JP2022157279A - Robot device - Google Patents

Abstract

To suppress detection errors of a current detecting part from accumulating in an integral term to further enhance response of supply of fluid to an artificial muscle.SOLUTION: A robot device includes at least one artificial muscle and a fluid supply device. The fluid supply device comprises: a fluid supply source; a fluid adjustment part that adjusts pressure or flow volumes of fluid from the fluid supply source side and outputs the fluid to the artificial muscle by driving linear solenoid valves; a current detecting part that detects currents flowing through electromagnetic parts of the linear solenoid valves; and a control part that controls power distribution of the electromagnetic part by generating a PWM signal on the basis of feedback- calculation including an integral term based on a difference between required currents and currents detected by the current detecting part. The control part, when supply of fluid to the artificial muscle is not required, sets the required currents to the electromagnetic parts of the linear solenoid valves to predetermined currents larger that a value zero in a range in which the linear solenoid valves are not activated.SELECTED DRAWING: Figure 5

Description

The present specification discloses a robotic device that includes at least one artificial muscle that receives a supply of fluid to operate, and a fluid supply device that supplies and discharges the fluid to and from the artificial muscle.

2. Description of the Related Art Conventionally, this type of robot apparatus includes a pulley pivotally supported on the tip of a support member erected on a base, an arm whose base end is fixed to the pulley and rotates as the pulley rotates, and a base. Two rubber artificial muscles, each having one end connected to a locking bracket attached to a pulley and having the other end connected to each other via a rope wound around a pulley, and hydraulic fluid from a hydraulic pressure source. and two pressure control valves for supplying pressure to the entrance and exit of the artificial rubber muscle (see, for example, Patent Document 1).

JP-A-63-216691

As a control of the linear solenoid valve (pressure control valve), a target current is set according to the pressure command value or the flow rate command value for the artificial muscle, and the current flowing through the electromagnetic part of the linear solenoid valve is detected by the current detection unit, and the target When generating a PWM signal by feedback calculation including a proportional term and an integral term based on the difference between the current and the current detected by the current detection unit to control the energization of the electromagnetic unit, the detection error included in the current detection unit Feedback control may not be performed appropriately. For example, when feedback calculation is performed by setting the target current to 0 with a pressure command value of 0, if the current detection unit includes a positive detection error, the detection error is accumulated in the integral term. Therefore, the next time an attempt is made to supply the fluid to the artificial muscle, the error accumulated in the integral term delays the supply of current to the electromagnetic unit, possibly degrading the fluid supply response of the artificial muscle.

The robot apparatus of the present disclosure controls the energization of the electromagnetic section by feedback control based on the difference between the target current and the current detected by the current detection section as control of the linear solenoid valve, and the detection error of the current detection section is integrated. The main purpose is to suppress the accumulation of fluid in the joint and improve the response of fluid supply to the artificial muscle.

The robotic device of the present disclosure employs the following means in order to achieve the above main object.

A robotic device according to the present disclosure includes at least one artificial muscle that operates by receiving a supply of fluid, and a fluid supply device that supplies and discharges the fluid to and from the artificial muscle, the fluid supply device comprising: A supply source of the fluid, a fluid adjustment unit that adjusts and outputs the pressure or flow rate of the fluid from the supply source side to the artificial muscle by driving a linear solenoid valve, and a current that flows through the electromagnetic unit of the linear solenoid valve. and a feedback calculation including an integral term based on the difference between the current detected by the current detection unit and the required current required by the electromagnetic unit of the linear solenoid valve. and a control unit for controlling energization of the electromagnetic unit by the PWM signal, wherein the control unit controls the electromagnetic unit of the linear solenoid valve when the fluid is not required to be supplied to the artificial muscle. is set to a predetermined current greater than 0 within a range in which the linear solenoid valve does not operate.

In the robot device of the present disclosure, a current detection unit that detects the current flowing through the electromagnetic part of the linear solenoid valve, and a difference between the required current required for the electromagnetic part of the linear solenoid valve and the current detected by the current detection part. a control unit that generates a PWM signal by feedback calculation including an integral term based on the PWM signal, and controls energization of the electromagnetic unit by the PWM signal. Then, when the artificial muscle is not required to be supplied with fluid, the control unit sets the required current to the electromagnetic unit of the linear solenoid valve to a predetermined current greater than 0 within a range in which the linear solenoid valve does not operate. . As a result, even if the current detection unit includes a positive detection error, it is possible to prevent the detection error from being accumulated in the integral term of the feedback calculation. As a result, good feedback control can be performed, and the response of fluid supply to the artificial muscle can be further improved.

