SE545424C2

SE545424C2 - Waste sorting robot and method of calibration

Info

Publication number: SE545424C2
Application number: SE2030326A
Authority: SE
Inventors: Harri Holopainen; Tuomas Lukka
Original assignee: Mp Zenrobotics Oy
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2023-09-05
Also published as: WO2022090624A1; SE2030326A1

Abstract

A method of calibrating a waste sorting robot (100) is disclosed. The waste sorting robot (100) has a manipulator (104) moveable within a working area (108) and a suction gripper (120) connected to the manipulator (104) and arranged to selectively grip a waste object (106) in the working area (108). The method comprises moving the suction gripper (120) to a testing position. The method also comprises determining one or more operational parameters of the suction gripper (120) when the suction gripper (120) is in the testing position. The method further comprises comparing the determined one or more operational parameters with one or more predetermined normal operational parameters. The method further yet comprises detecting one or more faults with the suction gripper (120) and / or the waste sorting robot (100) based on the comparison.

Description

Waste sorting robot and method of calibration The present disclosure relates to a waste sorting robot for sorting waste objects and a method of calibration. ln the waste management industry, industrial and domestic waste is increasingly being sorted in order to recover and recycle useful components. Each type of waste, or "fraction" of waste can have a different use and value. lf waste is not sorted, then it often ends up in landfill or is incinerated which may have an undesirable environmental and economic impact. lt is known to sort industrial and domestic waste using a waste sorting robot. The waste sorting robot may pick objects with a suction gripper which uses negative pressure for sucking and gripping an object to be sorted. A problem with existing suction grippers is that the waste sorting robot is used in an environment with a significant amount of dirt and debris.

This means that the waste sorting robot must be inspected, cleaned and maintained periodically. Often when the waste sorting robot undergoes maintenance, the waste sorting robot is dismantled. ln order to check the Waste sorting robot is operating correctly after maintenance, the operator must manually check the functionality of the components. ln some circumstances this is time consuming to perform regularly. Therefore, the operator may only realise that the Waste sorting robot is not operating correctly during a sorting operation. This reduces the efficiency of the waste sorting robot because the waste sorting robot must be taken offline whilst further maintenance and inspections are carried out.

Examples described hereinafter aim to address the aforementioned problems. ln a first aspect of the disclosure, there is provided a method of calibrating a waste sorting Optionally, the method comprises detecting a calibration trigger event and moving the suction gripper to the testing position in dependence of detecting the calibration trigger event.

Optionally, the detecting the calibration trigger event comprises detecting an interruption in suction gripper operations of the waste sorting robot.

Optionally, detecting the interruption comprises detecting that the Waste sorting robot has been switched on.

Optionally, detecting the calibration trigger event comprises receiving a user instruction.

Optionally, the moving the suction gripper to a testing position comprises engaging the suction gripper with a testing surface.

Optionally, the testing surface comprises one or more sensors for detecting pressure and /or force generated by the suction gripper in the testing position.

Optionally, the method comprises comparing a signal received from the one or more sensors of the testing surface with a signal from one or more sensors mounted in the suction gripper.

Optionally, the method comprises determining whether the difference in the received signals is indicative of a fault.

Optionally, the method comprises generating an alert in dependence of the detecting one or more faults.

Optionally, the method comprises determining the type of the one or more faults in dependence on the determined operational parameters and including the type of the one or more faults in the alert.

Optionally, the determining one or more operational parameters of the suction gripper comprises determining a maximum vacuum pressure of the suction gripper.

Optionally, the determining one or more operational parameters of the suction gripper comprises determining that the maximum vacuum pressure is outside a maximum vacuum pressure operating range.

Optionally, the determining one or more operational parameters of the suction gripper comprises determining a minimum air supply pressure supplied to the suction gripper.

Optionally, the determining one or more operational parameters of the suction gripper comprises determining that the minimum air supply pressure is outside a minimum air supply pressure operational range.

Optionally, the suction gripper comprises a blow tube for generating a positive air pressure and ejecting eject debris, dirt or other objects out of the suction gripper.

Optionally, the determining one or more parameters of the suction gripper comprises determining that the maximum blow pressure of the blow tube is outside a maximum blow pressure operating range.

Optionally, the method comprises determining that the one or more detected faults are one or more of: malfunctioning sensors, insufficient maximum vacuum pressure, the suction gripper is blocked, the suction gripper is damaged, insufficient air supply pressure, and /or a build-up of material inside the suction gripper. ln a second aspect of the disclosure, there is provided a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method according to the first aspect. ln a third aspect of the disclosure there is provided a waste sorting robot -' Various other aspects and further examples are also described in the following detailed description and in the attached claims with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of a waste sorting robot; Figure 2 shows a schematic front view of a waste sorting robot; Figure 3 shows a perspective view of a suction gripper; Figure 4 shows a cross-sectional view of a suction gripper; Figure 5 shows a schematic view of a waste sorting robot; Figures 6a, 6b, 6c show graphs of different operational parameters of the waste sorting robot according to operational scenarios; and Figure 7 shows a flow diagram for operation of a waste sorting robot.

