Theory and Applications on Machines, Mechanisms and Robots, and the Figure of Ettore Pennestrì

This editorial presents a book that marks the beginning of the MMR-T&A series, which compiles articles from the collection Machines, Mechanisms, and Robots: Theory and Applications (MMR-T&A), published in MDPI’s journal Machines. The first volume of this series includes the first ten published papers from the collection. It starts with one review [1] on contact models. Then, it continues with two papers [2,3] addressing obstacle avoidance in different contexts, one more paper [4] on geometric constraint programming, and three papers [5,6,7] presenting novel mechanisms. Finally, it closes with one paper [8] on mechanism performances and two papers [9,10] addressing manufacturing issues. Going forward, a new volume in the MMR-T&A series will be released for every ten papers published.

The book is dedicated to the memory of Ettore Pennestrì (Reggio Calabria, Italy, 16 May 1957–Rome, Italy, 29 August 2024), who co-authored one [1] of the papers included in this collection. Those who knew him knew how important sharing his knowledge and his findings was to him, especially with students and young researchers (Figure 1 shows him during a lecture).

Ettore Pennestrì earned his Laurea in Mechanical Engineering from the University La Sapienza of Rome in 1980. He continued his studies at Columbia University, earning a Master’s degree (1987) and a Ph.D. (1991) under the guidance of Ferdinand Freudenstein. Upon returning to Italy, he began his academic career at the University of Calabria and joined the University of Rome Tor Vergata faculty in 1991, where he initially served as an Associate Professor and then, from 2001, served as a Full Professor of Applied Mechanics.

Throughout his career, he focused on research into kinematics, dynamics of mechanisms, biomechanics, gear transmission design, and vibration damping. He authored over 100 scientific papers published in international journals and several textbooks used in university education.

His contributions span theoretical research, practical applications, and advanced numerical methodologies in applied mechanics. In computational kinematics, he developed algorithms using dual numbers and dual quaternions for the analysis of rigid body motion that are widely applied in robotics and biomechanics for motion optimization. In multibody dynamics, he authored/co-authored studies on the simulation and analysis of mechanical systems with multiple interconnected bodies, such as gears and linkages, which include modeling dynamic systems for applications in vehicles and robotics. In gear train efficiency, he published foundational research on the mechanical efficiency of gear trains, including epicyclic and hybrid systems that include closed-form formulas for analyzing power flow and losses in complex gear mechanisms. In biomechanics, he pioneered the development of musculoskeletal models for biomechanical analysis, particularly focusing on the upper limb, which contributed to ergonomics, rehabilitation engineering, and sports science. In vehicle powertrains and vibrations, he investigated vibration isolation techniques and efficiency in vehicle powertrain systems, emphasizing hybrid vehicle applications.

In addition to his scientific work, he held important roles in the editorial boards of international journals; for example, he was an Associate Editor of the ASME Journal of Mechanical Design; an honorary member of the Editorial Board of Mechanism and Machine Theory; and a member of the Advisory Board of the Journal of Multibody System Dynamics.

Ettore Pennestrì held numerous prestigious positions and participated actively in international initiatives, such as the following:

• He was a member of the scientific committee for the ECCOMAS Thematic Conferences on Multibody Dynamics in several editions: 2005 (Madrid), 2007 (Milan), 2009 (Warsaw), 2015 (Barcelona), 2017 (Prague), and 2019 (Duisburg). He also contributed to the scientific committees of international workshops in Romania and Italy.
• He was a representative of the National Research Council (CNR) at the International Union of Theoretical and Applied Mechanics (IUTAM).
• He was an elected coordinator of the Italian study group on kinematics and dynamics of multibody systems within AIMETA, the Italian Association of Theoretical and Applied Mechanics.

His passion for teaching led him to publish numerous influential books on kinematics, dynamics, and multibody system simulation methods. His last book, Design of Approximate Curve Tracing Linkages: The Chebyshev Min-Max Optimality Criterion (with V.R. Shanmukhasundaram and Marco Cirelli), was published a month before his passing away, and an e-book version was offered as a free download on his ResearchGate profile (https://www.researchgate.net/profile/Ettore-Pennestri, accessed on 9 December 2024), which is an example of his strong commitment towards the spread of knowledge.

Ettore Pennestrì was appreciated not only for his scientific contributions but also for his ability to support students and colleagues in their academic and professional journeys. As a scientist who loved science and books, his personal library contained over six hundred volumes on kinematics and applied mechanics.

He was a scientist who went beyond science. He never read books simply to understand their scientific content; he was also interested in the authors’ lives and the historical context in which they lived. His lectures, rich in scientific content, were also filled with references to the history of great scientists of the past.

His commitment, rigor, and generosity will continue to inspire both the scientific and academic communities. For those who had the privilege of knowing him, Ettore will remain a guide and a lighthouse, lighting the way for research and applied mechanics.