High-Speed High-Precision Proximity Sensor for Detection of Tilt, Distance, and Contact

Abstract

We developed a fingertip-size proximity sensor that detects the distance to and the tilt angle of the surface of an object with the peak-to-peak distance error less than 1/129th (<31 µm) and the measuring time less than 1/10th (<1 ms) those of existing sensors. In addition, we realized the task of catching a fragile object (paper balloon) with a high-speed robot hand equipped with the sensor. High-speed, high-precision sensing enables contact detection independently of the contact force. We describe a robust contact detection method that does not depend on the reflectance, the tilt angle, or the shape of target objects surface. In experiments, we confirmed that the sensor could measure a distance of 2.85-20 mm (resolution: 44 µm in <3 mm) and a tilt angle of ±45 • (error: 1.47 • ) for objects with reflectances of 18% and 90%. We demonstrated that the hand could catch the paper balloon when dropped from a height of about 20 cm without crushing it.

High-Speed, Small-Deformation Catching of Soft Objects Based on Active Vision and Proximity Sensing

“…The detection range includes distances of 2.85 ∼ 20 mm, tilt angles of −45 ∼ +45 • , and measurement times less than 1 ms. Moreover, within 2.85∼3 mm, the resolution is 50 μm and the peak-to-peak repeat measurement error is 13 μm [3]. The sensor can detect an object until it contacts the rubber on the sensor surface.…”

“…The sensor can detect an object until it contacts the rubber on the sensor surface. In our previous work [3], we proposed contact detection that did not depend on the contact force with only proximity sensing. The first objective of this study is to propose a combination of high-speed vision-and proximity-based controls.…”

“…D YNAMIC throwing and hitting of a rigid ball using a bat [1], [2] have been realized using a high-speed robot hand and arm with 1 ms visual feedback so far. We propose proximity sensor-based contact detection in which "zero distance" is defined as "contact", and we demonstrated the catching of a soft object at a high speed [3]. A combination of vision and proximity feedbacks enables continuous sensing from noncontact to contact states with 1 ms and high resolution without visual occlusion.…”

“…1. We used the high-speed and high-precision proximity sensor [3] in addition to the high-speed multifingered hand and high-speed vision sensor [2], to realize the following: 1. high-speed, high-resolution sensing, 2. reduction in the impact force and vibration, and 3. adaptation to variations in the softness and size of objects. We demonstrate catching of a marshmallow and paper balloon that are exceptionally soft and difficult to catch with small deformation.…”

A General‐Purpose Safety Light Curtain Using ToF Sensor for End Effector on Human Collaborative Robot

“…Several sensors for a robot gripper have been proposed [18][19][20][21], and most of them detect a gripping state [18,19] or proximity position of a work [20,21]. However, many of these sensors do not detect outside of an end effector to increase safety.…”