1 is a schematic configuration diagram showing a robot device of the present disclosure; FIG. 1 is an enlarged view of a robotic device of the present disclosure; FIG. 1 is a system diagram showing a fluid supply device of a robotic device of the present disclosure; FIG. 1 is a block diagram showing a control device of a robotic device of the present disclosure; FIG. FIG. 2 is a configuration diagram mainly showing a drive control unit included in the control device of the robot apparatus of the present disclosure; 4 is a schematic configuration diagram of a hand unit; FIG. FIG. 4 is an explanatory diagram showing how the hand section operates;

Next, embodiments for carrying out the invention of the present disclosure will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a robot device 1 of the present disclosure, and FIG. 2 is an enlarged view showing the robot device 1. As shown in FIG. A robotic device 1 shown in these drawings includes a robotic arm 2 and a fluid supply device (liquid supply device) 10 . In this embodiment, the robot device 1 is mounted on a carrier 20, which is a so-called automated guided vehicle (AGV) capable of self-propelled to a designated target position. However, the robot device 1 is not limited to being mounted on the carriage 20, and may be fixed at a predetermined installation location.

The robot arm 2 includes a plurality of (three in this embodiment) joints (pin joints) J1, J2, and J3, a plurality of (three in this embodiment) arms (links) 3, joints J1, A plurality of fluid actuators (hydraulic pressure actuators) M1, M2, M3, M4, M5, M6 as artificial muscles provided, for example, in an even number (two in this embodiment) for each of J2 and J3, and an arm on the tip side. It is a multi-joint arm including a hand portion (robot hand) 4 as a grasping portion (tip) attached to the arm 3. The hand portion 4 of the robot arm 2 is controlled by the control device 100 (see FIGS. 3 to 5) of the robot device 1 so as to grip a target object (hereinafter referred to as a "gripping target"). Further, the fluid supply device 10 is controlled by the control device 100 to supply and discharge working oil (liquid) as a fluid (working fluid) to each of the fluid actuators M1 to M6. As a result, the robot arm 2 can be hydraulically driven to move the hand portion 4 to a desired position.

Each of the fluid actuators M1-M6 of the robot arm 2 is a so-called McKibben-type artificial muscle including a tube T that expands and contracts by the pressure of hydraulic oil and a braided sleeve S that covers the tube T, as shown in FIG. is. The tube T is formed in a cylindrical shape from an elastic material such as a rubber material having high oil resistance. A hydraulic oil inlet/outlet IO is formed in a sealing member C on the base end side of the tube T (on the fluid supply device 10 side, the lower end side in FIG. 2). The braided sleeve S is formed in a cylindrical shape by weaving a plurality of cords oriented in a predetermined direction so as to intersect each other, and is contractible in the axial and radial directions. As the cords forming the braided sleeve S, fiber cords, high-strength fibers, metal cords composed of ultrafine filaments, and the like can be used. Hydraulic fluid is supplied from the inlet/outlet IO into the tubes T of the fluid actuators M1 to M6 to increase the pressure of the hydraulic fluid in the tubes T, so that the tubes T move radially due to the action of the braided sleeve S. It expands and contracts in the axial direction, generating a contraction force according to the pressure of the hydraulic oil inside.

As shown in FIGS. 1 and 2, among the plurality of arms 3, the arm 3 closest to the proximal end (the side closest to the fluid supply device 10) is rotatable by a support member 5 as a link via a joint J1. Supported. Also, the two arms 3 are rotatably connected to each other via a joint J2 or J3. Further, a connecting member 6 is fixed to the distal ends (tip-side ends) of the two arms 3 on the fluid supply device 10 side. As shown in the figure, the support member 5 rotatably supports the sealing member C on the proximal side of the fluid actuator M1 corresponding to the joint J1 on the most proximal side via the first connecting shaft, A sealing member C on the base end side of the fluid actuator M2 corresponding to the joint J1 is rotatably supported via a second connecting shaft.

In addition, each connecting member 6 rotates the sealing member C on the distal side (hand side) of the fluid actuator M1 or M3 corresponding to the joint J1 or J2 located on the proximal side via the first connecting shaft. Also, the sealing member C on the distal end side (hand side) of the fluid actuator M2 or M4 corresponding to the joint J1 or J2 is rotatably supported via the second connecting shaft. Further, each connecting member 6 rotatably supports the sealing member C on the base end side of the fluid actuator M3 or M5 corresponding to the joint J2 or J3 positioned on the distal end side through the first connecting shaft. , the sealing member C on the base end side of the fluid actuator M4 or M6 corresponding to the joint J2 or J3 is rotatably supported via the second connecting shaft.

