A hydraulic system and method arranged to prevent unintended movement by construction equipment

Abstract

A hydraulic system (170, 300, 400, 500) for controlling one or more hydraulic actuators (330, 330a, 330b) of movable members (110, 120, 130) on construction equipment (100), the hydraulic system comprising a control unit (150), a hydraulic tank (310), a hydraulic pump (320) arranged to generate hydraulic flow to hydraulic control valves (340, 340a, 340b) of the one or more hydraulic actuators (330, 330a, 330b), and an unintended movement prevention system (350, 410, 420, 510, 520, 540), where the control unit (150) is arranged to generate an electric pressure enable signal (360) in response to detecting an activated state of a remote-control device (200) associated with the construction equipment (100), where the unintended movement prevention system (350) is arranged to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves (340, 340a, 340b) to the hydraulic tank (310) in response to loss of the electric pressure enable signal (360).

Description

[0001] TITLE

[0002] A HYDRAULIC SYSTEM DESIGNED TO PREVENT UNINTENDED MOVEMENT BY CONSTRUCTION EQUIPMENT

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to hydraulically powered construction equipment, and in particular to hydraulically actuated demolition robots. There are disclosed hydraulic systems, control units, construction equipment, and methods for implementing cost-efficient and reliable safety features.

[0005] BACKGROUND

[0006] Many types of construction equipment, such as remote-controlled demolition robots, comprise moving members that may cause hazards to nearby persons and property, e.g., if they suddenly move in an unexpected manner.

[0007] Particularly strict safety standards apply to remote-controlled machinery where an operator walks next to the machine, since the operator is then sometimes within reach of the moving members on the machine due to operating space restrictions and for other reasons. The actuators and the control systems of such machinery may require certification according to the relevant safety standards that are applicable in jurisdictions where the machine is used.

[0008] ISO 13849 titled “Safety of machinery — Safety-related parts of control systems” is one such safety standard published by the International Organization for Standardization (ISO). ISO 13849 relates to the design and integration of safety- related parts of control systems that perform safety functions, including the design of software. The fourth edition of ISO 13849- 1 :2023 was published in 2023 and is relevant to some remote-controlled demolition robots.

[0009] There is a desire to fulfil the requirements related to unintended movement put in place by ISO 13849 and by other similar standards in a robust and cost- efficient manner, without hampering efficiency and performance of the hydraulic system.

[0010] JP4961901 A describes a movable lift with a hydraulic drive system and hydraulic actuator valves that are controlled from a remote control device. The disclosed hydraulic drive system comprises a bypass valve which is actuated automatically when actuator control signals are received from the remote control device. Thus, when the remote control device generates an actuator control signal to move the lift, the bypass valve automatically closes to allow hydraulic pressure to reach the actuator. The bypass valve is open when no actuator control signal is received from the remote control device, which means that unintended movement by the movable lift is prevented.

[0011] SUMMARY

[0012] It is an overall objective of the present disclosure to improve safety in construction equipment such as remote-controlled demolition robots. Some of the techniques disclosed herein seek to provide functional safety features, applicable with demolition robots and other construction equipment, that mitigate risks associated with unintended movement by the construction equipment.

[0013] The objective is at least in part obtained by a hydraulic system for controlling one or more hydraulic actuators of movable members on construction equipment, which movable members may cause hazards in case of, e.g., malfunction in the hydraulic system of the construction equipment. The hydraulic system comprises a control unit, a hydraulic tank, a hydraulic pump arranged to generate hydraulic flow to hydraulic control valves of the one or more hydraulic actuators, and an unintended movement prevention system. The control unit is arranged to receive control messages from a remote-control device associated with the construction equipment, for controlling various functions on the construction equipment including both functions that cause movement of the construction equipment and functions which do not cause movement by the construction equipment. The control unit is arranged to generate an electric pressure enable signal in response to receiving a control message from the remote control device and selectively detecting an activated state of a remote-control device associated with the construction equipment based at least in part on the contents of the received control message. The unintended movement prevention system is arranged to divert at least part of the hydraulic flow from the pump at a location upstream from the hydraulic control valves to the hydraulic tank, in response to loss of the electric pressure enable signal.

[0014] The unintended movement prevention system effectively punctures, i.e., unloads, the hydraulic system that powers the moving members, thus preventing hazardous movement by the moving members in case of a hazardous malfunction of the system which may cause risk for nearby persons and property. The electric pressure enable signal is required in order for the movable members to move fast and / or generate large enough force which may be hazardous to nearby persons and property. Consequently, as long as the electric pressure enable signal is only active or present when movement is intended, and not otherwise, unintended fast and / or high force movement is prevented.

[0015] The unintended movement prevention systems discussed herein go beyond the systems described in JP4961901 A at least in that the electric pressure enable signal is generated by the control unit in response to receiving a control message from the remote control device an selectively detecting an activated state of the remote-control device based on the received control message. Thus, simply receiving a transmission from the remote control device is not sufficient for the electric pressure enable signal to be generated as in JP4961901 A, since the contents of the received control message must also trigger detection of an activated state at the remote control device. This allows communication of various control messages such as keep-alive messages between the remote control device and the control unit of the construction equipment without the electric pressure enable signal necessarily being generated as in JP4961901 A. This is an advantage, e.g., since definition of what conditions are necessary for generating the electric pressure enable signal can be decided by a function implemented in the control unit. It is for instance possible to condition generation of the electric pressure enable signal on that at least one joystick of the remote-control device is offset from its respective neutral position, and / or on that an operator presence signal is received from the remote-control device. Transmissions from the remote control device to the control unit which do not meet the detection criteria will not trigger generation of the electric pressure enable signal, thus allowing various other forms of communication between the control unit and the remote control device while unintended movement is prevented by the unintended movement prevention system.

[0016] Using the present unintended movement prevention system, it is possible to allow movement by the hydraulic drive system and hydraulic actuators when no actual movement command is provided by the operator using the remote control device. The hydraulic drive system and hydraulic actuators may for instance be allowed to execute one or more autonomous functions as long as an operator is present and / or depresses a dedicated control input device such as a button or the like which is not directly connected to movement by any of the hydraulic actuators on the construction equipment.

[0017] The hydraulic control system can be divided into a safety-related control system part that meets a safety standard such as ISO 13849-1 :2023 and a general part which does not necessarily adhere to all parts of the safety standard, at least not to the same safety standard. Based on the risk reduction measures applied to the construction equipment, the safety control system may include protective measures which are dependent on the control system for their functionality. These functions are normally referred to as safety control functions and may include electronics and programmable digital components which in turn control hydraulic components on the construction equipment. Safety related and non-safety related functions can be implemented by shared components of the construction equipment or by separate components of the construction equipment.

[0018] According to a preferred embodiment, the unintended movement prevention system is comprised in the safety control system part, and the hydraulic pump is comprised in the general part. Thus, certification efforts involving the pump, and possibly also an electric motor used to drive the pump, can be limited or even avoided entirely without jeopardizing safety of the construction equipment, which is an advantage. In a preferred embodiment the unintended movement prevention system is comprised in a safety related part of control system (SRP / CS) as mentioned in the applicable standards.

