A demolition robot with a hydraulic system monitoring function

Abstract

Construction equipment (100) comprising a hydraulic system (110), where the hydraulic system (110) comprises a control unit (220), an oil filter (240, 250) arranged to filter hydraulic oil in the hydraulic system (110), a temperature sensor (TS) configured to determine an operating temperature of the hydraulic oil, and a pressure sensor (410) arranged in connection to the oil filter (240, 250) to determine data indicative of an operating pressure (P1) of the hydraulic oil upstream of the oil filter (240, 250), where the control unit (220) is arranged to monitor an output signal of the pressure sensor (410) as function of the operating temperature, where the control unit (220) is arranged to determine an oil filter contaminant load metric of the oil filter (240, 250) based at least in part on pressure data obtained from the pressure sensor (410) and on the corresponding operating temperature.

Description

[0001] TITLE

[0002] A DEMOLITION ROBOT WITH A HYDRAULIC SYSTEM MONITORING FUNCTION

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to construction equipment, and in particular to hydraulically powered remote controlled and tracked demolition robots. There are disclosed hydraulic systems, methods, and control units for monitoring a quality of the hydraulic oil in the construction equipment and also for determining a contaminant load of one or more oil filters in the hydraulic system. There are also disclosed back- end systems for administering tracked demolition robots and other types of construction equipment.

[0005] BACKGROUND

[0006] Demolition robots are relatively light-weight and agile construction machines which can be used for various tasks, such as smaller excavation jobs, transportation, and of course demolition tasks. The robots are normally remote controlled by an operator walking next to the robot, but the operator may also be located further away from the robot. Autonomous or semi-autonomous demolition robots are also known in the art.

[0007] Demolition robots are often powered by a hydraulic system, where hydraulic oil is pumped out to the different actuators on the robot to power these in response to control inputs from an operator or autonomous controller. This hydraulic oil comprises a base oil and a number of additives, such as antioxidants, rust inhibitors, antifoam agents, and the like. Both the base oil and the additives are worn during use and the hydraulic oil must therefore be replaced regularly. If the hydraulic oil becomes spent, i.e., worn out, before it is replaced, there is a risk of damaging the construction equipment, or at least subjecting parts of the construction equipment to increased levels of wear.

[0008] Hydraulic systems normally comprise one or more oil filters to trap and hold contaminants in the hydraulic oil. It is necessary to replace these filters as the contaminant load in the filters reach unacceptable levels, in order to maintain the filtering function and not obstruct hydraulic oil flow too much. It is generally desired to improve the hydraulic oil maintenance process for construction equipment, and in particular for hydraulically powered tracked demolition robots.

[0009] SUMMARY

[0010] It is an objective of the present disclosure to provide improved techniques for monitoring hydraulic oil quality and wear in hydraulic actuators on construction equipment such as tracked demolition robots. This objective is at least in part obtained by the features set out in the appended claims.

[0011] Aspects of the present disclosure relate to construction equipment comprising a hydraulic system. The hydraulic system comprises a control unit, an oil filter arranged to filter hydraulic oil in the hydraulic system, a temperature sensor configured to determine an operating temperature of the hydraulic oil, and a pressure sensor arranged in connection to the oil filter to determine data indicative of an operating pressure of the hydraulic oil upstream of the oil filter. The control unit is arranged to monitor an output signal of the pressure sensor as function of the operating temperature. The control unit is also arranged to determine an oil filter contaminant load metric of the oil filter based at least in part on pressure data obtained from the pressure sensor and on the corresponding operating temperature of the hydraulic oil. This way a low-cost yet reliable mechanism for determining filter contaminant load is provided which is based on the change in viscosity with oil temperature. As the oil heats up or cools down, the pressure drop over the oil filter changes, and the change is a function of the contaminant load of the oil filter. Hence, oil filter contaminant load can be determined by observing the pressure drop over the filter as function of oil temperature in a reliable and cost-efficient manner. The oil filter contaminant load metric can, for instance, be used to determine when an oil filter change is necessary, i.e., when the filter has become clogged with particles. The pressure sensor can be a pressure switch configured to trigger at a predetermined pressure level of the hydraulic oil upstream of the oil filter, i.e., a relatively simple sensor which can be added to the system at low cost, if it is not already present in the hydraulic system.

[0012] The contaminant load metric can be given as a unitless scale of, say 1 -10, as a percentage from 0-100%, where 0% indicates a fresh filter and 100% indicates a fully clogged filter, or by some other metric or scale. According to some aspects, the control unit is arranged to determine a remaining lifetime of the oil filter based on the oil filter contaminant load metric. This is an advantage, since the service interval for changing oil filters can then be synchronized with the service intervals for changing hydraulic oil in the system, such that only one visit to the service station is required instead of two separate visits.

[0013] The control unit is optionally arranged to communicate with a remote server that forms part of a back-end system of the construction equipment. The control unit can then be arranged to transmit data indicative of the determined oil filter contaminant load metric to the remote server, which allows several different functions to be realized at the remote server or in a back-end system of the demolition robot connected to the remote server. The data can, for instance, be used to optimize service scheduling.

[0014] Aspects of the disclosure also relate to a demolition robot comprising a hydraulic system arranged to power at least a tool carrier arm which comprises a tool interface configured to exchangeably support and to hydraulically power at least one tool, such as a bucket, steel shears, or a breaker tool. The demolition robot comprises a control unit connected to a temperature sensor which is arranged to measure an operating temperature of hydraulic oil in the hydraulic system of the demolition robot. The control unit is arranged to monitor operating time of the hydraulic system along with the operating temperature of the hydraulic oil in the hydraulic system, i.e., the control unit keeps track of usage time, and also the temperature of the oil during the usage time. In other words, the control unit keeps a record of operating temperature as function of operating time. The control unit is arranged to determine a quality metric of the hydraulic oil based at least in part on the monitored operating time and on the corresponding operating temperature, as well as to initiate an automated action by the demolition robot involving the determined quality metric. This way more reliable data indicative of the quality of the hydraulic oil is obtained since the operating temperature is recorded along with the operating time. Hydraulic oil which has been used at higher temperatures than some nominal temperature wears out much faster than hydraulic oil which is used at lower temperatures. This way the effect of temperature can be accounted for when determining the quality metric of the hydraulic oil.

[0015] According to a preferred embodiment, the control unit is configured to also obtain data indicative of a type of tool in use during the recorded operating time periods, and to determine the quality metric of the hydraulic oil at least in part based on the type of tool in use. This way the effect on hydraulic oil quality, such as oil wear and remaining lifetime, by the type of tool in use can be captured. Some tool types wear more on the oil compared to other tools, so accounting also for the type of tool in use during different operating periods may improve the accuracy of the quality metric significantly. The control unit may for instance comprise a digital storage medium, where a mapping or function between operating time, operating temperature, tool in use, and the quality metric is stored in the digital storage medium.

[0016] The quality metric is normally a decreasing function of operating time, where the rate of decrease increases with the operating temperature. Thus, the operating temperature is used to weigh the operating time when determining the quality metric, which means that operating time periods associated with high operating temperatures are considered more detrimental to oil quality compared to operating time periods where the oil was kept at lower temperatures. The automated action that is initiated by the control unit may simply be to store the quality metric in a memory of the control unit, so that it can be read out by an operator of the demolition robot, by a service technician, or by some other system. The automated action can also comprise triggering a notification and sending the oil quality metric to some external party such as a back-end system. Even more advanced automated actions are certainly conceivable, such as automated oil service scheduling and the like.

