Make your own Open-Source LegMap

The OSL is assembled from both machined and stock components. In selecting components used throughout the OSL, we attempted to minimize the price, lead times for machined parts, and the number of vendors from which stock parts are purchased. In addition, to ensure broad accessibility for researchers across diverse backgrounds, including those in controls, biomechanics, and clinical fields, we adhered to the following design principles for the Open-Source Leg hardware:


The OSL is designed to be assembled, controlled, and maintained with moderate 'hands-on' skills. To achieve this, we streamlined the number of components and suppliers. The majority of parts are machined from a single supplier, minimizing dependencies on other precision machine components or mechanisms.


We prioritized portability by ensuring that the OSL weighs less than its biological counterpart. Additionally, each joint is equipped with on-board batteries, sensing, and control, facilitating research activities outside of the traditional laboratory setting.

ComponentPrice (USD)
Machined Parts$9000.00
Actuators and Batteries$6900.00
Bearings and Fasteners$800.00
Angular Bearings$700.00

The OSL is a cost-effective solution, with a prototype ranging from approximately US$9,000 to 19,000, depending on degrees of freedom and sensing options. This affordability stands in stark contrast to commercially available powered prostheses, which can cost up to US$100,000 each, without providing access to control modifications.

These design principles collectively ensure that the OSL is not only user-friendly and adaptable but also cost-effective, making it a viable option for researchers with varying needs and resources. In addition, the OSL is designed to be highly customizable. Researchers have the flexibility to tailor the device to their specific needs, including adjusting the knee's series elastic element, selecting the foot type, and incorporating a load cell, among other customizable options. These customization options enable the OSL to be suited to the individual uses of each researcher. Both the knee and ankle functions either as a series elastic actuator (SEA) or rigid actuator, and the stiffness of the series elasticity can be selected by the researcher using custom designed spring disks. The springs fit inside the output pulley of the belt drive; the SEA configuration therefore does not change the volume of the OSL.

Drawings and Design Files

Drawings and STEP files for all the machined parts can be downloaded and sent to any machining shop of your choice. The drawings highlight only special features like hole placements, counterbores, etc in addition to tolerances.

Drawings/STEP Files for Knee w/ SEADownload
Drawings/STEP Files for Knee w/o SEADownload
Drawings/STEP Files for AnkleDownload
Quote for one or two Knee ProsthesesDownload
Quote for one or two Ankle ProsthesesDownload
Quote for one OSL v2.0 (Knee + Ankle)Download
STEP File for entire OSL AssemblyDownload

Note that the quotes above specify part color to be either natural or black. If you would like a different color, please communicate this to the manufacturer.

Bill of Materials

To streamline the manufacturing and assembly process, we've made the detailed bill of materials (BOM) easily accessible for download. Within the BOM, the Parts to Order sheet is your go-to resource for parts management. Each column of the BOM is described below.

AComponents are organized into distinct subsystems.
BCorresponding Solidworks part numbers.
CCorresponding McMaster-Carr part numbers.
DQuantity of each part needed for your assembly.
EDirect links embedded for quick access to ordering pages.
FRecommendations on quantities and ordering.
GDescription of each component for clarity.

Note that this BOM does not contain parts to build the E-stop, which is an emergency stop button that is recommended to be installed for safety reasons.