NO336059B1 - Method and apparatus for cleaning carbon anodes - Google Patents

Description

INTRODUCTION

This application relates to a method and an apparatus for automatic post-cleaning of carbon anodes in aluminum production.

BACKGROUND

In aluminum production, large carbon anodes are immersed in molten electrolyte

in reduction cells. The carbon anodes react with the oxygen from dissolved alumina in the electrolyte and aluminum and CO2 are produced. The carbon anodes are large rectangular blocks of carbon attached to an iron structure. Each carbon anode is attached to an anode hanger. The anode hanger consists of a steel yoke with four bolts that fit into the top of the anode and an aluminum rod connected to the upper part of the structure. The carbon anode is replaced regularly as a result of wear.

A used anode is called an anode stub, or simply stub. It consists mainly of carbon residues along with a significant amount of frozen electrolyte and alumina on top. This frozen electrolyte must be removed to recycle the residual carbon. The removal process is a partially automated process. An anode stub that has undergone the cleaning process is called a clean stub. Used carbon anodes are in some cases not sufficiently cleaned and must be inspected and cleaned manually in a post-cleaning process. After inspection and post-cleaning, the anode stub is separated from the anode hanger and sent for recycling.

N019853325 describes the cleaning of anodes using a robot. An opto-electronic device (a camera) is used to control the robot. A sensor detects the contour of the residual carbon during cleaning and controls the robot. An impact tool, scraping tool or milling tool, a water jet or compressed air is used.

SUMMARY OF THE INVENTION

The present invention provides a system and a method for automating the post-cleaning of carbon anodes in aluminum production. The automated method and system provides detection of electrolyte material on the spent carbon anode and an advanced robotic system for removing this material from the spent carbon anode.

In a first aspect, the invention provides a system for post-cleaning electrolyte from a used carbon anode in aluminum production, where the system comprises: - a robot with a manipulator arm equipped with a tool for removing the electrolyte;

- a vision system, comprising:

at least one 3D sensor for detecting a three-dimensional shape of a surface of said carbon anode, and an analysis system for identifying the electrolyte on said carbon anode from the three-dimensional shape of the surface; - a sensor for detecting tool breakthrough through the electrolyte on said carbon anode; and - a control system for controlling the robot manipulator arm and the tool based on information from the vision system and the sensor device for detecting tool breakthrough.

In one embodiment, the tool breakthrough detection sensor may comprise a force/torque (FT - Force/Torque) sensor. Alternatively, the tool breakthrough detection sensor may comprise the use of at least one of a sound sensor and an impedance measuring device.

The control system may include a force/torque (FT) sensor for force feedback control, where the force/torque (FT) sensor detects force interaction between the tool and the carbon anode. The control system can further comprise a movement planner for path optimization of the movement path of the robot manipulator arm and the tool in relation to the surface of the carbon anode to be cleaned.

The at least one 3D sensor may comprise at least one of structured light cameras, stereo cameras, ToF (Time-of-Flight) cameras and 3D laser scanners. The analysis system can provide color differentiation and positioning of the electrolyte in a coordinate system related to the three-dimensional shape of the surface of the carbon anode to be cleaned.

The tool may be a mechanical tool selected from at least one of a chisel tool, a grinding tool, and a sandblasting tool. The tool holder may comprise at least one vibration damper.

In a second aspect, the invention provides a method for post-cleaning electrolyte from a used carbon anode in aluminum production, where the system comprises a robot with a manipulator arm equipped with a tool for removing the electrolyte, the method comprising: - detecting a three-dimensional shape to a surface of said carbon anode; - analysis of the three-dimensional shape and identification of positions of the electrolyte on said carbon anode, - control of the robot manipulator arm with tools based on the three-dimensional shape and the identified positions of the electrolyte, and - detection of tool breakthrough through the electrolyte on said carbon anode for further control of the robot manipulator arm with tool.

In one embodiment, the method can further comprise the detection of tool breakthrough through the electrolyte on said carbon anode using a

force-torque (FT) sensor mounted on an end effector on the robotic manipulator arm. Alternatively, detection of tool breakthrough through the electrolyte on said carbon anode can be performed by using a sound sensor or by using impedance measurements between the tool and the cleaned carbon anode.