[0017] The control unit can with advantage be configured to determine the quality metric at least in part as an estimated remaining lifetime of the hydraulic oil in the hydraulic system. Thus, a more accurate estimate of the remaining lifetime of the hydraulic oil is obtained, compared to the case where operating time alone is used as quality metric. The remaining lifetime of the hydraulic oil is an important metric for planning service of the demolition robot.

[0018] According to some aspects, the control unit comprises a digital storage medium. A mapping or function between operating time and operating temperature on one hand, and the quality metric on the other hand, is stored in the digital storage medium, allowing the control unit to efficiently convert the operating time and operating temperature data into the quality metric.

[0019] According to other aspects, the control unit is connected to a plurality of temperature sensors arranged at different places in the hydraulic system in order to capture temperature fluctuations more accurately. The control unit can then be arranged to determine the quality metric of the hydraulic oil based at least in part on operating temperatures at the different places in the hydraulic system. This will have a positive effect on the accuracy of the determined quality metric, since some systems have significant temperature variation over different parts, such as a low temperature in the oil tank, and a much higher temperature close to actuators.

[0020] The demolition robot optionally comprises a pressure sensor arranged in connection to an oil filter of the hydraulic system, such as a return line filter or a suction line filter of the hydraulic system. The control unit can then be arranged to determine the quality metric of the hydraulic oil based at least in part on pressure data obtained from the pressure sensor. The pressure data from the pressure sensor is, among other things, indicative of filter contaminant load, which is indicative of the quality of the hydraulic oil in the hydraulic system of the demolition robot. By monitoring pressure in this manner, the oil quality metric can be improved.

[0021] According to some aspects, the control unit is arranged to communicate with a remote server which forms part of a back-end system of the demolition robot. The control unit can in this case be arranged to initiate transmission of the determined quality metric to the remote server, which enables several interesting functions that can be implemented at the remote server or in the back-end system, as will be discussed in the following. The control unit can also be arranged to receive data from the remote server, which data is indicative of a mapping or function for determining the quality metric based on at least operating temperature and operating time. This means that the quality metric determination function implemented by the control unit can be updated from the remote server, which potentially improves the accuracy of the oil quality estimation performed by the control unit.

[0022] Some demolition robots also comprise an oil quality sensor configured to determine a current quality or status of the hydraulic oil in the hydraulic system. In this case the control unit can be configured to obtain data from the oil quality sensor, which data is indicative of the quality metric of the hydraulic oil in the hydraulic system. The control unit may also comprise a digital storage medium, where a mapping or function between any of operating time, operating temperature, type of tool in use, and the quality metric is stored, and be configured to update the mapping or function based on the data obtained from the oil quality sensor. Thus, the oil quality sensor acts as a calibration sensor to calibrate the oil quality estimation based on, e.g., operating time and corresponding operating temperature. A mapping function which has been calibrated by a given demolition robot using an oil quality sensor can be transmitted to other demolition robots which do not comprise oil quality sensors. Thus, an oil quality sensor at one demolition robot also becomes useful in other demolition robots, which is an advantage.

[0023] There are also disclosed herein back-end systems, remote servers, methods, control units, computer programs and computer program products associated with at least some of the advantages mentioned above.

[0024] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure will now be described in more detail with reference to the appended drawings, where:

[0027] Figure 1 illustrates an example demolition robot;

[0028] Figure 2 schematically shows a hydraulic system;

[0029] Figures 3A-C show some example tools that can be used with a demolition robot;

[0030] Figure 4 illustrates an oil filter in a hydraulic system;

[0031] Figure 5 shows example graphs of hydraulic pressure vs operating temperature;

[0032] Figure 6 schematically illustrates an example hydraulic oil quality metric;

[0033] Figure 7 is a flow chart illustrating methods;

[0034] Figure 8 schematically illustrates a control unit;

[0035] Figure 9 schematically illustrates a computer program product; and Figure 10 shows an example remote control device.

[0036] DETAILED DESCRIPTION

[0037] Aspects of the present disclosure will now be described more fully with reference to the accompanying drawings. The different devices and methods disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout.

[0038] The terminology used herein is for describing aspects of the disclosure only and is not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0039] Figure 1 illustrates an example demolition robot 100. A demolition robot is a lightweight construction machine which can be used for various work tasks, such as smaller demolition tasks and for handling material at a work site. A demolition robot is often tracked, i.e., comprises tracks 130 for support on the ground surface and for propulsion. Most demolition robots also comprise a rotatable tower 190, as illustrated in Figure 1 . A tracked demolition robot is an example of more general construction equipment.

[0040] The demolition robot 100 comprises a hydraulic system 1 10 that powers the different actuators on the robot, such as the actuator cylinders 120, 121 , 122 that control the pose of the three-segmented tool carrier arm 140, the tool interface 150 comprised on the tool carrier arm, the rotation of the tower 190, and the tracks 130. The hydraulic system 110 comprises a hydraulic pump driven by a motor. Different types of hydraulic pump systems are known, such as fixed speed variable displacement pump arrangement, and variable speed fixed displacement pump arrangements.

[0041] The example robot 100 is powered via a cable 160 arranged to connect the robot 100 to electrical mains. Battery electric versions of demolition robots are also known, as well as hybrid electric designs powered partly from a battery bank and partly from electrical mains.

[0042] Demolition robots are often used at remote work sites distanced from service facilities. Thus, it is desired that the hydraulic system is not serviced unnecessarily often since hydraulic oil servicing drives cost and also takes the demolition robot out of operation for a time period.

[0043] Demolition robots can be used with different types of tools, where some tools wear more on the hydraulic system of the demolition robot compared to other tools. A breaker for instance causes more wear than a bucket tool. Thus, for demolition robots in particular, the rate that the hydraulic oil is worn varies between machines.

[0044] The present disclosure is not limited to tracked remote controlled demolition robots, although many of the techniques and methods disclosed herein are particularly useful in tracked demolition robots capable of carrying different types of tools on the tool carrier arm.

[0045] Hydraulic oil consists of a base oil and additives. The number of additives is different between manufacturers and type of oil, but modern high-quality oils can have more than five or even more than ten different additives. The additives may comprise antiwear agents, antioxidants, rust inhibitors, antifoam agents, friction modifiers and viscosity modifiers.

[0046] The quality or state of the hydraulic oil in the hydraulic system, i.e., its current wear level compared to new fresh oil, plays an important part in the lifetime of a hydraulic machine. If the hydraulic oil is kept in a good condition, and is filtered properly, the wear of the machine will be kept to a minimum and the power efficiency will be higher.

