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Markerless Computer-Vision Joint-Angle Analysis for Ergonomic Risk Assessment of Engineering Students During Bench-Work Practicum Rafael Girvan; Hasna Muthia Maghfira; Ferry Anugerah; Muhammad Rizal Cahyo Prayogo; Hartanto Prawibowo; Elta Diah Pasmanasari; Farika Tono Putri; Novie Susanto; Wiwik Purwati; Supriyo; Amrisal Kamal Fajri; Rifky Ismail
Journal of Mechanical Engineering and Applied Technology Vol. 4 No. 2 (2026): VOLUME 4 ISSUE 2 YEAR 2026 (JULY 2026)
Publisher : Politeknik Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jmeat.v4i2.7821

Abstract

Bench work (kerja bangku) is a foundational manual-skills practicum in mechanical and manufacturing engineering education. It requires sustained non-neutral postures—forward trunk flexion, downward neck flexion toward the vice, and repetitive upper-limb exertion—that expose students to work-related musculoskeletal disorder (WMSD) risk early in their careers. Conventional ergonomic evaluation relies on manual observation, which is subjective, labour-intensive, and difficult to scale across large student cohorts. This study presents a markerless computer-vision pipeline that estimates body joint angles from ordinary RGB video and automatically derives Rapid Upper Limb Assessment (RULA) scores for students performing bench-work tasks. Two-dimensional pose estimation localized anatomical landmarks; sagittal joint angles for the neck, trunk, upper arm, lower arm, and wrist were computed from landmark coordinates and mapped to RULA segment scores. Thirty engineering students were recorded performing five representative tasks (filing, hacksawing, marking/scribing, chiselling, and hand-tapping). The mean RULA grand score across tasks was 6.0, with 92% of observations falling in action levels 3–4 (“investigate and change”). Vision-derived joint angles agreed with manual goniometry to within a mean absolute error of 4.8°, and RULA grand scores matched an expert assessor within ±1 point in 96.7% of cases (weighted Cohen’s κ = 0.82). The results show that markerless computer vision offers a low-cost, objective, and scalable instrument for ergonomics education, posture feedback, and bench-station redesign.
Penerapan Teknologi Biodigester Bumdes Arum Mandiri Untuk Pengembangan Integrated Farming Dan Waste To Energy Erwan Tri Efendi Erwan; Supriyo; Anis Roihatin; Nur Fatowil Aulia
Dharma: Jurnal Pengabdian Masyarakat Vol. 7 No. 1 (2026): Mei
Publisher : Universitas Pembangunan Nasional "Veteran" Yogyakarta

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Abstract

The limited availability of fossil fuels and their negative impact on the environment has led to the increasing development of alternative energy sources, particularly new and renewable energy. One such alternative energy development is biogas derived from livestock waste. Arum Mandiri, a village-owned enterprise (Bumdes), located in Tegowanu Village, Tegowanu District, Grobogan Regency, manages a cattle farm with eight cows. The manure, which is still managed independently, has so far been used only as organic fertilizer for the community's agricultural needs. One adult cow alone can produce 10-15 kg of manure per day, resulting in nearly 80-120 kg of manure produced daily. However, only 10-20% of the organic fertilizer utilized from the cow manure must first be dried. Unused cow manure is ultimately disposed of, disrupting the environment and producing an unpleasant odor. Therefore, it is necessary to develop appropriate technology to optimize the utilization of cow manure and achieve economic value. The application of biodigester technology to produce biogas is a solution offered, considering its ease of installation and relatively affordable costs, and can promote energy independence. Keywords: cow dung, biogas, digester, renewable energy
Penerapan Mesin Gerinda Pengasah Pisau Dengan Sudut Ketajaman 45° Untuk Meningkatkan Proses Produksi UD. Hasil Logam Padang Yanuar; Mochamad Denny Surindra; Ignatius Gunawan Widodo; Atikah Ayu Janitra; Sri Harmanto; Ampala Khoryanton; Slamet Priyoatmojo; Supriyo; Luqman Al Huda; Muhammad Devan Balaya
AMMA : Jurnal Pengabdian Masyarakat Vol. 5 No. 6 : Juli (2026): AMMA : Jurnal Pengabdian Masyarakat
Publisher : CV. Multi Kreasi Media

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Abstract

This community service initiative was carried out to address the need to improve the productivity of the small and medium enterprises (SME) UD. Hasil Logam Kudus, which specialises in the production of animal feed chopping knives. The knife sharpening process is still carried out manually using a hand-held grinder, taking approximately 25 minutes per knife and resulting in inconsistent sharpening angles. The community engagement team from the Semarang State Polytechnic implemented grinding machine technology featuring a fixed 45° clamping system capable of sharpening three knives simultaneously. Measuring 1134 × 970 × 720 mm, the machine is powered by a 1 HP electric motor with a water-cooling system utilising a 12-volt pump. The results of the project demonstrated a 76 per cent improvement in sharpening efficiency and greater uniformity in the blade’s sharpening angle. Through the application of this appropriate technology, the partner organisation has been able to significantly increase both production capacity and product quality.