The Programmable Logic Controller (PLC) is widely used in the industrial world, e.g. in manufacturing, chemical processing, materials handling, etc. The PLC-based control system can be regarded as a control system with low-resolution inputs and outputs. This paper presents a sophisticated
control policy which can enhance the control performance for such a class of control system even if the complete information of the plant is not available. In particular, the case of existing uncertainty or perturbations in the input matrix is addressed. The key contribution of this paper
is to clarify the identifiability condition for parameters included in the input matrix from measured low-resolution inputs and outputs. This investigation leads to the development of an indirect adaptive control policy with low-resolution inputs and outputs. Finally, the proposed indirect
adaptive control policy is applied to the line-following control of a two-wheeled vehicle and its usefulness is demonstrated through experiment.