[0047] Both the base oil and its additives are affected negatively when the hydraulic oil operating temperature increases. The base oil becomes degraded faster at higher temperatures and the additives are spent, i.e., worn out, more rapidly at high oil operating temperatures. The service schedule for servicing the hydraulic oil is set to change oil quite often so that the “worst-case” machines that operate in hot environments using high power tools do not get damaged from worn out hydraulic oil. However, this means that that most machines change oil more often than necessary. Changing hydraulic oil is undesired for many reasons, among them cost and machine down-time. It is particularly undesired that the hydraulic oil of a demolition robot reaches its estimated end of life when the robot is engaged with a work task at a remote work site, since then this work task may need to be paused until the hydraulic system of the machine has been transported to the service location, serviced, and then transported back again to the work site. The example demolition robot 100 in Figure 1 is configured to communicate with a remote server 170 via a communication channel 175. This allows the demolition robot 100 and the remote server 170 to exchange data, such as status messages and configuration settings. The connection to the remote server 170 also enables remote upgrade of system parameters, as will be discussed in more detail in the following. The remote server may form part of a back-end system 180 of the demolition robot 100. A back-end system is a system which allows an operator, a fleet manager, or a service organization to monitor the demolition robot 100 and make sure that the demolition robot 100 is operating as intended and is not suffering any faults. Some of the techniques disclosed herein allow for additional functions to be implemented at the back-end system, such as improved service scheduling functions that determine when it is suitable to replace the hydraulic oil and / or one or more oil filters of the hydraulic system. The back-end system can also, by the techniques disclosed herein, maintain more accurate status information about a given demolition robot, or a fleet of demolition robots. The back-end system 180 may comprise additional processing devices 185 for processing the data available at the remote server 170.

[0048] The tool interface 150 is configured to support a tool, such as steel shears, a bucket, or a breaker. A number of different types of tools can be attached to the tool interface 150, and an operator can select which type of tool to mount on the tool carrier depending on the work task at hand. The tools that can be mounted on the tool interface 150 are in other words tools that are exchangeably supported on the tool carrier. Some tools, such as shears and breakers are active tools that are powered by the hydraulic system 110 of the demolition robot, while some other type of tools, such as buckets, are passive tools that are only attached at the tool interface 140 where they are used by maneuvering of the arm 140, tracks, and tower 190. Figures 3A-C show some example tools 310, 320, 330. Figure 3A illustrates an example breaker 310, Figure 3B shows an example bucket 320, and Figure 3C shows steel shears 330. All these tool types are generally known and will therefore not be discussed in more detail herein.

[0049] The exchangeable tools that can be used together with the demolition robot are different in terms of the load they exert on the hydraulic system 1 10 in use. The breaker 310, for instance, is an active high-power tool that normally generates much higher load on the hydraulic system 1 10 compared to the bucket 320 which is a passive tool. A demolition robot that often uses a breaker 310 wears out its hydraulic oil much faster than a demolition robot which more often uses a bucket or some other passive tool. This makes it difficult to keep track of hydraulic oil wear on a demolition robot, since operating time alone, i.e., the time passed since last hydraulic oil service, is such a poor measure of hydraulic oil quality in a demolition robot. This is at least in part due to that the operating temperature of the hydraulic oil in the hydraulic system varies significantly depending on how the demolition robot is used, i.e., what work tasks it is being used for, and also in which environment the demolition robot is operating.

[0050] It has been realized that, by measuring operating temperature of the hydraulic oil and for how long time period that the oil remains in different operating temperature ranges, it is possible to estimate the remaining lifetime of the hydraulic oil in a reasonably accurate manner. This way a more accurate estimate of current hydraulic oil quality and remaining hydraulic oil lifetime can be obtained, compared to if estimating hydraulic oil quality solely based on operating time. By using this more accurate estimation of hydraulic oil quality it is possible to optimize the oil exchange cycle better, which is an advantage. Construction equipment that operate within lower temperature ranges most of the time, and / or less often with high power tools such as hydraulic breakers, will extend the time between oil changes compared to equipment that more often run hot and / or that more often use hydraulic breakers or other high power tools.

[0051] For machines with large amounts of oil it is often advantageous to send an oil sample to a laboratory for analysis in order to determine if it is time to change the hydraulic oil or not. This is a good way of maximizing the use of hydraulic oil, but it is not often used for smaller machines with for example 30 liters of oil since the money saved by maximizing the use of the hydraulic oil is less than the price paid for the periodic oil quality analysis.

[0052] The present disclosure relates to a demolition robot 100 that comprises a hydraulic system 110 arranged to power tracks 130 and a tool carrier arm 140, as exemplified in Figure 1. The tool carrier arm comprises a tool interface 150 configured to exchangeably support and to hydraulically power at least one tool 310, 320, 330, such as a breaker tool. A demolition robot can be used for widely different work tasks and in different work environments, and with different types of tools. This makes it difficult to determine hydraulic oil quality from operating time alone. A demolition robot like that exemplified in Figure 1 can for instance operate outdoors in cold climates using a passive bucket and also indoor in a smelter or foundry where it is hot and where a high power breaker is used for prolonged periods of time.

[0053] Figure 2 schematically illustrates some components of an example hydraulic system 110. A hydraulic pump 210 (driven by some form of motor, not shown in Figure 2) pumps oil to various actuators 230 of the construction equipment, such as the exchangeable tools 310, 320, 330, the tracks 130, and the cylinders 120, 121 , 122 of the tool carrier arm 140. The example hydraulic system 110 illustrated in Figure 2 comprises a return line hydraulic filter 240 and a suction line hydraulic filter 250 which are both configured to trap particles and contaminants in the hydraulic oil. One or both of these filters can be used, i.e., some hydraulic systems lack one or both of these filters, although hydraulic systems with no filtering whatsoever are uncommon. Some hydraulic systems comprise more than two oil filters.

[0054] A control unit 220 control the various functions of the hydraulic system 110. The control unit 220 may also control other functions on the construction equipment 100, such as communication with the back-end system 180. Example implementations of the control unit 220 will be discussed below in connection to Figure 8. Generally, the demolition robots discussed herein comprise a control unit 220 connected to at least one temperature sensor TS that is arranged to measure an operating temperature of hydraulic oil in the hydraulic system 110. The operating temperature may be given in degrees Celsius or Fahrenheit, on a continuous or discrete scale. It is also possible that the temperature sensor is a temperature switch which only indicates if the hydraulic oil is above a temperature threshold or not. The temperature sensor is often a digital sensor configured to report the operating temperature data to the control unit 220 by a digital message, such as a message over a Computer Area Network (CAN) bus of the demolition robot. Analog temperature sensors are also possible to use in this application. Temperature sensors that are able to measure an operating temperature of hydraulic oil are generally known and will therefore not be discussed in more detail herein. It is appreciated that the hydraulic system 110 may comprise one or more temperature sensors, arranged at one or more places throughout the hydraulic system. The temperatures in the hydraulic system may vary depending on location. It normally takes a longer time to heat up the oil in the oil tank compared to the temperature close to an actuator or in the hydraulic oil pump. Thus, the hydraulic oil may be subject to high temperature at some place in the system even if the oil temperature in the hydraulic oil tank is low. An advantage of measuring temperature at more than one place in the hydraulic system, i.e., a hydraulic system comprising a plurality of temperature sensors distributed throughout the hydraulic system 110, is that a better overview of the instantaneous hydraulic system operating temperature state is obtained. Some or all of the temperature sensors may be integrated with pressure sensors, and possibly also with oil quality sensors, as will be discussed in more detail below.

[0055] The control unit 220 is arranged to monitor operating time of the hydraulic system 110 and a corresponding operating temperature of the hydraulic oil in the hydraulic system 1 10. The monitoring of operating time can be achieved using an on-board clock or a timer in a known manner. This on-board clock or timer may with advantage be calibrated by the back-end system 180, if such a back-end system is available. The on-board clock or timer can also be calibrated using other sources, such as the GPS system, or an Internet connection. The operating temperature of the hydraulic oil in the hydraulic system can be monitored continuously by the temperature sensor TS and recorded or sampled periodically and recorded. The temperature values thus obtained can be stored in a record of operating temperature in the digital storage medium 830, and / or at the remote server 170 in the back-end system 180. Statistics of the operating temperature can also be stored, such as a running average temperature value, a maximum operating temperature value in a given time window, and so on. The operating temperature and the operating time can be stored in the same record. A recording of operating temperature as function of time during operation of the demolition robot is an implicit record of operating time, since operating temperature is recorded during operation of the demolition robot.

