Enable switch device and load drive control apparatus equipped with same

The present disclosure relates to an enable switch device and a load drive control apparatus including the enable switch device.

In industrial robots, a work of teaching such as initially setting a robot controller and operating a robot is often performed through a teaching pendant provided with a robot controller. During a work of teaching, an operator needs to come close to a robot while operating a teaching pendant. Thus, a failure of devices including a robot or an operation error made by an operator may cause a serious accident.

To prevent such accidents, the teaching pendant is usually equipped with a three-position switch. By using the three-position switch, the robot is emergently stopped by an action of releasing an operation switch or tightly gripping the operation switch, and this secures safety of the operator.

Patent Literature 1 discloses an enable device including two three-position switches and two monitor circuits for monitoring the state of the three-position switches. Two monitor devices are connected to two three-position switches, respectively. With such a configuration, even when either of the two monitor circuits is short-circuited, safety of operation is secured.

Patent Literature

PTL 1: Unexamined Japanese Patent Publication No. 2004-209579

Technical Problem

In an enable switch device including two-position switch, it is desirable that a robot reliably transitions to a safe state, corresponding to the state of a two-position switch. When a short fault or an open fault occurs in the two-position switch in the enable switch device, the failure state needs to be detected and the robot needs to be transitioned to a safe state. The conventional configuration disclosed in Patent Literature 1 can detect a short fault of a monitor circuit but has no function of detecting a failure in the two-position switch.

The conventional enable switch device disclosed in Patent Literature 1 outputs the state of the three-position switch via a plurality of electromagnetic on-off relays. However, the life of the electromagnetic on-off relay is short, and thus the electromagnetic on-off relay has to be replaced very frequently. This disadvantageously increases the cost for replacing components of the enable switch device.

The present disclosure has been made in view of the above point. An object of the present disclosure is to provide an enable switch device capable of determining an operated state with a simple configuration and detecting a failure in an internal two-position switch, and a load drive control apparatus including the enable switch device.

Solution to Problem

To achieve the above object, an enable switch device according to the present disclosure is an enable switch device that transitions to a first position that is OFF state when not operated, to a second position that is ON state when mid-operated, and to a third position that is OFF state when full-operated, the enable switch device including at least a first switch, a second switch, and a first signal processor, where each of the first switch and the second switch is a two-position switch, and the first signal processor is configured to determine in which one of the first position, the second position, and the third position an operated state of the enable switch device is, based on an output signal of the first switch and an output signal of the second switch, and detect presence or absence of failure in each of the first switch and the second switch.

The load drive control apparatus according to the present disclosure includes at least the enable switch device and a control device communicatable with the enable switch device. When it is determined that the enable switch device is in ON state, the control device transmits a drive permission signal to a load communicatable with the control device, and when it is determined that the enable switch device is in OFF state, the control device transmits a drive stop signal to the load.

Advantageous Effect of Invention

According to an enable switch device of the present disclosure, an operated state can be determined with a simple configuration. In addition, failure in an internal two-position switch can be detected.

According to the load drive control apparatus of the present disclosure, happening of accident caused by an operation error made by an operator, for example, can be prevented, and safety of the operator is secured. In addition, an unintentional operation of a load can be prevented.

FIG. 1 is a schematic configuration diagram of a robot system according to a first exemplary embodiment.

FIG. 2 is a schematic configuration diagram of a load drive control apparatus.

FIG. 3 is a schematic diagram illustrating transition of an operated state of an enable switch device.

FIG. 4 is a diagram illustrating a determination result of a first state determination unit.

FIG. 5 is a schematic diagram illustrating transition of an operated state of an enable switch device according to a second exemplary embodiment.

FIG. 6 is a schematic configuration diagram of a load drive control apparatus according to a third exemplary embodiment.

FIG. 7 is a schematic diagram illustrating transition of an operated state of an enable switch device.

FIG. 8 is a diagram illustrating determination results of a first state determination unit and a second state determination unit.

FIG. 9 is a schematic diagram illustrating transition of an operated state of an enable switch device according to a fourth exemplary embodiment.

