Sensors & Transducers
Vol. 270, Issue 3, November 2025, pp. 30-39
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Machine-learning-based Evaluation of Upper Limb Motion Using 8×8 Time-of-flight and LiDAR Sensors: SVM Classification and Deep Neural Network Analysis
1, * Yasutaka UCHIDA, 1 Eiichi OHKUBO, 1 Manami NISHI, 2 Tomoko FUNAYAMA and 3 Yoshiaki KOGURE
1
Teikyo University of Science, Dept. of Life Science, Adachi-ku,
120-0045 Tokyo, Japan
2
Teikyo University of Science, Dept. of Occupational therapy, Uenohara-shi,
409-0193 Yamanashi, Japan
3
Teikyo University of Science, professor emeritus, Adachi-ku,
120-0045 Tokyo, Japan
1
Tel.: +81369101010, Fax: +81369103800
E-mail: uchida@ntu.ac.jp
Received: 30 May 2025 / Revised: 10 Nov. 2025 / Accepted: 18 Nov. 2025 /
​Published: 28 Nov. 2025
​
Abstract:
Upper limb rehabilitation methods, such as the table sliding technique and pegboard exercises, are widely used
because of their low physical burden on patients. A critical aspect of these methods is the ability to evaluate whether the
exercises are appropriate for the patient’s condition and objectively assess the recovery progress. Traditionally, therapists have
relied on direct observations and predefined evaluation criteria to assess movement performance and recovery. However, these
approaches often require specialized equipment and technical expertise. To address these limitations, inertial measurement
units (IMUs) have been proposed as a means of quantifying task performance and supporting clinical decision-making using
objective data. Our previous studies, presented at SEIA’2024 and published in Sensors and Transducers, explored the
application of IMUs in upper limb rehabilitation. However, challenges remain regarding sensor miniaturization and
simultaneous multisensor measurements, owing to peg-size constraints. Recent advancements in time-of-flight (ToF) sensor
technology have enabled the development of compact and cost-effective sensors. ToF sensors offer privacy advantages by not
capturing direct images, making them suitable for healthcare applications. In this study, we compared two types of ToF-based
sensors: one that detects object presence within an 8×8 pixel area based on height and another that uses 360° infrared light to
measure object positions in 2D. We first applied support vector machine classification to the images obtained from both
sensors, followed by classification using TensorFlow. The results were analyzed to evaluate the differences in the classification
accuracy between the two sensor types and methods.
Keywords: Time of flight, LiDAR, Raspberry Pi, Upper limb rehabilitation, SVM, TensorFlow.
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