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Sensors 2019, 19(2), 303; https://doi.org/10.3390/s19020303

Assistive Grasping Based on Laser-point Detection with Application to Wheelchair-mounted Robotic Arms

1
Industrial Research Institute of Robotics and Intelligent Equipment, Harbin Institute of Technology, Weihai 264209, China
2
Department of Industrial Engineering, University of Houston, Houston, TX 77004, USA
*
Author to whom correspondence should be addressed.
Received: 25 December 2018 / Revised: 10 January 2019 / Accepted: 11 January 2019 / Published: 14 January 2019
(This article belongs to the Special Issue Semantic Representations for Behavior Analysis in Robotic system)
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Abstract

As the aging of the population becomes more severe, wheelchair-mounted robotic arms (WMRAs) are gaining an increased amount of attention. Laser pointer interactions are an attractive method enabling humans to unambiguously point out objects and pick them up. In addition, they bring about a greater sense of participation in the interaction process as an intuitive interaction mode. However, the issue of human–robot interactions remains to be properly tackled, and traditional laser point interactions still suffer from poor real-time performance and low accuracy amid dynamic backgrounds. In this study, combined with an advanced laser point detection method and an improved pose estimation algorithm, a laser pointer is used to facilitate the interactions between humans and a WMRA in an indoor environment. Assistive grasping using a laser selection consists of two key steps. In the first step, the images captured using an RGB-D camera are pre-processed, and then fed to a convolutional neural network (CNN) to determine the 2D coordinates of the laser point and objects within the image. Meanwhile, the centroid coordinates of the selected object are also obtained using the depth information. In this way, the object to be picked up and its location are determined. The experimental results show that the laser point can be detected with almost 100% accuracy in a complex environment. In the second step, a compound pose-estimation algorithm aiming at a sparse use of multi-view templates is applied, which consists of both coarse- and precise-matching of the target to the template objects, greatly improving the grasping performance. The proposed algorithms were implemented on a Kinova Jaco robotic arm, and the experimental results demonstrate their effectiveness. Compared with commonly accepted methods, the time consumption of the pose generation can be reduced from 5.36 to 4.43 s, and synchronously, the pose estimation error is significantly improved from 21.31% to 3.91%. View Full-Text
Keywords: wheelchair-mounted robotic arm; human-robot interaction; laser point; CNN wheelchair-mounted robotic arm; human-robot interaction; laser point; CNN
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Zhong, M.; Zhang, Y.; Yang, X.; Yao, Y.; Guo, J.; Wang, Y.; Liu, Y. Assistive Grasping Based on Laser-point Detection with Application to Wheelchair-mounted Robotic Arms. Sensors 2019, 19, 303.

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