This book presents the proceedings of 5th International and 20th National Conference on Machines and Mechanisms (iNaCoMM 2021) held at PDPM IIITDM Jabalpur during 9-11 December 2021. The conference was held in collaboration with the Association of Machines and Mechanisms (AMM) India and International Federation for the Promotion of Mechanism and Machine sciences (IFToMM). Various topics covered in this book include kinematics and dynamics of machines, compliant mechanisms, gear, cams and power transmission systems, mechanisms and machines for rural, agricultural and industrial applications, mechanisms for space applications, mechanisms for energy harvesting, robotics and automation, human-centric robotics, soft robotics, man-machine system, mechatronics and micrömechanisms, CAD and CAGD, control of machines, vibration of machines & rotor dynamics, acoustic and noise, tribology, condition monitoring and failure analysis, fault diagnosis and health monitoring, biomedical engineering, and composites and advanced materials. Given the contents, the book will be useful for researchers and professionals working in the various domains of mechanical engineering.