[0056] The operating time can be determined as a time period from when an operator activates the machine, i.e., turns the machine on, until the machine is inactivated, i.e., turned off again. A record of operating time can be stored in the digital storage medium 830, and / or at the remote server 170 in the back-end system 180 together with operating temperature. Thus, the control unit 220 keeps track of how long time period the demolition robot is operated, and what the temperature of the hydraulic oil is when the demolition robot is being operated. Thus, according to an example, there is a corresponding temperature measurement for each time instant the demolition robot is active. The demolition robot may be defined as “active” when the hydraulic pump is operating to move hydraulic oil through the hydraulic system. There can be one or more temperature sensors arranged in the hydraulic system 110. The control unit 220 can for instance be connected to a plurality of temperature sensors arranged at different places in the hydraulic system 220 as mentioned above. The control unit then has access to more than one temperature reading and can refine its determination of the hydraulic oil quality metric using this plurality of temperature values. One temperature sensor may be arranged to sense a temperature in the hydraulic oil tank, one or more temperature sensors can be configured in a valve stack to sense the temperature or temperatures on the outgoing lines to the different actuators, and one or more temperature sensors can also be arranged in connection to a return line of the hydraulic system.

[0057] The control unit 220 is furthermore arranged to determine a quality metric of the hydraulic oil based at least in part on the monitored operating time and on the corresponding operating temperature, and also to initiate some sort of automated action by the demolition robot 100 that involves the determined quality metric, such as determining when it is time to change the hydraulic oil, determining if the oil quality is sufficient for the work task at hand, and so on.

[0058] A rule of thumb used in hydraulic engineering is that every 10°C above 60°C will cut the lifetime of the oil in half. In many applications a hydraulic oil is expected to last up to 2000h, but this can be as short as 250h if the oil reaches operating temperatures of 90°C or so for a sustained period of time. Also, use of hydraulic breaker will heavily affect the lifetime of the hydraulic oil. Below numbers are an estimation and values can be updated. The effect of hydraulic oil temperature on hydraulic oil wear have been extensively studied in the literature and will therefore not be discussed in more detail herein. The percentage values for breaker usage is to be interpreted as the percentage of operating time of the hydraulic system where a breaker is active. For instance, if a breaker tool is active for 200h out of a total operating time of 10OOh, then the breaker usage is 20%.

[0059] Oil temp expected lifetime Actual lifetime % of expected lifetime

[0060] < 60°C 2000h 2000h 100%

[0061] 70°C 2000h 1000h 50%

[0062] 80°C 2000h 500h 25%

[0063] 90°C 2000h 250h 12.5% Breaker exoected lifetime Actual lifetime % of exoected lifetime

[0064] 0% 2000h 2000h 100%

[0065] 20% 2000h 1300h 65%

[0066] 40% 2000h 1000h 50%

[0067] 60% 2000h 800h 40%

[0068] 80% 2000h 600h 30%

[0069] The expected lifetime of the hydraulic oil in the hydraulic system 1 10 will, as mentioned above depend on the type of oil in the hydraulic system, and the application where it is used, i.e., how the demolition robot is used, and which tools it carries. The influence of operating temperature will also be different for different types of oils. Thus, the mapping or function between the operating time and operating temperature on one hand, and the quality metric of the hydraulic oil, can be made dependent of the type of oil used, the type of construction equipment, which work tasks that are being performed, which tools that are used and for how long, etc. Different configurations of the mapping can, e.g., be stored at the remote server 170 or elsewhere in the back- end system 180 and downloaded to the demolition robot in dependence of the type of oil used.

[0070] By keeping track of numbers of operating hours spent at each temperature, it is possible to estimate the remaining lifetime of the oil. For example, suppose that a given type of hydraulic oil has an expected lifetime of 2000h. This lifetime can be converted to 2000 temperature life units (TLU) and optionally 2000 Breaker life units (BLU). For each hour spent at temperature <60°C one TLU is subtracted from the remaining lifetime. At 70°C two TLUs are subtracted each hour, and at 80°C four TLUs are subtracted each hour, and so on. Note that this is just an example of the mapping or function that takes operating time and temperature and converts this into an oil quality metric.

[0071] For tool usage a similar approach can be used. Each hour a percentage use of the breaker is calculated. If breaker has been activated 20% of the time 2000 / 1300=1 .54 BLUs are deducted from the remaining BLU of the construction equipment.

[0072] It is normally the lowest value of TLU and BLU that will be setting the oil change interval. But it is also possible to use a combination of the two values, such as the average (TLU+BLU) / 2. It is possible to show oil wear in percentage and estimated number of hours remaining until oil service if temperature is kept at same levels as earlier. This can be shown on a machine display, in a connected service application, and / or communicated to the back-end system 170.

[0073] Figure 10 shows an example remote control device 1000 suitable for use with a demolition robot such as the robot 100 in Figure 1. The remote control device 1000 comprises a display 1010 which can be used to display notifications and information to an operator of the machine, such as when it is time to change oil, when it is time to change an oil filter, and also estimated remaining time periods to oil and / or filter service. The remaining lifetime of the hydraulic oil can, for instance, be shown to an operator of the demolition robot on the display 1010. The wear rate of the hydraulic oil can also be shown, possibly along with a warning if the wear rate becomes high. An operator using the machine in a way that wears the oil fast can then take action to reduce the rate of wear, which is an advantage.

[0074] Figure 6 illustrates an example 600 where an oil quality metric bar starting at 100% gradually decreases 610 with time. The rate of decrease is, as discussed herein, determined at least by the operating temperature of the hydraulic oil during use of the construction equipment. This type of bar can be displayed on a construction equipment display unit. The representation can be used to indicate remaining time until next oil change.

[0075] When oil wear is at a certain percentage, for example 95%, or a certain number of hours remain of the hydraulic oil lifetime, for example 50h, a service message can be sent to the operator of the construction equipment 100, either by machine interface or by online message from the back-end system 180.

[0076] Different types of quality metrics can be envisioned, and more than one metric can of course be used by the control unit to describe the current state of the hydraulic oil in the hydraulic system 110 of the construction equipment. However, generally, the quality metric is a decreasing function of operating time, where the rate of decrease increases with operating temperature, i.e., the oil wears faster if it is operated at a high temperature compared to if the oil is operated at a lower temperature. The quality of the hydraulic oil generally deteriorates over time, and this rate of deterioration increases with increasing temperature. The control unit 220 is optionally configured to determine the quality metric at least in part as an estimated remaining lifetime of the hydraulic oil in the hydraulic system 110. This type of quality metric is useful since it simplifies service scheduling. An operator, or the back-end system, can for instance refrain from sending out a demolition robot on an assignment that is expected to take more time than what remains until the hydraulic oil needs to be serviced. A back-end system that is managing a fleet of demolition robots can implement more advanced scheduling functions, where demolition robots are assigned to different work sites and / or different work tasks based on the remaining lifetime of the respective hydraulic oil quantities in the demolition robot units.