Figure 1 shows a perspective view of a waste sorting robot 100. ln some examples, the waste sorting robot 100 can be a waste sorting gantry robot 100. ln other examples, other types of waste sorting robots can be used. For the purposes of brevity, the examples will be described in reference to waste sorting gantry robots but the examples described below can be used with other types of robot such as robot arms or delta robots. ln some other examples, the waste sorting robot 100 is a Selective Compliance Assembly Robot Arm (SCARA).

The waste sorting robot 100 comprises a controller 200 (schematically shown in Figure 2) for sending control and movement instructions to a manipulator 104 for interacting with a waste object 106 to be sorted. For the purposes of clarity, only one waste object 106 is shown in Figure 1 but there can be any number of waste objects 106 moving past the waste sorting robot 100. The controller 200 may be implemented on hardware, firmware or software operating on one or more processors or computers. A single processor can operate the different functionalities or separate individual processors, or separate groups of processors can operate each functionality.

The combination of the controller 200 sending control instructions to the manipulator 104 can also be referred to as a "robot". The controller 200 is located remote from the manipulator104 and in some examples is housed in first and second cabinets 112, 116. ln other examples, the controller 200 can be integral with the manipulator 104 and / or a gantry frame 102. ln some examples, part of the gantry frame 102 is housed in the first and second cabinets 112, 116 for shielding one or more components of the waste sorting robot The manipulator 104 physically engages and moves the waste object 106 that enters a working area 108 in order to sort the waste object 106. The working area 108 of a manipulator 104 is an area within which the manipulator 104 is able to reach and interact with the waste object 106. The working area 108 as shown in Figure 1 is a cross hatched area beneath the manipulator The manipulator104 is configured to move at variable heights above the working area 108. ln this way, the manipulator 104 is configured to move within a working volume defined by the height above the working area 108 where the robot can manipulate the waste object 106. The manipulator 104 comprises one or more components for effecting relative movement with respect to the waste object 106. The manipulator 104 will now be described in further detail.

As shown in Figure 1, the manipulator 104 is configured to move within the working volume. The manipulator 104 comprises one or more servos, pneumatic actuators or any other type of mechanical actuator for moving the manipulator 104 in one or more axes. For the purposes of clarity, the servos, pneumatic actuators or mechanical actuators are not shown in Figure 1. Movement of the manipulator104 is known and will not be discussed any further. A suction gripper 120 is coupled to the manipulator104 and the suction gripper 120 is discussed in further detail below.

The servos, pneumatic actuators or mechanical actuators are connectively connected to the controller 200 and the controller 200 is configured to issue instructions for actuating one or more of the servos, pneumatic actuators or mechanical actuators to move the manipulator104 within the working area 108. Connections (not shown) between the servos, pneumatic actuators or mechanical actuators and the controller 200 can comprise one or more data and / or power connections. The control of servos, pneumatic actuators or mechanical actuators to move of the manipulator104 is known and will not be discussed any further.

The waste object 106 is moved into the working area 108 by a conveyor belt 110. The path of travel of the conveyor belt 110 intersects with the working area 108. The direction of the conveyor belt 110 is shown in Figure 1 by two arrows. This means the waste object 106 moving on the conveyor belt 110 will pass through the working area 108. The conveyor belt 110 can be a continuous belt, or a conveyor belt formed from overlapping portions. The conveyor belt 110 can be a single belt or alternatively a plurality of adjacent moving belts (not shown). ln other examples, the waste object 106 can be conveyed into the working area 108 via other conveying means. The conveyor belt 110 can be any suitable means for moving the waste object 106 into the working area 108. For example, the waste object 106 are fed under gravity via a slide (not shown) to the working area The waste sorting robot 100 is arranged to sort the waste object 106 into fractions according to one or more parameters of the waste object 106. The controller 200 receives information from the at least one sensor (not shown) corresponding to the waste object 106 on the conveyor belt 110. The at least one sensor is positioned in front of the manipulator 104 so that detected measurements of the waste object 106 are sent to the controller 200 before the waste object 106 enters the working area 108. ln some examples, the at least one sensor can be any sensor suitable for determining a parameter of the waste object 106 e.g. one or more of a RGB camera, an infrared camera, a metal detector, a hall sensor, a temperature sensor, visual and /or infrared spectroscopic detector, 3D imaging sensor, terahertz imaging system, radioactivity sensor and /or a laser e.g. LIDAR.

The controller 200 determines instructions for moving the manipulator 104 based on the received information according to one or more criteria. Various information processing techniques can be adopted by the controller 200 for controlling the manipulator 104. Such information processing techniques are described in WO2012/089928, WO2012/052615, WO2011/161304, WO2008/102052 which are incorporated herein by reference. Techniques for sorting the waste object 106 are known and will not be discussed any further.

