The Implementation of the Mechanical System for Automatic Charging of Electric Vehicles: A Project Overview

Abstract

With the advancement of autonomous and electric vehicles, an increasing demand has been observed for the automatic robot-controlled charging of electric vehicles. The idea of developing such charging stations was raised at several research institutions and universities as early as the 2010s, however the appearance of automatic charging stations with higher Technology Readiness Levels (TRL) can only be dated from 2019 onwards. In most of the developed concepts and solutions, a dedicated parking system is required by vehicle drivers, since the operating range of the robots used for charging is limited. In most cases, solutions do not incorporate robots with unique geometries; instead, proven industrial solutions are applied. The robots in these prototypes are typically installed in a fixed position, similar to industrial applications, and are not mobile. The charging of one vehicle is usually performed by one robot. A high-level summary of the developed mechanical system is presented in this project overview. In this research, an automated, robot-controlled electric vehicle charging system was designed, in which vehicles are parked perpendicularly adjacent to each other, and multiple vehicles are charged using a single collaborative robot. The mechanical system was implemented with a robot mounted on an extendable arm attached to a carriage, which is guided in two directions along rails. In this manner, the automatic charging system is positioned precisely at the parking location of the vehicle to be charged.

1. Introduction to the Topic

The concept of automatic charging for electric vehicles was already proposed around 2010. In December 2014, it was announced on Twitter by Elon Musk (CEO of Tesla Motors) that a robot for charging electric vehicles was being developed. The charging was carried out by a segmented flexible robotic arm mounted on a mobile platform, with the charging process executed by a multi-segmented robotic arm. In this concept, no details were disclosed by Tesla experts regarding the electronics responsible for the positioning of the robotic arm or the precise connection process. In the provided video and image recordings [1], the multi-segmented snake-like robotic arm is shown connecting the charging cable. However, the method of identifying the charging port is not clearly discernible in these recordings.

Research groups at universities also became involved early in the development of automatic chargers. A project named AlanE was launched by the Technical University of Dortmund, with the goal of developing a robot capable of charging a parked electric vehicle after the driver positioned the car in front of the charging robot (the AlanE acronym stands for an automated charging system for sustainable electric mobility) [2].

Patents for automatic charging stations were already filed in 2019 by Motors Liquidation Co., Delphi Technologies Inc., and Raytheon Co. [3]. This early concept was designed to charge electric vehicles equipped with a front-located charging port using a short, three-segment robotic arm. Solutions aimed at eliminating the human factor were also proposed without the use of robots, such as in the 2020 patent by Rivian IP Holdings LLC, where the charging cable is connected to the exposed side-mounted charging port of the electric vehicle through a magnetic mechanism [4] (robots are not included in this solution).

In the 2020s, an increasing number of solutions developed by large corporations and startup companies were introduced. Ford’s [5] side-charging solution, which requires precise vehicle alignment, was implemented with the robotic system housed in a lockable enclosure. Doosan’s [6] system featured a robotic arm mounted on a rail system, capable of charging electric vehicles with front-mounted charging ports. In the solution proposed by the Hyundai Motor Group [7], the charging process was carried out by a robot installed on a fixed charging post, which was likely designed to serve not only vehicles with side-mounted charging ports.

A common characteristic of the above-mentioned systems is that vehicles must be positioned in such a way that their charging ports are as close as possible to the robotic arm. Since the position of charging ports on electric vehicles is not as uniformly arranged as in vehicles powered by gasoline, diesel, or even LPG, these systems cannot accommodate all vehicle types unless charging stations of sufficient size are provided to allow access from multiple directions.

In Figure 1, the positioning to the fixed charging pillar (fixed robot) is modeled, and it can be clearly observed that conventional parking methods cannot be applied here. Similarly, in the case of robots moving on a rail system shown in Figure 2, only customized positioning allows for the charging of different types of vehicles.