Exemplary embodiments of the present disclosure will now be described with reference to the drawings. The following descriptions of preferable exemplary embodiments are merely illustrative in nature, and are not intended to limit the scope, applications, or use of the present disclosure in any way.

First Exemplary Embodiment

[Configuration of Robot System]

FIG. 1 is a schematic configuration diagram of a robot system according to the present exemplary embodiment, and robot system 1 includes robot 2 and load drive control apparatus 200 . Load drive control apparatus 200 includes robot controller (control device) 3 and teaching pendant 4 .

Robot 2 is a vertical articulated robot, and includes a plurality of robot arms 2 a and a plurality of joint shafts 2 b . Motor M (see FIG. 2 ) is connected to each of the plurality of joint shafts 2 b.

Robot controller 3 is a known central processing unit (CPU) or a computer. Robot controller 3 is communicatable with a plurality of motors M. Robot controller 3 controls the operation of each of the plurality of motors M.

Teaching pendant 4 is an input device for performing initial setting of robot controller 3 . Teaching pendant 4 is a teaching device for teaching operations of robot 2 .

Teaching pendant 4 includes operation switch 4 a and enable switch device 100 (see FIG. 2 ) connected to operation switch 4 a . The internal state of enable switch device 100 changes, corresponding to the operated state of operation switch 4 a . According to the change in the state, robot 2 is permitted to operate and is regulated.

In FIG. 1 , robot controller 3 and teaching pendant 4 can exchange data with each other via communication cable 5 . However, the present invention is not particularly limited to this configuration. Robot controller 3 and teaching pendant 4 may be able to exchange data with each other by wireless communication.

[Configuration of Load Drive Control Apparatus and Enable Switch Device]

FIG. 2 illustrates a schematic configuration diagram of the load drive control apparatus, and FIG. 3 schematically illustrates transition of the operated state of the enable switch device. FIG. 4 illustrates a determination result of a first state determination unit. In FIG. 2 , only enable switch device 100 , of teaching pendant 4 , is illustrated in a form of a circuit diagram. For convenience of description, only motor M connected to one of joint shafts 2 b is illustrated, but as described above, motor M is provided by a number corresponding to the number of joint shafts 2 b . Driving of each motor M is permitted and regulated in response to an output signal of enable switch device 100 .

Enable switch device 100 includes first switch SW 1 , second switch SW 2 , and first signal processor 10 . Enable switch device 100 includes power source 30 . Note that, power source 30 may be external to enable switch device 100 .

First switch SW 1 and second switch SW 2 are two-position switches, and each have terminals a, b, c. Terminals c are common terminals of first switch SW 1 and second switch SW 2 , and are each connected to power source 30 . That is, first switch SW 1 is connected in parallel with second switch SW 2 . Each of first switch SW 1 and second switch SW 2 switches between a state where terminal c and terminal a are in a conduction state and a state where terminal c and terminal b are in a conduction state by an operation of operation switch 4 a described above. A terminal connected to power source 30 via terminal c becomes high potential (hereinafter, referred to as H potential), and a terminal electrically separated from power source 30 becomes low potential (hereinafter, referred to as L potential).

First signal processor 10 is a known CPU or a computer. First signal processor 10 includes at least first signal input unit 11 , first state determination unit 12 , and first state output unit 13 .

First signal input unit 11 receives an output signal of each of first switch SW 1 and second switch SW 2 and inputs the output signal to first state determination unit 12 . Note that, the output signal of first switch SW 1 is represented by a combination of the potential of terminal a and the potential of terminal b (see FIG. 4 ). Similarly, the output signal of second switch SW 2 is represented by a combination of the potential of terminal a and the potential of terminal b (see FIG. 4 ).

First state determination unit 12 determines the operated state of enable switch device 100 based on the signal input from first signal input unit 11 . First state determination unit 12 detects presence or absence of failure in each of first switch SW 1 and second switch SW 2 based on the signal input from first signal input unit 11 . These will be described later.