Once the manipulator 104 has received instructions from the controller 200, the manipulator 104 executes the commands and moves the suction gripper 120 to pick the waste object 106 from the conveyor belt 110. The process of selecting and manipulating the waste object 106 on the conveyor belt 110 is known as a "pick". The controller 200 is arranged to send instructions to the manipulator 104 and suction gripper 120 to perform a gripping operation needed for the pick. Once a pick has been completed, the manipulator 104 drops or throws the waste object 106 into a chute 114 adjacent to the conveyor belt ln order for the waste sorting robot 100 to successfully perform a gripping operation and in turn a picking operation, the waste sorting robot 100 must be operating correctly. lt is important that the waste sorting robot 100 is calibrated correctly after inspection, maintenance and / or Cleaning. Since the waste sorting robot 100 is handling waste objects, the waste sorting robot 100 regularly becomes dirty and frequent maintenance may be required. This means that the operator must check the performance of the waste sorting robot 100 before restarting the waste sorting robot 100. For example, the waste sorting robot 100 may be reassembled incorrectly adversely affecting performance of the waste sorting robot 100. ln particular, the operator must ensure that the suction gripper 120 and the pneumatic system 222 are operating normally. Calibration of the waste sorting robot 100 and the suction gripper 120 is discussed below.

The waste sorting robot 100 will now be described in more detail in reference to Figures 2 and 5. Figure 2 shows a schematic front view of the waste sorting robot 100. Figure 5 shows a detailed schematic view of the suction gripper 120 connected to the controller 200. The suction gripper 120 comprises a suction cup 220 for physically engaging with a surface of the waste object The pneumatic system 222 comprises at least a first air hose 202 for connecting the suction gripper The suction gripper 120 is in fluid communication with a pneumatic system 120 to a compressed air supply. For the purposes of clarity, only the first air hose 202 is shown in Figure 2 connecting the suction gripper 120 to the compressed air supply but there can be any number of air hoses connected between the suction gripper 120 and the compressed air supply. For example, there can optionally be at least a second air hose connecting the suction gripper 120 to the compressed air supply. ln this way, a second source of air is provided to the suction gripper 120 for operating a blow tube 402 (discussed in reference to Figure 4 below). ln some examples, the first air hose 202 can be connected to a plurality of downstream air hoses 500, 502 for supplying compressed air to a plurality of pneumatic components in the pneumatic system 222. For example, the first air hose 202 is a single, unitary air hose mounted on the manipulator 104. By providing only the first air hose 202 which is mounted on the manipulator 104 to the suction gripper 120, installation and maintenance of the waste sorting robot 100 can be simplified. The first air hose 202 is flexible and mounted to the gantry frame 102 and / or the manipulator104. The first air hose 202 is sufficiently flexible to move and flex so as to change shape as the manipulator 104 moves without impeding the movement of the manipulator The pneumatic system 222 comprises an air compressor 206 for generating a source of compressed air. Optionally, the pneumatic system 222 can also comprise an air storage tank (not shown) for compressed air. Furthermore, the pneumatic system 222 can also comprise one or more pneumatic valves 204 for selectively providing air to the suction gripper 120. ln this way, the pneumatic system 222 comprises air supply such as air compressor 206 in fluid connection to the suction gripper 120 configured to generate an airflow along an airflow path between the air supply e.g. the air compressor 206 and the suction gripper 120. ln other examples, the air supply can be provided by any suitable source of compressed air or compressed gas.

The pneumatic system 222 is schematically shown as being located within the first cabinet 112. However, in other examples the pneumatic system 222 can be partially or wholly located remote from the waste sorting robot 100. For example, there may be a plurality of waste sorting robots 100 on a sorting line (not shown) each of which require a source of air. ln this way, a single air compressor 206 can be connected to a plurality of waste sorting robots 100 via a plurality of air hoses. Accordingly, the pneumatic system 222 may be located between waste sorting robots Operation of the pneumatic system 222 is controlled by the controller 200. The controller 200 is connected via pneumatic control lines 208, 210 to the pneumatic system 222, the air compressor 206 and the pneumatic valve 204. The controller 200 is configured to send control instructions to the pneumatic system 222, the air compressor 206, and the pneumatic valve 204. This means that the controller 200 can selectively operate e.g. the air compressor 206 or the pneumatic valve 204 to deliver a supply of air to the suction gripper An example of the suction gripper 120 will now be discussed in reference to Figures 3 and 4. Figure 3 shows a perspective view of the suction gripper 120 without the suction cup 220. Figure 4 shows a cross-sectional side view of the suction gripper 120. As mentioned previously, the suction gripper 120 comprises a suction cup 220 (as shown in Figure 4). The suction cup 220 as shown in Figure 4 has a cup shape e.g. an approximate hemispherical shape. However, other known suction cups can be used instead e.g. a ribbed cylindrical suction cup 506 (as shown in Figure 5).

The suction gripper 120 as shown in Figure 4 comprises an integrated suction tube 400 and blow tube 402 for carrying out grip / pick operations and throwing operations. This is known and will not be discussed in any further detail.

The suction gripper 120 comprises a suction tube air supply inlet 300 which is in fluid communication with the first air hose 202 (not shown in Figure 3). The suction tube air supply inlet 300 introduces a fast, high pressure source of air into the suction tube 400 which creates a vacuum pressure in the suction tube 400 represented by the arrows in Figure 3. The vacuum pressure is also created in the suction cup 220 since the suction cup 220 is in fluid communication with the suction tube As shown in Figure 4, the suction gripper 120 also comprises a blow or "sneezing" tube 402 connected to the suction tube 400. The blow tube 402 is essentially the same as the suction tube 400 but reversed in orientation to generate a positive air pressure rather than a negative air pressure.

