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Active sensing using vibration with robot hand


In recent years, the demand for production using general-purpose robots has increased in order to achieve high-mix low-volume production. Because of this, the demand for automation of product inspection has also increased. On the other hand, except for visual inspection using cameras, dedicated machines are often used for automatic product inspection.
Therefore, in this research, we deal with the product inspection using a general-purpose robot hand. Specifically, it deals with vibration inspection that detects abnormalities inside the object that cannot be detected by visual inspection. By using a general-purpose robot hand for inspection, it is possible to detect abnormalities in products during production work, which is thought to lead to improved productivity.
We propose the inspection method that a robot hand attached a 6-axis force sensor to the fingertip grasps the object and applies vibration. Then, by analyzing the time-series data of the force at that time, the abnormality is detected. This time, evaluations are done by ROC-AUC (Area Under the Receiver Operating Characteristic Curve) for three features (the peak-to-peak value of the signal, the peak-to-peak value of the filtered signal(80-1000 Hz bandpass filter), and the power of high-frequecy vibration) of each axis. In addition, the parameters of vibration are determined using the Bayesian optimization method to improve detection accuracy.
We have conducted experiments and succeeded in inspecting the looseness of bolts of objects fastened with bolts (in a place that cannot be seen from the outside) and discriminating liquids with different viscosities in containers that cannot be seen from the outside.

Fig.1 Target: Bolt fastening in an opaque box.
Fig.2 Vibration to the target by the robot hand (vibrates in the direction of the arrow.)


  1. Fumiya Shimada, Kenichi Murakami, Taku Senoo, and Masatoshi Ishikawa, Bolt loosening detection using multi-purpose robot hand, The 2020 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM2020) (Boston, 2020.7.9 [online])/Proceedings, pp.1860-1866, (2020).
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