The method can further comprise identification of the positions of the electrolyte on said carbon anode through color differentiation. Selection of at least one tool to be used in the post-cleaning of the carbon anode can be carried out based on the identified positions of the electrolyte. The method can further include the use of a motion planner for path optimization of the movement path of the robot manipulator arm and the tool in relation to the surface of the carbon anode to be post-cleaned. The method may further comprise generating a point-to-point path for cleaning the carbon anode optimized with respect to time. The generation of the point-to-point path can be based on the method RRT

(Rapidly-exploring Random Trees). A collision-free path of the tool with respect to the surface of the carbon anode to be cleaned can be generated. A number of trajectories may be simulated prior to initiating the post-cleaning process and determining an actual trajectory based on cleaning efficiency with respect to time. The path of movement to be followed by the tool during the cleaning process can be updated based on real-time detection of the three-dimensional shape of the carbon anode surface.

The automated system for the post-cleaning of used carbon anodes (anode stubs) offers a number of advantages compared to the manual chiseling in the known technique. • Safer post-cleaning of used carbon nodes and better HSE (Health, Environment, Safety)

• More efficient post-cleaning process

• Faster response time and higher quality of the spent carbon anode, as less electrolyte is left on the stubs • Fewer workers on the actual production line, reduced costs Increased productivity in the anode cleaning line

Increased accuracy in the post-cleaning of stumps

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments of the invention will now be described with support in the following drawings, where: Figure 1a illustrates an automated robot system for chiseling used carbon anodes according to an embodiment of the present invention; Figures 1b and 1c are flowcharts of a cleaning operation according to an embodiment of the present invention; Figure 2a illustrates a tool holder and a tool, a vibration damper and a force sensor for the robot according to an embodiment of the present invention; Figure 2b is an image of a chisel tool arranged on the tool holder with vibration recorders, FT sensor and an adapter plate connecting the tool to the robot arm, in accordance with an embodiment of the present invention; Figure 3 schematically illustrates a flow diagram for planning the path of movement for the chiseling operation according to an embodiment of the present invention; Figure 4 shows a robot manipulator with an air hammer that performs a chiseling operation according to an example of an embodiment of the present invention; Figure 5 shows an image of an experimental result of chiseling performed by the robot manipulator from Figure 4 on carbon anode with electrolyte; Figure 6 shows a graph of force (N) as a function of time (s) as detected by a force sensor on the robot shown in Figure 4, and shows detection of breakthrough to the carbon stumps according to an example of an embodiment of the present invention; and Figure 7 shows an air sander arranged on a robot manipulator for testing the concept according to the present invention.

DETAILED DESCRIPTION

The overall concept according to the present invention is illustrated in Figure 1a. The robot system in Figure 1a provides an integrated system with subsystems for detection and control. Detection of a three-dimensional shape of the clean carbon stub, detection of electrolyte on the clean carbon stub, and detection of tool breakthrough through the electrolyte deposited on the stub are provided. Information from the detection systems is fed to the control systems, which control a manipulator arm on the robot system.

In Figure 1a, the robotic manipulator arm of the robotic system is equipped with a suitable tool for removing electrolyte from a used, clean carbon stub. A vision system is provided for the collection and analysis of data. A tool system ensures the calculation of the position of electrolyte pits in the surface of the used, clean stump and enables the detection of bath materials and the selection of tools. A motion planner generates a motion path for the robot manipulator. Furthermore, the robot system is equipped with a robot control unit. The robot control unit provides functions for force and position control for the robot manipulator as well as tool assembly. Electrolyte breakdown is also detected by the tool system. A user interface enables control of the robot system by an operator. However, when the clean carbon stump is positioned for post-cleaning and the process is initiated, the post-cleaning procedure is fully automated and performed by the robotic system.

The robot system comprises a robot manipulator with a suitable tool. The robot control unit includes a motion planner, a path follower and a power control unit (hybrid control unit). The robot manipulator can be a commonly available industrial manipulator. Industrial manipulators are supplied with commercial control units for articulated and Cartesian control of the manipulator. The motion planner will operate independently of the commercial control unit. The hybrid control unit will generate joint references to the commercial control unit for the manipulator.

The motion planner will generate the motion path of the manipulator's end effector based on the detection of unclean parts of the stumps. The detection system can consist of different types of sensors. The path follower will ensure optimal movement between the foul areas of the stumps and the power control unit will control the manoeuvre.

