System comprising an industrial robot and an end effector with power tool and charger

A system comprising: an industrial robot comprising a robot arm end portion and a power supply circuit arranged to supply current to the robot arm end portion, and an end effector comprising a power tool and an accumulator module (such as a battery) arranged to power operation of the power tool, the end effector being attached to the robot arm end portion, the end effector further comprising a charger arranged to draw current from the power supply circuit at the robot arm end portion and to supply charging current to the accumulator module. Charging of the accumulator module for the power tool is facilitated and the efficiency of the manufacturing process is increased.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Patent Application (filed under 35 § U.S.C. 371) of PCT/EP2022/080437, filed Nov. 1, 2022 of the same title, which, in turn claims priority to Swedish Patent Application No. 2130340-9 filed Dec. 2, 2021 of the same title; the contents of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present disclosure generally relates to the field of industrial robots having end effectors for operating power tools. More specifically, the present disclosure relates to charging accumulator modules for powering such power tools.

BACKGROUND OF THE INVENTION

In manufacturing industry, industrial robots may be used to process objects by means of power tools. Such industrial robots are equipped with a so called end effector, which is a device attached to the end of the robot arm and designed to interact with the objects and/or surrounding environment. The end effector is usually referred to as the last link of the robot. The end effector may typically comprise the power tool and is mounted to the robot arm end portion. The end effector may also comprise some kind of (energy) accumulator module, such as a battery, to power operation of the power tool.

The accumulator module needs to be regularly charged in order to power the power tool properly. The robot then typically unloads the empty accumulator module in a charger stand, and picks up another, charged, accumulator module from the stand. This process is cumbersome and time consuming and, thus, reduces the efficiency of the manufacturing process.

SUMMARY OF THE INVENTION

It would be advantageous to achieve a system overcoming, or at least alleviating, the above mentioned drawback. In particular, it would be desirable to enable a system facilitating charging of power tools operated by industrial robots.

To better address one or more of these concerns, a system having the features defined in the independent claim is provided. Preferable embodiments are defined in the dependent claims.

A system is provided comprising an industrial robot comprising a robot arm end portion and a power supply circuit arranged to supply current to the robot arm end portion. The system further comprises an end effector comprising a power tool and an (energy) accumulator module arranged to power operation of the power tool. The end effector is attached to the robot arm end portion. The end effector further comprises a charger arranged to draw current from the power supply circuit at the robot arm end portion and to supply charging current to the accumulator module.

The inventors have realized that the current available at the robot arm end portion can be utilized to charge the accumulator module for the power tool. The current available from the power supply circuit of a standard industrial robot is typically not enough to provide the power tool with its peak operating current, but it may be used to continuously charge the accumulator module when needed. Hence, the accumulator module may provide the power tool with its peak power during operation, while the current from the industrial robot is utilized for recharging the accumulator module as needed. This reduces the need of replacing empty accumulator modules with charged ones, which saves time in the manufacturing process. Further, the need for a separate charging stand for accumulator modules is reduced, which saves resources in the manufacturing process. In conclusion, charging of the accumulator module for the power tool is facilitated and the efficiency of the manufacturing process is increased.

For example, the system may be arranged such that the charging current (available from the power supply circuit of the industrial robot) is a fraction of a peak current consumed by the power tool during its operation, such as less than ⅓rdof the peak current consumed by the power tool during its operation, such as less than ⅕thof the peak current consumed by the power tool during its operation, such as around 1/10thof the peak current consumed by the power tool during its operation.

For example, the current available from the power supply circuit may be around 1-3 A, while the peak current consumed by the power tool may be around 15 A-30 A. Hence, the accumulator module may be utilized to provide the relatively high peak current needed for operating the tool, while the relatively low current available from the industrial robot is used for charging the accumulator module.

For example, the capacity of the accumulator module may be adapted to provide an entire peak current consumption of the power tool when it is operated. Hence, the main power source for operating the power tool may be the accumulator module.

According to an embodiment, the system may further comprise a control device configured to control the charging of the accumulator module by the charger. Hence, the control device may be utilized to manage the charging of the accumulator module in different ways, thereby enabling several advantages as will be described further below.

The term “control device” is to be broadly interpreted as any means, distributed or centralized, configured to control the charging of the accumulator module. The control device may alternatively be referred to as a control unit, control system or control circuit.