As a result, on both sides of each arm 3 extending from the joint axis of the joints J1 to J3 to the hand side (hand portion 4 side), corresponding two of the fluid actuators M1 to M6 are arranged in parallel with the arm 3. . Fluid actuators M1, M3 and M5 arranged on one side of each arm 3 constitute a first artificial muscle (one antagonistic muscle) corresponding to one joint J1, J2 or J3. Two fluid actuators M2, M4, M6 arranged on the other side constitute a second artificial muscle corresponding to one joint J1, J2 or J3 paired with the first artificial muscle.

However, the first and second artificial muscles may each be composed of two or more (same number) fluid actuators, and the number of fluid actuators constituting the first artificial muscle and the number of fluid actuators constituting the second artificial muscle A different number of fluid actuators may be used. Furthermore, in the present embodiment, the plurality (two) fluid actuators M1, M2, etc. provided for one joint J1, J2 or J3 have the same specifications, but constitute the first artificial muscle. The specification of the fluid actuator that constitutes the second artificial muscle may be different from the specification of the fluid actuator that constitutes the second artificial muscle.

Further, in this embodiment, each arm 3 is formed hollow, and a plurality of hoses H (see broken lines in FIG. 2) as fluid supply pipes are arranged inside each arm 3 . Each hose H is connected to an inlet/outlet IO formed in a sealing member C on the base end side of the corresponding fluid actuator M1-M6. Hydraulic oil (hydraulic pressure) is supplied from the supply device 10 .

Therefore, by controlling the fluid supply device 10 with the control device 100, the hydraulic pressure in the tube T such as the fluid actuator M1 constituting the first artificial muscle and the second artificial muscle paired with the first artificial muscle are controlled. can be made different from the hydraulic pressure in the tube T of the fluid actuator M2 or the like that constitutes . As a result, a force (rotational force) is applied to each arm 3 via the connecting member 6 from the two fluid actuators M1, M2, etc., which are arranged to oppose each other, that is, a pair of first and second artificial muscles. torque) to rotate each arm 3 with respect to the support member 5 or the arm 3 on the base end side, thereby changing the joint angles of the joints J1 to J3. In this embodiment, the fluid actuators M1 and the like that constitute the first artificial muscle and the fluid actuators M2 and the like that constitute the second artificial muscle paired with the first artificial muscle are configured such that the tube T is positioned from the natural state. Antagonistically driven by the hydraulic pressure from the fluid supply device 10, the initial state is a state in which the axial direction is contracted by a fixed amount (for example, about 10% of the natural length).

In this embodiment, during operation of the robot device 1 (robot arm 2), the maximum required output for the fluid actuator M1 is the maximum among all the fluid actuators M1-M6. The required output for fluid actuators M1-M6 is the product (power or power) of the retraction force and retraction velocity required for fluid actuators M1-M6.

As shown in FIG. 1, the fluid supply device 10 of the robot device 1 that supplies hydraulic fluid to the fluid actuators M1 to M6 and the like includes a tank 11 that defines a hydraulic fluid reservoir (fluid reservoir), and the tank 11 and a base portion 12 rotatably supported around a rotating shaft extending in the vertical direction (see one-dot chain line in FIG. 1). The tank 11 is, for example, a cylindrical body with closed upper and lower ends, and can store hydraulic oil therein. In this embodiment, the support member 5 of the robot arm 2 is fixed to the upper wall portion 11u of the tank 11 via a bolt or the like (not shown) so as to extend coaxially with the rotation axis of the tank 11 (see FIG. 2). ). That is, the robot arm 2 is supported by the tank 11 (upper wall portion 11 u) of the fluid supply device 10 .

The base portion 12 is mounted (fixed) on the carriage 20 so as to be positioned below the robot arm 2 and the tank 11 . The base portion 12 also supports a rotation drive unit (not shown) that rotates the tank 11 about the rotation axis by a predetermined angle (eg, 360°). Accordingly, by operating the rotation drive unit, the robot arm 2 can be rotated integrally with the tank 11 around the rotation axis. In this embodiment, the rotary drive unit is a swing motor driven by hydraulic pressure supplied from the fluid supply device 10 . However, the rotary drive unit may include an electric motor, a gear mechanism, or the like.

Further, as shown in FIG. 3, the fluid supply device 10 includes, in addition to the tank 11 and the base portion 12, a pump 13 as a fluid supply source, a valve body (not shown) arranged in the tank 11, and a relief valve ( a pressure control valve) RV, a check valve CV, an accumulator (pressure accumulator) 14, a plurality of linear solenoid valves 151, 152, 153, 154, 155, 156 and control valves as fluid adjustment valves (fluid adjustment units) (pressure control valve) 16;

The pump 13 is an electric pump controlled by the control device 100, sucks hydraulic oil stored in the tank 11, and discharges (pressure-feeds) the hydraulic oil from a discharge port to the oil passage L1. In this embodiment, the pump 13 includes a pump portion arranged inside the tank 11 and a drive unit 130 having an electric motor, a reduction gear mechanism, etc. and arranged inside or outside the tank 11 .