Vision system and identification of uncleaned areas

The vision system consists of one or more 3D sensors. Examples of such sensors are structural light cameras, stereo cameras, ToF cameras or 3D laser scanners. The measurements are distributed over a standard interface, such as CameraLink or Gigabit Ethernet to a PC for further analysis, where commonly available software such as Scorpion Vision from Tordivel can be used. The result is a 3D view of the surface of the stump to be cleaned. The location of the impure areas is identified through color differentiation and positioning in a Cartesian coordinate system related to the three-dimensional shape of the stump to be cleaned. The three-dimensional shape of the stump and the identified impurity areas are fed into a motion planning system for planning the motion of the robot manipulator. The movement of the robot manipulator is planned to achieve a fast and reliable post-cleaning of the stump.

Visual measurements are preferably performed by the vision system at intervals during the cleaning operation to check if the anode is clean enough. After a chiseling operation, the anode is scanned by the vision system to check if all the electrolyte has been removed or if another tool needs to be used to clean the anode. The visual information from the 3D view of the surface is thus used as feedback to the tool system to ensure successful removal of the electrolyte. Scanning of the anode of the vision system is normally not performed during the actual cleaning operation, as dust and residues from the cleaning operation destroy the quality of the visual measurement. The three-dimensional shape of the stump is also fed to the tool system for selecting one or more tools to be used to clean the stump. Figure 1 b shows a flow diagram of the post-cleaning process for electrolyte from a spent carbon anode. The anode is set in position in an anode holder. The anode is scanned by the vision system, which produces a 3D view of the anode. The visual 3D data from the vision system is analyzed in an analysis system. The areas of electrolyte on the anode and the contour of the anode are detected, and a path of movement is created between the electrolyte covered areas. If there are no areas of electrolyte on the carbon anode, the cleaning is complete. If there are areas of electrolyte on the anode, a tool is selected for the cleaning operation. Local path points are then created based on the identified electrolyte area and the tool selected for the cleaning operation. The area is then cleaned. After cleaning an area is performed by the tool, the anode is rescanned by the vision system, which produces a new 3D view of the anode. The new 3D view is analyzed to detect remaining electrolyte and the contour of the anode. If there are multiple areas of electrolyte on the anode, a tool is reselected, local path points are created based on the identified remaining electrolyte areas, and the area is cleaned. The process is repeated until the carbon anode is sufficiently cleaned. Figure 1c shows a flow diagram of an example of carrying out the process for cleaning an electrolyte area on the carbon anode. If the area is sufficiently cleaned, the area is finished. If the area is not sufficiently cleaned, the tool is moved to the path point for this area, which was created earlier in the scan and analysis step. Cleaning with the tool begins when the tool is in position. The tool moves towards the surface of the carbon anode.

If the tool is a grinding tool, the grinding tool is set to follow the contour of the anode to the next path point. Grinding is carried out until the next path point is reached. When the next path point is reached, the tool is retracted. If the area is not sufficiently cleaned, the tool is again moved to the path point.

If the tool is a chisel tool, chiseling is performed until breakthrough is detected. The chisel tool is then retracted. If breakthrough is not detected within a specified interval, the tool is retracted and moved towards the anode again. An alternative tool can also be selected, after which the alternative tool is moved towards the anode.

If the area is identified as clean, the area is finished. As explained above, the area to be cleaned is scanned with the 3D vision system to check whether the desired cleaning result was achieved or not. Cleaning is carried out until the desired cleaning result is achieved.

Tool system

The robotic system comprises a robotic manipulator with a suitable tool for removing electrolyte from the clean stubs. The tool is placed in/on a tool holder arranged on an end effector on the robot manipulator. The manipulation can be performed by a mechanical tool. The mechanical tool can e.g. be a chisel tool, a grinding tool or a sandblasting tool. The chisel tool can e.g. be an air chisel tool and the grinding tool can e.g. be a steel grinding tool (brush).

The choice of tools to be used for cleaning the stump is made by the tool system after an analysis of the 3D view of the surface of the stump fed in from the vision system. The three-dimensional shape of the stump to be cleaned is identified and the positions of the uncleaned areas of the stump are identified through color differentiation. The choice of tool will depend on the amount of electrolyte on the stumps and the complexity of the impure areas of the stump. A pre-defined decision tree built on experience is used to identify the best tool and this will be part of the tool system. The decision tree uses a knowledge database that is continuously built up based on experience from previous cleaning operations. The knowledge database includes sensor information from previous cleaning operations and linked with human knowledge. Operator-based choice of tools will depend on the contaminated area and this experience will be linked with the images taken of the contaminated area. The decision tree can be a look-up table that compares real-time sensor information with content in the database.