According to an embodiment, the control device may be configured to control the charging current to be below a (preset) current threshold being less than the total available current from the power supply circuit (of the industrial robot). Hence, part of the current from the power supply circuit may be utilized for other purposes, such as for a vison camera or a gripping tool installed at the industrial robot. For example, if the total available current from the industrial robot is around 2 A, the charging current may be controlled to not exceed a current threshold of 0.7 A.

According to an embodiment, the current threshold may simply be preset, such as to a static value. For example, it may be preset by an operator setting up the system or preset factory wise.

According to another embodiment, the current threshold may be based on one or more dynamic parameters (e.g. control signals), which enables a smarter control of the charging. For example, if a control system of the robot indicates that the robot and its power tool is not to be operated for a certain period of time, the current threshold can be increased, thereby speeding up the charging of the accumulator module. On the other hand, if more current is needed for operation of the industrial robot, the threshold may be lowered.

According to an embodiment, the control device may be configured to control the charging such that the accumulator module is charged by the charger between operations performed by the power tool, and optionally also during operations performed by the power tool.

According to embodiments, the control device may be arranged in the industrial robot and/or in the end effector. For example, the control device may be arranged in the accumulator module, in the power tool or in a holder of the end effector for holding the power tool. Alternatively, the control device may be arranged separate from, but in communication to, the industrial robot and the end effector.

According to an embodiment, the control device may be configured to control the charging such that a charging level of the accumulator module is kept below a maximum charge capacity of the accumulator module, such as below 80% of the maximum charge capacity of the accumulator module, such as below 70% of the maximum charge capacity of the accumulator module, such as below 60% of the maximum charge capacity of the accumulator module. Having an upper charging limit increases the energy accumulator life time, and is particularly advantageous in the present system since the accumulator module may be connected to the charger for most of the time.

According to an embodiment, the control device may be configured to control the charging such that a charging level of the accumulator module is kept above a minimum threshold, such as above 20% of the maximum charge capacity of the accumulator module, such as above 30% of the maximum charge capacity of the accumulator module, such as above 40% of the maximum charge capacity of the accumulator module. Avoiding the accumulator module getting fully depleted increases its life time and reduces the risk of interrupted operation of the power tool.

As the accumulator module in the present system may be connected to the charger for most of the time and, in addition, time consuming operations of replacing an empty accumulator module can be avoided, a relatively small state of charge window can be used, which is beneficial for the accumulator module health.

According to an embodiment, the control device may be configured to trigger a warning signal when the charging level of the accumulator module is too low and/or too high. This is to reduce the risk of the accumulator module getting depleted, which may interrupt the manufacturing process as the power tool cannot be operated, and/or the risk of the accumulator module being more charged than wanted, which may be unhealthy for the accumulator module.

For example, a warning signal may be provided if the charging level of the accumulator module is below a certain threshold defining a lowest acceptable charging level, and/or above another certain threshold defining a highest acceptable charging level.

According to an embodiment, the end effector may comprise a holder arranged to hold the power tool, the holder being attached to the robot arm end portion. This facilitates changing power tool, e.g. to another type of power tool. Hence, the power tool and holder may be separate parts.

Alternatively, the power tool may be an integrated part of the end effector. Changing power tool may then include changing the whole end effector.

According to embodiments, the charger may be arranged at the power tool, or elsewhere in the end effector, such as at the holder.

According to an embodiment, the accumulator module may be attached and connected to the charger.

According to an embodiment, the robot arm end portion may comprise an electrical contact (such as a socket) adapted to mate with an electrical contact of the end effector for electrically connecting the charger of the end effector with the power supply circuit of the industrial robot.

It is noted that embodiments of the invention relates to all possible combinations of features recited in the claims.

All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the embodiments, wherein other parts may be omitted. Like reference numerals refer to like elements throughout the description.

DETAILED DESCRIPTION OF EMBODIMENTS

As illustrated inFIG.1, a system1according to an embodiment comprises an industrial robot2and an end effector5to be operated by the robot2. The system1may be automated and capable of movement on at least one, but preferably two or more axes. For example, the system1may be adapted to be used for manufacturing, such as for assembling parts.

