Research on solution property of automatic production system scheduling problem under just-in-time environment

Abstract

Automatic production system is a kind of artificially intelligent technology. To improve the intelligence of automatic production systems and easily implement simulation experiments, the solution properties of automatic production system scheduling problems under the JIT environment are researched. Firstly, to minimize total earliness/tardiness time, a mixed integer programming of the proposed problem is shown for simultaneously optimizing job scheduling and robotic move sequence. Secondly, to combine job scheduling and robot move sequence, the definition of robotic activity is applied, therefore, two-dimension scheduling problem can be transferred to one dimension scheduling problem. Thirdly, the robotic activity sequence represents the solution to the proposed problem. and solution definition is presented. Finally, the properties of the solution are discussed. The first property means the first two robotic activities and the last two robotic activities of the solution move the first job and the last job of job scheduling, respectively. That is to say, when job scheduling is given, the first two robotic activities and the last two robotic activities of the solution are determined. Thus the number of solutions is reduced from n(m+1)! to [n(m+1)-4]!. Solution space is reduced. The second property means the start moving time of the first robotic activity of each solution is non-negative. The third property and the fourth property show the relation of adjacent tanks. Robotic activity exchanges and job exchanges are discussed in the fifth property and the sixth property, respectively. According to these proposed properties, one solution can turn into another solution, and a theoretical foundation is provided for designing an optimization operator for solving automatic production system scheduling problem under just-in-time environment. The novel mode which optimizes the proposed problem will be developed for constructing simulation experiments.