The operation can be performed using a number of possible tools, including a tool change system, and can be performed using a single tool or a composite multi-tool. The composite multi-tool can be specially made for the purpose and can include a number of tool elements, such as e.g. chisel, sharpener and brush.

Figure 4 shows an example where an air hammer is connected to a damper system for the robot manipulator's end effector. Figure 5 shows an example where an air grinder is arranged on the robot's manipulator arm. The air sander performs an ironing operation for post-cleaning the stump. Tests were carried out with these robots, where the manipulator arm followed a pre-programmed path. The tests showed that in this specific case, the electrolyte was successfully removed within seconds. The robot was of the industrial manipulator type supplied by ABB. Other types of industrial manipulators can also be used.

The speed of the cleaning process depends on the amount of electrolyte to be cleaned, the efficiency of the tool, the desired quality of the cleaning result, but also on the type of sensor used and the measurement frequency. Today, the manual cleaning process requires several man-years. Using a robotic cleaning system will require less than one man-year in an average aluminum plant.

Today, post-cleaning is manual and largely dependent on the operator's experience. Layers of dust cover the spent carbon anode, and frozen electrolyte lies beneath the dust.

Post-cleaning is currently carried out as a manual process using heavy manual chisel tools where unclean areas are detected by visual inspection, and the rest by touch detection as frozen electrolyte feels softer than the carbon that forms the stubs. When the chisel tool breaks through the frozen electrolyte, this is clearly felt by the operator and the operator stops the chisel. This feeling experienced by the operator during manual post-cleaning is transferred to the robot solution according to the present invention with the use of force feedback sensors.

Figure 2a shows an example of the design of a tool holder. In this embodiment, the tool holder is equipped with a force/torque sensor (FT sensor) which provides force feedback for detection of electrolyte breakthrough. The FT sensor is of an industrial type and robust in relation to harsh environments. The sensor is arranged on the end effector of the tool holder so that the tool forces are aligned with the sensor elements. Adapter plates connect the FT sensor to the robot end effector. The adapter plates are arranged between the FT sensor, the tool holder and the vibration damper. The adapter plates are firmly attached to the robot end effector.

The FT sensor is used for feedback-based force control of the robot. This will be explained later. Figure 2b is a picture of a chisel tool arranged on the tool holder as in figure 2a with vibration recorders, FT sensor and an adapter plate that connects the tool to the robot arm.

Strong vibrations from the tools, and especially from air tools, can cause

frequent occurrence of errors on the robot control unit, resulting in a poor result of the post-cleaning. Vibration dampers are provided on the robot end effector to remove these errors and enable precise control of the robot. In the embodiment shown in Figures 2a and 2b, the vibration dampers are in the form of parallel aluminum plates

with rubber-based vibration recorders connected with machine screws. Fasteners other than machine screws can also be used. The parallel aluminum plates are connected between the adapter plates and the tool end effector so that they

the parallel aluminum plates are set up perpendicular to the tool forces. The plates can be attached using machine screws. The parallel aluminum plates in the design example in Figure 2b were 88 cm<2> and 1.5 cm thick. Other individually adapted vibration dampers are also conceivable.

Experiments have been carried out with and without vibration dampers. Vibrations from the air tools caused the robot to stop due to overload. These errors were no longer observed after the vibration dampers were added.

Movement planner

The three-dimensional information about the surface of the stump is fed to the motion planner for planning the motion path of the robotic arm to which the tool is attached. The motion planner is formed by a path planner for movement of the tool along the surfaces of the stubs. Concepts range from manual to automatic path planning with obstacle avoidance. The manual path planning will be performed in case the system is not able to detect unclean areas. There will be a continuous update of the movement path to be followed by the tool during the cleaning process based on real-time information from the vision system. The vision system identifies the progress of the cleaning process.

The path planning considered will take place in two parts:

- a first part for generating movement paths for cleaning unclean areas, and - a second part for optimal path planning of robot movement between the unclean areas.

Generation of movement paths for cleaning unclean areas

The three-dimensional information about the stump surface provided by the vision system identifies the dirty areas of the stumps. Path planning can then be carried out through analysis of the three-dimensional information and generation of point-to-point paths. The cleaning process will thus be a point-to-point movement based on continuous updating from the vision system, the FT sensor and the tool system module. This will be explained in more detail below.

Optimal path planning for movement between the unclean areas:

The movement of the robot arm with the tool between the unclean areas can be considered as a point-to-point path planning task in an environment with or without obstacles.