Similar to the suction tube 400, the blow tube 402 comprises a blow tube air supply inlet 302 which is in fluid communication with the first air hose 202. Accordingly, the blow tube air supply inlet 302 introduces a second air supply into the suction gripper ln some examples, the first air hose 202 is coupled between the air compressor 206 and a pneumatic valve 204. ln some examples, the pneumatic valve 204 which is a three-way valve 504. The three-way valve 504 is configured for selectively providing an air flow to either the suction tube 400 or the blow tube ln some examples, the suction tube 400 comprises a first opening 404 to receive a first pressure sensor 408 to measure the vacuum pressure in the suction gripper 120. ln some examples, the first pressure sensor 408 is configured to detect the maximum vacuum pressure pvmax in the suction gripper The controller 200 is connected to the first pressure sensor 408 (as shown in Figure 4) via a communication line 218. The first pressure sensor 408 is arranged to detect the vacuum pressure in the suction cup 220 and the suction tube 400. The first pressure sensor 408 is configured to send pressure measurement information to the controller 200 indicating the vacuum pressure in the suction cup 220. The controller 200 can determine whether the suction cup 220 is able to make a seal against the surface of the waste object 106. This means that the controller 200 can determine whether the suction gripper 120 is not able to grip, lift and move the waste object Likewise, the blow tube 402 optionally comprises a second opening 406 to receive a second pressure sensor 410 to measure the positive pressure psneeze max when the suction gripper 120 operates in a blow mode. ln some examples, the blow tube 402 does not comprise a second opening 406. lnstead there is a single pressure sensor e.g. the first pressure sensorwhich is configured to measure the pressure difference between the suction gripper 120 and ambient air pressure. ln this way the first pressure sensor 408 can measure both the negative pressure e.g. vacuum pressure and the positive pressure e.g. the sneeze pressure in the suction cup 120. ln some examples, the first pressure sensor 408 is configured to measure pressure within a range of -1 bar to 10 bar. Hereinafter, the pressure sensor is referred to as the first pressure sensor 408, however the first pressure sensor 408 can be replaced with a first and second pressure sensor 408, 410 to respectively measure the negative pressure and positive pressure in the suction gripper The first pressure sensor 408 is connected to the controller 200 and send signals to the controller 200. Only the communication line 218 between the first pressure sensor 408 and the controller 200 is shown for the purposes of clarity in Figures 2 and The first pressure sensor 408 is configured to measure the pressure in the suction tube 400 and the suction cup 220. ln some examples, the controller 200 can receive pressure measurement information from the first pressure sensor 408. The controller 200 is configured to determine the maximum vacuum pressure pvmax of the suction tube The vacuum pressure p., of the suction tube 400 defined as follows: pi; = patm _ pabs Wherein palm is the atmospheric pressure and paaa is the absolute pressure in the suction gripper120. Absolute pressure is the pressure in the suction gripper120 measured in respect to a hard vacuum (e.g. a pressure of 0 bar). ln this way, the maximum vacuum pressure pl, max of the suction tube 400 is the greatest difference between atmospheric pressure and the absolute pressure of the suction tube 400. ln other words, this measures the ability of the pneumatic system 222 to create a partial vacuum in the suction tube The maximum vacuum pressure pvmax of the suction gripper 120 is an important parameter of the suction gripper120 because it relates to the maximum weight of the waste object 106 that can be lifted by the suction gripper 120. The maximum vacuum pressure pv max is also important because not every gripping operation will achieve the maximum vacuum pressure pvmax. For example, the waste object 106 can have an irregular shape and surface texture so a good seal may not be possible in every gripping operation. Accordingly, the suction gripper 120 may need to generate a certain maximum vacuum pressure pvmax to pick the waste object 106 with an imperfect seal between the suction gripper 120 and the waste object ln addition, the first pressure sensor 408 sends pressure information to the controller 200 in respect of the positive pressure in the suction gripper 120 when performing a "sneeze" operation . A sneeze operation is when the suction gripper 120 creates a positive pressure in the suction gripper 120 to eject debris, dirt or other objects which can potentially clog the suction gripper. ln other words, the sneeze operation is an unblocking operation for the suction gripper 120. The sneeze operation is carried out after the waste object 106 has been thrown and released by the suction gripper 120. ln this way, the sneeze operation does not interfere with the trajectory of the thrown waste object ln some examples, the waste sorting robot 100 is configured to perform a sneezing operation over the chute 114. This is because some waste objects 106 are thin and flexible such as foils or other thin materials like plastic sheets. A thin and flexible material does not fly predicably towards the chute 1154 when thrown by the waste sorting robot 100. Therefore, in some examples, it can be desirable to urge thin and flexible waste object with a sneeze operation directly above the chute 114. This means that the thin and flexible waste object will successfully separate from the suction gripper 120 and drop down into the chute This means that the controller 200 can determine the maximum sneeze pressure psneeze max of the blow tube 402. The maximum sneeze pressure psneeze max is important because it helps keep the waste sorting robot 100 clean. For example, debris blocking the suction gripper 120 can be ejected by the suction gripper 120 when the maximum sneeze pressure psneeze max iS high enough. Furthermore, if the maximum sneeze pressure psneeze max drops below an operating threshold, then the waste sorting robot 100 may not be able to clear the suction gripper 120 and grip other waste objects The pneumatic system 222 also comprises an air supply pressure sensor 224. The air supply pressure sensor 224 is connected to the controller 200 via a communication line 226. The air supply pressure sensor 224 is configured to measure the pressure of the compressed air supply to the suction gripper 120. ln some examples, the air supply pressure sensor 224 is mounted in the first cabinet 112. ln some other examples, the air supply pressure sensor 224 is mounted on the suction tube 400, for example mounted at the suction tube air supply inlet 300 of the suction tube 400. ln some other examples, the air supply pressure sensor 224 is mounted on the first air hose 202, for example a gauge (not shown). ln this way, the air supply pressure sensor 224 sends pressure information to the controller 200. The controller 200 isconfigured to determine the minimum pressure pas min of the air supplied to the suction gripper The minimum air supply pressure pas min is an important parameter of the suction gripper 120 because it relates to whether suction gripper 120 e.g. the suction tube 400 and the blow tube 402 are operational for a specified gripping performance.

