Provided is an article retrieval system including: a sensor that measures the states of articles stored in a storage container; an article detection part for detecting the articles on the basis of the states of the articles measured by the sensor; handling part for retrieving the articles or changing the positions and/or orientations of the articles detected by the article detection part; and a controller that controls the sensor, the article detection part, and the handling part. The controller includes: a space dividing part for dividing the space in which the articles exist according to the states of the articles measured by the sensor; and a switching part for switching at least one of a method of measurement with the sensor, a method of detection with the article detection part, and a method of retrieval with the handling part in each of the spaces divided by the space dividing part.

Motion of multiple agents with identical non-linear dynamics is controlled to change density of the agents from the initial to the final density. A first control problem is formulated for optimizing a control cost of changing density of the agents from the initial density to the final density subject to dynamics of the agents in a density space. The first control problem, which is a non-linear non-convex problem over a multi-agent control and a density of the agents, is transformed into a second control problem over the density of the agents and a product of the multi-agent control and the density of the agents. The second control problem is a non-linear convex problem that is solved to produce the control input for each section of the state space. A motion of each agent is controlled according to a control input corresponding to its section of the state space.