To clean the stump, the tool is brought to the unclean areas of the stump. Lane optimization with respect to time is provided by the lane planner to achieve an efficient and reliable post-cleaning process. The point-to-point path planning method can be based on Rapidly-exploring Random Trees (RRT). The method builds up a collision-free movement path by using randomly sampled points from the robot configuration space, where each point and path segment is tested against the collision space. Open source code from Lavalle can be used for testing motion path concepts. Different trajectories can be simulated by the motion planner system before the actual post-cleaning process is initiated for the robot manipulator. The actual path of movement selected for each post-cleaning process is determined based on cleaning efficiency with respect to time.

The robot configuration space is given by the robot structure and kinematics of the actual robot used. The collision space is defined and detected by the vision system.

Robot control unit

Precise control of the robot manipulator ensures good quality in the post-cleaning of the stumps. The predefined motion path planned by the motion planner must be followed closely to enable rapid and reliable removal of the electrolyte. The identified impure areas may also be small. Industrial robots have very high accuracy (typically 0.1 mm), and since this method is based on the use of such robots, this accuracy will be achieved in this process. The accuracy is thus higher than an operator can achieve.

During the post-cleaning process, the robot manipulator is controlled to ensure that the robot manipulator follows the predefined path. Path following is achieved through the use of motion control based on feedback from position and speed measurements of the movement of each robot joint. This functionality is provided by the supplier of the robot control unit.

The manipulation part of the operation will be based on force interaction between the tool and the carbon anode and/or a combination of force and motion control. The force interaction is detected by the FT sensor and the control methods will depend on the choice of tool. A chisel tool will use position control of the robot and on/off power control. A grinding tool will use continuous position and force control in cascade.

Learning strategies that facilitate learning will be applied in the force feedback loop and in the generation of the decision tree for tool selection.

Breakthrough detection

Several methods can be used to detect electrolyte breakthrough, for example when the tip of the tool has reached the carbon. Examples of methods include the use of an FT sensor, audio or impedance measurements. These methods will be explained in more detail below.

FT sensor

FT sensor measurements are used to detect the variations in oppositely directed forces that will occur depending on contact with carbon or electrolyte. This is due to the difference in density between the two materials. Analysis of these force measurements will be used to detect when the cleaning tool has a breakthrough through the electrolyte. The information from the force measurement is fed to the robot control unit. The force measurement procedure is shown schematically in figure 3. If the analyzes of the force measurement establish the presence of electrolyte, the robot control unit continues the chiseling operation. If the analyzes of the force measurement determine the presence of carbon, the robot control unit stops the chiseling operation. When the chiseling operation is stopped, the area of the stump that has been chiseled is inspected by the vision system. If the vision system identifies the stub as clean in this area, this information is fed to the robot control unit, which selects an appropriate tool and moves the tool end effector to the next position in the predefined path and begins the chiseling operation in this area.

An example of electrolyte breakthrough detection using a force/torque sensor is shown in Figure 7. The curve in Figure 7 was produced using the robotic manipulator with an air hammer as shown in Figure 4. Figure 7 shows a graph of force (N) which function of time (s) as detected by the force sensor. Detection of breakthrough to the carbon stubs is shown by a dip in the curve at approximately 20 seconds, 39 seconds and 57 seconds as the force goes to zero and becomes negative. The falls in the curve thus show the presence of carbon.

Sound

A different sound pattern is detected when the tip of the tool breaks through the electrolyte and hits the carbon. The sound is detected by a microphone and fed to the robot control unit.

Impedance

Impedance measurements can be used by measuring the difference in electrical resistance between the tip of the tool and the electrolyte/carbon materials in the bit. The electrolyte and the carbon materials have different electrical properties. The result of the impedance measurement is fed to the robot control unit.

Combination of methods

The methods described above can be combined in different environments using a Kalman filter or other estimation methods to improve the detection of breakthroughs. Alternatively, the breakthrough detection methods can be used in a cascaded, parallel or serial set of control loops. The choice of methods depends on the tool. For example, sound is only used when chisel tools are used. FT sensor is used in all solutions. Cascaded control loops are used in cases where it is necessary to follow a contour. An advantage of using cascaded control loops is the realization of several control loops based on different measurements, for example speed and power. Parallel control loops enable the use of different measurements in parallel, both of which are capable of changing the state of the system. For example, sound and force detection where the first loop detects a breakthrough will change the state of the system. Serial control is when one control loop provides the reference to the next loop; e.g. speed control and breakthrough detection.