According to some examples, the waste sorting robot 100 is ca|ibrated using one or more sensors of the waste sorting robot 100. ln some examples, the one or more sensors of the waste sorting robot 100 are pressure sensors associated with the pneumatic system 222. One or more pressure sensors 408, 410, 224 are used to measure the pressure in different parts of the suction gripper 120 and pneumatic system 222 during operation. The pressure measurements can be used to detect faults in the waste sorting robot The calibration of the waste sorting robot 100 will be discussed in reference to Figures 6a, 6b, 6c, and Figure 7. Figures 6a, 6b, 6c show graphs of different parameters of the waste sorting robot 100 during calibration and operation. Figure 7 shows a flow diagram of operation of the waste sorting robot 100 according to an example.

The controller 200 determines when to calibrate the waste sorting robot 100. This means that the controller 200 periodically performs the self-calibration. Advantageously this means that the operator does not have to carry out the calibration which can be time consuming and cumbersome.

As shown in step 700 in Figure 7, the controller 200 detects a trigger for calibration. The trigger for calibration can be one or more predetermined events for causing the calibration operation. ln some examples, the controller 200 sends control instructions to the manipulator 104 and suction gripper 120 to perform the calibration operation when the controller 200 determines that the waste sorting robot 100 has been switched off, or not in operation, for a period of time. ln this way, the controller 200 initiates the calibration operation every time the waste sorting robot 100 is switched on. This means that the waste sorting robot 100 has been ca|ibrated before every sorting operation. ln some other examples, additionally or alternatively, the controller 200 initiates the calibration operation having determined on or more of the following conditions: o The controller 200 determines that a period of time has elapsed since the last calibration operation;o The controller 200 determines that a predetermined number of gripping or sorting operations have occurred since the last calibration operation; o A condition of the waste sorting robot 100 has been detected by the controller 200 e.g. a maintenance procedure, an inspection procedure and /or a cleaning procedure o An operator instruction to initiate the calibration operation has been received by the controller ln some examples, the controller 200 is arranged to initiate the calibration operation in response to any condition or change that can affect the normal operation of the waste sorting robot ln some examples, the controller 200 initiates the calibration operation by moving the manipulator 104 to a testing position as shown in step 702. Figure 2 shows a first testing position A wherein the manipulator 104 is moved within the second cabinet 116. ln some examples, the first testing position A is outside of the working area 108 of the waste sorting robot 100. This means that the calibration operation does not impact on the normal operation of the waste sorting robot By positioning the manipulator 104 within the second cabinet 116 during the calibration operation, the manipulator 104 is at one end of the gantry frame 102. This means that an operator can more easily inspect the manipulator 104 during the calibration operation. This can be helpful if the operator needs to visually inspect the manipulator 104 before operation of the waste sorting robot 100 or during the calibration operation.

Alternatively, the manipulator 104 can be positioned between the first and second cabinets 112, 116 during the calibration operation as shown in Figure 2 by a second testing position B. ln other words, the manipulator 104 is within the working area 108 during the calibration operation. During the calibration operation the controller 200 tests the operation of the suction gripper 120 and the pneumatic system 222. Since the manipulator 104 grips the waste object 106 with the suction gripper 120 it is important to understand whether the suction gripperand the pneumatic system 222 are functioning correctly.

The controller 200 instructs the manipulator 104 to position the suction gripper 120 against a testing plate 212. The testing plate 212 comprises a testing surface 232 for the suction gripper 120 to abut and exert a force against during the calibration operation. ln this way, the testing surface 232 is a known surface for testing the suction gripper 120. ln some examples, thetesting surface 232 is a smooth flat surface providing the optimum surface for creating a good sea| bet\Neen the testing surface 232 and the suction cup 220. This means that the maximum vacuum pressure pvmax can be measured accurately.

As shown in Figure 2, the testing plate 212 is fixed to the gantry frame 102 in the second cabinet 116. ln other examples, the testing plate 212 is mounted on the outside of the second cabinet 116 to the side of the gantry frame 102. ln other examples, the testing plate 212 can be mounted at any other suitable location on the gantry frame 102. This means that the testing plate 212 is at a predetermined position with respect to the gantry frame 102. Accordingly, the controller 200 can issue instructions to move the manipulator 104 and the suction gripper 120 to the same position for each calibration operation. This is desirable because the calibration operation occurs in the same place each time and reduces variation in the calibration results. ln some examples, the testing plate 212 is mounted at the first testing position A within the second cabinet 116. This means that the testing plate 212 is outside the working area 108 and does not interfere with the manipulator 104 or the suction gripper 120 during a picking operation.

