This book presents the proceedings of SympoSIMM 2021, the 4th edition of the Symposium on Intelligent Manufacturing and Mechatronics. Focusing on "Strengthening Innovations Towards Industry 4.0", the book is divided into five parts covering various areas of manufacturing engineering and mechatronics stream, namely, intelligent manufacturing and artificial intelligence, Instrumentation and control, design modelling and simulation, process and machining technology, and smart material. The book will be a valuable resource for readers wishing to embrace the new era of Industry 4.0.