In order to overcome the disadvantages of systems equipped with fixed charging posts, several solutions have been developed in which the robot approaches the vehicles on an autonomous service platform. These concepts and prototypes have emerged over the past one to two years. In such cases, the chargers are capable of serving multiple types of vehicles; however, locating the charging port can be a time-consuming process. One reason for this slowness is that the robots operate in environments where human presence or other obstacles may be encountered, requiring the use of collaborative robots, which are limited to a maximum speed of 0.25 m/s for safety reasons. An additional drawback is that the robot moves together with the battery unit, resulting in significant space requirements—as seen in the solution by Neura Robotics [8], where the battery is mounted on a tracked carrier platform.

In concept designs such as the charging robot presented in VW’s 2021 concept plan, where the AGV (Automated Guided Vehicle) is controlled by the AMR (Autonomous Mobile Robot) that carries the robotic arm, the battery pack can be charged separately. However, the robot must make multiple turns due to the process of plugging in and unplugging the charging cable [9].

Despite the long search times and the large space requirements of robots, an increasing number of such concepts and prototypes are being developed. Naturally, the aim of this article is not to present all previous solutions or concepts for vehicle charging with the assistance of robots. A wide range of concepts is showcased in a video [10], in which robots are not only used to charge electric vehicles but also demonstrate existing and planned solutions for refueling liquid-fuel vehicles. Some designs are also presented, where human robots assist in various processes, such as refueling vehicles. While the solutions spanning a truly broad spectrum are advantageous in some respects, they often have several drawbacks.

In the present research, an effort was made to develop a prototype of a charging system that addresses the limitations of existing solutions while integrating the advantages of previously proposed systems. In most proposed concepts and solutions, a dedicated parking system is required for vehicle users, as the operational range of the charging robots is limited [11]. One of the primary objectives of this project was to design a robust mechanical system incorporating a collaborative robot mounted on an extending arm, which is attached to a carriage that moves along two axes on rails. This design allows the automatic charging system to be precisely positioned at the parking spot of the vehicle requiring charging.

The paper is organized as follows: The first section presents the introduction, followed by a brief overview of the project in the second section. The third section describes the architecture of the electromechanical system, and the fourth section presents the discussion, concluding with the final remarks in the conclusion section.

2. A Robot Charging Solution Supported by a Multi-Segmented Automated Guided Vehicle

The University of Dunaújváros initiated a multi-year research project in 2020 under the GANZ KK 2020-1.1.2-PIACI-KFI-2020-00173 code, titled “Research and Development of a Charging Robot for Automatic Charging of Electric Vehicles,” aimed at enabling electric vehicles to be charged via a wired connection with the help of a collaborative robot manipulator. One of the primary objectives of the project was to charge as many types of fully electric and plug-in hybrid vehicles as possible. To achieve this, the precise localization of the vehicle’s charging port was required, followed by accurate insertion of the charging plug, typically within a few millimeters of positional tolerance, what was achieved with an industrial 3D camera, accompanying vision algorithm and a collaborative robot. Perhaps the greatest challenge in the research was that, unlike internal combustion engine vehicles, manufacturers of electric vehicles did not follow uniform principles for the charging port design, such as the method of opening the charging cover or securing the fuel cap. As a result, several vehicle types had to be excluded from later experimental development at the outset of the research, as the placement of the cover opening prevented collision-free access to the connector for these models.

Another significant consideration in the research was the ability to charge multiple vehicles with a single robotic arm, ensuring that the vehicles did not occupy excessive space and that the parking arrangement was uniform (it was expected that drivers would park in such a way that the vehicle’s charging port would be closest to the charging system). Due to space efficiency, perpendicular parking was considered the most suitable option.