Alternatively, the operator manually mounts a testing accessory 228 on the suction gripper 120 at the second testing position B or the first testing position A. The testing accessory 228 comprises an accessory testing surface 230. The accessory testing surface 230 is similar to the testing surface 232 of the testing plate Optionally, the testing plate 212 is connected to a force sensor 214. The force sensor 214 is configured to determine the force exerted on the testing plate 212 during the calibration operation. The force sensor 214 is connected to the controller 200 via a connection line 216. The force sensor 214 can measure the force caused by the suction gripper 120 during the calibration operation. ln some examples, the force sensor 214 can optionally measure the blowing force caused by the suction gripper 120 due to the maximum sneeze pressure psneeze max. Optionally force sensor 214 can optionally measure the suction force caused by the maximum vacuum pressure pv max. Since the cross-sectional area of the suction gripper 120 is known, the controller 200 can determine the pressure of the suction gripper 120 during the calibration operation from the measurement signal from the force sensor 214. ln this way, the controller 200 can calibrate the first pressure sensor 408 to the results of the force sensor 214. ln someother examples, the controller 200 determine that the first pressure sensor 408 is faulty based on comparison with the pressure calculated from the force sensor Once the suction gripper 120 is in the first testing position A (or the second testing position B), then the controller determines one or more operational parameters of the suction gripper 120 as shown in steps 704, 706, 708. Whilst three different operational parameters of the suction gripper 120 are determined by the controller 200, in other examples, any number of operational parameters of the suction gripper 120 can be measured and determined. For example, a single operational parameter such as minimum air supply pressure pas mm can be measured in the calibration operation. Measuring a single operational parameter can allow for a quicker calibration operation focused on one operational aspect of the waste sorting robot pressure pasmfn, the maximum vacuum pressure pvmax, and maximum sneeze pressure psneeze ln a preferred example, the controller determines at least the minimum air supply ITIHX - The controller 200 initiates the suction gripper 120 to carry out a test gripping operation against the testing plate 212. The controller 200 receives pressure sensor information from air supply pressure sensor 224 and determines the minimum air supply pressure pas mm as shown in step 704. At the same time, the controller 200 receives pressure sensor information from the first pressure sensor 408 in respect of the maximum vacuum pressure pvmax.

Optionally, the controller 200 then sends a control instruction to the suction gripper 120 to reverse the airflow and blow air. ln some examples, the suction gripper 120 blow against the rigid testing plate 212 and the maximum sneeze pressure psneeze max iS FGCOFÖGÖ- ln SOmG examples, the suction gripper 120 does not blow against the rigid testing plate 212 because this can affect the measurement of the maximum sneeze pressure psneeze max. Accordingly, the controller 200 sends a control instruction to the manipulator 104 to move the suction gripper 120 away from the testing plate The controller 200 then receives pressure sensor measurement information from the pressure sensors 408, 224 and determines the operational parameters of the suction gripper 120 as shown in steps 704, 706, 708. Some or all of the steps 704, 706, 708 can be carried out in parallel as shown in Figure 7 or alternatively can be carried out sequentially (not shown).

Once the controller 200 has determined the operational parameters of the suction gripper 120, the controller 200 compares the determined operational parameters with predetermined normal operational parameters as shown in step 710. ln some examples, the step of comparing comprises checking that the maximum sneeze pressure panaaza max, the maximum vacuum pressure px max, and the minimum air supply pressure paa mm during the calibration operation are respectively within the normal paaaaaa max range 600, the normal pxmax range 604, and the normal paa mm range The predetermined normal operational parameters are stored in the memory (not shown) of the controller 200. ln some examples, the normal panaaaa max range 600, the normal pxmax range 604, and the normal paa mm range 608 are based on the size, components, and functionality of the waste sorting robot 100. ln some examples the normal panaaza max range 600, the normal pxmax range 604, and the normal paa mm range 608 are based on long term historical averages of the operational parameters of the waste sorting robot Representative graphs plotting the received pressure sensor measurement information during the calibration operation is shown in Figures 6a, 6b, and 6c. The process of the controller 200 determining whether the suction gripper 120 is within operational parameters will now be discussed.

Figure 6a shows a graph of the maximum sneeze pressure paaaaaa max (bar) during the calibration operation, Figure 6b shows a graph of the maximum vacuum pressure pxmax (mbar) during the calibration operation, and Figure 6c shows a graph of the minimum air supply pressure paa mm (bar) during the calibration operation.

Figures 6a, 6b, 6c show a series of four calibration operations over time. The different series of four calibration operations are separated indicating that there is a period of time between the series of calibration operations where the waste sorting robot 100 was not in operation. The first three calibration operations shown in dotted box 612 represent normal behaviour of the waste sorting robot 100. The fourth calibration operation shows abnormal functionality of the waste sorting robot 100 indicating a fault with the waste sorting robot 100. ln some examples, the calibration operation can comprise a plurality of actuations ofthe suction gripper 120 actuated when in the first testing position A. The results of a plurality of successive suction gripper actuations can be averaged during the calibration operation. ln some alternative examples, the calibration operation can be a single actuation of the suction gripper 120 when in the first testing position A.