[0077] The control unit 220 may advantageously comprise a digital storage medium 830 where a mapping or function between operating time and operating temperature on one hand, and the quality metric on the other hand is stored in the digital storage medium 830. This means that the control unit 220 has access to some sort of mechanism which converts operating times at different operating temperatures to the quality metric, e.g., the remaining lifetime of the hydraulic oil in the system. According to one example, the function for determining a quality metric Q is a predetermined function on the form f(t,T) = Q where t is a time record of usage and T is a temperature record which comprises information about the operating temperature for the time record of usage. There may be more than one temperature sensor in the hydraulic system, as noted above, hence more than one temperature reading may be available at any given point in time. The temperature sensors need not be synchronized to each other, nor be configured to report temperature data at the same rate. The inputs t and T may be continuous or discrete variables. The function (■) can be a predetermined analytical function, a multi-dimensional look-up table, or some other type of function or method. The function (■) can be determined by practical experimentation using repeated analysis of hydraulic oil quality for different use cases. The function (■) can also be determined using computer simulation. If the demolition robot 100 is connected to a back-end system, then the back-end system can gather actual hydraulic oil quality data from machines comprising special physical hydraulic oil quality sensors and calibrate the function (■) accordingly to make it more accurate.

[0078] According to a straightforward example, the function (■) comprises a look-up table indexed by operating time and a statistical measure of operating temperature, such as average operating temperature. According to another straightforward example, the function (■) is a type of bookkeeping function which initially starts out with a predetermined number of units, say 100 units. The units are then decreased as function of operating time, where more units are taken away if the operating temperature is high compared to if the operating temperature is low. In other words, with reference to the example 600 in Figure 6, the hydraulic system oil quantity is assigned a discrete “score” of, say 100 units or percent when it is new. Certain deductions 610 are then made from this score based on operating time and corresponding operating temperature, and optionally also based on what the construction equipment was doing during the operating time, such as if a breaker were used or if the machine was just moving around using the tracks 130. The deductions from the score can be discrete as in Figure 6, or continuous.

[0079] The control unit 220 can be configured to obtain data indicative of a type of tool 310, 320, 330 in use, and to determine the quality metric of the hydraulic oil at least in part based on the tool in use. According to an example, the operator can manually input information about a current tool in use via the remote control device 1000 or via some other input device connected to the control unit 220, e.g., by selecting between different tool modes on the remote control device. The construction equipment 100 can according to another example comprise a radio frequency identification (RFID) system, or a camera based system which can be used to identify which type of tool that is currently mounted on the tool carrier arm 140. Alternatively, or as a complement, the control unit 220 can determine the type of tool attached to the tool carrier arm by analyzing the pressure and flow in the hydraulic system 1 10. A breaker, for instance, gives a fairly distinct pressure pulse pattern in the hydraulic system, which can be sensed by pressure sensors, or by the hydraulic pump drive motor as it provides hydraulic power to the breaker. A bucket gives different hydraulic system behavior compared to the breaker. Hence, the control unit 220 can identify which tool that is currently in use and use this data as input to the function (■) in order to refine the hydraulic oil quality metric Q. According to some aspects, the control unit 220 comprises a digital storage medium 830, where a mapping or function between operating time, operating temperature, tool in use, and the quality metric is stored in the digital storage medium 830.

[0080] There is disclosed a demolition robot 100 comprising a hydraulic system 1 10 arranged to power at least a tool carrier arm 140, where the tool carrier arm comprises a tool interface 150 configured to exchangeably support and to hydraulically power at least one tool 310, 320, 330. The control unit 220 is arranged to monitor operating time of the hydraulic system 110 and also the type of tool 310, 320, 330 in use during the operating time. The control unit 220 is arranged to determine a quality metric of the hydraulic oil based at least in part on the monitored operating time and on the type of tool 310, 320, 330 in use, where the control unit 220 is configured to initiate an automated action by the demolition robot 100 involving the determined quality metric. The control unit 220 can for instance be configured to determine a remaining lifetime metric of the hydraulic oil in the hydraulic system based on which tool is in use, where some types of tools decrease the lifetime metric faster than other types of tools according to a predetermined function. Use of some types of tools such as breakers and shears reduce lifetime faster compared to other types of tools such as buckets and the like. A metric similar to the BLU metric discussed above can be used to keep track of remaining lifetime. By keeping track of the number of operating hours spent with each type of tool, it is possible to estimate the remaining lifetime of the oil. For example, suppose that a given type of hydraulic oil has an expected nominal lifetime of 2000h. This lifetime can be converted to a given number of life units as discussed above. For each hour spent using a given type of tool, the number of life units is decreased by an amount which has been preconfigured for the type of tool is use. Use of a breaker or other high-power tool will decrease the number of life units faster compared to use of, e.g., a passive bucket. The decrease in life units per tool type can be preconfigured or a value obtained in a dynamic manner from the remote server. This is a robust way to estimate remaining lifetime of the hydraulic oil in the hydraulic system which does not require extensive computational power.

[0081] According to an example, the control unit 220 keeps track of which tool that is in use, and for how long the tool is used, i.e., the control unit 220 keeps a record of operating time which also comprises the type of tool in use during any given active time period. The control unit 220 can then process the record and determine an estimated remaining lifetime of the hydraulic oil in the hydraulic system, using a predetermined function of lifetime as function of operating time and the type of tool in use during the operating time.

[0082] The tracked demolition robot 100 may furthermore comprise a pressure sensor 410 arranged in connection to an oil filter 240, 250 of the hydraulic system 1 10, as illustrated in Figure 4. The oil filter can, for instance, be a suction line oil filter 250 or a return line oil filter 240 as exemplified in Figure 2. In this case the control unit 220 can be arranged to determine the quality metric of the hydraulic oil based at least in part on pressure data obtained from the pressure sensor 410. Generally, the longer the hydraulic oil is used, the more contaminants build up in the oil filter, resulting in increased backpressure by the oil filter, i.e., an increased hydraulic pressure P1 upstream from the filter. This means that, for a given operating temperature, the pressure P1 upstream of the oil filter can be used as input to the function (■) to determine the hydraulic oil quality metric with increased accuracy and reliability.

[0083] The viscosity of an oil is simply the resistance of the oil to flow. A higher viscosity oil implies a slower flow and a thicker oil. The viscosity of the hydraulic oil in the hydraulic system 1 10 decreases with increasing operating temperature. A high viscosity oil does not penetrate an oil filter as easily as a low viscosity oil does. This means that there is a higher backpressure upstream of the filter 240, 250 when operating temperature is low, and that this backpressure then decreases as the operating temperature of the hydraulic oil increases. At the same time, the contaminant load of the oil filter, i.e., how much particulate matter that has gotten stuck in the filter, has an effect on the backpressure of the filter. The more clogged the oil filter is, i.e., the higher the contaminant load of the oil filter is, the larger the backpressure generally is. The interaction between operating temperature, oil filter contaminant load, and backpressure (or pressure drop over the oil filter) can be used to determine the filter contaminant load of the oil filter and thus also how much time that remains until the oil filter has to be replaced with a new oil filter.

[0084] For instance, suppose that a pressure trigger sensor 410 is arranged upstream of the oil filter in Figure 4, and that this trigger sensor is configured to close a circuit or generate some sort of notification signal when the hydraulic pressure P1 upstream of the filter rises above some threshold. The backpressure of the filter always decreases with increasing operating temperature, hence, depending on the contaminant load of the oil filter, this trigger sensor will be inactivated at an operating temperature which increases with the contaminant load of the oil filter. When the inactivation temperature of the pressure trigger sensor reaches a predetermined temperature level, it is time to change the filter. If a pressure sensor that outputs continuous pressure data is used instead of a discrete trigger sensor, then the output pressure data of the sensor is compared to, e.g., a pressure threshold or some other detection criterion, and the temperature at which the pressure passes the threshold or satisfies the detection criterion is used as indicator of when it is time to change the filter. More generally, the evolution of pressure upstream from the filter as function of temperature is used to detect when it is time to change the filter.