The relief valve RV can limit the pressure of the hydraulic oil discharged by the pump 13 so as not to exceed a predetermined upper limit pressure Plim (upper limit, eg, about 6-7 MPa). The check valve CV allows hydraulic oil from the pump 13 (and relief valve RV) side to flow out to the oil passage LL, and regulates the flow of hydraulic oil from the oil passage LL side to the pump 13 (and relief valve RV) side. do. The accumulator 14 has an inlet/outlet for hydraulic oil connected (directly connected) to the oil passage LL on the downstream side of the check valve CV, and stores hydraulic pressure from the pump 13 side. As the accumulator 14, one having a maximum working pressure equal to or higher than the upper limit pressure Plim is used. Further, in the oil passage LL, a source pressure sensor PS is installed downstream of the check valve CV and upstream of the accumulator 14 to detect the pressure (original pressure) of the working oil in the oil passage LL.

The linear solenoid valves 151 - 156 have a common configuration, are each arranged in a valve body and controlled by the controller 100 . In this embodiment, the linear solenoid valve 151 adjusts the signal pressure to the control valve 16, and the linear solenoid valve 152 adjusts the hydraulic pressure (driving pressure) to the fluid actuator M2. Also, the linear solenoid valve 153 adjusts the hydraulic pressure (driving pressure) to the fluid actuator M3, and the linear solenoid valve 154 adjusts the hydraulic pressure (driving pressure) to the fluid actuator M4. Furthermore, the linear solenoid valve 155 adjusts the hydraulic pressure (driving pressure) to the fluid actuator M5, and the linear solenoid valve 156 adjusts the hydraulic pressure (driving pressure) to the fluid actuator M6.

As shown in FIG. 3, each of the linear solenoid valves 151-156 includes an electromagnetic portion 15e that is energized and controlled by the control device 100, a spool 15s that is axially movably arranged in a sleeve, and a spool 15s that is connected to the electromagnetic portion 15e. and a spring 15sp that biases toward the side (from the output port 15o side to the input port 15i side, the upper side in FIG. 3). Furthermore, the linear solenoid valves 151-156 include an input port 15i, an output port 15o, a feedback port 15f communicating with the output port 15o, and a drain port 15d communicating with the input port 15i and the output port 15o. The input ports 15i of the linear solenoid valves 151-156 communicate with the oil passage LL on the downstream side of the accumulator 14, respectively. Also, the output ports 15o of the linear solenoid valves 152-156 communicate with hydraulic oil inlets and outlets IO of the corresponding fluid actuators M2-M6 (tube T) via oil passages, hoses H, etc. formed in the valve bodies. Further, the drain ports 15d of the linear solenoid valves 151-156 communicate with the hydraulic oil reservoirs in the tank 11 via oil passages LD, respectively.

In this embodiment, the linear solenoid valves 151-156 are normally closed valves that open when current is supplied to the electromagnetic part 15e. The spool 15s is axially moved so as to communicate with the output port 15o. As a result, the electromagnetic portion 15e acts on the spool 15s due to the thrust generated by the power supply to the electromagnetic portion 15e (coil), the biasing force of the spring 15sp, and the hydraulic pressure (driving pressure) supplied from the output port 15o to the feedback port 15f. By balancing the thrust to the side, it becomes possible to adjust the hydraulic oil from the pump 13 (and relief valve RV) side supplied to the input port 15i to a desired pressure and to flow it out from the output port 15o. .

In addition, by feeding back the hydraulic pressure (signal pressure or drive pressure) supplied to the fluid actuators M1-M6 to the linear solenoid valves 151-156, the robot arm 2 driven by the fluid actuators M1-M6 as artificial muscles When an external force is applied from a source other than the fluid actuators M1-M6, it is possible to absorb oil pressure fluctuations according to volume changes of the tubes T of the fluid actuators M1-M6 due to the external force. In addition, after the external force disappears, it is possible to quickly supply hydraulic pressure (driving pressure) to the fluid actuators M1 to M6 according to the demand.

The control valve 16 adjusts the pressure of the working oil from the oil passage LL according to the signal pressure from the linear solenoid valve 151, and supplies it to the tube T of the fluid actuator M1 that maximizes the maximum required output. The control valve 16 is a spool valve that includes a spool 16s arranged in a valve body and a spring 16sp that biases the spool 16s. 3, the control valve 16 includes an input port 16i, an output port 16o, a feedback port 16f, a signal pressure input port 16c and a drain port 16d.

