Swarm robots in mechanized agricultural operations: A review about challenges for research

•Agricultural mechanization have increased their powers by 3,300%.•This generated excessive consumption of fossil fuel, excessive weight on soil, high operating costs.•A swarm of small electric robotic tractors could replace a large tractor combustion engine. Agricultural mechanization is an area of knowledge that has evolved a lot over the past century, its main actors being agricultural tractors that, in 100 years, have increased their powers by 3,300%. This evolution has resulted in an exponential increase in the field capacity of such machines. However, it has also generated negative results such as excessive consumption of fossil fuel, excessive weight on the soil, very high operating costs, and millionaire acquisition value. The objective of this paper aims at exploring the upcoming challenges of employing swarm robot tractors that together have the same field capacity as a large tractor with an internal combustion engine. A systematic literature review technique is used to survey 32 representative papers that report research about swarm robots in agriculture. These papers are analyzed in an organized manner concerning the operationalization of swarm robots to fulfill agricultural mechanization missions. A comprehensive evaluation is conducted from the aspects of technology readiness level (TRL), configurability, adaptability, dependability, motion ability, perception ability and decision autonomy. Based on the evaluation result, upcoming challenges are detected and summarized, suggesting the development of a roadmap for future research. Another systematic review was done for these challenges by assessing the distance between what is being studied and the needs for a commercial operation of a robotic tractor swarm.