Figure 6a shows the maximum sneeze pressure paneeze max as the instantaneous maximum sneeze pressure panaaza max detected in the blow tube 402 of the suction gripper 120. ln othereXafnpleS, the rnaXirnum sneeze pressure pamaaza max calculated by the controller 200 is a maximum sneeze pressure average gíanaaaa max for the duration of the calibration operation.

As shown in Figure 6a, in normal operation the instantaneous maximum sneeze pressure panaaza max is generally above a predetermined threshold. Accordingly, the controller 200 checks during the calibration operation whether the maximum sneeze pressure pamaaza max iS above the predetermined threshold or within a normal operating range as shown in step 712. The normal panaaza max range 600 is shown by a rectangle which represents a range between 5 to 7 bar. A below normal panaaza max range 602 of the is shown by a rectangle which represents 4 to 5 bar. During normal operation, the maximum sneeze pressure panaaza max iieS Within the normal panaaaa max range 600. ln some examples, the normal panaaaa max range 600 can be varied to any other suitable ranges or combination thereof e.g. between 6 to 8 bar, 7 to 9 bar, 8 to 10 bar. suitable ranges or combination thereof e.g. between 5 to 6 bar, 5 to 7 bar, 6 to 8 bar etc. ln some examples, the below normal paa mm range 610 can be varied to any other ln some examples, if the maximum sneeze pressure pamaaza max rernainS in OF |0W6F than the b6|0W n0ffnal panaaza max range 602, then the controller 200 determines that the suction gripper 120 is operating outside normal ranges and /or not calibrated correctly as shown in step 712. This can indicate a fault with the waste sorting robot 100 or the suction gripper 120 and the controller 200 can generate an alert to the operator as shown in step Figure 6b shows the maximum vacuum pressure px, max as the instantaneous maximum vacuum pressure detected in the suction gripper 120. ln other examples, the maximum vacuum pressure px, max calculated by the controller 200 is a maximum vacuum pressure average px,max for the duration of the calibration operation.

As shown in Figure 6b, in normal operation the instantaneous maximum vacuum pressure px, max is generally above a predetermined threshold. Accordingly, the controller 200 checks during the calibration operation whether the maximum vacuum pressure px, max is above the predetermined threshold or within a normal operating range as shown in step 712. The normal px,max range 604 is shown by a rectangle which represents a range between 600 to 800 mbar. A below normal px,max range 606 of the is shown by a rectangle which represents 500 to 600 mbar. During normal operation, the maximum vacuum pressure px,max lies within the normal p, max range 604. ln some examples, the normal px,max range 604 can be varied to any other suitable ranges or combination thereof e.g. between 650 to 850 mbar, 700 to 900 mbar,to 950 mbar. ln some examples, the below normal px,max range 606 can be varied to any othersuitable ranges or combination thereof e.g. betvveen 550 to 650 mbar, 600 to 700 mbar, 700 to 850 mbar etc. ln some examples, if the maximum vacuum pressure pvmnx remains in or lower than the below normal pi, max range 606, then the controller 200 determines that the suction gripper 120 is operating outside normal ranges and /or not calibrated correctly as shown in step 712. This can indicate a fault with the waste sorting robot 100 or the suction gripper 120 and the controller 200 can generate an alert to the operator as shown in step As shown in Figure 6c, the minimum air supply pressure pan min is the instantaneous air supply pressure detected in the suction gripper 120, the first air hose 202 or another component in the pneumatic system 222 suppling the compressed air to the suction gripper 120. ln other examples, the minimum air supply pressure pan min is a minimum air supply pressure average ñas min during the calibration operation. ln normal operation, the instantaneous minimum air supply pressure pns min is generally above a predetermined threshold. ln normal operation the minimum air supply pressure pns min is above a predetermined threshold. Accordingly, the controller 200 checks during the calibration operation whether the minimum air supply pressure pns min is above the predetermined threshold or within a normal operating range as shown in step 712. The normal pns min range 608 is shown by a rectangle which represents a range between 5 to 7 bar. A below normal pns min range 610 is shown by a rectangle which represents 4 to 5 bar. ln some examples, if the minimum air supply pressure pns min remains in or lower than the below normal pas min range 610, then the controller 200 determines that the suction gripper 120 is operating outside normal ranges and /or not calibrated correctly. This can indicate a fault with the waste sorting robot 100 or the suction gripper120 and the controller 200 can generate an alert to the operator as shown in step ln some examples, the normal pan min range 608 can be varied to any other suitable ranges or combination thereof e.g. between 6 to 8 bar, 7 to 9 bar, 8 to 10 bar. ln some examples, the below normal pns min range 610 can be varied to any other suitable ranges or combination thereof e.g. between 5 to 6 bar, 5 to 7 bar, 6 to 8 bar etc. lf the controller determines that the calibration operation e.g. as shown in dotted boxrepresent normal behaviour of the waste sorting robot 100, the controller 200 ends the calibration operation as shown in step 716. The controller 200 can optionally issue a messageor alert to the operator that the waste sorting robot 100 is correctly calibrated and / or ready for sorting operations.