[0019] According to a first example, the hydraulic system comprises a load sensing (LS) system arranged to control a magnitude of the hydraulic flow from the hydraulic pump in accordance with a pressure and / or flow requirement of the hydraulic system loads. The unintended movement prevention system may then comprise a first valve which may also be referred to as a pilot stage valve that is arranged to connect the LS system to the hydraulic tank in response to loss of the electric pressure enable signal, and a second valve which may also be referred to as a main stage valve that is arranged to divert at least part of the hydraulic flow from the pump to the actuators at a location upstream from the hydraulic control valves to the hydraulic tank in response to loss of hydraulic pressure in the LS system (caused by the loss of the electric pressure enable signal), thereby effectively puncturing the hydraulic system to prevent unintended movement by the construction equipment, or at least fast and / or large force movement, in response to loss of the electric pressure enable signal. An optional orifice is arranged in the LS system upstream from the second valve of the pressure relief valve arrangement.

[0020] According to a second example, the hydraulic system comprises a pilot line that is connected to the pressure side of the hydraulic pump. The unintended movement prevention system may then comprise a first valve which may also be referred to as a pilot stage valve that is arranged to connect the pilot line to the hydraulic tank in response to loss of the electric pressure enable signal, and a second valve which may also be referred to as a main stage valve that is arranged to divert at least part of the hydraulic flow upstream from the hydraulic control valves to the hydraulic tank in response to loss of hydraulic pressure in the pilot line, thereby effectively puncturing the hydraulic system to prevent unintended movement by the construction equipment. An optional orifice is arranged on the pilot line upstream from the first and second valves of the pressure relief valve arrangement. The optional orifice may be realized as a pressure compensated orifice.

[0021] According to some aspects, the control unit is arranged to generate the electric pressure enable signal as long as at least one joystick of the remote-control device is offset from its respective neutral position. Thus, no movement by the movable members of the construction equipment is possible unless an operator moves a joystick away from its neutral position. The control unit, having received a transmission from the remote control device, checks to see whether the transmission comprises an indication of movement by a joystick away from its neutral position, and detects the activated state if this is the case. Other various transmissions between the remote control device and the control unit will not trigger generation of the electric pressure enable signal unless the transmission also comprises contents which results in detection of the activated state.

[0022] According to some other aspects, the control unit is arranged to generate the electric pressure enable signal as long as an operator presence signal is received from the remote-control device. In this case received transmissions from the remote control device are screened by the control unit to check if the messages comprise an indication of operator presence, which if present will trigger detection of the activated state. The operator presence signal may be provided by a presence sensor or contact sensor, such as a capacitive sensor that detects when an operator holds the joysticks of a remote-control device or carries the remote-control device in a harness or the like. The operator presence signal may also comprise input data from a vision-based proximity detection system or the like which is set up to detect when persons or property is within reach of the movable members on the construction equipment.

[0023] According to further aspects, the control unit is arranged to generate the electric pressure enable signal conditioned on that a wireless or wired link between the control unit of the construction equipment and a remote-control device of the construction equipment is operational. In other words, the control unit may be arranged to generate the electric pressure enable signal only if an active data connection with a remote control device of the construction equipment is established. The control unit will cease to generate the electric pressure enable signal if the wireless or wired connection to the remote control device is interrupted or otherwise lost. If a transmission is received from a device which is not part of a wireless or wired link involving the construction equipment, then detection of the activated state will not occur. This means, among other things, that transmissions from remote control devices other than the device intended to control the construction equipment cannot cause movement by the construction equipment, which is an advantage.

[0024] The control unit can also be arranged to generate the electric pressure enable signal with a hold function that comprises maintaining the electric pressure enable signal for a given time period after conditions for its generation has ceased to be valid. This way valve operating delays and the like will have less of an effect on the operation of the construction equipment. An operator can for instance let go of the joysticks on the remote control device for a second or two without triggering the unintended movement prevention system. The hold time may be on the order of 1 -5 seconds, such as at least 3 seconds. The hold time may be at least party configurable by an operator or a service technician of the construction equipment, or simply a fixed predetermined hold time.

[0025] According to further aspects, the control unit is arranged to generate the electric pressure enable signal conditioned on a keyed activation of the construction equipment. This means that the electric pressure enable signal can only be generated if a keyed activation of the construction equipment has taken place (within some predetermined time period), and not otherwise. This further enhances the safety of the construction equipment. The keyed activation may comprise activation by physical key, activation code, or other digital, analog, or physical authorization token.

[0026] The control unit may, according to some examples, be arranged to generate the electric pressure enable signal in response to receiving a keyed override signal, regardless of input control device state such as joystick position, or the status of the wireless or wired communication link between the control unit of the construction equipment and the remote control device. The keyed override signal allows an operator to temporarily inactivate the safety systems of the construction equipment. However, since the override is keyed, only authorized operators are able to override the safety system, and the override cannot be performed inadvertently. The override feature is useful in some special cases where the safety systems of the construction equipment prevent completion of some operation, such as machine servicing or trouble shooting, or when performing advanced operations under special circumstances.

[0027] According to some example aspects, the control unit is arranged to generate the electric pressure enable signal in response to receiving an autonomous function or a semi-autonomous function activation command from the remote control device. The autonomous function or semi-autonomous function activation command may for instance comprise an instruction to automatically feed a tool in a given direction or to perform some other automated task, which the construction equipment will undertake as long as the autonomous function or semi-autonomous function activation command is received from the remote control device. The execution of the function will cease when the autonomous function or semi-autonomous function activation command is no longer received. The remote control device may, e.g., comprise a special button or the like which the operator needs to operate in order for the construction equipment to perform the autonomous or semi-autonomous function. Operation of this special button can be taken as detection criteria for detecting the activated state of the remote-control device. The hydraulic system preferably comprises a fixed displacement pump driven by a speed controlled electric motor. This way a more efficient and responsive hydraulic system may be obtained. It is an advantage that this type of advanced hydraulic pump system can be placed outside of the safety-related control system part according to the relevant safety standard, since it may be hard to certify in a cost-efficient manner. Electro-proportional hydraulic pumps may also be used in a hydraulic system of the kind discussed herein.

[0028] According to some aspects, the unintended movement prevention system is configured to divert at least part of the hydraulic flow from the hydraulic pump at a location upstream from the hydraulic control valves to the hydraulic tank by means of a proportional pressure limiting hydraulic control valve. By diverting at least part of the hydraulic flow in this manner, the maximum speed of the movable members will be drastically reduced down to a safe level. For instance, suppose that the nominal hydraulic pump flow is 100 l / min (liters per minute), and that the unintended movement prevention system diverts 95% of this flow. This means that the movable members operate at a flow of just 5 l / min, i.e., at 5% of the nominal speed of the movable members. This significant reduction in movement speed by the movable members mitigates risks associated with unintended movement by the construction equipment, since this movement will be very slow and / or weak. A control valve of the type proportional pressure limiting hydraulic control valve has been found to provide a quick enough response, be relatively easy to certify according to the relevant safety standards, and also relatively cost-effective. A proportional pressure limiting hydraulic control valve can be designed to meet the requirements of the applicable safety standards without adding significant complexity and cost to the overall system design. The requirements may comprise mean time to dangerous failure (MTTFd) and / or a fast enough response time for transitioning the system into a safe state.

