; no execution, fit or compatibility test.

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] · Editorial assessment

Cost

No current, complete configuration-specific build cost has been established for this profile.

Power, stop configuration and cost are separate work

The electrical document describes R-LINK as Windows-only and PCAN-USB as also supporting Linux; R-LINK's UART connection is used for configuration and calibration. Current interface compatibility was not tested. It also describes supply/backEMF handling and a stop circuit that must account for stored energy. Its discussion includes material adapted from a simple-pendulum example. Review it for the selected two-motor setup; this profile does not validate a circuit or prescribe a capacitor/supply combination. [7]

No current complete delivered build price was established. The mechanical/actuator list must be supplemented with fabrication, host, interface, power/stop hardware, tools, delivery and tax. The root BSD-3-Clause notice applies to project contributions; purchased motor/controller designs and vendor bodies retain separate rights. Original files are linked, not redistributed. No CAD-kernel, manufacturing, wiring, calibration, powered-control or performance test was performed. [2] [10] [13]

3D preview

Preview not available yet. Original assembly STEP bytes and file structure were inspected; no hosted preview or CAD-kernel fit validation has been performed. Match the selected configuration and third-party components before reusing geometry.

Model sources

Original assembly STEP bytes and file structure were inspected; no hosted preview or CAD-kernel fit validation has been performed. Match the selected configuration and third-party components before reusing geometry.

Project notes

What the physical sources establish

The inspected original double_pendulum.STEP is a complete exchange-file payload with solid and assembly declarations. Its byte hash and Git identity match the pinned source. This establishes a real geometry artifact, not assembly fit, tolerances or editable SolidWorks feature history. Match the selected geometry to the intended configuration and parts list before fabrication. [3] [9] [13]

The fabrication notes describe a folded-metal motor mount, lightweight sandwich links, an elbow motor and an end weight. The assembly instructions also explain cable routing around non-hollow motor shafts and a counter-extension when the second link is longer than the first. These are configuration details to resolve before ordering or making parts; they were not physically assembled here. [6] [9]

Start with a bounded software route

At reviewed revision 1e8544e67f3da72a51ee52fbbb278e131ce2a43f, the installation guide recommends Python 3.8 or later and provides Ubuntu 20/22 dependency routes. It documents make install, or creating the environment from environment.yaml with mamba before installation. C++/iLQR and Acados support have additional instructions; make pythonfull and controller extras bring larger dependencies. Start with the upstream examples/ideal directory and select the intended Acrobot or Pendubot example before expanding to additional optimizers or RL methods. No installation or simulation was run. [5] [11] [12]

The motor overview explicitly says fuller mjbots documentation will be added. Do not transfer the documented T-Motor BOM and configuration to that alternative and call it verified equivalent. [8]

What we checked

Source research only. Selected text and original artifact byte/container identities inspected; no upstream compilation, dependency installation, native CAD application/fit/strength validation, simulation, manufacturing, wiring/calibration, powered commissioning, control performance or assay performed. Original CAD remains private; source links are not permission to redistribute vendor/third-party material.

Not yet established

  • Requirements: operating system, host computer, tools

Updates

Upstream last updated
Not established
Latest release
Not established
Profile updated
Nov 1, 2026
Sources last checked
Nov 1, 2026
Next review
Dec 1, 2026
Reviewed revision
1e8544e67f3da72a51ee52fbbb278e131ce2a43f; original CAD snapshot identities retained separately

Source files and licenses

Distinct inspectable physical research design reference with actual source and a bounded next step. Original file inspection is not fabrication, physical operation or complete support qualification.

LayerAvailability / license
mechanical designavailable · BSD-3-Clause
Original STEP exchange payload byte/git identity and basic structure checked; no native parametric feature-history, topology, fit or manufacturing validation. Root project notice does not clear third-party/vendor bodies. [13] [2]
electronicsnot found · License not fully assessed
No complete source/rights review of bought-in motor/driver/Pi interface layers established within this bounded repository/hardware-document review; not a claim of absence elsewhere. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
firmwarenot found · License not fully assessed
No complete source/rights review of bought-in motor/driver/Pi interface layers established within this bounded repository/hardware-document review; not a claim of absence elsewhere. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
softwareavailable · BSD-3-Clause
Scoped repository declaration; purchased components, external software/labware/tool assets and vendor bodies have separate terms. No commercial/manufacturing or experimental-performance clearance implied. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
documentationavailable · BSD-3-Clause
Scoped repository declaration; purchased components, external software/labware/tool assets and vendor bodies have separate terms. No commercial/manufacturing or experimental-performance clearance implied. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

No model weights/dataset or separate hardware manufacturing claim selected for the initial source-inspection workflow.

References

Each source links to the exact revision we read. “Used for” shows where this page relies on it.

Correction guidance · Discussion is not enabled · Profile format 0.7.0-draft.5

Change history