The input port 16i communicates with the oil passage LL downstream of the accumulator 14 . The output port 16o communicates with the hydraulic fluid inlet/outlet IO of the fluid actuator M1 (tube T) via an oil passage formed in the valve body, a hose H, and the like. The feedback port 16f communicates with the output port 16o through an oil passage formed in the valve body. The signal pressure input port 16c communicates with the output port 15o of the linear solenoid valve 151 through an oil passage formed in the valve body. The drain port 16d communicates with the hydraulic oil reservoir in the tank 11 via the oil passage LD.

The spool 16s of the control valve 16 moves in the axial direction against the biasing force of the spring 16sp due to the signal pressure from the linear solenoid valve 151 corresponding to the current applied to the electromagnetic portion 15e. This balances the thrust applied to the spool 16s by the action of the signal pressure, the biasing force of the spring 16sp, and the thrust acting on the spool 16s by the hydraulic pressure (driving pressure) supplied from the output port 16o to the feedback port 16f. As a result, part of the hydraulic fluid from the pump 13 (and the relief valve RV) supplied to the input port 16i is drained appropriately through the drain port 16d, and is discharged from the output port 16o to the tube T of the fluid actuator M1. The supplied hydraulic fluid can be adjusted to the desired pressure. As a result, it is possible to reliably supply the required hydraulic pressure to the fluid actuator M1, which requires a large output, while making the size smaller than that of a single linear solenoid valve. However, all the fluid actuators (artificial muscles) M1 to M6 may be configured so that hydraulic fluid is supplied from the corresponding linear solenoid valves. Further, the hydraulic fluid may be supplied to two or more fluid actuators from control valves corresponding to each.

In the fluid supply device 10, at least one of the linear solenoid valves 151-156 may be a normally open valve. In this case, the normally open valve balances the thrust from the electromagnetic section and the thrust from the hydraulic pressure supplied to the feedback port so as to act in the same direction as the thrust from the electromagnetic section with the biasing force of the spring. There may be. In addition, at least one of the linear solenoid valves 151-156 does not have a dedicated feedback port, and is configured so that the output pressure (driving pressure) acts on the spool as feedback pressure inside the sleeve that accommodates the spool. (See, for example, Japanese Unexamined Patent Application Publication No. 2020-41687). Similarly, the control valve 16 may also be configured so that the output pressure (driving pressure) acts on the spool as feedback pressure inside the spool.

A control device 100 of the robot device 1 includes a microcomputer including a CPU, a ROM, a RAM, an input/output interface, etc., and various logic ICs (all not shown). As shown in FIGS. 4 and 5, the control device 100 includes at least one of hardware such as a CPU, ROM, RAM, and logic IC, and software such as various programs installed in the ROM. 110, a plurality of valve drive control units 120a-120f connected to the electromagnetic units 15e (coils) of the corresponding linear solenoid valves 151-156, and a pump drive control unit 130a connected to the drive motor of the pump 13. Built as functional blocks (modules). Note that FIG. 5 shows only one valve drive control section for the sake of simplicity of explanation.

Further, the control device 100 inputs the detection values of the source pressure sensor PS and voltage sensors (not shown) for detecting the voltage of the power source Vc such as the linear solenoid valves 151-156. Further, the control device 100 controls (duty control) the drive unit 130 of the pump 13 so that the oil pressure (source pressure) in the oil passage LL detected by the source pressure sensor PS becomes a target value. Further, the control device 100 controls (duty control) the current supplied to the electromagnetic portions 15e of the linear solenoid valves 151-156.

As shown in FIG. 5, each valve drive control unit 120a-120f of the control device 100 detects a current Ireq required by the electromagnetic unit 15e (coil) of the corresponding linear solenoid valve 151-156 and a current detection unit 125, which will be described later. A target current calculator 121 that calculates the target current Itag by feedback calculation based on the difference from the detected current Ie, and a PWM signal generator 123 that generates a PWM signal based on the target current Itag calculated by the target current calculator 121. , the drive circuit 124 connected to the electromagnetic portion 15e of the corresponding linear solenoid valve 151-156, and the current (detection current Ie) flowing through the electromagnetic portion 15e (coil) of the corresponding linear solenoid valve 151-156. and a detection unit 125 .