[0029] According to some aspects, the control unit is arranged to reduce the flow of the hydraulic pump to an idling flow level in response to loss of the electric pressure enable signal. This results in less energy expenditure during time periods of movement prevention by the pressure relief valve arrangement. The time to reach full performance is reduced, since the hydraulic pump is kept running, which is an advantage. The pump will for instance reduce the flow if the operator releases the joysticks, or if the connection between the control unit of the construction equipment and a remote control device of the construction equipment is lost. The hydraulic system is then able to quickly assume normal operation in case the operator again operates the joysticks or if the wireless connection to the remote control device is restored.

[0030] There are also disclosed herein hydraulic systems, construction equipment, processing circuits, computer programs, computer program products as well as methods associated with the advantages mentioned above.

[0031] 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.

[0032] BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present disclosure will now be described in more detail with reference to the appended drawings, where

[0034] Figure 1 shows an example remote-controlled demolition robot;

[0035] Figure 2 shows an example portable remote-control device; Figure 3 illustrates an example hydraulic system;

[0036] Figure 4 shows an example hydraulic circuit;

[0037] Figures 5A-B show other example hydraulic circuits;

[0038] Figure 6 schematically illustrates an example hydraulic control valve;

[0039] Figures 7-8 are flow charts that illustrate methods; and

[0040] Figure 9 schematically illustrates a computer program product.

[0041] DETAILED DESCRIPTION

[0042] The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0043] It is to be understood that the present invention is not limited to the embodiments described herein and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

[0044] Figure 1 illustrates a remote-controlled demolition robot, which is an example of more general construction equipment 100 where the techniques discussed herein can be applied. The demolition robot comprises endless tracks 1 10 for propelling the robot over ground. An upper body 120 is rotatably mounted on the bottom section that comprises the tracks 110. An arm 130, sometimes referred to as a tool carrier, extends out from the body 120. Various tools, such as pneumatic or hydraulic hammers, buckets, cutters, and the like can be mounted at the distal end 140 of the arm 130. The techniques and hydraulic systems disclosed herein can also be applied in other types of hydraulically powered construction equipment such as road saws, wall saws, smaller excavators, wheel loaders, forklifts, drilling rigs, and so on.

[0045] Each of the different movable members 110, 120, 130 of the construction equipment 100 are actuated by at least one respective hydraulic actuator. The hydraulic actuators may comprise both linear actuators such as hydraulic cylinders and rotary actuators such as hydraulic motors. It is also possible that some actuators on the construction equipment 100 are electric actuators such as electric motors used for rotating the upper body 120 of the machine 100 or for driving the tracks 1 10. The unintended movement prevention systems discussed herein are, however, primarily focused on hydraulic actuators.

[0046] The actuators on the construction equipment 100 are powered by a hydraulic system 160 which in turn is controlled by a control unit 150. The control unit 150 and the hydraulic system 160 are only schematically illustrated in Figure 1 . The control unit 150 controls various operations of the hydraulic system 160, such as control of actuator valves and one or more hydraulic pumps of the hydraulic system 160.

[0047] The various technical features and functions disclosed herein will be exemplified by a remote-controlled demolition robot, i.e., the type of construction equipment illustrated in Figure 1. It is, however, appreciated that the present disclosure is in no way limited to demolition robots, but can be applied generally in many types of construction equipment, such as excavators, wheel loaders, haulers, mobile cranes, and so on.

[0048] The movable members 1 10, 120, 130 on the construction equipment 100 may cause hazard to persons and property in vicinity of the equipment. A person such as an operator of the equipment 100 that is standing next to the machine may, e.g., be injured if the body 120 all of a sudden starts to rotate (ROT), or if the arm 130 suddenly makes an unexpected pivoting motion (PIV) about one or more of its pivot axes. The construction equipment 100 may also be damaged in case of unintended movement. Unintended movement may for instance cause instability and cause the machine to tip over, cause the machine to drive over a ledge, or cause the machine to enter zones where the machine should not be located. Such unexpected motion by one or more movable members of the equipment 100 may be caused accidentally by an operator of the equipment 100, but it may also be caused by malfunction in the machine, such as malfunction in one or more hydraulic control valves that control the various actuators of the construction equipment 100, or a software error in the control unit 150 of the construction equipment 100.

[0049] ISO13849, e.g. ISO 13849-1 :2023 4thEdition, is a safety standard published by the ISO which applies to parts of machinery control systems that are assigned to providing safety functions (called safety-related control system parts). The standard is one of a group of sector-specific functional safety standards that were created to tailor various system reliability and safety functions to different types of machines in different industries. Some demolition robots may be required to adhere to this safety standard, at least when operating in certain environments and in certain jurisdictions.

[0050] As part of the risk reduction process aimed at reducing the risks associated with machinery such as the demolition robot illustrated in Figure 1 , risk reduction measures using electronic control systems may be applied. Measures required for design, verification and allocation of safety control functions, also known as functional safety, in the general architecture of the system are outlined in standards such as ISO13849-1 :2023, ISO13849-2:2012 and ISO 19014-1 :2018 to ISO 19014-5:2021 .

[0051] ISO 13849 may be referred to as a type-B standard. Type-B standards (generic safety standards) deal with one or more safety aspect(s), or one or more type(s) of safeguards, that can be used across a wide range of machinery

[0052] ISO 19014-1 through ISO 19014-5 may be referred to as type-C standards specially developed for earth moving machineries such as the demolition robot in Figure 1 . Type-C standards (machinery safety standards) deal with detailed safety requirements for a particular machine or group of machines. Movement by the one or more movable members on the construction equipment 100 may represent a hazard to persons and property located nearby the equipment 100. Movement of the demolition robot arm 130, body 120 and tracks 110 are normally controlled by remote-control device and are considered hazardous movements that can harm the operator or bystanders. It is important that no hazardous movements occur unless the joysticks or some other control input device is intendedly activated by an operator. As soon as the joystick on the remote-control device is returned to neutral position all the hazardous movements by the demolition robot shall cease.

[0053] The control unit 150 may as noted above be arranged to receive control commands from a remote-control device. An example remote-control device 200 is illustrated in Figure 2. The construction equipment 100 may also be arranged for autonomous operation or semi-autonomous operation, in which case the control unit 150 generates control commands for the different actuators internally in a sequence designed to complete a pre-determined work task. A control unit 150, a remote-control device 200, an autonomous control function, and a semi-autonomous operator assistance function may all suffer malfunction that may cause unexpected and undesired motion by the construction equipment 100. One of the objectives of the present disclosure is to mitigate the potential hazards resulting from such a malfunction.