The Basic Operation and the Expectations of the System

The charging process begins with the identification of the vehicle and the authorization of the charging by the provider, after which the mechanical system positions the charging robot to the vehicle’s charging socket. The position and orientation of the charging socket on the vehicle is stored in a pre-recorded database relative to the wheel closest to the charging port. The robotic arm’s integrated camera then precisely assesses the spatial position and orientation of the charging pillar with the charging gun, and the vehicle’s charging socket. The robot then uses a specially designed gripping mechanism to grasp the charging gun, inserts it into the charging socket, and, after a secure connection is made, releases the gun and moves away from the vehicle. At this point, the charging station automatically initiates the charging process. Upon completion of the charging or its interruption for any reason, the robot removes the charging gun from the vehicle in a manner similar to the previously described steps and returns it to the charging pillar. During the robot’s movement, the system continuously monitors the work area and, if human presence or another unexpected obstacle is detected, immediately halts the movement or, if necessary, returns to a safe default position.

The detailed flowchart of the process is shown in Figure 3.

According to the specifications defined at the beginning of the research, the system was required to meet the following criteria:

• It should be capable of automatically charging electric vehicles.
• It should be suitable for serving up to four vehicles simultaneously, with the flexibility to expand capacity as needed.
• The increase in the number of vehicles to be served should not significantly raise production costs.
• It should handle varying placements of vehicle charging connectors flexibly.
• It should be easily transportable and quickly deployable.

3. The Architecture of the Electromechanical System

3.1. The Placement of the System in a Container

To ensure ease of transportation and rapid deployment—particularly for events, exhibitions, or other demonstrations—the system was integrated into a transport container compliant with ISO standards. All components are mounted within the container, and both sides—designated as parking areas—are covered by a modular roof. The electronic components and the charging gun, along with its holder, are housed inside the container, thereby providing protection against environmental factors such as dust, water, and other weather-related conditions. In order to enable the simultaneous charging of four vehicles, a layout was designed that allows two vehicles to be positioned on each of the container’s longer sides. The length of the container was determined based on the width of the vehicles, resulting in the selection of a standard nine-meter-long unit [12]. The container’s foldable side panels were designed to function as ramps, allowing vehicles to easily drive onto the platform (Figure 4).

This implementation was not only designed to ensure practical transportability but was also intended to provide protection against basic weather conditions. The enclosure was constructed to shield the system from precipitation and intense sunlight, while the integrated air conditioning unit was included to facilitate temperature regulation. For future expansion of the system and the charging of additional vehicles, a longer container may be selected, and the connection of multiple containers has also been made possible.

3.2. The Motion with Six Degrees of Freedom Provided by the Robotic Arm

Several mechanical solutions were examined and evaluated to ensure the precise and reliable insertion of the charging gun into the vehicle’s charging socket. Particular attention was paid to determining the number of degrees of freedom and achieving an optimal kinematic design. Based on the investigations, a six degrees of freedom (6 DOF) configuration was selected, as the orientation of the vehicle’s charging socket can vary arbitrarily, thus requiring the system to be capable of full control over both, the position and orientation.

In defining the conceptual structure of the robot, conventional articulated robotic arms, SCARA (selective compliance assembly robot arm) systems, and parallel robot structures were considered. Ultimately, a six-axis articulated robotic arm was chosen, as this configuration was found to be the most suitable for tasks requiring high maneuverability and precision, especially in spherical or irregular workspaces.

In earlier research, custom-designed robotic arms were also developed, such as the model presented in [13]. However, in the current study, considering the broad and appropriate range of commercially available products offered by manufacturers, a robotic arm that met the specific requirements of the project was selected from the market. The Universal Robots UR10e model was chosen (Figure 5), as its 1300 mm working envelope was found to be ideal for maneuvering between vehicles, and its maximum payload of 12.5 kg was sufficient for handling and operating the charging plug, gripper mechanism, and integrated camera system [14]. Hence, the UR10e robot was utilized for execution of different motion patterns (such as charger insertion and removal, or charger attachment and detachment). The corresponding Denavit–Hartenberg parameters enable the derivation of forward kinematics of the robot [13]. The forward kinematics is solved based on the joint angles, $q=({\theta }_1,\dots ,{\theta }_6)$ [13]. The transformation matrices form the kinematic chain, thus enable the calculation of TCP position and orientation as a homogeneous transformation matrix:

$$T_0^6=T_0^1\left({\theta }_1\right)\cdot T_1^2\left({\theta }_2\right)\cdot \dots \cdot T_5^6\left({\theta }_6\right),$$