The target current calculation unit 121 includes a proportional term calculation unit 122p that calculates a proportional term by multiplying the difference between the requested current Ireq from the calculation processing unit 110 and the current Ie detected by the current detection unit 125 by a proportional gain; an integral term calculator 122i that accumulates the difference between Ireq and the current Ie over a predetermined calculation cycle and calculates an integral term by multiplying the accumulated value by an integral gain, and the sum of the proportional term and the integral term is A target current Itag is calculated by correcting the required current Ireq based on the above. Note that the target current calculation unit 121 further includes a differential operation unit that time-differentiates the difference between the requested current Ireq and the current Ie and multiplies the differential value by a differential gain to calculate a differential term. The target current Itag may be calculated based on the sum of the terms.

The PWM signal generator 123 sets a target current duty according to the target current Itag calculated by the target current calculator 121, and generates a pulse signal (PWM signal) based on the target current duty at a preset cycle. and output to the corresponding drive circuit 124 .

The drive circuit 124 includes first and second switching elements Tr1 and Tr2 configured by, for example, MOSFETs, bipolar transistors or IGBTs. The drain of the first switching element Tr1 is connected to the power supply Vc, the source of the first switching element Tr1 and the drain of the second switching element Tr2 are connected to each other, and the source of the second switching element Tr2 is grounded. The electromagnetic portions 15e of the linear solenoid valves 151-156 corresponding to the driving circuit 124 are connected to the source of the first switching element Tr1, the drain of the second switching element Tr2, and the source of the second switching element Tr2, which are connected to each other. It is connected. Furthermore, the PWM signal generator 123 is connected to the gates of the first and second switching elements Tr1 and Tr2. As a result, when the first switching element Tr1 is turned on and the second switching element Tr2 is turned off by the PWM signal from the PWM signal generation unit 123, the voltage of the power source Vc corresponds to the electromagnetic parts of the linear solenoid valves 151 to 156. 15e (coil), and an electromotive current flows through the electromagnetic portion 15e. On the other hand, when the first switching element Tr1 is turned off and the second switching element Tr2 is turned on by the PWM signal from the PWM signal generator 123, the corresponding electromagnetic parts 15e (coils) of the linear solenoid valves 151 to 156 are grounded. and a back electromotive current flows through the electromagnetic portion 15e. In this embodiment, the first and second switching elements Tr1 and Tr2 are configured by N-channel type transistors (FETs), but are not limited to this. A combination of an N-channel transistor and an N-channel transistor, or a combination of an N-channel transistor and a diode, can control energization to the electromagnetic part 15e by switching a switching element based on a PWM signal. Any configuration can be adopted.

The current detection unit 125 includes a shunt resistor connected in series to the electromagnetic unit 15e, an operational amplifier that detects the voltage difference of the shunt resistor, an A/D converter that converts the output of the operational amplifier into a digital signal, and the like. . The detected current Ie detected by the current detector 125 is output to the target current calculator 121 .

The arithmetic processing unit 110 of the control device 100 sets the required current Ireq required for the electromagnetic part 15e of the corresponding linear solenoid 151-156 based on the hydraulic pressure command value of each of the fluid actuators M1-M6, and the set required current Ireq to the target current calculation unit 121 side of the corresponding valve drive control units 120a to 120f. Further, in this embodiment, a lower limit guard processing unit 111 is provided between the arithmetic processing unit 110 and each of the valve drive control units 120a to 120f, and the request current Ireq from the arithmetic processing unit 110 is applied to the lower limit guard processing unit 111, the lower limit is guarded with the lower limit current Imin. That is, the lower limit guard processing unit 111 sets the larger one of the required current Ireq from the arithmetic processing unit 110 and the lower limit current Imin as a new required current Ireq, and the valve drive control unit 120a corresponding to the set required current Ireq. Output to -120f. Here, the lower limit current Imin is set to a value greater than 0 within a range in which the thrust from the electromagnetic portion 15e (the sum of the force and the feedback pressure) does not exceed the biasing force of the spring 15sp. As a result, even if there is no request for hydraulic pressure to the fluid actuators M1-M6, the value 0 is not set to the request current Ireq, and the electromagnetic portions 15e of the linear solenoid valves 151-156 basically have , a minute current (for example, about 0.1 A to 0.2 A) that does not move the spool 15s will always flow.

Next, the operation of the robot apparatus 1 configured in this manner will be described.

When a start switch (not shown) is turned off and the operation of the robot device 1 is completely stopped, the hand part 4 is held by a locking part formed on a support base (not shown). As a result, the posture of the robot arm 2 is forcibly held at the predetermined standby posture. Further, when the start switch of the robot device 1 is turned on and the system start-up is completed, the control device 100 controls the oil pressure ( The pump 13 is controlled so that the original pressure) becomes a predetermined relatively low standby pressure Pst (approximately 700-900 kPa).