[0054] The example remote-control device 200 illustrated in Figure 2 is a portable device intended to be carried by an operator in use. The device 200 comprises left and right joysticks 210I, 21 Or, a display 220 for communicating information to an operator, and a plurality of buttons and levers 230 for controlling various functions on the construction equipment 100. The remote-control device 200 is configured to communicate with the construction equipment 100 via wireless radio link, such as a Bluetooth link, a wireless local area network (WLAN) radio link, or a cellular connection link, such as the cellular access network links defined by the third generation partnership program (3GPP), i.e. , 4G, 5G and so on. Wired remote control devices can also be used to control construction equipment such as the demolition robot illustrated in Figure 1 . The communication link between the construction equipment 100 and the remote-control device may be interrupted, e.g., in case the radio link is subject to interference or in case a wired communication link suffers from cable rupture. In this case the system cannot determine if movement by the construction equipment 100 is intended or unintended. According to a preferred embodiment, all movement by the construction equipment is prevented in case the wireless or wired communication link to the remote control device is lost. In other words, according to a preferred embodiment, the construction equipment 100 is configured to enter a safe state in case of an interrupted communication link to the remote-control device 200. The hydraulic system used for controlling the one or more hydraulic actuators of the movable members 1 10, 120, 130 on the construction equipment 100, may then comprise a control unit 150, a hydraulic tank 310, a hydraulic pump 320 arranged to generate hydraulic flow to hydraulic control valves 340, 340a, 340b of the one or more hydraulic actuators 330, 330a, 330b, and an unintended movement prevention system 350, 410, 420, 510, 520, 540. The control unit 150 is arranged to generate an electric pressure enable signal which is conditioned on that a wireless or wired communication link to a remote-control device 200 of the construction equipment 100 is operational, i.e., in an active connected state, where the unintended movement prevention system 350 is arranged to divert at least part of the hydraulic flow from the hydraulic pump 320 at a location upstream from the hydraulic control valves 340, 340a, 340b to the hydraulic tank 310 in response to loss of the electric pressure enable signal.

[0055] It is appreciated that, by conditioning detection of activated state on the presence of a wireless or wired link to a specific remote control device, unintended movement cannot be caused by transmissions which are received from remote control devices other than the device which is intended to control the construction equipment. The specific remote control device intended to control the construction equipment may be referred to as a paired remote control device. Operation of the construction equipment 100 may according to an example require that the remote control device 200 is first paired with the control unit 150 of the construction equipment 100 in order to become a paired remote control device. The control unit 150 will then only generate the electric pressure enable signal 360 in response to receiving a control message from a remote control device 200 which has been paired with the control unit 150 beforehand, and only if the control unit detects an activated state of the remotecontrol device 200 based on the contents of the control message received from the paired remote control device. Methods for pairing a remote control device to a device to be controlled (in this case the construction equipment) are known in the art and will therefore not be discussed in more detail herein.

[0056] That the wireless or wired communication link to the remote-control device 200 of the construction equipment 100 is operational, i.e., in the active connected state may be detected by exchanging small control messages between the construction equipment 100 and its remote control device 200. These messages may be keep-alive messages exchanged regularly, such as every 50ms or so. In case the exchange of this message is not successful, then the remote-control device 200 may be deemed not to be in its activated state. The keep-alive message is an example of the various types of transmissions from the remote control device to the control unit which may not necessarily trigger generation of the electric pressure enable signal.

[0057] In other words, the remote-control device 200 can only be in its active state if the communication link between the construction equipment 100 and the remote-control device is operational.

[0058] Some control devices 200 are arranged to generate an operator presence signal 240 in addition to the control signal generated in response to movement of the joysticks and manipulation of the buttons and levers 230. This operator presence signal 240 is indicative of the presence of an operator by the control device 200. The operator presence signal 240 may comprise just a normal control input provided by an operator, perhaps with a hold function. Le., the operator presence signal 240 is active as long as an operator has provided at least one input command over a predetermined time period, such as a time period of 3 seconds or so. The operator presence signal 240 may also be provided by a presence sensor or contact sensor, such as a capacitive sensor that detects when an operator holds the joysticks 2101, 21 Or or carries the remote-control device 200 in a harness (not shown in Figure 2). Presence sensors and contact sensors are generally known and will therefore not be discussed in more detail herein. Lidar systems, radar systems, and visionbased operator recognition systems are also known in the art.

[0059] An indication of intended movement by the construction equipment 100 is that one or both joysticks 2101, 21 Or are offset from their neutral position. That a joystick is offset from its neutral position indicates that an operator has manipulated the joystick and desires the equipment 100 to move in some way.

[0060] The neutral position of a joystick or other control input device such as a knob or wheel is the position that corresponds to inactivity. Most joysticks have their neutral positions as the position where the joystick extends up normal to some base plane of the remote-control device. However, other positions may also correspond to the neutral position. Most joysticks are biased towards the neutral position, meaning that the joystick reverts back automatically to the neutral position in case the operator lets go of the joystick.

[0061] The remote-control device 200 may also comprise a mechanism for generating an override signal 250. This override signal could for instance be related to controlling the construction equipment 100 to intentionally perform a hazardous operation. The override signal may be a keyed override signal.

[0062] The remote-control device 200 and / or the construction equipment 100 may also comprise a keyed activation function.

[0063] Keyed systems often form an important safety and control mechanism which is used in various industries, including remote-controlled construction equipment. These systems require an operator to input a unique key such as a physical key intended to be inserted into a mechanical lock, a passcode to be input on a keypad or the like, or an encrypted digital signal transmitted to the machine in some way, to activate or override specific functions of the machine. This approach ensures that only authorized personnel can engage in critical functions, offering a controlled and secure environment for operating powerful and potentially hazardous machinery.

[0064] In construction equipment, a keyed override signal is a deliberate control action that bypasses certain automated or pre-set restrictions, allowing for manual intervention when necessary. This signal is only activated when a unique key is used, which can be a physical key or a digital input like a code or password. When the key is inserted, it overrides the automated system, granting the operator temporary manual control over the machine or specific operations that are otherwise restricted.

[0065] For example, in remote-controlled demolition robots, a keyed override may be used to disable certain safety interlocks or bypass automated controls during maintenance, emergency operations, or specialized tasks. Only trained personnel with access to the unique key can trigger these overrides, ensuring that critical functions are not accidentally or maliciously altered.

[0066] One of the most significant advantages of keyed override systems is enhanced security. Only authorized operators with the correct key or code can activate these systems, reducing the risk of accidental or unauthorized use of critical equipment.

[0067] Safety is also a crucial aspect of remote-controlled equipment. In emergency situations where the operator must manually intervene or override safety interlocks (e.g., to prevent a machine from malfunctioning or to address a potential hazard), keyed override signals ensure that the decision to bypass automated safety measures is deliberate and controlled. This reduces the likelihood of unintended or unsafe operations.

[0068] Construction equipment such as demolition robots often require routine maintenance and diagnostics. In many cases, certain safety mechanisms or operational limits need to be temporarily disabled to perform these tasks. Keyed override functions allow trained technicians to manually control the equipment during maintenance procedures, such as inspecting internal components or testing systems that are otherwise locked during normal operations. This ensures that these critical functions are only accessible during scheduled, supervised maintenance sessions, thereby preventing tampering or unintended damage.

[0069] A potential solution to mitigate hazards due to unexpected motion by the construction equipment 100 is to equip the machine with one or more motion sensors that monitor motion by the one or more movable members 110, 120, 130 of the construction equipment 100 and trigger some sort of action by the control unit 150 in response to detecting unexpected motion. Such motion sensors may comprise, e.g., displacement sensors, accelerometers, linear transducers, angle transducers, cameras and the like. A drawback of using such motion sensors is an increased system cost and complexity. The sensors themselves may also malfunction, and redundancy is therefore often required. It may also be desired to provide redundancy in the safety systems of the construction equipment 100. Thus, even if the construction equipment 100 also comprises a motion detection safety system, an alternative independent system may be desired.

[0070] To satisfy the requirements of ISO 13849 and similar standards the entire hydraulic system of the construction equipment 100, including its control means, may form the safety-related control system part that should conform to the relevant standards. However, this means that components such as the hydraulic pump of the hydraulic system 160 and the electric motor used to drive this pump must be certified according to ISO 13849. This may drive cost.

