[en] The covariant formulation of the Bogolyubov collective coordinates method is considered on the basis of one-soliton sector quantization of self-acting scalar field in the two-dimensional space-time. In contrast to the Dirac approach the separation of the space-time symmetry group is realized directly at quantized variables while to additional conditions required for conservation of the number of degrees freedom of the system one can attach a sufficiently clear meaning. In fact they are equivalent to the Dirac relations, however they do not require appealing to Hamiitonian formatism and are obtained directly in the Lagrange formulation and do not contain problems related to operator ordering. Covariant in each order perturbation theory near one-soliton solution suggests to consider directly the Heisenberg field in the proper approximation. This gives a possibility to correctly introduce asymptotic model states on the basis of the LSZ procedure and give physical interpretation of quantized field excitation spectrum in perturbation theory orders considered