Next, the control device 100 fills the tubes T of the fluid actuators M1-M6 with hydraulic oil in a predetermined order, and directs the electromagnetic portions 15e of the linear solenoid valves 151-156 to bring the tubes T into the initial state. to control the current of As a result, hydraulic fluid is supplied to the tubes T of the fluid actuators M1-M6 from any one of the control valve 16 and the linear solenoid valves 152-156, and each tube T moves from its natural state to a predetermined amount (for example, natural about 10% of the length) in the axial direction. After that, current is continuously supplied to each electromagnetic part 15e of the linear solenoid valves 151 to 156 until the hand part 4 is placed on the support base or the like and the operation of the robot apparatus 1 is stopped. The valves 151-156 adjust the pressure of hydraulic fluid from the pump 13 side according to the current supplied to the electromagnetic portion 15e.

After completion of the work start preparation of the robot device 1 as described above, when the start of work using the robot arm 2 and the hand unit 4 is instructed, the control device 100, based on the detection value of the source pressure sensor PS, The pump 13 is operated so that the hydraulic pressure (original pressure) in the oil passage LL is lower than the upper limit pressure Plim and is a relatively high normal pressure Pw (for example, about 5-6 MPa) determined to be equal to or higher than the minimum operating pressure of the accumulator 14. Control. Further, the control device 100 supplies the hydraulic pressure required to hold the robot arm 2 in the standby posture without external force (support base) to the tubes T of the fluid actuators M1 to M6 in a predetermined order. The current to the electromagnetic portion 15e of the linear solenoid valves 151-156 is controlled to supply the current.

Then, the control device 100 sets the required current Ireq to each electromagnetic part 15e so that the hydraulic pressure corresponding to the request to the robot arm 2 is supplied from the linear solenoid valves 151 to 156 to each of the fluid actuators M1 to M6. and controls the current supplied to each electromagnetic part 15e based on the requested current Ierq. As a result, hydraulic pressure (driving pressure) adjusted according to demand by the control valve 16 and the linear solenoid valves 152-156 can be supplied to the tubes T of the fluid actuators M1-M6. As a result, each arm 3 can be rotated by a plurality of fluid actuators M1 to M6 to move the hand section 4 of the robot device 1 to a desired position.

Here, in the present embodiment, as described above, the target current calculator 121 of each of the valve drive controllers 120a to 120f stores the difference between the requested current Ireq from the arithmetic processor 110 and the detected current Ie of the current detector 125. An integral term calculator 122i that calculates an integral term based on the difference is included. Current detection unit 125 normally includes some detection error, and when current detection unit 125 includes a positive detection error, request current Ireq is set to a value of 0. Then, since the current supplied to the electromagnetic section 15e cannot be less than 0, the positive detection error of the current detection section 125 is accumulated in the integral term calculated by the integral term calculation section 122i. Even if hydraulic pressure is requested to the fluid actuators M1-M6 (artificial muscles) with a positive detection error accumulated in the integral term, and the requested current Ireq rises in response to the hydraulic pressure request, the detection error The accumulated integral term suppresses the rise of the target current Itag, and delays the supply of hydraulic pressure to the corresponding fluid actuators M1-M6. Therefore, in the present embodiment, even if there is no request for hydraulic pressure to the fluid actuators M1 to M6, the current detection unit 110 sets the required current Ireq larger than the value 0 with the lower limit current Imin as the lower limit. When the positive detection error is included in the part 125, the target current Itag is calculated so that the current supplied to the electromagnetic part 15e becomes smaller than the lower limit current Imin due to the action of the feedback control. Accumulation of the detection error of the current detection unit 125 in the integral term calculated by the unit 122i can be suppressed. Therefore, when hydraulic pressure is next requested to the fluid actuators M1-M6, the increase in the target current Itag is not suppressed by the integral term, and the hydraulic pressure to the fluid actuators M1-M6 (artificial muscles) is not suppressed. It is possible to respond quickly to requests for

Further, in the present embodiment, in preparation for starting work of the robot device 1, as described above, the hydraulic fluid is filled in the tubes T of the fluid actuators M1 to M6 in a predetermined order, and each of the fluid actuators M1 to M6 A waiting state is established until the turn comes, and hydraulic pressure is not required for the fluid actuators in the waiting state. In this case, when a request current Ireq of 0 is set for the solenoid portion 15e of the linear solenoid valve corresponding to the fluid actuator in the turn waiting state, the fluid actuator whose order of filling is later is feedback of the corresponding solenoid valve. A large detection error may be accumulated in the integral term in the control. In the present embodiment, even if hydraulic pressure is not requested, the lower limit current Imin larger than the value 0 is set to the required current Ireq, so the detection error of the current detection unit 125 is accumulated in the integral term in the feedback control. can be suppressed. As a result, when the hydraulic fluid is filled, the hydraulic pressure that meets the demand can be quickly supplied, so that preparations for starting work can be completed early.