[0071] To satisfy the requirements of ISO 13849 and similar standards in a cost efficient and robust manner, it is proposed herein to add an unintended movement prevention system to the hydraulic system of the construction equipment 100. The unintended movement prevention system comprises a pressure relief valve arrangement, such as a proportional pressure relief valve, to the hydraulic system, at a location upstream from the hydraulic actuators of the movable members 110, 120, 130. This unintended movement prevention system can be designed to adhere to, e.g., ISO 13849, in a cost efficient and robust manner. The system can be designed to generate an electric pressure enable signal in response to detecting an activated state of the remote-control device 200, and the unintended movement prevention system can be designed to immediately puncture or at least significantly reduce hydraulic pressure in the hydraulic system 160 by the pressure relief valve in response to loss of the electric pressure enable signal. When the hydraulic system is punctured in this manner, it does not matter what the hydraulic pump does, since any significant flow generated by the hydraulic pump does not reach the actuators where it may cause unintended movement by the one or more movable members 110, 120, 130.

[0072] To summarize, with reference also to Figure 3, there is disclosed a hydraulic system 170, 300 for controlling one or more hydraulic actuators 330, 330a, 330b of movable members 1 10, 120, 130 on construction equipment 100. The hydraulic system comprises a control unit 150, a hydraulic tank 310, a hydraulic pump 320 arranged to generate hydraulic flow to hydraulic control valves 340, 340a, 340b of the one or more hydraulic actuators 330, 330a, 330b, and an unintended movement prevention system 350.

[0073] Various realizations and examples of this unintended movement prevention system 350 will be described below in connection to Figure 4 and Figures 5A- B. An example hydraulic control valve will be discussed in connection to Figure 6.

[0074] As mentioned above, SRP / CS (safety related parts of controlled system) can be shared with non-safety related functions, i.e. a part which is used in the safety system can also perform non-safety related functions in different operation modes. The pressure relief valve may in some examples also function as a circulation valve that is part of a non-safety related function designed to send hydraulic oil from the pump directly to a hydraulic oil filter which mitigates hydraulic oil contamination and / or a hydraulic oil cooler which reduces the temperature of the hydraulic oil.

[0075] The control unit 150 is arranged to generate an electric pressure enable signal 360 in response to receiving a control message from the remote control device 200 and also selectively detecting an activated state of the remote-control device 200 associated with the construction equipment 100 based on the contents of the received control message. It is appreciated that the electric pressure enable signal 360 assumes an active state or ON-state when the remote-control device 200 is in an activated state. A non-zero voltage and / or non-zero electric current is present when the electric pressure enable signal 360 is in the active state. The electric pressure enable signal 360 assumes an inactive state or OFF-state when the remote-control device 200 is not in the activated state. Power loss, signal cable damage, and the like will be interpreted by the system as absence of the electric pressure enable signal 360, since then there is no voltage or electric current present. This is an advantage, since a malfunctioning system is less likely to inadvertently generate the electric pressure enable signal 360. It is emphasized that the term “selectively” means that not all received control messages will trigger generation of the electric pressure enable signal 360, since the generation is conditioned on receiving a control message and also selectively detecting an activated state based on the contents of the control message. There may be several different types of control messages, such as keep-alive messages and other various messages, which do not give rise to generation of the electric pressure enable signal. It is an advantage that communication between the remote control device and the control unit of the construction equipment can take place without causing the unintended movement prevention system 350 to open up the hydraulic passage between the pump and the hydraulic actuators.

[0076] It is also appreciated that many of the functions and features disclosed herein can be implemented together with a non-selective generation of an electric pressure enable signal in response to receiving a control message from the remote control device. Thus, many of the optional features described herein can also be implemented with a system where the control unit 150 is arranged to generate an electric pressure enable signal 360 in response to detecting an activated state of a remote-control device 200 associated with the construction equipment 100.

[0077] The unintended movement prevention system 350 is arranged to divert at least part of the hydraulic flow upstream from the hydraulic control valves 340, 340a, 340b to the hydraulic tank 310 in response to loss of the electric pressure enable signal 360, thereby reducing the pressure in the hydraulic system to levels which cannot generate hazardous movement by the construction equipment 100, such as fast movement and / or movement with high force.

[0078] The remote control device 200, and / or the construction equipment 100, may comprise a visible indicator 180, 260 configured to indicate the status of the unintended movement prevention system, i.e., to indicate the status of the electric pressure enable signal 360 and / or the status of the unintended movement prevention system 350. The remote control device 200 and / or the construction equipment 100 may, e.g., comprise a light emitting diode (LED) that turns red when the electric pressure enable signal 360 is generated by the control unit, and green when the electric pressure enable signal 360 is not generated by the control unit 150.

[0079] With reference to Figure 3, when the hydraulic system 300 is activated and performing a work task, hydraulic flow from the pump 320 enters via the pressure line P to the actuators. A return line T connects the actuators to the hydraulic tank 310, thus closing the hydraulic circuit. The flow generated by the hydraulic pump 320 generates an operating pressure in the hydraulic system 300. The control of pressure and flow in the hydraulic system 300 can be managed according to methods known in the art. A load sensing (LS) system can for instance be used to regulate hydraulic flow out from the hydraulic pump 320 and hydraulic pressure in the system.

[0080] Note that the unintended movement prevention system does not comprise a valve or restricting orifice on the main pressure line, which could otherwise hamper efficiency of the hydraulic system by incurring losses. The unintended movement prevention system is a bypass which creates a passage from the pressure side of the hydraulic pump to the hydraulic tank without obstructing hydraulic flow in the normal use-case. When the bypass conduit controlled by the unintended movement prevention system is open the hydraulic pressure in the system, in particular at the actuators of the movable members, is not high enough to cause movement, at least not rapid movement, by the movable members.

[0081] An LS system is a hydraulic circuit that connects the various loads in the system to a hydraulic pump controller, either hydraulically or electrically. The hydraulic pump controller then ensures that the hydraulic system is fed with sufficient flow and pressure to maintain the desired operation. The maximum operating pressure of the different loads is reported to the pump’s controller through a chain of non-return valves, schematically illustrated in Figure 4 and in Figures 5A-B. This is known as the load sense pressure. The controller adjusts the delivery rate of the pump so that it delivers the correct hydraulic pressure and the correct delivery volume to achieve the required actuator speeds. LS systems are generally known in the technical field of hydraulics and will therefore not be discussed in more detail herein.

[0082] The hydraulic system 300 requires that the electric pressure enable signal 360 is present in order to transmit hydraulic operating flow to the hydraulic control valves 340 that control the hydraulic actuators 330. This is because the electric pressure enable signal 360 operates a solenoid 355 or other electric actuator which governs the state of the unintended movement prevention system 350. If the electric pressure enable signal 360 is lost, e.g., due to that the operator has let go of the joysticks 2101, 21 Or, or because the electric signal cable has been damaged, then the hydraulic pressure in the hydraulic pressure line will move the unintended movement prevention system 350 into a state where the hydraulic flow upstream from the hydraulic control valves 340 is diverted to the tank 310. This change in state to a safe state is indicated in Figure 3 by the dashed arrow D.