As mentioned above, if the controller 200 determines that one or more of the operational parameters of the waste sorting robot 100 or the suction gripper 120 are outside the normal operating ranges 600, 604, 608, then the controller 200 issues an alert to the operator. ln some examples, the alert is an error message displayed on a user terminal. ln some examples, the controller 200 includes information as to how the Waste sorting robot 100 failed the calibration and information relating to fixing a fault in the waste sorting robot ln another example two or more examples are combined. Features of one example can be combined with features of other examples. Examples of the disclosure have been discussed with particular reference to the examples illustrated. However it will be appreciated that variations and modifications may be made to the examples described within the scope of the disclosure. 19

Claims

1. A method of calibrating a Waste sorting robot (100) having a frame (102) and manipulator (104) moveable within a working area (108) and a suction gripper (120) connected to the manipulator (104) and arranged to selectively grip a waste object (106) in the working area (108), the method comprising: moving the suction gripper (120) to a testing plate having a testing surface (232) configured to receive the suction gripper in a testing position wherein the testing plate (212) is fixed to the frame (102); determining one or more operational parameters of the suction gripper (120) when the suction gripper (120) is in the testing position; comparing the determined one or more operational parameters with one or more predetermined normal operational parameters; and detecting one or more faults with the suction gripper (120) and / or the Waste sorting robot (100) based on the comparison; wherein the determining one or more operational parameters of the suction gripper (120) comprises determining one or more pressure parameters of the suction gripper (120).

2. A method according to claim 1 wherein the method comprises detecting a calibration trigger event and moving the suction gripper (120) to the testing position in dependence of detecting the calibration trigger event.

3. A method according to claim 2 wherein the detecting the calibration trigger event comprises detecting an interruption in suction gripper (120) operations of the Waste sorting robot (100).

4. A method according to claim 3 wherein detecting the interruption comprises detecting that the waste sorting robot (100) has been switched on.

5. A method according to claim 2 wherein detecting the calibration trigger event comprises receiving a user instruction.

6. A method according to any of the preceding claims wherein the moving the suction gripper (120) to a testing position comprises engaging the suction gripper (120) with testing surface (232).

7. A method according to any of the preceding claims Wherein the testing surface (232) comprises one or more sensors for detecting pressure and / or force generated by the suction gripper (120) in the testing position.

8. A method according to claim 7 Wherein the method comprises comparing a signal received from the one or more sensors of the testing surface (232) with a signal from one or more sensors mounted in the suction gripper (120).

9. A method according to claim 8 Wherein the method comprises determining whether the difference in the received signals is indicative of a fault.

10. A method according to any of the preceding claims Wherein the method comprises generating an alert in dependence of the detecting one or more faults.

11. A method according to claim 10 Wherein the method comprises determining the type of the one or more faults in dependence on the determined operational parameters and including the type of the one or more faults in the alert.

12. A method according to any of the preceding claims Wherein the determining one or more operational parameters of the suction gripper (120) comprises determining a maximum vacuum pressure of the suction gripper (120).

13. A method according to claim 12 Wherein the determining one or more operational parameters of the suction gripper (120) comprises determining that the maximum vacuum pressure is outside a maximum vacuum pressure operating range.

14. A method according to any of the preceding claims Wherein the determining one or more operational parameters of the suction gripper (120) comprises determining a minimum air supply pressure supplied to the suction gripper (120).

15. A method according to claim 14 Wherein the determining one or more operational parameters of the suction gripper (120) comprises determining that the minimum air supply pressure is outside a minimum air supply pressure operational range.

16. A method according to any of the preceding claims wherein the suction gripper (120) comprises a blow tube (402) for generating a positive air pressure and ejecting eject debris, dirt or other objects out of the suction gripper (120).

17. A method according to claim 16 wherein the determining one or more parameters of the suction gripper (120) comprises determining that the maximum blow pressure of the blow tube (402) is outside a maximum blow pressure operating range.

18. A method according to any of the preceding claims wherein the method comprises determining that the one or more detected faults are one or more of: malfunctioning sensors, insufficient maximum vacuum pressure, the suction gripper (120) is blocked, the suction gripper (120) is damaged, insufficient air supply pressure, and /or a build-up of material inside the suction gripper (120).

19. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method according to any of claims 1 to

20. A waste sorting robot (100) comprising: a frame (102); a manipulator (104) moveable within a working area (108) and a suction gripper (120) connected to the manipulator (104) and arranged to selectively grip a waste object (106) in the working area (108); a testing plate testing surface (232) configured to receive the suction gripper (120) in a testing position wherein the testing plate is fixed to the frame; and a controller (200) configured to: move the suction gripper (120) to the testing position; determine one or more operational parameters of the suction gripper (120) when the suction gripper (120) is in the testing position; compare the determined one or more operational parameters with one or more predetermined normal operational parameters of the suction gripper (120); and detect one or more faults with the suction gripper (120) and / or the waste sorting robot (100) based on the comparison wherein the one or more operational parameters of the suction gripper (120) comprises one or more pressure parameters of the suction gripper (120). 22