SNR modeling and material dependency test of a low-cost and simple to fabricate 3D force sensor for soft robotics

Tomo, Tito Pradhono; Wong, Wai Keat; Schmitz, Alexander; Kristanto, Harris; Somlor, Sophon; Hwang, Jinsun; Sugano, Shigeki

doi:10.1109/sii.2016.7844036

Cited by 4 publications

(4 citation statements)

References 24 publications

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“…Figure 13 shows the obtained curves for SNR values. These results verify that the sensor can reach values between 58 dB and 65 dB, which are analogous to values presented for similar magnetic sensors [33]. Moreover, we notice that the SNR is influenced more significantly by the force applied to the sensor than by the amperage on the coil.…”

Section: Signal-to-noise Ratiosupporting

confidence: 88%

A Multimodal, Adjustable Sensitivity, Digital 3-Axis Skin Sensor Module

Holgado

Tomo

Somlor

et al. 2020

Sensors

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This paper presents major improvements to a multimodal, adjustable sensitivity skin sensor module. It employs a geomagnetic 3-axis Hall effect sensor to measure changes in the position of a magnetic field generated by an electromagnet. The electromagnet is mounted on a flexible material, and different current values can be supplied to it, enabling adjustments to the sensitivity of the sensor during operation. Capacitive sensing has been added in this iteration of the module, with two sensing modalities: “pre-touch” detection with proximity sensing and normal force capacitive sensing. The sensor has been designed to be interconnected with other sensor modules to be able to cover large surfaces of a robot with normal and shear force sensing and object proximity detection. Furthermore, this paper introduces important size reductions of the previous sensor design, calibration results, and further analysis of other sensor characteristics.

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Section: Signal-to-noise Ratiosupporting

confidence: 88%

A Multimodal, Adjustable Sensitivity, Digital 3-Axis Skin Sensor Module

Holgado

Tomo

Somlor

et al. 2020

Sensors

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“…Therefore, there is no data in between these two values. The SNR value was higher compared to our previous work [6]. In Table I, the SNR values of uSkin for the flat (i.e.…”

Section: E Signal To Noise Ratiocontrasting

confidence: 52%

“…As our sensor uses magnetic field changes induced by the skin deformation as its sensing principle, different object materials, in particular ferromagnetic objects, can potentially affect the measurement. Also our preliminary work showed that different kinds of material that are in contact with the sensor may affect its output response [6]. For compensating the influence of the external magnetic field or material properties, a reference sensor could be used.…”

Section: Current Limitationsmentioning

confidence: 99%

“…However, each 3-axis force measurement unit requires a volume of 14x14x7 mm, resulting in a low spatial density; also making it difficult to cover a multi-curved shape, such as a fingertip, with this sensor. More recently, we introduced a single 3-axis Hall-effect based skin sensor including its characterization and SNR modeling in [5] and [6]. Subsequently, this sensor was upgraded into a flat distributed skin sensor for robot phalanges with 4x4 load cells (each 3-axis) per module and the sensor was integrated into the Allegro Hand [7].…”

Section: Introductionmentioning

confidence: 99%

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Covering a Robot Fingertip With uSkin: A Soft Electronic Skin With Distributed 3-Axis Force Sensitive Elements for Robot Hands

Tomo

Schmitz

Wong

et al. 2018

IEEE Robot. Autom. Lett.

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Distributed tactile sensing is crucial to perform stable, subtle, and precise manipulation so that a robot can recognize and handle objects properly. However, currently existing skin sensors still have common problems such as complex and expensive production or are difficult to integrate into robot hands. In particular, a practical distributed soft skin sensor system that can cover various parts of the robot hand, measure force in 3axis, with a subcentimeter spatial density, and digital output at the same time does not exist yet. This paper discusses uSkin, a soft, distributed, 3-axis force sensor for robot hands and presents its implementation for multi-curved fingertips. The sensor is lowcost, easy to manufacture, and can measure normal and shear forces. The experimental results revealed that this sensor has 10% hysteresis for perpendicular force with a maximum range of 6 N. The Signal to Noise Ratio (SNR) value of 54 dB for 0.4 N load was achieved, which constitutes the state of the art for this kind of sensors. Evaluation experiments also showed that the distributed 3-axis load cells could produce vectors that represent the shape of objects. This opens the possibility that the sensor can be used for classifying different shapes. Furthermore, the fingertip sensor was installed on the Allegro hand and the changing force measurements when the robot is grasping an object are presented.

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