(1)

which provides the 3 × 1 position vector (x, y, z) and enables the obtainment of orientation in terms of Euler angles or quaternion based on the 3 × 3 rotation matrix.

In case of inverse kinematics, the goal is to obtain the joint configuration related to a tool center point (TCP) position and orientation, which is crucial for motion planning and control. This problem is solved with inverse kinematics (IK) solvers provided by UR’s software [13].

3.3. Longitudinal Movement—The Rail System

The subsequent task was to ensure that the robot could effectively reach the vehicles, which essentially required linear motion along the length of the container. To accomplish this, a rail-and-carriage system was developed, enabling the robot—along with its controller and associated electronic components—to be positioned accurately.

In designing the rail-and-carriage system, the mechanical interface between the moving carriage and the rail had to be defined. In industrial applications, this type of task is typically addressed using linear ball-bearing carriages paired with precision guide rails. These systems provide fast and precise linear movement while supporting substantial loads [15]. However, due to the potential fragility of such components and the challenges associated with public use environments, a more robust and wear-resistant solution was deemed necessary.

Taking these factors into account, the longitudinal motion was implemented using the rail-and-carriage configuration shown in Figure 6. The rail was constructed from a C-profile steel section with a cross-sectional height of 160 mm and a width of 65 mm, mounted using steel fasteners. The rail system was deliberately over-engineered with a robust design—including dense support placement and a thick steel profile—to ensure that any deflection remains negligible. The carriage module was equipped with seven wheels on each side, fulfilling three principal functions: the lower three wheels supported the structure’s weight, the upper two provided anti-tip protection, and the lateral two ensured linear guidance along the rail. Similar systems are commonly used in industrial settings for material and goods transport, such as the Dambach MONOFLEX rail-guided vehicle system [16].

The size and hardness of the wheels were selected based on anticipated dynamic loads and surface irregularities during movement. The lateral and upper wheels were designed with adjustable positioning to achieve precise alignment with the rail.

Several drive solutions for the carriage were evaluated. Although actively driven wheels (e.g., [17]) are commonly used, they complicate accurate position tracking under slippage. Rack-and-pinion systems were rejected due to backlash, and ball screw mechanisms were considered unsuitable for the required travel distance. Ultimately, a toothed belt and pulley drive system was selected as the most appropriate solution. As a result, a tensioned toothed belt was installed along the entire length of the rail, interfacing with a toothed pulley mounted on the carriage and driven by a gear-reduced servo motor (Figure 6). The reduction unit employed was a conventional planetary gearbox with a 10:1 ratio, and the drive motor was a 750 W servo motor.

3.4. The Frame Structure for the Storage of Electromechanical Components

The task of the carriage, in addition to the robot’s longitudinal movement, is also the storage of the system’s electronic components. For this purpose, a frame structure made of welded steel profiles was designed on the carriage. The motors, reducers, and drives responsible for the movements, the robot’s control unit, and other electronic components were placed within this frame structure (Figure 7a). The carriage is connected to the control computer by a sliding-type energy chain located at the center of the rail system. In order to protect it against dust and moisture, the frame structure was provided with a steel sheet cover (Figure 7b). The cover is equipped with a service door and ventilation openings to ensure access to electrical components and proper ventilation.

