The problems of centralized control of motion of a separate mini-train that is part of a robot group are discussed. Each mini-train consists of 5-6 trolleys jointly connected one by one. These trolleys are a kind of a «nonholonomic tail» whose lateral movements are difficult to control and adjust, thus being a danger to other members of the group. These lateral oscillations worsen the trajectory compactness, and they also significantly reduce the stability of the whole chain and affect the dynamics and maneuvering of the heading module. To estimate these dangers and select the maximum permissible speed of the mini-train, a mathematical model of motion of such nonholonomic chain is built and analyzed in the article. It allows the central operator to predict the shape and dimensions of the danger zone for a separate mini-train, and to therefore prevent the occurrence of abnormal situations. Citation: Smirnov A.S., Smolnikov B.A., Leontev V.A. Principles of Nonholonomic Mechanics in Controlling a Transport Robot Group. St. Petersburg State Polytechnical University Journal. Computer Science. Telecommunications and Control Systems. 2017, Vol. 10, No. 3, Pp. 83–91. DOI: 10.18721/JCSTCS.10307