[0085] Figure 5 shows three examples of the trigger signal as function of hydraulic oil operating temperature. In the first example the oil filter is a fresh filter, which means that there is never enough backpressure upstream of the filter to generate a triggering of the pressure sensor. The output of the pressure trigger sensor is thus constant zero. In the second example the oil filter has been used for some time, and there is some contaminant load, although not enough to clog the filter. In this case the low temperature high viscosity hydraulic oil contributes to an increased backpressure which triggers the pressure sensor. However, as operating temperature increases (and viscosity decreases), the backpressure drops. In this example the combination of contaminant load and viscosity is no longer enough to trigger the pressure sensor at temperature T 1 .

[0086] The third example at the bottom in Figure 5 shows what happens if the oil filter has a higher contaminant load compared to the second example. In this case the backpressure resulting from the filter clogging is high enough to require a relatively low viscous oil in order for the backpressure to go back below the pressure trigger threshold of the pressure sensor, which in this case happens at temperature T2. The temperature T2 can in this case be used as detection criterion for when it is time to change the oil filter.

[0087] Thus, it is appreciated that the temperature difference 510 can be used to estimate the contaminant load of the oil filter in a straight-forward manner, where the contaminant load in the filter increases as the temperature difference 510 decreases. In other words, there is disclosed herein tracked demolition robots and other construction equipment which comprises a pressure sensor 410 arranged in connection to an oil filter 240, 250 of the hydraulic system 1 10. The control unit 220 is arranged to determine an oil filter contaminant load metric of the oil filter 240, 250 based at least in part on pressure data obtained from the pressure sensor 410 and on the operating temperature of the hydraulic oil in the hydraulic system 110. The pressure sensor can be a sensor that is configured to output continuous pressure data, or a sensor that only outputs pressure data in discrete values. A pressure trigger sensor can also be used which only indicates if the pressure is above or below a pressure threshold. The detection criterion, for instance the temperature threshold or the pressure vs temperature relationship, which is used to detect when it is time to change the oil filter can be configured by practical experimentation using different filters having different contaminant load, by experiments using a testbed in a laboratory, or by computer simulation.

[0088] The techniques illustrated in Figure 4 and in Figure 5 are applicable also on more general construction equipment. There is disclosed construction equipment 100 comprising a hydraulic system 1 10, where the hydraulic system 110 comprises a control unit 220, an oil filter 240, 250 arranged to filter hydraulic oil in the hydraulic system 1 10, a temperature sensor TS configured to determine an operating temperature of the hydraulic oil, and a pressure sensor 410 arranged in connection to the oil filter 240, 250 to determine data indicative of an operating pressure P1 of the hydraulic oil upstream of the oil filter 240, 250. The control unit 220 is arranged to monitor an output signal of the pressure sensor 410 as function of the operating temperature to see how the pressure changes with temperature, e.g., as the machine warms up at the start of a workday. The control unit 220 is arranged to determine an oil filter contaminant load metric of the oil filter 240, 250 based at least in part on pressure data obtained from the pressure sensor 410 and on the corresponding operating temperature. This determination can be done in a number of different ways, such as having a predetermined mapping or function which takes a pressure behavior and maps it to an oil filter contaminant load metric. The mapping may be a straightforward look-up table, as discussed above. The pressure sensor 410 does not have to be very advanced, i.e., capable of providing continuous pressure readings at high accuracy. A pressure switch configured to trigger at a predetermined pressure level of the hydraulic oil upstream of the oil filter 240, 250 is sufficient in many cases to obtain satisfactory performance. The control unit 220 may also be arranged to determine a remaining lifetime of the oil filter 240, 250 based on the oil filter contaminant load metric, based on a predetermined mapping.

[0089] The control unit 220 can also be arranged to communicate 175 with a remote server 170 which forms part of a back-end system of the construction equipment 100. In this case the control unit may transmit data indicative of the determined oil filter contaminant load metric to the remote server 170, which can store the data in a database to be used for optimizing service schedules and the like, as discussed above. The back-end system can also use the oil quality metric data together with the filter load data to decide on a suitable service schedule. According to some aspects, the control unit 220 is arranged to determine the oil filter contaminant load metric at least in part based on an operating temperature where the operating pressure P1 satisfies a pressure detection criterion, such as a pressure threshold or pressure range. However, it is also possible to use a reverse mechanisms, i.e., where the control unit 220 determines the oil filter contaminant load metric at least in part based on an operating pressure P1 where the operating temperature satisfies a temperature detection criterion such as a threshold or temperature range.

[0090] The techniques disclosed herein are particularly advantageously used together with a remote server 170 of a back-end system which the control unit 220 is arranged to communicate with. In this case the demolition robot 100 can periodically transmit the determined quality metric to the remote server 170. Several functions can then be implemented in the back-end system to improve, e.g., hydraulic oil maintenance routines, scheduling of work tasks, monitoring of machine health, and so on.

[0091] According to some aspects, the control unit is also arranged to receive data from the remote server 170 indicative of the mapping or function (■) that is used for determining the quality metric from the. The control unit 220 may receive a complete specification of the mapping or function, or just updates such as new values for use in a look-up table, or updated function parameters to use. According to an example, the construction equipment may query the back-end system 180 by sending parameters such as type of oil and specifications of the hydraulic system to the back- end system and receive a mapping or function back which can be used to estimate remaining lifetime of the hydraulic oil.

[0092] According to some aspects, the tracked demolition robot 100 comprises an oil quality sensor QS, exemplified in Figure 2, that is configured to determine a current quality status of the hydraulic oil in the hydraulic system 1 10. Such hydraulic oil quality sensors are generally known and will therefore not be discussed in more detail herein. The control unit 220, having access to the hydraulic oil quality information from the oil quality sensor QS can in this case obtain a more accurate and / or a more reliable hydraulic oil quality metric. The control unit 220 optionally also comprises a digital storage medium 830 where a mapping or function between any of: operating time, operating temperature, tool in use, and the quality metric is stored. The control unit 220 can then be configured to update the mapping or function based on data obtained from the oil quality sensor QS. By transmitting measured oil quality data from the oil quality sensor to the back-end system, the back-end system may refine the mapping or function between operating time and operating temperature, and hydraulic oil quality, which is an advantage. This updated mapping or function can then be shared with other demolition robots that do not comprise this type of oil quality sensor.

[0093] The refinement of the mapping function based on oil quality sensor data can be done in a number of different ways. A nominal mapping function can for instance be used to determine an oil quality metric which is continuously or periodically compared to an actual measurement of oil quality. The mapping can then be adjusted by increasing the oil wear or decreasing the oil wear depending on if the mapping overestimates or underestimates the oil wear. The oil quality sensor data can, for instance, be used to update the type of table data described above, where an expected oil lifetime as function of temperature and type of tool is provided.