3.5. The Crosswise Movement—An Extendable Arm

The solutions presented previously ensure the robot’s longitudinal positioning relative to the vehicles. However, the 1300 mm work area of the UR10e robotic arm is insufficient on its own to reach the charging sockets located at various points of the vehicles. The reason for this, as previously mentioned, is the significant variation in the charging socket positions of the vehicles to be charged. The variability of the placement of the charging sockets, their non-uniform positioning, and the resulting problems are detailed in the study [11]. Therefore, it was necessary to develop a solution that allows the robotic arm to move crosswise, i.e., in a direction perpendicular to the track. This could be achieved using a mechanical movement device-extending arm mounted on the frame of the carriage. Telescopic mechanisms are often used for such tasks (for example, the telescopic fork unit presented in [18]); however, they are complex and unnecessarily complicate the system.

In order to achieve crosswise movement of the robotic arm, a rotating extendable arm was developed (Figure 8). The robot is placed at the end of this arm (robot base axis), and the arm performs rotational movement around the symmetry axis of the carriage (carriage base axis). The maximum crosswise displacement value matches the distance between the two base axes, which, in the implemented system, is 650 mm. This dimension was determined by considering the system’s spatial requirements and the placement of the charging connectors on the vehicles.

The arm consists of two aluminum parts (lower and upper plates), with the robot’s signal and power cables routed through the middle section. To compensate for the robot’s weight, ballast weights were placed at the opposite end of the arm. The mass of these weights was determined through dynamic simulations. This joint is also driven by a 750 W servo motor; however, the reducer has a special 1:100 ratio with a hollow shaft harmonic drive [19]. The advantage of harmonic reducers is their extremely high gear ratio and minimal backlash relative to their compact size, making them an ideal choice for this task [20]. Additionally, the cables for the robot can be conveniently routed through the hollow shaft located at the center of the reducer.

In order to determine the deflection and properly dimension the extendable arm, a finite element analysis (FEA) was performed. Figure 9 shows the deflection and internal stresses in the arm under a 700 N load applied at the base axis of the robot. This load corresponds to twice the combined weight of the robot and the camera/gripper (30 + 5 kg), accounting for the shift in the center of gravity due to the extension of the robot, as well as serving as a safety factor.

The analysis revealed that under this load, the extendable arm would deflect by approximately 1.11 mm. While this is a notable deformation, it is acceptable for the intended application. The arm is only responsible for bringing the collaborative robot into an approximate pre-position; after that, it remains stationary. The precise positioning of the charging plug is subsequently performed by the robot itself.

3.6. The Complete Mechanical System

The complete system, ensuring practical transportability, protection against basic weather conditions, longitudinal and crosswise movement, as well as six degrees of freedom reach, which consists of a rail system, an extendable arm, and a collaborative robot placed inside the container, is shown in Figure 10.

3.7. The Charging Gun Gripper

In addition to positioning the charging gun in the correct position and orientation, the safe grasping and releasing of the gun also presented a challenge that needed to be addressed. For this purpose, a special mechanism had to be developed, capable of performing the task with appropriate safety and precision. This mechanism is composed of a Schunk industrial gripper [21], custom-designed fingers (Figure 11a), and a clamp that fits the charging gun (Figure 11b).

As the first step in the gripping process, the fingers of the gripper must be moved to the correct position relative to the clamp. Subsequently, the pins on the fingers are inserted into the notches on the clamp as the fingers close. During initial testing and measurements, a few millimeters of deviation from the nominal connection position were observed when the gripper and clamp were moved relative to each other. This deviation was a combined result of data measured by the camera and inaccuracies in the mechanical system. In order to eliminate these discrepancies, the final design included conical geometry for the pins of the gripper and the bushings placed on the clamp. This design allows for the automatic compensation of these small geometric deviations, ensuring a fault-tolerant and reliable fit.

The success of the gripping process is determined based on feedback from the gripper. In its closed position, the gripper senses the enclosed distance. If this distance matches the width of the clamp, the operation is considered successful. In case of deviation, if the measured distance is smaller, it indicates that the clamp was not in the correct position, while a larger distance indicates the presence of an obstacle or blockage.