The function of first state determination unit 12 is implemented by executing predetermined software in first signal processor 10 . That is, first state determination unit 12 is a functional block in first signal processor 10 .

First state output unit 13 outputs the operated state of enable switch device 100 based on the determination result of first state determination unit 12 .

When operation switch 4 a is not operated, both first switch SW 1 and second switch SW 2 are in OFF state. In this case, as illustrated in FIG. 3 , the operated state of enable switch device 100 is in position 1 . As illustrated in FIG. 4 , first switch SW 1 is in OFF state when terminal a is in H potential and terminal b is in L potential. When terminal a is in L potential and terminal b is in H potential, first switch SW 1 is in ON state. Similarly, second switch SW 2 is in OFF state when terminal a is in H potential and terminal b is in L potential. When terminal a is in L potential and terminal b is in H potential, second switch SW 2 is in ON state.

When the operated state of enable switch device 100 is in position 1 , enable switch device 100 is in OFF state. First state output unit 13 outputs a signal to robot controller 3 . Since robot controller 3 recognizes that enable switch device 100 is in OFF state, robot controller 3 transmits a drive stop signal to motor M. As a result, drive control of motor M cannot be performed, and robot 2 does not operate.

Enable switch device 100 is configured such that first switch SW 1 first transitions to ON state when the operator operates operation switch 4 a . When first switch SW 1 is in ON state and second switch SW 2 is in OFF state, as illustrated in FIG. 3 , the operated state of enable switch device 100 is in position 2 . This state is also referred to as a mid-operated state.

When the operated state of enable switch device 100 is in position 2 , enable switch device 100 is in ON state. First state output unit 13 outputs a signal to robot controller 3 . Since robot controller 3 recognizes that enable switch device 100 is in ON state, robot controller 3 transmits a drive permission signal to motor M. As a result, drive control of motor M can be performed, and robot 2 performs a predetermined operation based on a teach content given by teaching pendant 4 .

In the mid-operated state, when operation switch 4 a is further tightly gripped by the operator, both first switch SW 1 and second switch SW 2 transition to ON state. As described above, in a case when the operator performs an erroneous operation and thinks that the operator or robot system 1 may fall into a dangerous situation, it is expected that operation switch 4 a is gripped tightly. In this case, as illustrated in FIG. 3 , the operated state of enable switch device 100 is in position 3 . This state is also be referred to as a full-operated state.

When the operated state of enable switch device 100 is in position 3 , enable switch device 100 is in OFF state. First state output unit 13 outputs a signal to robot controller 3 . Since robot controller 3 recognizes that enable switch device 100 is in OFF state, robot controller 3 transmits a drive stop signal to motor M. As a result, drive control of motor M cannot be performed, and robot 2 does not operate.

When first switch SW 1 or second switch SW 2 fails, first state determination unit 12 determines that the operated state of enable switch device 100 is neither in positions 1 to 3 .

When output signals of first switch SW 1 and second switch SW 2 are not in the patterns illustrated in FIG. 4 , a failure may have occurred in the switches. For example, both terminal a and terminal b of first switch SW 1 may be in H potential. In this case, a short fault may have occurred between terminal a and terminal b. In another case, both terminal a and terminal b of second switch SW 2 may be in L potential. In this case, a junction in second switch SW 2 may have stuck and the junction is not in contact with neither of terminal a nor terminal b, that is, an open fault may have occurred.

First state determination unit 12 determines presence or absence and the type of failure as described above from output signals of first switch SW 1 and second switch SW 2 . An output signal from first state output unit 13 is information on the operated state of enable switch device 100 . Failure information on each of first switch SW 1 and second switch SW 2 , that is, information on presence or absence and the type of failure is not directly included in the output signal. However, when no failure has occurred in first switch SW 1 or second switch SW 2 , the operated state of enable switch device 100 does not correspond to any of positions 1 to 3 . In such a case, it is determined that enable switch device 100 is in OFF state.

Therefore, on receiving the output signal, robot controller 3 transmits a drive stop signal to motor M. As a result, drive control of motor M cannot be performed, and robot 2 does not operate.