[0083] The hydraulic system 170, 300 can now be divided into a safety-related control system part according to a safety standard such as ISO 13849 and a general part which does not have to conform to, e.g., ISO 13849. The unintended movement prevention system 350 is preferably comprised in the safety control system part while the hydraulic pump 320 is preferably comprised in the general part. Thus, the hydraulic pump 320 and also the electric motor used to drive the pump does not have to be adhere to the same safety standards as, e.g., the pressure release valve of the unintended movement prevention system 350, which is an advantage. The hydraulic control valves 340 and the hydraulic actuators 330 may also be excluded from the safety- related control system part, as shown in Figure 3.

[0084] The safety-related parts of the system and non-safety related parts of the system can use shared components. The pressure relief valve arrangement can for instance also be used to send the hydraulic oil to the hydraulic tank through a hydraulic filter and / or through a hydraulic oil cooler to keep the hydraulic medium at the right temperature and at an acceptable contamination level.

[0085] Figures 4 and 5A-B show two examples of how the unintended movement prevention system 350 may be implemented in practice on, e.g., a demolition robot such as that illustrated in Figure 1. The hydraulic system 400 schematically illustrated in Figure 4 comprises an LS system 440 arranged to control the hydraulic flow from the hydraulic pump 320. The LS system 440 operates according to principles known in the art. The unintended movement prevention system here comprises a first valve 410 which may also be referred to as a pilot stage valve arranged to connect the LS system 440 to the tank 310 in response to loss of the electric pressure enable signal 360, and a second valve 420 which may also be referred to as a main stage valve arranged to divert at least part of the hydraulic flow upstream from the hydraulic control valves 340, 340a, 340b to the hydraulic tank 310 in response to loss of hydraulic pressure in the LS system 440. The unintended movement prevention system is a watchdog type of system which will kick in if malfunction occurs, i.e., if the hydraulic pump generates flow in the absence of a corresponding request for hydraulic flow. As long as the hydraulic system operates correctly there will not be any puncture of the system. The first valve 410 may be spring loaded such that it transitions into the pressure puncturing state in case of power loss. When the first valve 410 opens up as indicated by the dashed arrow O, the pressure in the LS system drops. The second valve 420 can then no longer resist the pressure from the pilot line 425 connected to the pressure side of the hydraulic pump 320, resulting in puncture of the hydraulic system 400. In other words, when the electric pressure enable signal 360 is not present, then the LS pressure drops, which in turn results in that the second valve 420 moves into a state where at least part of the hydraulic flow upstream from the hydraulic control valves 340, 340a, 340b is diverted to the hydraulic tank 310.

[0086] The first valve 410 and the second valve 420 may be spring biased valves, where the spring forces are configured in dependence of other hydraulic system parameters such as expected pressure in the pilot line 425 and force generated by the solenoid device 355.

[0087] It is appreciated that many different types of electrically actuated control mechanisms can be used to obtain the desired effect of transitioning the unintended movement prevention system into its different states in dependence of whether the electric pressure enable signal 360 is present or not. The solenoids 355 schematically illustrated in Figure 4 and in Figures 5A- B are just example actuators.

[0088] A solenoid device may be configured to pull or to push in response to an active coil current. Thus, solenoids operated based on presence or absence of the electric pressure enable signal 360 may either pull or push onto valve parts such as valve poppets. The electric pressure enable signal 360 may be used directly to energize the solenoid coil, or indirectly to generate a coil energizing current based on presence or absence of the electric pressure enable signal 360.

[0089] An optional orifice 430 is arranged in the LS system 440 upstream from the second valve 420 of the pressure relief valve arrangement, to adjust operating flow of the pressure relief valve arrangement. Figure 5A illustrates another example realization 500 of the hydraulic system 170. In this case a pilot line 525 is connected to the pressure side of the hydraulic pump 320. The unintended movement prevention systemin this case also comprises a first valve 510 which may also be referred to as a pilot stage valve and a second valve 520 which may also be referred to as a main stage valve with similar function as in Figure 4. However, in this case the first valve 510 is arranged to connect the pilot line 525 to the tank 310 in response to loss of the electric pressure enable signal 360. The second valve 520 is arranged to divert at least part of the hydraulic flow upstream from the hydraulic control valves 340, 340a, 340b to the hydraulic tank 310 in response to loss of hydraulic pressure in the pilot line 525. An optional orifice 530 is arranged on the pilot line 525 upstream from the first and second valves 510, 520 of the unintended movement prevention system to adjust operating flow of the pressure relief valve arrangement. The first valve 510 and the second valve 520 may be spring loaded valves as shown in Figure 5A. It is appreciated that the first valve 510 and the second valve 520 are examples which can be replaced by alternative valve configurations without changing the fundamental function of the pressure relief valve arrangement, which is to divert at least part of the hydraulic flow upstream from the hydraulic control valves to the hydraulic tank in response to loss of the electric pressure enable signal, thereby puncturing the pressure line of the hydraulic system before it reaches the actuators and can cause unintended movement of the movable members 110, 120, 130 on the construction equipment 100. Figure 5B illustrates one such alternative valve configuration.

[0090] The first valve 510 and the second valve 520 may be spring biased valves, where the spring forces are configured in dependence of other hydraulic system parameters such as expected pressure in the pilot line 425 and force generated by the solenoid device 355.

[0091] Figure 5B shows another example realization where a pressure relief valve 540 is arranged inbetween the output from the hydraulic pump 320 (P) and the return line to the hydraulic tank 310 (T). T1

[0092] The pressure relief valves in the examples illustrated in Figure 4 and in Figures 5A-B are watchdog valves which will only transmit hydraulic oil to the tank in case of malfunction. According to the intended (correct) operation of the system, the hydraulic pump should reduce its output flow in case no input command is received from the system control unit. Only in case of malfunction will the pump generate output flow that is not requested by the system. The control unit 150 may according to some example realizations be arranged to generate the electric pressure enable signal 360 as long as at least one joystick 210I, 21 Or of the remote-control device 200 is offset from its respective neutral position, as discussed above. The control unit 150 may also be arranged to generate the electric pressure enable signal 360 as long as an operator presence signal 240 is received from the remote-control device 200. Thus, the movable members 110, 120, 130 will respond to an operator of the equipment 100 desiring movement by the equipment. However, if no input is provided to the joysticks by the operator no movement by the movable members is possible, since then there will not be any electric pressure enable signal 360 and consequently also no hydraulic operating pressure sufficient to cause movement by the members, or at least not rapid movement by the movable members.

[0093] The electric pressure enable signal 360 is optionally associated with a hold function. I.e., the electric pressure enable signal 360 may remain active as long as an operator has provided at least one input command via a joystick (or other input command device) over a predetermined time period, such as a time period of 1 -3 seconds, such as a time period of at least one second, at least two seconds or at least three seconds. More generally, the control unit 150 is optionally arranged to generate the electric pressure enable signal 360 with a hold function comprising maintaining the electric pressure enable signal 360 active for a given hold time period after conditions for its generation has ceased to be valid. The hold time period may be configured at around 1 -3 seconds or so. Generally, herein, that an operation such as the generation of a signal is conditioned on one or more events or states means that the events or states are prerequisites for the operation to occur. In other words, if the generation of a given signal is conditioned on an event, then that event must take place in order for the signal to be generated. The one or more conditions are necessary but not sufficient for the operation to take place.