3.8. The Camera and Sensor Unit

The robot’s vision system is provided by an integrated camera and sensor unit located above the gripper. This unit consists of a Mech-Mind Nano [22] industrial 3D camera and a Keyence LR-TB5000CL distance measuring sensor.

The distance sensor is required to ensure that the camera is positioned within the measurement range relative to the vehicle, as no data will be available outside this range, rendering the 3D point cloud—serving as the basis for measurement—unusable. The “TOF” (Time of Flight) measurement method determines distance by calculating the time taken for a light pulse to return to the sensor after being emitted, reaching the target object, and then reflecting back. This enables stable detection, which is not influenced by the surface condition or color of the detected workpiece. The sensor is also equipped with an analog output, allowing not only the detection of whether the object is within or outside the measurement range but also enabling the measurement of whether the distance between the camera and the vehicle is smaller or larger than the specified range. Based on the sensor data, the distance can be corrected prior to the generation of the 3D image.

The task of the 3D optical measurement system is to provide accurate 3D positioning for the collaborative robot performing the automatic charging of electric vehicles at all stages of the charging process where the position is unknown or its verification is required for safety reasons. The exact position and orientation of the charging gun holder pillar, the charging gun, and the vehicle’s charging socket are determined by the 3D camera mounted on the end-effector at the end of the collaborative robot’s arm.

3.9. The Positioning of Vehicles on the Parking Spot

In the case of automatic charging performed by a robotic arm, the parking position of the vehicles is of significant importance, as discussed in several literature sources [1,2,3,4,5,6,7,8,9,10,11]. In the system presented in this study, the driver must not only ensure the proximity of the vehicle’s charging socket to the robotic arm but also the vehicle’s precise, perpendicular alignment. This ensures that the camera located at the end of the robotic arm can optimally search for the charging socket relative to the vehicle’s position. To aid proper positioning, flexible bumpers have been applied. Additionally, to prevent parked vehicles from coming dangerously close to the charging system, physical barriers have been placed between the rail system and the parking area. The arrangement of these barriers and bumpers is shown in Figure 12.

In order to ensure the precise parking of vehicles in the designated position, a pair of force sensors and a Banner 60.5 GHz [23] radar sensor have been implemented at each parking spot. The detection of the vehicle’s presence is also achieved with these force sensors and the industrial radar sensor placed between them, enhancing safety. The force sensors, which detect the engagement of the vehicle’s front or rear wheels, have been designed using industrial strain gauge stamps. The operation of the sensors is controlled by a programmable logic controller (PLC). A critical aspect of sensor placement was ensuring that the vehicle parks close enough for the robotic arm to reach the connector socket, while also leaving sufficient workspace for the robotic arm’s unobstructed movement.

4. Discussion

The automatic charging system designed for electric vehicles has been successfully implemented, as shown in Figure 13. Subsequently, continuous trial operation and testing were conducted, during which it was concluded that, despite some minor, primarily software-related, identified errors, the system effectively performs the tasks set out. It can be concluded that the robot arm, the linear rail system, and the extending arm are capable of reaching the charging sockets of the targeted vehicles within the designated work area, while the 3D camera is capable to detect the exact position and orientation of the searched objects.

A Mech-Mind Nano [22] 3D camera was employed to generate point clouds, while Cognex VisionPro 9 software [24], along with its 3D Vision Tools, was utilized for the development of the vision algorithms. Using the 3D camera with the developed vision algorithm, the exact position and orientation of the searched object can be detected. According to the manufacturer’s documentation, the camera provides a Z-value repeatability and measurement accuracy of 0.1 mm at a distance of 0.5 m. The camera supports two working distance ranges: 300–450 mm and 450–600 mm, each optimized through appropriate lens selection. In this project, the lens designed for the shorter working range was selected to ensure accurate measurements at approximately 350 mm. The resolution of the camera is 1280 × 1024 pixels. Additionally, a Keyence [25] Time-of-Flight distance sensor was used to verify and maintain the required 350 mm distance between the 3D camera and the target objects. If the system fails to detect the charging port on the vehicle, the robotic arm returns the charging gun to its docking station, into the holder. In the event of an unsuccessful connection attempt during the plug-in process, the robotic system releases the charging gun and returns to its initial position.