Data transmission from first state output unit 13 to robot controller 3 may be made by wired communication or wireless communication.

The determination result of first state determination unit 12 may be stored in a storage unit (not illustrated). In this case, the storage unit may be external to first signal processor 10 . The information stored in the storage unit includes not only the operated state of enable switch device 100 but also failure information on first switch SW 1 and second switch SW 2 .

Effects

As described above, enable switch device 100 according to the present exemplary embodiment transitions to position 1 (first position) which is OFF state when not operated, to position 2 (second position) which is ON state when mid-operated, and to position 3 (third position) which is OFF state when full-operated.

Enable switch device 100 includes at least first switch SW 1 , second switch SW 2 , and first signal processor 10 . Each of first switch SW 1 and second switch SW 2 is a two-position switch. First switch SW 1 is connected in parallel with second switch SW 2 .

First signal processor 10 is configured to determine in which one of positions 1 to 3 the operated state of enable switch device 100 is, based on an output signal of each of first switch SW 1 and second switch SW 2 . First signal processor 10 can detect presence or absence of failure in each of first switch SW 1 and second switch SW 2 .

According to the present exemplary embodiment, the operated state of enable switch device 100 can be determined with a simple configuration. This will avoid the operator falling into a dangerous situation by an erroneous operation made by the operator, for example. In addition, an unintentional operation of robot 2 can be prevented, and robot system 1 can be operated safely.

According to the present exemplary embodiment, presence or absence and the type of failure in each of first switch SW 1 and second switch SW 2 provided in enable switch device 100 can be detected easily. This will prevent robot 2 connected to enable switch device 100 from unintentionally operating, and robot system 1 can be operated safely. In addition, replacement and repair of teaching pendant 4 including enable switch device 100 can be performed easily. This will reduce the downtime and operation cost of robot system 1 .

First signal processor 10 includes at least first signal input unit 11 , first state determination unit 12 , and first state output unit 13 .

First signal input unit 11 receives an output signal of each of first switch SW 1 and second switch SW 2 and inputs the output signal to first state determination unit.

First state determination unit 12 determines in which one among positions 1 to 3 the operated state of enable switch device 100 is, based on the signal input from first signal input unit 11 . First state determination unit 12 detects presence or absence of failure in each of first switch SW 1 and second switch SW 2 .

First state output unit 13 outputs the operated state of enable switch device 100 to robot controller 3 based on the determination result of first state determination unit 12 . Note that, first state output unit 13 may output failure information on each of first switch SW 1 and second switch SW 2 to robot controller 3 as necessary.

With such a configuration of first signal processor 10 , the operated state of enable switch device 100 , presence or absence of failure in each of first switch SW 1 and second switch SW 2 , and the like can be determined easily.

In the present exemplary embodiment, first signal processor 10 executes predetermined software to determine the operated state of enable switch device 100 , presence or absence of failure in each of first switch SW 1 and second switch SW 2 , and the like. In this manner, the number of relays used can be reduced as compared with the conventional configuration disclosed in Patent Literature 1. Thus, the replacement cycle of enable switch device 100 and also that of teaching pendant 4 can be lengthened. This will also reduce the downtime and operation cost of robot system 1 .

Load drive control apparatus 200 according to the present exemplary embodiment includes at least enable switch device 100 and robot controller (control device) 3 . Robot controller 3 is communicatable with enable switch device 100 .

When it is determined that enable switch device 100 is in ON state, robot controller 3 transmits a drive permission signal to motor (load) M that is communicatable with robot controller 3 .

When it is determined that enable switch device 100 is in OFF state, robot controller 3 transmits a drive stop signal to motor M.

According to the present exemplary embodiment, robot controller 3 permits or regulates driving of motor M, corresponding to the state of enable switch device 100 . This will prevent happening of an accident caused by an operation error made by the operator, for example, and safety of the operator is secured. In addition, an unintentional operation of robot 2 can be prevented, and robot system 1 can be operated safely.

