The Turmell-Meter: In Vivo Ankle Kinematics by Using Draw-Wire and Inertial Sensors

Abstract

Objective: To implement a prototype specific for human ankle kinematics studies in limited spaces, immobile, or lying down patients. Based on anatomy and anthropometry, using a screw theory model, draw-wire and inertial sensors were employed Methods: We included ankle injury studies to highlight the importance of measuring the in vivo range of motion; we studied the ankle anatomy, biomechanics, and anthropometry to estimate the size and movements of the device. We simulated the biaxial representation of ankle motion through the product of exponential mapping. Finally, we designed a structure based on trilateration by projecting tetrahedrons, an acquisition circuit with firmware and calibration software. Results: The prototype has two main parts: support and adjustable platform. We proposed a method to find the position by projecting three apexes on the base using draw-wire sensors, an acquisition board, a single-board computer, a display, Bluetooth, Wi-Fi, and two inertial measurement units. The power source had battery backup with boost and buck converters. Conclusion: We proposed an ankle model in the screw theory framework, a method for localization, and a novel device for in vivo measurements specific for lying patients on a bed, the ground, outdoors, or remote locations without complex setups. The double-battery management is robust and long lasting. Significance: The device is an alternative for measuring the range of motion in laying down patients. We will use it in modeling, diagnosis, and rehabilitation.<br>

Using Screw Theory for the Kinematics and Statics Design of the Turmell-Bot: a Cable-Driven, Reconfigurable and Compliant Ankle Rehabilitation Parallel Robot

“…We introduced the dimensions and geometrical model in a Jupyter Notebook using a SageMath 10 kernel [82] in [83]. We provided the CAD model in [84] and the sources in GitHub [85]. We identified the tendons involved in ankle movement acting as an over-actuated biomechanism (two degrees-of-freedom and four tendon groups).…”

Applying Screw Theory to Design the Turmell-Bot: A Cable-Driven, Reconfigurable Ankle Rehabilitation Parallel Robot

“…Following that, we used the open-source digital model (z-anatomy) [21] to identify the bones, insertions, tendons, and muscles related to the ankle movement. We introduced the dimensions and geometrical model in a Jupyter Notebook using a SageMath 10 kernel [82] in [83]. We provided the CAD model in [84] and the sources in GitHub [85].…”

“…We introduced the dimensions and geometrical model in a Jupyter Notebook using a SageMath 10 kernel [82] in [83]. We provided the CAD model in [84] and the sources in GitHub [85]. We identified the tendons involved in ankle movement acting as an over-actuated biomechanism (two degrees-of-freedom and four tendon groups).…”

“…Additionally, it is used for model-based control. We provided the XML source in [85]. The simulation process is easy, and we edited the tendon lengths in the text editor and reloaded the simulation in MuJoCo 2.3.1.…”

Turmell-Bot: A Configurable Cable-Driven Robot for Human Ankle Physical Therapy

“…We introduced the dimensions and geometrical model in a Jupyter Notebook using a SageMath 10 kernel [30]. Furthermore, we provided an online Jupyter notebook [31], and the CAD model [32], also on Figshare [33] and GitHub repository [34]. We identified that the tendons involved in ankle movement are an over-actuated bio-mechanism (two degrees-of-freedom four tendon groups).…”