[0094] According to some aspects, the control unit 150 is arranged to generate the electric pressure enable signal 360 conditioned on an active data connection with a remote control device 200 of the construction equipment 100. Thus, if connection to the remote control device 200 is lost, then the control unit 150 will cease to generate the electric pressure enable signal 360. Keep-alive messages may be transmitted between the control unit 150 and the remote control device 200 in order to monitor the state of the data connection there inbetween, to verify that the communication link is indeed operational. The connection between the control unit 150 of the construction equipment 100 and the remote control device 200 may be a wired connection or a wireless connection.

[0095] According to some aspects, the control unit 150 is furthermore arranged to generate the electric pressure enable signal 360 conditioned on a keyed activation of the construction equipment 100. Thus, unless the construction equipment 100 has been activated by an authorized operator no movement by the equipment 100 will be possible. These systems require an operator to input a unique key such as a physical key, a passcode, or encrypted digital signal, to activate specific functions of the machine.

[0096] According to some other aspects, the control unit 150 is arranged to generate the electric pressure enable signal 360 in response to receiving a keyed override signal 250, as discussed above. The keyed override signal 250 may be generated in response to that an operator uses a unique key such a physical key, passcode, or encrypted digital signal.

[0097] The hydraulic pump 320 schematically illustrated in Figures 3-4 and in Figures 5A-B may be a fixed displacement pump or a variable displacement pump. A fixed displacement pump can be speed-controlled in order to vary the hydraulic flow out from the pump. Electro-proportional hydraulic pumps are variable displacement pumps with a displacement that is controlled by a control signal from the control unit 150.

[0098] The hydraulic systems disclosed herein are particularly suitable for use with more advanced speed-controlled fixed displacement pumps and also with advanced electro-proportional pumps, since these pumps will not need to be certified according to the relevant safety standards governing unintended movement. In other words, the hydraulic pump 320 does not have to form part of the safety-related control system part according to a safety standard for unintended movement such as ISO 13849-1 :2023.

[0099] The hydraulic pump 320 may be driven by a speed controlled electric motor 325. Again, this motor 320 does not have to be certified according to the relevant safety standards governing unintended movement, since the electric motor does not need to form part of the form part of the safety-related control system part according to a safety standard such as ISO 13849-1 :2023.

[0100] According to some aspects, the control unit 150 is also arranged to reduce the flow of the hydraulic pump 320 to an idling flow level in response to loss of the electric pressure enable signal 360. In other words, the control unit 150 will actively reduce the flow of the hydraulic pump in case at least part of the hydraulic flow from the hydraulic pump 320 is diverted to the hydraulic tank 310 in response to loss of the electric pressure enable signal 360. This way the power consumption of the hydraulic system during periods of movement prevention is limited, which is an advantage. The hydraulic pump is, however, still running, which means that the hydraulic system can be ramped up to full performance in a short period of time, once the electric pressure enable signal 360 is again generated by the control unit 150.

[0101] The unintended movement prevention system 350, 410, 420, 510, 520, 540 is, according to an example, arranged to divert at least part of the hydraulic flow (not necessarily the entire pump flow) at a location upstream from the hydraulic control valves 340, 340a, 340b to the hydraulic tank 310 by means of a proportional pressure limiting hydraulic control valve 420, 520, 600. An alternative to a proportional pressure limiting hydraulic control valve is an on / off valve, sometimes referred to as a two-way directional valve. Proportional pressure relief valves generate a more seamless function compared to on / off directional valve and may be preferred for this reason. On / off valves are often slower and have more distinct characteristics which may cause jerky movement while changing state from open to closed.

[0102] Figure 6 illustrates an example proportional pressure relief valve 600. This valve is electro-proportionally controlled. The pilot line 610 urges the valve to an open state by a force F1 , while the spring 620 and the solenoid 630 together urge the valve to its closed state by respective forces F2 and F3. If the coil of the solenoid 630 is energized, indicating presence of the electric pressure enable signal 360, then the valve 600 is closed, thus disconnecting the pressure port P from the tank port T. As soon as the electric pressure enable signal 360 is lost the pressure in the pilot line 610 will open up the valve 600.

[0103] The main criteria in selecting a relief valve is normally the response time of the valve, i.e., how fast it closes from its open state (safe state) and how fast it releases again, i.e., reverts back from its safe state. In other words, the response time of a hydraulic valve is the time it takes from issuance of a control signal to change the state of the valve to the time instant when the change in state has been completed. The proportional pressure limiting hydraulic control valve 420, 520, 600 preferably has a response time below 50ms, and preferably below 40ms.

[0104] Other criteria for selecting the relief valve that may be of interest is the rest pressure i.e. the pressure when the valve has zero electrical signal which is similar to its spring offset pressure. For example, in the example illustrated in Figure 4 it can be between 10 bar and 30 bar, which is the sum of the load sensing pressure, and the load sensing offset pressure (delta-P LS).

[0105] Another criteria of interest may be the flat Pressure-Flow curve of the valve. Another important criteria is that the valve shall have high enough MTTFd value (according to ISO 13849), i.e., how robust the valve is. A preferred value of MTTFd for a suitable pressure relief valve is about 150 years.

[0106] Figures 7-8 are flow charts that illustrate methods of preventing unintended movement by construction equipment such as demolition robots. The methods summarize the discussion above. There is disclosed a computer-implemented method for controlling one or more hydraulic actuators 330, 330a, 330b of movable members 110, 120, 130 on construction equipment 100. The method comprises: configuring S1 a control unit 150, a hydraulic tank 310, a hydraulic pump 320 arranged to generate hydraulic flow to hydraulic control valves 340, 340a, 340b of the one or more hydraulic actuators 330, 330a, 330b, and an unintended movement prevention system 350, 410, 420, 510, 520, 540, monitoring S2 a state of a remote-control device 200 associated with the construction equipment 100, generating S3, by the control unit 150, an electric pressure enable signal 360 in response to detecting an activated state of the remote-control device 200, and operating S4 the unintended movement prevention system 350 to divert at least part of the hydraulic flow upstream from the hydraulic control valves 340, 340a, 340b to the hydraulic tank 310 in response to loss of the electric pressure enable signal 360.

[0107] Figure 9 schematically illustrates, in terms of a number of functional units, the general components of a control unit 900, such as the control unit 150 or a module comprised in the remote-control device 200. Processing circuitry 910 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 storage medium 930. The processing circuitry 910 may further be provided as at least one application specific integrated circuit ASIC, or field programmable gate array FPGA.

[0108] Particularly, the processing circuitry 910 is configured to cause the device 900 to perform a set of operations, or steps, such as the methods discussed in connection to Figure 7 and Figure 8 and the discussions above. For example, the storage medium 930 may store the set of operations, and the processing circuitry 910 may be configured to retrieve the set of operations from the storage medium 930 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 910 is thereby arranged to execute methods as herein disclosed.

[0109] The storage medium 930 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.

[0110] The device 900 may further comprise an interface 920 for communications with at least one external device. As such the interface 920 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of ports for wireline or wireless communication.

[0111] The processing circuitry 910 controls the general operation of the control unit 900, e.g., by sending data and control signals to the interface 920 and the storage medium 930, by receiving data and reports from the interface 920, and by retrieving data and instructions from the storage medium 930.

[0112] There is also disclosed herein a computer readable medium carrying a computer program comprising program code means for performing the methods illustrated in Figure 7 and in Figure 8, when said program product is run on a computer. The computer readable medium and the code means may together form a computer program product.