When it is detected that either first switch SW 1 or second switch SW 2 has failed, robot controller 3 transmits a drive stop signal to motor M.

This configuration will prevent robot 2 connected to enable switch device 100 from unintentionally operating, and robot system 1 can be operated safely. In addition, presence or absence and the type of failure in each of first switch SW 1 and second switch SW 2 can be detected easily. As a result, replacement and repair of teaching pendant 4 including enable switch device 100 can be performed easily, and the down time and operation cost of robot system 1 can be reduced.

Second Exemplary Embodiment

FIG. 5 schematically illustrates transition of the operated state of an enable switch device according to the present exemplary embodiment. For convenience of description, in FIG. 5 and in subsequent drawings, the same part as that of the first exemplary embodiment is denoted with the same reference mark, and detailed description thereof will be omitted.

Enable switch device 100 of the present exemplary embodiment is different from enable switch device 100 of the first exemplary embodiment in the following points.

As illustrated in FIG. 5 , when the operated state of enable switch device 100 has transitioned from position 1 (first position) to position 2 (second position), first state determination unit 12 determines, when transition time T 1 has elapsed after detection of transition of the state, that the operated state of enable switch device 100 has transitioned.

When the operated state of enable switch device 100 has transitioned from position 3 (third position) to position 1 , first state determination unit 12 determines, when transition time T 1 has elapsed after detection of transition of the state, that the operated state of enable switch device 100 has transitioned. In the present exemplary embodiment, transition time T 1 is set to 24 msec, but the present invention is not particularly limited to this.

When the operated state of enable switch device 100 has transitioned from position 2 to position 1 or position 3 , first state determination unit 12 determines, when transition time T 0 (<T 1 ) has elapsed after detection of transition of the state, that the operated state of enable switch device 100 has transitioned.

According to the present exemplary embodiment, the start timing of driving motor M can be delayed by transition time T 1 from the timing when enable switch device 100 enters into the mid-operated state. This will prevent robot 2 from starting an operation without being noticed by the operator, and safety of the operator can be secured. There is a case that enable switch device 100 that has transitioned from the mid-operated state to the full-operated state then transitions to the non-operated state. In such a case, determination that enable switch device 100 has transitioned from the full-operated state to the non-operated state is made after a delay of transition time T 1 . Thus, the timing of starting an operation of robot 2 by a subsequent mid-operation can be delayed, and safety of the operator can be enhanced.

Meanwhile, when enable switch device 100 transitions from the mid-operated state to the full-operated state or the non-operated state, the operation of robot 2 needs to be stopped immediately to secure safety of the operator.

In such a case, determination that the operated state of enable switch device 100 has transitioned is made immediately after detecting transition of the state, and thus robot controller 3 can immediately transmit a drive stop signal to robot 2 to stop the operation of robot 2 . This will enhance safety of the operator.

Third Exemplary Embodiment

FIG. 6 illustrates a schematic configuration diagram of a load drive control apparatus according to the present exemplary embodiment, and FIG. 7 schematically illustrates transition of the operated state of an enable switch device. FIG. 8 illustrates determination results of a first state determination unit and a second state determination unit. In FIG. 6 , only enable switch device 100 , of teaching pendant 4 , is illustrated in a form of a circuit diagram as in the first exemplary embodiment. Similarly, in FIG. 6 , only motor M connected to one joint shaft 2 b is illustrated.

Enable switch device 100 of the present exemplary embodiment is different from enable switch device 100 of the first exemplary embodiment in the following points.

As illustrated in FIG. 6 , enable switch device 100 includes at least first to fourth switches SW 11 to SW 22 , first signal processor 10 , and second signal processor 20 .

Each of first to fourth switches SW 11 to SW 22 is a two-position switch. Terminals c are common terminals of first to fourth switches SW 11 to SW 22 , and are each connected to power source 30 . That is, first to fourth switches SW 11 to SW 22 are connected in parallel among each other. Operations of first to fourth switches SW 11 to SW 22 are similar to the operations of first switch SW 1 and second switch SW 2 described in the first exemplary embodiment.