A detailed explanation of the vision and sensor systems is beyond the scope of this paper and will be addressed in a separate publication.

The robustness of the designed rail and carriage system was confirmed during testing. The system efficiently compensates for any potential inaccuracies in the rail, is resistant to surface contamination, and tolerates minor defects arising from the manufacturing process, such as welding errors.

The extendable arm demonstrated adequate stiffness, ensuring precise and accurate positioning of the robot. The design of the arm allows for efficient operation even in tight spaces between vehicles, and the rotational movement does not cause a significant increase in space requirements.

In the entire mechanical system, precise operation is observed with minimal backlash, and no vibration is experienced. The gripper of the charging gun is capable to compensate dimensional variations within the specified tolerances, ensuring reliable grasping. The feedback mechanism of the gripper is adequately able to detect any jams or unsuccessful operations during the connection process (Figure 14).

The positioning accuracy of the charging gun exhibits a typical positional error of a few millimeters and an orientation error of approximately 1 degree. During experimental measurements, the deviation in position and orientation varied, but did not exceed 4 mm and 2 degrees, respectively. These inaccuracies arose from a combination of factors: the intrinsic limitations of the vision system, inaccuracies in the camera-to-end-effector calibration, mechanical tolerances in the alignment between the gun and its gripper, as well as the precision limitations of the collaborative robot.

Error compensation was achieved through two mechanisms. First, during the grasping phase, a conical geometry was employed for the gripper pins, as described previously. Second, during the insertion of the gun into the socket, a Peg-in-Hole (PiH) algorithm [26,27] was applied.

As a result of this compensation strategy, the success rate of establishing a charging connection reached 100%. The average time required for successful connection was approximately 3 min, with a typical variance of ±0.5 min. Additionally, the response time of the fail-safe system was measured to be 0.1 s.

The robot’s workspace is monitored using SICK safety sensors (Safe 3D camera: safeVisionary2) [28] specifically designed for integration with collaborative robots. These safety systems are tailored to ensure the safe operation of collaborative robot applications by preventing human contact with the moving robot manipulator. A safety laser scanner continuously monitors the ground-level area surrounding the manipulator. By employing both a protective field and a warning field, the system allows the robot to stop its motion only when a person enters the immediate hazard zone. Once the individual leaves the monitored area, the robot automatically resumes its operating speed and continues normal operation.

Finally, it should be mentioned that in the system the Wallbox eNext Elite T charger station with 22 kW is utilized [29].

5. Conclusions

In this paper, an automatic, robot-controlled electric vehicle charging system is presented, which allows vehicles to be parked perpendicularly next to each other, with multiple vehicles being charged by a single robot. The implemented mechanical system is equipped with a robot mounted on an extending arm, which is attached to a carriage that moves along two directions on rails. This configuration enables the automatic charging system to be precisely positioned at the parking spot of the vehicle to be charged. Continuous trial operations and testing were conducted, and it can be concluded that the charging sockets of the targeted vehicles within the designated work area can be reached by the implemented mechanical system, while the exact position and orientation of the searched object can be detected by the 3D camera and the corresponding vision algorithm.

Future Works

In the future, the determination of the length of the extending arm needs to be researched in order to enable the charging of the greatest possible number of types of electric vehicles with the simplest possible movement of the charging robot. Also, the plan is to test different electric vehicle port standards. Further, the robustness of the entire robotic charging system needs to be investigated with regard to its industrial application in order to obtain the necessary safety certifications. Furthermore, the entire system is currently undergoing the European patent application process, which is expected to be completed in the near future.