[0094] For example, suppose that a demolition robot has a nominal mapping between oil quality and temperature / operating time record at its disposal. The demolition robot also comprises an oil quality sensor which measures actual oil quality. The control unit on the demolition robot can then compare the oil quality estimated from the temperature / operating time record to the output of the oil quality sensor. The mapping is then adjusted such that the two estimates agree. The mapping may as discussed above be implemented by assignment and removal of TLUs and / or BLUs as discussed above. The adjustment of the mapping can then comprise adjusting the assigned number of TLUs and / or BLUs to a system, and / or adjusting the rate at which TLUs and / or BLUs are removed from the hydraulic system. In other words, if the oil quality sensor shows worse oil quality than estimated by the control unit then the rate of removal of the TLUs and / or BLUs is increased, and vice versa.

[0095] It is appreciated that the oil quality sensor QS and the temperature sensor TS may be separate sensors or integrally formed as a single unit that measures both oil quality and oil temperature.

[0096] The present disclosure also relates to a back-end system which comprises at least a remote server 170 arranged to communicate 175 with a control unit 220 of the demolition robot 100, as discussed above. The remote server 170 is arranged to receive a quality metric associated with hydraulic oil in a hydraulic system 1 10 of the demolition robot 100 from the demolition robot 100. The back-end system 180 is also configured to initiate an automated action based on the received quality metric. The automated action may be just to store the quality metric in a database of the back- end system, which an operator of the back-end system, such as a fleet manager, can consult to discern the oil quality in a plurality of demolition robots and other construction equipment associated with the back-end system. This way the back-end system can facilitate more efficient servicing of the hydraulic oil in a fleet of demolition robots.

[0097] According to some aspects, the back-end system is configured to automatically schedule hydraulic oil servicing for the equipment in the database of the back-end system, when it is time to change the hydraulic oil or perform some other maintenance operation involving the construction equipment associated with the back-end system.

[0098] According to some other aspects, the back-end system also keeps track of the quality of the oil filters, such as the contaminant load of the oil filters, by receiving data from the construction equipment that is indicative of the quality of the oil filters. This data may, e.g., be obtained by the demolition robots and other construction equipment using the techniques discussed above in connection to Figure 4 and Figure 5. The quality of the oil filters can also be stored in the database at the back-end system and used to schedule service of the construction equipment. It may, for instance, be advisable to synchronize oil filter change and hydraulic oil change. By having both oil filter quality data and hydraulic oil quality data in the same database, it is possible to schedule maintenance in a more efficient manner, such that both oil filter change and hydraulic oil change is performed at the same service instant.

[0099] According to some aspects, the remote server 170 of the back-end system is arranged to receive oil quality sensor data from the demolition robot 100, which data is indicative of an output from an oil quality sensor QS of the demolition robot. The back- end system 180 can then update a mapping or function between any of: operating time, operating temperature, tool in use, and a quality metric associated with hydraulic oil in a hydraulic system 110 of the demolition robot 100 based on the oil quality sensor data. This means that the back-end system can compare the quality metrics inferred from the operating temperature data and the operating time data to actual measurements of oil quality obtained from the oil quality sensors. In case there is a discrepancy between the two, which is to be expected, the function or mapping can be updated to reduce the discrepancy. This updated function or mapping can then be sent back to the construction equipment associated with the back-end system, which can then update their local functions to improve the estimation of, e.g., remaining lifetime of hydraulic oil and / or oil filters. Oil quality sensors can be used with advantage on tracked demolition robots. There is disclosed a tracked demolition robot 100 comprising a hydraulic system 1 10 arranged to power tracks 130 and a tool carrier arm 140, where the tool carrier arm comprises a tool interface 150 configured to support and to hydraulically power at least one exchangeable tool 310, 320, 330. The demolition robot comprises a control unit 220 connected to an oil quality sensor QS arranged to measure a current oil quality of hydraulic oil in the hydraulic system 110. The control unit 220 is arranged to monitor the oil quality, and to initiate an automated action by the demolition robot 100 in case the oil quality fails to satisfy an oil quality acceptance criterion. The automated action may, e.g., be to trigger generation of a message on a display to inform an operator of the poor oil quality, trigger generation of a message to a back-end system of the demolition robot, or schedule oil maintenance.

[0100] Figure 7 is a flow chart that illustrates a computer-implemented method performed by a control unit 220 for a tracked demolition robot 100 comprising a hydraulic system 110 arranged to power tracks 130 and a tool carrier arm 140, where the tool carrier arm comprises a tool interface 150 configured to support and to hydraulically power at least one exchangeable tool 310, 320, 330. The method summarizes the discussion above, in that it at least comprises measuring S1 an operating temperature of hydraulic oil in the hydraulic system 1 10, monitoring S2 operating time of the hydraulic system 1 10 and a corresponding operating temperature of the hydraulic oil in the hydraulic system 110, determining S3 a quality metric of the hydraulic oil based at least in part on the monitored operating time and on the corresponding operating temperature, and initiating S4 an automated action by the demolition robot 100 involving the determined quality metric.

[0101] Figure 8 schematically illustrates, in terms of a number of functional units, the general components of the control unit 800, such as the control unit 220, the remote server 170 and the processing devices 185 discussed above. Processing circuitry 810 is provided using any combination of one or more of a suitable central processing unit CPU, multiprocessor, microcontroller, digital signal processor DSP, etc., capable of executing software instructions stored in a computer program product, e.g., in the form of a digital storage medium 830. The processing circuitry 810 may further be provided as at least one application specific integrated circuit ASIC, or field programmable gate array FPGA. Particularly, the processing circuitry 810 is configured to cause the demolition robot 100 to perform a set of operations, or steps, such as the methods discussed in connection to Figure 5 and the discussions above. For example, the digital storage medium 830 may store the set of operations, and the processing circuitry 810 may be configured to retrieve the set of operations from the digital storage medium 830 to cause the device to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 810 is thereby arranged to execute methods as herein disclosed.

[0102] The digital storage medium 830 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0103] The control unit 800 may further comprise an interface 820 for communications with at least one external device. As such the interface 820 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of ports for wireline or wireless communication.

[0104] The processing circuitry 810 controls the general operation of the control unit 800, e.g., by sending data and control signals to the interface 820 and the digital storage medium 830, by receiving data and reports from the interface 820, and by retrieving data and instructions from the digital storage medium 830.

[0105] Figure 9 illustrates a computer readable medium 910 carrying a computer program comprising program code means 920 for performing the methods illustrated in Figure 7, when said program product is run on a computer. The computer readable medium and the code means may together form a computer program product 900.

Claims

CLAIMS1 . Construction equipment (100) comprising a hydraulic system (1 10), where the hydraulic system (110) comprises a control unit (220), an oil filter (240, 250) arranged to filter hydraulic oil in the hydraulic system (1 10), a temperature sensor (TS) configured to determine an operating temperature of the hydraulic oil, and a pressure sensor (410) arranged in connection to the oil filter (240, 250) to determine data indicative of an operating pressure (P1 ) of the hydraulic oil upstream of the oil filter (240, 250), where the control unit (220) is arranged to monitor an output signal of the pressure sensor (410) as function of the operating temperature, where the control unit (220) is arranged to determine an oil filter contaminant load metric of the oil filter (240, 250) based at least in part on pressure data obtained from the pressure sensor (410) and on the corresponding operating temperature.

2. The construction equipment (100) according to claim 1 , where the pressure sensor (410) is a pressure switch configured to trigger at a predetermined pressure level of the hydraulic oil upstream of the oil filter (240, 250).

3. The construction equipment (100) according to claim 1 or 2, where the control unit (220) is arranged to determine the oil filter contaminant load metric at least in part based on an operating temperature where the operating pressure (P1) satisfies a pressure detection criterion.