First signal processor 10 is configured to determine the state of each of first switch SW 11 and second switch SW 21 . That is, the states of first switch SW 11 and second switch SW 21 , whether ON state or OFF state, are determined. First signal processor 10 detects presence or absence of failure in each of first switch SW 11 and second switch SW 21 .

In more detail, similar to the first exemplary embodiment, first signal processor 10 includes at least first signal input unit 11 , first state determination unit 12 , and first state output unit 13 . Since the function of first signal input unit 11 is similar to that described in the first exemplary embodiment, description thereof will be omitted.

First state determination unit 12 determines the state of each of first switch SW 11 and second switch SW 21 based on a signal input from first signal input unit 11 . That is, the states of first switch SW 11 and second switch SW 21 , whether ON state or OFF state, are determined. First state determination unit 12 detects presence or absence of failure in each of first switch SW 11 and second switch SW 21 based on the signal input from first signal input unit 11 . Presence or absence and the type of failure in each of first switch SW 11 and second switch SW 21 are detected by a method similar to that described in the first exemplary embodiment. For example, when both terminal a and terminal b of first switch SW 11 are in H potential, it is determined that a short fault has occurred in first switch SW 11 . When both terminal a and terminal b of second switch SW 21 are in L potential, it is determined that an open fault has occurred in second switch SW 21 .

First state output unit 13 outputs, to robot controller 3 , information on the state of each of first switch SW 11 and second switch SW 21 , that is, information on the states of first switch SW 11 and second switch SW 21 , whether ON state or OFF state, based on the determination result of first state determination unit 12 . Note that, first state output unit 13 may output failure information on each of first switch SW 11 and second switch SW 21 to robot controller 3 .

The function and configuration of second signal processor 20 are similar to the function and configuration of first signal processor 10 . Second signal processor 20 handles input signals of third switch SW 12 and fourth switch SW 22 .

Second signal processor 20 is configured to determine the state of each of third switch SW 12 and fourth switch SW 22 . That is, the states of third switch SW 12 and fourth switch SW 22 , whether ON state or OFF state, are determined. Second signal processor 20 detects presence or absence of failure in each of third switch SW 12 and fourth switch SW 22 .

In more detail, second signal processor 20 includes at least second signal input unit 21 , second state determination unit 22 , and second state output unit 23 .

Second signal input unit 21 receives an output signal of each of third switch SW 12 and fourth switch SW 22 and inputs the output signal to second state determination unit 22 .

Second state determination unit 22 determines the state of each of third switch SW 12 and fourth switch SW 22 based on the signal input from second signal input unit 21 . That is, the states of third switch SW 12 and fourth switch SW 22 , whether ON state or OFF state, are determined. Second state determination unit 22 detects presence or absence of failure in each of third switch SW 12 and fourth switch SW 22 based on the signal input from second signal input unit 21 .

Second state output unit 23 outputs, to robot controller 3 , information on the state of each of third switch SW 12 and fourth switch SW 22 , that is, information on the states of third switch SW 12 and fourth switch SW 22 , whether ON state or OFF state, based on the determination result of second state determination unit 22 . Note that, second state output unit 23 may output failure information on each of third switch SW 12 and fourth switch SW 22 to robot controller 3 .

Enable switch device 100 determines the operated state of enable switch device 100 based on the determination result of first signal processor 10 and the determination result of second signal processor 20 .

As described above, first signal processor 10 determines only the state of each of first switch SW 11 and second switch SW 21 . Second signal processor 20 determines only the state of each of third switch SW 12 and fourth switch SW 22 . The operated state of enable switch device 100 is finally determined based on the determination result of first signal processor 10 and the determination result of second signal processor 20 .

As illustrated in FIGS. 7 and 8 , when all first to fourth switches SW 11 to SW 22 are in OFF state, it is determined that the operated state of enable switch device 100 is in position 1 (first position). That is, enable switch device 100 is determined to be in OFF state (non-operated state).

