Rugged and Compact Three-Axis Force/Torque Sensor for Wearable Robots
<p>Structure of the proposed sensor. (<b>a</b>) Exploded view of the proposed sensor. (<b>b</b>) Prototype of the proposed sensor.</p> "> Figure 2
<p>Sectional view and the bolt-nut connection of the proposed sensor.</p> "> Figure 3
<p>Cross-sectional view of the sensing structure of the proposed sensor. (<b>a</b>) Displacement by applied force. (<b>b</b>) Displacement by applied torque.</p> "> Figure 4
<p>Conceptual view for measuring three-axis force. (<b>a</b>) Isometric view of the bolt head and three electrodes. (<b>b</b>) Displacement of electrodes when Z-axis force is applied. (<b>c</b>) Displacement of electrodes when Y-axis torque is applied.</p> "> Figure 5
<p>Schematics of the three-axis force/torque element and the decomposed forces applied to the sensor.</p> "> Figure 6
<p>Force and torque configuration with the decomposed forces applied to the eye-nut.</p> "> Figure 7
<p>Actual components of the sensor.</p> "> Figure 8
<p>Fabrication process of the developed sensor. (<b>a</b>) Connect the sensing board with the base part. (<b>b</b>) Add a silicon adhesive. (<b>c</b>) Hang a conductive wire. (<b>d</b>) Tight with a bolt. (<b>e</b>) Coagulate adhesive. (<b>f</b>) Fabrication complete.</p> "> Figure 9
<p>The model of the DNN calibration method.</p> "> Figure 10
<p>Experimental setup for comparing the three-axis force/torque data measured by the developed sensor with the reference sensor. (<b>a</b>) Calibration setup used to obtain the measured data from the developed sensor and the reference sensor. (<b>b</b>) Actual assembled state.</p> "> Figure 11
<p>Calibration results. (<b>a</b>) Time domain responses of the capacitance change in the three sensing electrodes. (<b>b</b>) Time domain response of the z-direction force measured by the developed sensor (red dot) and the reference sensor (gray line). (<b>c</b>) Time domain response of the x-direction torque measured by the developed sensor and the reference sensor. (<b>d</b>) Time domain response of the y-direction torque measured by the developed sensor and the reference sensor.</p> "> Figure 12
<p>Hysteresis graph and estimation of the angles and magnitude of the applied forces. (<b>a</b>) Hysteresis graph of the developed sensor. (<b>b</b>) Position angle (<math display="inline"><semantics> <mi>θ</mi> </semantics></math>) and direction angle (<math display="inline"><semantics> <mi>γ</mi> </semantics></math>) of the applied forces. (<b>c</b>) Magnitude of the applied forces.</p> "> Figure 13
<p>Experiment for checking repeatability. (<b>a</b>) Front and side views of the experimental setup configuration. (<b>b</b>) Results of the three repeatability experiments.</p> "> Figure 14
<p>Experiment to evaluate high-load capacity. (<b>a</b>) Configuration of the experimental setup. (<b>b</b>) Experimental scene when loading mass disks of 10 kg, 20 kg, and 30 kg. (<b>c</b>) Result of the high-load capacity experiment.</p> "> Figure 15
<p>Conceptual assembly modeling of integration of the developed sensor and the wearable robot.</p> "> Figure 16
<p>Performance tests with the sensor integrated to an artificial muscle actuator. (<b>a</b>) Experimental setup composed of the developed sensor, reference sensor, and an artificial muscle. (<b>b</b>) Resulting force of the artificial muscle measured by the developed sensor (red dot) and the reference sensor (black line).</p> ">
Abstract
:1. Introduction
2. Development of the Proposed Sensor
2.1. Design of the Proposed Sensor
2.2. Sensing Principle
2.3. Fabrication Process
3. Experimental Evaluation
3.1. Calibration Using Deep Neural Network
3.2. Experiments
4. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Cell 1 | Cell 2 | Cell 3 | ||
---|---|---|---|---|
+ | + | + | + | |
- | - | - | - | |
+ | - | Δ | + | |
- | + | Δ | - | |
+ | - | + | - | |
- | + | - | + |
Quantity | Value | Unit |
---|---|---|
Sensing range of force | +300 | N |
Sensing range of torques | ±1, ±1 | Nm |
Resolution of force | 0.25 | N |
Resolution of torques | 1.38, 2.47 | m Nm |
Sensitivity of force | 0.0012 | pF/N |
Sensitivity of torques | 0.22, 0.12 | pF/Nm |
Relative error of force and torque | 2.25, 1.71, 1.64 | % of FSR * |
Average force repeatability | 1.75 | % of FSR * |
Hysteresis of force | 17.3 | % of FSR * |
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Jeong, H.; Choi, K.; Park, S.J.; Park, C.H.; Choi, H.R.; Kim, U. Rugged and Compact Three-Axis Force/Torque Sensor for Wearable Robots. Sensors 2021, 21, 2770. https://doi.org/10.3390/s21082770
Jeong H, Choi K, Park SJ, Park CH, Choi HR, Kim U. Rugged and Compact Three-Axis Force/Torque Sensor for Wearable Robots. Sensors. 2021; 21(8):2770. https://doi.org/10.3390/s21082770
Chicago/Turabian StyleJeong, Heeyeon, Kyungjun Choi, Seong Jun Park, Cheol Hoon Park, Hyouk Ryeol Choi, and Uikyum Kim. 2021. "Rugged and Compact Three-Axis Force/Torque Sensor for Wearable Robots" Sensors 21, no. 8: 2770. https://doi.org/10.3390/s21082770