Also in the embodiments that use sound, impedance measurements as well as when combining methods, the vision system inspects the area when carbon is detected to ensure that the area is clean before the tool is moved to the next point in the predefined movement path, as explained for the FT sensor.

The invention is of course not limited in any way to the embodiments described above. On the contrary, many possibilities for modifications of these will be obvious to the person skilled in the art without departing from the basic idea of the invention, as defined in the appended claims.

Claims (20)

1. System for post-cleaning electrolyte from a used carbon anode in aluminum production, where the system comprises: - a robot with a manipulator arm equipped with a tool for removing the electrolyte; - a vision system, comprising: at least one 3D sensor for detecting a three-dimensional shape of a surface of said carbon anode, and an analysis system for identifying the electrolyte on said carbon anode from the three-dimensional shape of the surface; - a sensor for detecting tool breakthrough through the electrolyte on said carbon anode; and - a control system for controlling the robot manipulator arm and the tool based on information from the vision system and the sensor device for detecting tool breakthrough. 2. System according to claim 1, wherein the tool breakthrough detection sensor comprises a force/torque (FT) sensor. 3. System according to claim 1 or 2, where the sensor for detection of tool breakthrough comprises the use of at least one of a sound sensor and an impedance measuring device. 4. System according to at least one of claims 1 -3, where the control system comprises a force/torque (FT) sensor for force feedback control, where the force/torque (FT) sensor detects force interaction between the tool and the carbon anode. 5. System according to at least one of claims 1-4, where the control system further comprises a movement planner for path optimization of the movement path of the robot manipulator arm and the tool in relation to the surface of the carbon anode to be cleaned. 6. System according to at least one of claims 1-5, where the at least one 3D sensor comprises at least one of structural light cameras, stereo cameras, ToF (Time-of-Flight) cameras and 3D laser scanners. 7. System according to at least one of claims 1-6, where the analysis system provides color differentiation and positioning of the electrolyte in a coordinate system related to the three-dimensional shape of the surface of the carbon anode to be cleaned. 8. System according to at least one of claims 1-7, where the tool is a mechanical tool selected from at least one of a chisel tool, a grinding tool and a sandblasting tool. 9. System according to at least one of claims 1-8, where the tool holder comprises at least one vibration damper. 10. Method for post-cleaning electrolyte from a used carbon anode in aluminum production, the system comprising a robot with a manipulator arm equipped with a tool for removing the electrolyte, where the method comprises: - detecting a three-dimensional shape to a surface of said carbon anode; - analyze the three-dimensional shape and identify positions of the electrolyte on said carbon anode, - control the robot manipulator arm with tools based on the three-dimensional shape and the identified positions of the electrolyte, and - detect tool breakthrough through the electrolyte on said carbon anode for further control of the robot manipulator arm with tools. 11. Method according to claim 10, further comprising detecting tool breakthrough through the electrolyte on said carbon anode by using a force/torque (FT) sensor arranged on an end effector on the robotic manipulator arm. 12. Method according to claim 10 or 11, further comprising detecting tool breakthrough through the electrolyte on said carbon anode by using a sound sensor or by using impedance measurements between the tool and the cleaned carbon anode. 13. Method according to at least one of claims 10-12, further comprising identifying the positions of the electrolyte on said carbon anode by means of color differentiation. 14. Method according to at least one of claims 10-13, further comprising selecting at least one tool to be used in the post-cleaning of the carbon anode based on the identified positions of the electrolyte. 15. Method according to at least one of claims 10-14, further comprising the use of a movement planner for path optimization of the movement path of the robot manipulator arm and the tool in relation to the surface of the carbon anode to be cleaned. 16. Method according to at least one of claims 15, further comprising generating a point-to-point path for cleaning the carbon anode optimized with respect to time. 17. Method according to at least one of claims 15, further comprising generating the point-to-point path based on the Rapidly-exploring Random Trees method. 18. Method according to at least one of claims 15-17, further comprising generating a collision-free path for the tool with respect to the surface of the carbon anode to be cleaned. 19. Method according to at least one of claims 15-18, further comprising simulating a number of paths before starting the post-cleaning process and determining an actual path based on cleaning efficiency with respect to time. 20. Method according to at least one of claims 15-19, further comprising updating the movement path to be followed by the tool during the cleaning process based on real-time detection of the three-dimensional shape of the surface of the carbon anode.