When first switch SW 11 and third switch SW 12 are in ON state and second switch SW 21 and fourth switch SW 22 are in OFF state, it is determined that the operated state of enable switch device 100 is in position 2 (second position). That is, enable switch device 100 is determined to be in ON state (mid-operated state).

When all first to fourth switches SW 11 to SW 22 are in ON state, it is determined that the operated state of enable switch device 100 is in position 3 (third position). That is, enable switch device 100 is determined to be in ON state (full-operated state). Note that, the timing at which either second switch SW 21 or fourth switch SW 22 enters into ON state is the timing at which the operated state of enable switch device 100 is determined to be in position 3 .

It goes without saying that when a failure has occurred in any of first to fourth switches SW 11 to SW 22 , enable switch device 100 is determined to be in OFF state.

To obtain a final determination result, first signal processor 10 and second signal processor 20 are configured to be communicatable with each other. In the example illustrated in FIG. 6 , serial communication is performed between first signal processor 10 and second signal processor 20 .

When the determination result of first signal processor 10 and the determination result of second signal processor 20 match, it is determined that the determination result is the operated state of enable switch device 100 .

Meanwhile, when the determination result of first signal processor 10 and the determination result of second signal processor 20 do not match, it is determined that enable switch device 100 is in OFF state.

Note that these determinations may be executed by first signal processor 10 that has received the determination result of second state determination unit 22 , for example, by first state determination unit 12 . Alternatively, these determinations may be executed by second signal processor 20 that has received the determination result of first state determination unit 12 , for example, by second state determination unit 22 .

Another determination unit (not illustrated) may be provided in one of first signal processor 10 and second signal processor 20 or in enable switch device 100 . In this case, this determination unit receives the determination result of first signal processor 10 and the determination result of second signal processor 20 , and determines the state of enable switch device 100 .

Alternatively, it may be configured that robot controller 3 that has received an output signal of first state output unit 13 and an output signal of second state output unit 23 determines the state of enable switch device 100 .

According to the present exemplary embodiment, an effect similar to that obtained by the configuration illustrated in the first exemplary embodiment can be obtained. That is, the operated state of enable switch device 100 can be determined with a simple configuration. This will avoid the operator falling into a dangerous situation by an erroneous operation made by the operator, for example. In addition, an unintentional operation of robot 2 can be prevented, and robot system 1 can be operated safely.

According to the present exemplary embodiment, presence or absence and the type of failure in each of first to fourth switches SW 1 to SW 22 provided in enable switch device 100 can be detected easily. This will prevent robot 2 connected to enable switch device 100 from unintentionally operating, and robot system 1 can be operated safely. In addition, replacement and repair of teaching pendant 4 including enable switch device 100 can be performed easily. This will reduce the downtime and operation cost of robot system 1 .

Enable switch device 100 illustrated in the present exemplary embodiment is a so-called duplex circuit including two sets of combination circuits each including two switches and a signal processor illustrated in the first exemplary embodiment. Enable switch device 100 illustrated in the present exemplary embodiment is configured to correctly determine the operated state of enable switch device 100 only when both the two combination circuits are functioning normally.

For this reason, first signal processor 10 and second signal processor 20 are communicatable with each other. When the determination result of first signal processor 10 and the determination result of second signal processor 20 do not match, it is determined that enable switch device 100 is in OFF state.

With this configuration, safety of the operator can be enhanced. In addition, an unintentional operation of robot 2 can be prevented, and robot system 1 can be operated safely.

In load drive control apparatus 200 according to the present exemplary embodiment, when it is detected that there is a failure in any one of first to fourth switches SW 11 to SW 22 , robot controller 3 transmits a drive stop signal to motor M.

This configuration will prevent robot 2 connected to enable switch device 100 from unintentionally operating, and robot system 1 can be operated safely. Presence or absence and the type of failure in each of first to fourth switches SW 11 to SW 22 can be detected easily. As a result, replacement and repair of teaching pendant 4 including enable switch device 100 can be performed easily, and the down time and operation cost of robot system 1 can be reduced.

Fourth Exemplary Embodiment

FIG. 9 schematically illustrates transition of the operated state of an enable switch device according to the present exemplary embodiment.

