A Novel Low-Cost, Large Curvature Bend Sensor Based on a Bowden-Cable

Abstract

Bend sensors have been developed based on conductive ink, optical fiber, and electronic textiles. Each type has advantages and disadvantages in terms of performance, ease of use, and cost. This study proposes a new and low-cost bend sensor that can measure a wide range of accumulated bend angles with large curvatures. This bend sensor utilizes a Bowden-cable, which consists of a coil sheath and an inner wire. Displacement changes of the Bowden-cable’s inner wire, when the shape of the sheath changes, have been considered to be a position error in previous studies. However, this study takes advantage of this position error to detect the bend angle of the sheath. The bend angle of the sensor can be calculated from the displacement measurement of the sensing wire using a Hall-effect sensor or a potentiometer. Simulations and experiments have shown that the accumulated bend angle of the sensor is linearly related to the sensor signal, with an R-square value up to 0.9969 and a root mean square error of 2% of the full sensing range. The proposed sensor is not affected by a bend curvature of up to 80.0 m−1, unlike previous bend sensors. The proposed sensor is expected to be useful for various applications, including motion capture devices, wearable robots, surgical devices, or generally any device that requires an affordable and low-cost bend sensor.

Design and Evaluation of a Bowden-Cable-Based Remote Actuation System for Wearable Robotics

“…The input torque τ in corresponds to: A bending angle sensor based on a principle presented in [30] is used to measure the bending angle σ in an additional wire (sensing wire). Sheath and rope are fixed relatively to each other at the output.…”

“…For mechanical output powers higher than 3 W, the motor needs to be replaced by a more powerful alternative. By using a different Hall effect sensor, the measurable bending angle range can be increased [30].…”

A soft, synergy-based robotic glove for grasping assistance

“…Methods for detecting these changes have been recently presented and will be useful in future development of wearable, tendon-driven devices (Jeong and Cho, 2016).…”

Inspection and Reconstruction of Metal-Roof Deformation under Wind Pressure Based on Bend Sensors

“…We adopted the FS-L-0112-103-ST flex sensor (Spectra System, Salt Lake, UT, USA) in the experiment [ 13 ]. It is cheap, easy to integrate and requires no complicated signal processing.…”

“…Therefore, we chose bend sensors that can be conveniently pasted on the surface of metal roof panels to detect their local deformation. Bend sensors [ 13 ] are sensitive to deformation based on optical fiber, conductive ink, electronic textiles, piezoelectric zinc oxide (ZnO) thin films [ 14 ], and tailored nanocomposite materials [ 15 ]. Bend sensors have been widely used in different fields, from simple angle measurements to the bending amount of human body joints [ 13 , 16 , 17 , 18 ] and shape-sensing in mechanical structures [ 13 ].…”