Claims

1. CLAIMS1. A hydraulic system (170, 300, 400, 500) for controlling one or more hydraulic actuators (330, 330a, 330b) of movable members (110, 120, 130) on construction equipment (100), the hydraulic system comprising a control unit (150), a hydraulic tank (310), a hydraulic pump (320) arranged to generate hydraulic flow to hydraulic control valves (340, 340a, 340b) of the one or more hydraulic actuators (330, 330a, 330b), and an unintended movement prevention system (350, 410, 420, 510, 520, 540), where the control unit (150) is arranged to receive control messages from a remote-control device (200) associated with the construction equipment (100) for controlling various functions on the construction equipment (100), where the control unit (150) is arranged to generate an electric pressure enable signal (360) in response to receiving a control message from the remote control device (200) and selectively detecting an activated state of the remotecontrol device (200), where the unintended movement prevention system (350) is arranged to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves (340, 340a, 340b) to the hydraulic tank (310) in response to loss of the electric pressure enable signal (360).

2. The hydraulic system (170, 300, 400, 500) according to claim 1 , where the hydraulic system is divided into a safety-related control system part according to a safety standard such as ISO 13849-1 :2023 and a general part, where the unintended movement prevention system (350, 410, 420, 510, 520, 540) is comprised in the safety control system part and where the hydraulic pump (320) is comprised in the general part.

3. The hydraulic system (170, 300, 400) according to claim 1 or 2, comprising a load sensing, LS system (440) arranged to control the hydraulic flow from the hydraulic pump (320),where the unintended movement prevention system (350, 410, 420) comprises a first valve (410) arranged to connect the LS system (440) to the tank (310) in response to loss of the electric pressure enable signal (360), and a second valve (420) arranged to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves (340, 340a, 340b) to the hydraulic tank (310) in response to loss of hydraulic pressure in the LS system (440).

4. The hydraulic system (170, 300, 500) according to claim 3, where an orifice (430) is arranged in the LS system (440) upstream from the second valve (420) of the pressure relief valve arrangement.

5. The hydraulic system (170, 300, 500) according to claim 1 or 2, where a pilot line (525) is connected to the pressure side of the hydraulic pump (320), where the unintended movement prevention system(350, 510, 520) comprises a first valve (510) arranged to connect the pilot line (525) to the tank (310) in response to loss of the electric pressure enable signal (360), and a second valve (520) arranged to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves (340, 340a, 340b) to the hydraulic tank (310) in response to loss of hydraulic pressure in the pilot line (525).

6. The hydraulic system (170, 300, 500) according to claim 5, where an orifice (530) is arranged on the pilot line (525) upstream from the first and second valves (510, 520) of the pressure relief valve arrangement.

7. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to generate the electric pressure enable signal (360) as long as at least one joystick (2101, 21 Or) of the remotecontrol device (200) is offset from its respective neutral position.

8. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to generate the electric pressure enable signal (360) as long as an operator presence signal (240) is received from the remote-control device (200).

9. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to generate the electric pressure enable signal (360) conditioned on an active data connection with the remotecontrol device (200) ot the construction equipment (100).

10. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to generate the electric pressure enable signal (360) with a hold function comprising maintaining the electric pressure enable signal (360) for a given time period after conditions for its generation has ceased to be valid.

11. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to generate the electric pressure enable signal (360) conditioned on a keyed activation of the construction equipment (100).

12. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to generate the electric pressure enable signal (360) in response to receiving a keyed override signal (250).

13. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to generate the electric pressure enable signal (360) in response to receiving an autonomous function or a semi- autonomous function activation command.

14. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the hydraulic pump (320) is a fixed displacement pump.

15. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the hydraulic pump (320) is driven by a speed controlled electric motor (325).

16. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the unintended movement prevention system (350, 410, 420, 510, 520, 540) is configured to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves(340, 340a, 340b) to the hydraulic tank (310) by means of a proportional pressure limiting hydraulic control valve (420, 520, 600).

17. The hydraulic system (170, 300, 400, 500) according to claim 16, where the proportional pressure limiting hydraulic control valve (420, 520, 600) has a response time below 50ms, and preferably below 40ms.

18. The hydraulic system (170, 300, 400, 500) according to any previous claim, where the control unit (150) is arranged to reduce the flow of the hydraulic pump (320) to an idling flow level in response to loss of the electric pressure enable signal (360).

19. Construction equipment (100) comprising a hydraulics system (170, 300, 400, 500) according to any previous claim.

20. Construction equipment (100) according to claim 19, comprising a visible indicator (180, 260) configured to indicate the status of the electric pressure enable signal (360) and / or of the unintended movement prevention system (350).21 . Construction equipment (100) according to claim 19 or 20, constituted by a demolition robot.

22. A computer-implemented method for controlling one or more hydraulic actuators (330, 330a, 330b) of movable members (110, 120, 130) on construction equipment (100), the method comprising configuring (S1 ) a control unit (150), a hydraulic tank (310), a hydraulic pump (320) arranged to generate hydraulic flow to hydraulic control valves (340, 340a, 340b) of the one or more hydraulic actuators (330, 330a, 330b), and an unintended movement prevention system (350, 410, 420, 510, 520, 540), where the control unit (150) is arranged to receive control messages from a remote-control device (200) associated with the construction equipment (100) for controlling various functions on the construction equipment (100), monitoring (S2) a state of the,generating (S3), by the control unit (150), an electric pressure enable signal (360) in response to receiving a control message from the remote control device (200) and detecting an activated state of the remote-control device (200), and operating (S4) the unintended movement prevention system (350) to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves (340, 340a, 340b) to the hydraulic tank (310) in response to loss of the electric pressure enable signal (360).

23. A hydraulic system (170, 300, 400, 500) for controlling one or more hydraulic actuators (330, 330a, 330b) of movable members (110, 120, 130) on construction equipment (100), the hydraulic system comprising a control unit (150), a hydraulic tank (310), a hydraulic pump (320) arranged to generate hydraulic flow to hydraulic control valves (340, 340a, 340b) of the one or more hydraulic actuators (330, 330a, 330b), and an unintended movement prevention system (350, 410, 420, 510, 520, 540), where the control unit (150) is arranged to generate an electric pressure enable signal (360) in response to detecting an activated state of a remote-control device (200) associated with the construction equipment (100), where the unintended movement prevention system (350) is arranged to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves (340, 340a, 340b) to the hydraulic tank (310) in response to loss of the electric pressure enable signal (360).

24. A computer-implemented method for controlling one or more hydraulic actuators (330, 330a, 330b) of movable members (110, 120, 130) on construction equipment (100), the method comprising configuring (S1 ) a control unit (150), a hydraulic tank (310), a hydraulic pump (320) arranged to generate hydraulic flow to hydraulic control valves (340, 340a, 340b) of the one or more hydraulic actuators (330, 330a, 330b), and an unintended movement prevention system (350, 410, 420, 510, 520, 540),monitoring (S2) a state of a remote-control device (200) associated with the construction equipment (100), generating (S3), by the control unit (150), an electric pressure enable signal (360) in response to detecting an activated state of the remote-control device (200), and operating (S4) the unintended movement prevention system (350) to divert at least part of the hydraulic flow from the hydraulic pump (320) at a location upstream from the hydraulic control valves (340, 340a, 340b) to the hydraulic tank (310) in response to loss of the electric pressure enable signal (360).

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