Dextra

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Dextra is a groundbreaking human-sized robotic hand that's being developed as an open-source and affordable alternative to commercial robotic hand prosthetics. As designed for use as a prosthesis, this cutting-edge robotic hand also has potential applications in education, research, or more general robotics projects. Key design features of Dextra include an adaptive grip, compact size, mechanical simplicity, and ease of replication. The robust mechanical design of Dextra is centered around the finger module. A finger module comprises a compact linear actuator based on a geared DC micro motor, position feedback provided by a magnetic encoder, and the mechanical printable finger itself. This module is used in all four fingers of the hand, with the thumb being a variation of this same design. To minimize size and mechanical complexity, Dextra's fingers are underactuated - they have more degrees of freedom (DOF) than actuators. Each finger module has three DOF and one motor, while the thumb boasts two DOF and one motor. Additionally, the thumb's abduction/adduction is independently actuated by a servomotor. The motion of Dextra's fingers is controlled by a position control loop. Each finger is controlled by a PID loop that takes a position setpoint as input and uses the feedback position measured by a magnetic quadrature encoder to adjust the real position of the DC motor driving the finger. To see Dextra in action, check out these videos: More details about Dextra's design and operation can be found on its hackaday.io project page (https://hackaday.io/project/9890-dextra) and on its Github repository (https://github.com/Alvipe/Dextra.git).