The configuration of enable switch device 100 of the present exemplary embodiment is similar to that described in the third exemplary embodiment. That is, enable switch device 100 and a duplex circuit are included.

Similarly to the second exemplary embodiment, in determining the operated state of enable switch device 100 according to the present exemplary embodiment, enable switch device 100 determines, when a predetermined transition time has elapsed after detection of transition of the state, that the operated state of enable switch device 100 has transitioned.

Specifically, when the operated state of enable switch device 100 has transitioned from position 1 to position 2 , first state determination unit 12 and second state determination unit 22 determine, when transition time T 2 has elapsed after detection of transition of the state, that the operated state of enable switch device 100 has transitioned.

When the operated state of enable switch device 100 has transitioned from position 3 to position 1 , first state determination unit 12 and second state determination unit 22 determine, when transition time T 2 has elapsed after detection of transition of the state, that the operated state of enable switch device 100 has transitioned.

Note that, transition time T 2 may be the same as or different from transition time T 1 described in the second exemplary embodiment. Enable switch device 100 of the present exemplary embodiment includes first to fourth switches SW 11 to SW 22 . Considering reaction times of first to fourth switches SW 11 to SW 22 , transition time T 2 is preferably longer than transition time T 1 .

When the operated state of enable switch device 100 has transitioned from position 2 to position 1 or position 3 , first state determination unit 12 and second state determination unit 22 determine, immediately after detection of transition of the state, in this case, when transition time T 0 (<T 1 , T 2 ) has elapsed, that the operated state of enable switch device 100 has transitioned.

According to the present exemplary embodiment, an effect similar to that obtained by the configuration illustrated in the second exemplary embodiment can be obtained. That is, the start timing of driving motor M can be delayed by transition time T 2 from the timing that is immediately after enable switch device 100 has entered into the mid-operated state. This will prevent robot 2 from starting an operation without being noticed by the operator, and safety of the operator can be secured. There is a case that enable switch device 100 that has transitioned from the mid-operated state to the full-operated state then transitions to the non-operated state. In such a case, determination that enable switch device 100 has changed from the full-operated state to the non-operated state is made after a delayed of transition time T 2 . Thus, the timing of starting an operation of robot 2 by a subsequent mid-operation can be delayed, and safety of the operator can be enhanced.

Meanwhile, when enable switch device 100 transitions from the mid-operated state to the full-operated state or the non-operated state, the operation of robot 2 needs to be stopped immediately to secure safety of the operator.

In such a case, determination that the operated state of enable switch device 100 has transitioned is made immediately after detecting transition of the state, and thus robot controller 3 can immediately transmit a drive stop signal to robot 2 to stop the operation of robot 2 . This will enhance safety of the operator.

As described in the third exemplary embodiment, either first state determination unit 12 or second state determination unit 22 may finally determine the state of enable switch device 100 . Alternatively, the state of enable switch device 100 may be finally determined by another determination unit (not illustrated) provided in enable switch device 100 .

When robot 2 unintentionally operates or stops in an industrial machine used for welding work or processing work, there is a high risk of an operator being exposed to danger.

Thus, enable switch device 100 and load drive control apparatus 200 of the present specification are preferably connected to robot 2 provided in the industrial machine to be used.

The enable switch device of the present disclosure can determine an operated state with a simple configuration and can detect failure in an internal two-position switch, and thus is useful to be used for industrial machines including a robot.

1 : robot system

2 : robot

2 a : robot arm

2 b : joint shaft

3 : robot controller (control device)

4 : teaching pendant

4 a : operation switch

5 : communication cable

10 : first signal processor

11 : first signal input unit

12 : first state determination unit

13 : first state output unit

20 : second signal processor

21 : second signal input unit

22 : second state determination unit

23 : second state output unit

30 : power source

100 : enable switch device

200 : load drive control apparatus

M: motor (load)

SW 1 : first switch

SW 2 : second switch

SW 11 : first switch

SW 21 : second switch

SW 12 : third switch

SW 22 : fourth switch