The industrial robot2may comprise a robot arm16, which may have one or more joints17for enabling movement of the robot arm16around one or more axes. A robot arm end portion3is provided at the distal end of the robot arm16. The industrial robot2further comprises a power supply circuit4arranged to supply current to the robot arm end portion3. The power supply circuit4may e.g. draw current from the mains. The power supply circuit4may comprise, or be connected to, a control device9for the industrial robot2. The control device9may be configured to control the power supply circuit4. For example, the industrial robot2may be stationary and may be arranged to be placed along an assembly line.

The end effector5is attached to the robot arm end portion3and comprises a power tool6and an accumulator module7arranged to power operation of the power tool6. The power tool6may e.g. be some kind of tightening tool, riveting tool, or drill.

The accumulator module7may e.g. comprise a battery, a capacitor or any other kind of means for accumulating energy to be used for powering the tool6.

For example, the end effector5may comprise a holder11arranged to hold the power tool6. The holder11may be the part of the end effector5that is attached to the robot arm end portion3. The power tool6may be mounted to the holder11. Alternatively, the holder11may be integrated with the power tool6. For example, the accumulator module7may be attached to/comprised in the holder11as illustrated inFIGS.1and2, or be attached to/comprised in the power tool6(not shown).

The end effector5further comprises a charger8arranged to draw current from the power supply circuit4at the robot arm end portion3and to supply charging current to the accumulator module7. An electrical connection may be provided between the power supply circuit4at the robot arm end portion3and the charger8in the end effector5so as to supply current there between for enabling charging. The charger8may comprise an electrical contact15adapted to mate with an electrical contact14of the accumulator module7(seeFIG.2). During operation, current flows from the power supply circuit4to the end effector5and its' charger8, and then from the charger8to the accumulator module7. Preferably, the accumulator module7may be connected (and attached) to the charger8during operation of the system1, including operation of the power tool6.

The system1may further comprise a control device10configured to control the charging of the accumulator module7by the charger8. The control device10may be arranged in the end effector5, such as in the holder11as illustrated inFIG.1, or in the power tool6(not shown). Alternatively, the control device10may be arranged in the industrial robot2, such as in (or in connection to) the control device9for the power supply circuit4.

Turning now toFIG.2, embodiments of the system1will be described in more detail. For example, the holder11may comprise a charger portion18including the charger8and arranged to hold the accumulator module7. A cable12may provide the charger portion18with power from the power supply circuit4in the robot arm end portion3. The cable12may be routed outside or inside (the latter not shown) the robot arm end portion3and the end effector5. The end effector5may comprise circuitry for providing power from the accumulator module7to the power tool6. For example, a cable13may provide the power tool6with power from the charger portion18.

According to an embodiment, the charging current for charging the accumulator module7may be just a fraction of the peak current that is consumed by the power tool6during its operation. The power tool6may typically require a peak current around 15-30 A when operated while the charging current may be limited to around 0.5-3 A. For example, the charging current may be less than ⅓rdof the peak current consumed by the power tool6during its operation, such as less than ⅕thof the peak current consumed by the power tool6during its operation.

For example, the accumulator module7may have a capacity that can provide the power tool6with its peak current during operation. The accumulator module7may e.g. comprise a 18, 24, 36 or 48 V battery.

According to an embodiment, the control device9may be configured to control the charging of the accumulator module7such that the charging current is kept below a (preset or dynamic) threshold being lower than the total available current from the power supply circuit4. Hence, the charging of the power tool6may only utilize some of the available current from the industrial robot2, thereby enabling some of the current available from the industrial robot2to be utilized for other purposes.

The power tool6may be charged only between operations of the power tool6, or simply continuously as long as the charging level of the accumulator module7is below a certain (preset) threshold.

The control device10may be configured to control the charging level of the accumulator module7to be below a (preset) maximum threshold and optionally also above a (preset) minimum threshold. This may be referred to as the state of charge window of the accumulator module7. The state of charge window may e.g. have a lower threshold comprised within a range of 20-40% of the maximum charge capacity. The upper threshold may be comprised within a range of 60-80% of the maximum charge capacity. As the accumulator module7can be continuously charged in the end effector5, the state of charge window may be kept relatively small, which is beneficial for the accumulator module7health.

According to an embodiment, the control device10may be configured to provide a warning signal in response to the charging level of the accumulator module7falling below a minimum threshold and/or exceeding a maximum threshold. An operator of the system1may then be notified that charging of the accumulator module7has not been performed as excepted. The warning signal may e.g. be a visual signal and/or an audio signal.

The person skilled in the art realizes that the present invention by no means is limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.