# Development of Automatic Electric Drive Drilling System for Core Drilling
## 1 Introduction  
Drilling systems have been used in various fields, such as mineral exploration, the development of oil and gas resources, underground water development, and geothermal power. As a necessary means of resource exploration, core drilling plays an essential role in resource exploitation and economic development. However, core drilling is characterized by miniaturization, a low degree of automation, low profits, and high labor intensity [1; 2]. Most well drilling costs are not product-cost-dependent but time-dependent. Therefore, the main goals of core drilling optimization are to reduce the total time and labor intensity [3; 4]. Drilling speed, commonly called the rate of penetration (ROP), becomes a key performance indicator. ROP optimization involves selecting the operational parameters to improve the drilling speed in this case. Rock formation, hole diameter, hole cleaning and hydraulics, weight-on-bit (WOB), rotational speed (RPM), and bit type are the six factors that influence ROP [5]. Instead of choosing a suitable drill bit and drilling fluid type before drilling, a new solution relies on real-time analysis to optimize the operational parameters, WOB and RPM, during drilling. Intelligent and automatic drilling systems suggest operational parameters for drillers by correlating real-time drilling data with vast amounts of historical data stored in a database, or by exerting complete control of all rig equipment with significant decision points. The latter describes the levels of automation that are likely years away from deployment in the field. Developing a drilling system under laboratory conditions will contribute to research on automated drilling and drilling rate optimization in the core drilling field [6; 7; 8; 9; 10]. The drilling systems automation technical section of the Society of Petroleum Engineers (DSATS) developed a DSATS drillbotics program. The program is an international competition for universities to design and build a small drilling rig for petroleum and gas automation. However, it is hard to find automation in core drilling. Compared with petroleum and gas drilling, core drilling has the characteristics of small equipment volume, small bore diameter, fast construction time, and low economicbenefits; thus, core drilling has a low level of automation. Owing to the poor working environment of core drilling and drilling rig product molding, the drive mode of the core drilling rig is generally a hydraulic or mechanical drive. The hydraulic drill rig has the disadvantages of complicated maintenance, high cost, and poor delay control, but it has the advantages of large WOB and large torque. The electric drive drill has the advantages of simple structure and high control accuracy, but it has the disadvantages of large volume. [PERSON] et al. developed a multiparameter hydraulic submersible hammer test platform to achieve drilling through hydraulic drive [11]. [PERSON] developed a multifunction hydraulic drilling test platform [12]. In addition, the Commonwealth Scientific and Industrial Research Organisation (CSRIO) transformed a power head drill rig into an intelligent real-time formation identification system, which is equipped with a parameter monitoring console. The system can analyze real-time rig parameters, infer bit status, and identify formation information. The electric drive core drilling system can simulate actual drilling, provide the measurement and recording of various drilling parameters, provide the basis for improving drilling technology, develop drilling equipment, and provide ideas for drilling optimization [13; 14]. The key goal of drilling automation at this stage is to develop digital and robust tools to assist drillers in critical phases and, if possible, to automate routine tasks that machines can easily control [15]. IRI and NOV (Houston, TX, USA), Dreco (Edmonton, AB, Canada), Hitec (Sola, Norway), Siemens (Munich, Germany), and others have developed rig systems with AC frequency conversion as the driving force.