4. The construction equipment (100) according to any previous claim, where the control unit (220) is arranged to determine the oil filter contaminant load metric at least in part based on an operating pressure (P1 ) where the operating temperature satisfies a temperature detection criterion.

5. The construction equipment (100) according to any previous claim, where the control unit (220) is arranged to determine a remaining lifetime of the oil filter (240, 250) based on the oil filter contaminant load metric.

6. The construction equipment (100) according to any previous claim, where the control unit (220) is arranged to communicate (175) with a remote server (170) which forms part of a back-end system of the construction equipment (100), where the control unit is arranged to transmit data indicative of the determined oil filter contaminant load metric to the remote server (170).

7. A demolition robot (100) comprising a hydraulic system (110) arranged to power at least a tool carrier arm (140), where the tool carrier arm comprises a tool interface (150) configured to exchangeably support and to hydraulically power at least one tool (310, 320, 330), the demolition robot comprising a control unit (220) connected to a temperature sensor (TS) arranged to measure an operating temperature of hydraulic oil in the hydraulic system (1 10), where the control unit (220) is arranged to monitor operating time of the hydraulic system (110) and a corresponding operating temperature of the hydraulic oil in the hydraulic system (1 10), where the control unit (220) is arranged to determine a quality metric of the hydraulic oil based at least in part on the monitored operating time and on the corresponding operating temperature, where the control unit (220) is configured to initiate an automated action by the demolition robot (100) involving the determined quality metric.

8. The demolition robot (100) according to claim 7, where the quality metric is a decreasing function of operating time, and where the rate of decrease increases with operating temperature.

9. The demolition robot (100) according to claim 7 or 8, where the control unit (220) is configured to determine the quality metric at least in part as an estimated remaining lifetime of the hydraulic oil in the hydraulic system (1 10).

10. The demolition robot (100) according to any of claims 7-9, where the control unit (220) comprises a digital storage medium (830), where a mapping or function between operating time and operating temperature on one hand, and the quality metric on the other hand, is stored in the digital storage medium (830).

11. The demolition robot (100) according to any of claims 7-10, where the control unit (220) is configured to obtain data indicative of a type of tool (310, 320, 330) in use, and to determine the quality metric of the hydraulic oil at least in part based on the type of tool in use.

12. The demolition robot (100) according to claim 1 1 , where the control unit (220) comprises a digital storage medium (830), where a mapping or function betweenoperating time, operating temperature, tool in use, and the quality metric is stored in the digital storage medium (830).

13. The demolition robot (100) according to any of claims 7-12, where the control unit (220) is connected to a plurality of temperature sensors arranged at different places in the hydraulic system (220), where the control unit (220) is arranged to determine the quality metric of the hydraulic oil based at least in part on operating temperatures at the different places in the hydraulic system (220).

14. The demolition robot (100) according to any of claims 7-13, comprising a pressure sensor (410) arranged in connection to an oil filter (240, 250) of the hydraulic system (110), where the control unit (220) is arranged to determine the quality metric of the hydraulic oil based at least in part on pressure data obtained from the pressure sensor (410).

15. The demolition robot (100) according to any of claims 7-14, comprising a pressure sensor (410) arranged in connection to an oil filter (240, 250) of the hydraulic system (1 10), where the control unit (220) is arranged to determine an oil filter contaminant load metric of the oil filter (240, 250) based on pressure data obtained from the pressure sensor (410) and on the operating temperature of the hydraulic oil in the hydraulic system (1 10).

16. The demolition robot (100) according to any of claims 7-15, where the control unit (220) is arranged to communicate (175) with a remote server (170) which forms part of a back-end system of the demolition robot (100), where the control unit is arranged to initiate transmission of the determined quality metric to the remote server (170).

17. The demolition robot (100) according to claim 16, where the control unit is arranged to receive data from the remote server (170), where the data is indicative of a mapping or function for determining the quality metric based on at least operating temperature and operating time.

18. The demolition robot (100) according to any of claims 7-17, comprising an oil quality sensor (QS) configured to determine a current quality of the hydraulic oil in the hydraulic system (1 10), where the control unit (220) is configured to obtain data from the oil quality sensor (QS), which data is indicative of the quality metric of the hydraulic oil in the hydraulic system (1 10).

19. The demolition robot (100) according to claim 18, where the control unit (220) comprises a digital storage medium (830), where a mapping or function between any of: operating time, operating temperature, type of tool in use, and the quality metric is stored, where the control unit (220) is configured to update the mapping or function based on the data obtained from the oil quality sensor (QS).

20. The demolition robot (100) according to any of claims 7-19, where the tool interface (150) is configured to support and to hydraulically power a breaker tool (310).

21. A computer-implemented method performed by a control unit (220) for a demolition robot (100) comprising a hydraulic system (110) arranged to power at least a tool carrier arm (140), where the tool carrier arm comprises a tool interface (150) configured to support and to hydraulically power at least one exchangeable tool (310, 320, 330), the method comprising measuring (S1 ) an operating temperature of hydraulic oil in the hydraulic system (110), monitoring (S2) operating time of the hydraulic system (110) and a corresponding operating temperature of the hydraulic oil in the hydraulic system (1 10), determining (S3) a quality metric of the hydraulic oil based at least in part on the monitored operating time and on the corresponding operating temperature, and initiating (S4) an automated action by the demolition robot (100) involving the determined quality metric.

22. A back-end system (180) for a demolition robot (100), the back-end system comprising a remote server (170) arranged to communicate (175) with a control unit (220) of the demolition robot (100), where the remote server (170) is arranged to receive a quality metric associated with hydraulic oil in a hydraulic system (1 10) of the demolition robot (100) from the demolition robot (100), where the back-end system (180) is configured to initiate an automated action based on the received quality metric.

23. The back-end system (180) according to claim 22, where the remote server (170) is arranged to receive oil quality sensor data from the demolition robot (100) indicative of an output from an oil quality sensor (QS) of the demolition robot, where the back-end system (180) is arranged to update a mapping or function between any of: operating time, operating temperature, tool in use, and a quality metric associatedwith hydraulic oil in a hydraulic system (1 10) of the demolition robot (100) based on the oil quality sensor data.

24. A demolition robot (100) comprising a hydraulic system (110) arranged to power at least a tool carrier arm (140), where the tool carrier arm comprises a tool interface (150) configured to support and to hydraulically power at least one exchangeable tool (310, 320, 330), the demolition robot comprising a control unit (220) connected to an oil quality sensor (QS) arranged to measure a current oil quality of hydraulic oil in the hydraulic system (110), where the control unit (220) is arranged to monitor the oil quality, and to initiate an automated action by the demolition robot (100) in case the oil quality fails to satisfy an oil quality acceptance criterion.

25. A demolition robot (100) comprising a hydraulic system (110) arranged to power at least a tool carrier arm (140), where the tool carrier arm comprises a tool interface (150) configured to exchangeably support and to hydraulically power at least one tool (310, 320, 330), where the control unit (220) is arranged to monitor operating time of the hydraulic system (110) and the type of tool (310, 320, 330) in use during the monitored operating time, where the control unit (220) is arranged to determine a quality metric of the hydraulic oil based at least in part on the monitored operating time and on the type of tool (310, 320, 330) in use during the monitored operating time, where the control unit (220) is configured to initiate an automated action by the demolition robot (100) involving the determined quality metric.

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