Furthermore, in the case where the driving portion of the hand portion 4 of the robot device 1 includes a fluid actuator M7 as shown in FIG. The required current Ireq for the electromagnetic section 157 may be set to the lower limit current Imin. That is, the hand part 4 includes a support part 4b provided at the tip of the robot arm 2, a pair of gripping claws 4ca and 4cb slidable in directions toward and away from each other with respect to the support part 4b, and a pair of gripping claws 4ca. , 4cb as an artificial muscle, and a spring 4sp (elastic body) provided in parallel with the fluid actuator M7 between a pair of grasping claws 4ca and 4cb so as to form a pair with the fluid actuator M7. and The pair of gripping claws 4ca and 4cb extend in the sliding direction of the pair of gripping claws 4ca and 4cb so that the tips of the gripping claws 4ca and 4cb face outward, and are biased in a direction away from each other by the biasing force of the spring 4sp. When the hydraulic oil is supplied to the tube T of the actuator M7, the hydraulic pressure corresponding to the hydraulic oil supplied to the tube T generates a contraction force, so that they approach each other. That is, the tips of the pair of gripping claws 4ca and 4cb are pulled inward by supplying hydraulic pressure to the fluid actuator M7 from the fluid supply device 10, and protrude outward by releasing the hydraulic pressure acting on the fluid actuator M7. The fluid supply device 10 includes a linear solenoid valve 157 that adjusts and outputs hydraulic pressure to the fluid actuator M7. 120g, and the valve drive control section 120g generates a PWM signal by the feedback calculation including the proportional term and the integral term, and controls the energization of the electromagnetic section of the linear solenoid valve 157. For example, as shown in FIG. 7, the robot apparatus 1 having the hand portion 4 constructed in this manner handles a workpiece W which is formed in a box shape with an open top and has handle holes Ha and Hb on both sides facing each other. It can be used to hold the workpiece W by the part 4 and transport it. The workpiece W is gripped by supplying hydraulic pressure to the fluid actuator M7 to draw the pair of gripping claws 4ca and 4cb inward, and in this state, the hand unit 4 is moved into the workpiece W to pull the pair of gripping claws 4ca and 4cb. This can be done by aligning the toe with the handle holes Ha, Hb, releasing the hydraulic pressure acting on the fluid actuator M7, and engaging the toe with the handle holes Ha, Hb. The work W is released from the grip by reversing the gripping procedure, that is, by supplying hydraulic pressure to the fluid actuator M7 to pull the pair of gripping claws 4ca and 4cb inward, thereby opening the handle holes Ha and Hb at the tip of the claw. This can be done by releasing the engagement with and pulling out the hand portion 4 from the inside of the workpiece W in this state, and releasing the hydraulic pressure acting on the fluid actuator M7. While the workpiece W is being gripped, the gripping state is maintained by the biasing force of the spring 4sp, so hydraulic pressure is not required for the fluid actuator M7. Even in this case, the required current Ireq to the electromagnetic part of the linear solenoid valve 157 is set to the lower limit current Imin larger than the value 0, so the detection error of the current detection part 125 is accumulated in the integral term in the feedback control. can be suppressed. Therefore, when starting to grip the workpiece W or releasing the gripping of the workpiece W, the required hydraulic pressure can be quickly supplied, so that the gripping start operation and the gripping release operation can be performed quickly. .

As described above, in the robot apparatus 1, the current detection unit 125 for detecting the detected current Ie flowing through the electromagnetic units 15e of the linear solenoid valves 151 to 156, the required current Ireq required by the electromagnetic units 15e and the current detection unit 125 Valve drive control units 120a to 120f that generate a PWM signal by feedback calculation including a proportional term and an integral term based on the difference from the detected current Ie, and control the energization of the electromagnetic unit 15e by the PWM signal. Prepare. When the hydraulic pressure of the fluid actuators M1-M6 is not requested, the control device 100 sets the required current Ireq to the electromagnetic part 15e of the corresponding linear solenoid valve 151-156 to a value greater than 0 within a range in which the spool 15s does not move. The lower limit current Imin (predetermined current) is set.

Thereby, even if the current detection unit 125 includes a positive detection error, it is possible to prevent the detection error from being accumulated in the integral term of the feedback calculation. As a result, good feedback control can be performed, and the response of fluid supply to the artificial muscle can be further improved.

Further, the control device 100 (lower limit guard processing unit 111) sets the larger one of the current corresponding to the hydraulic pressure request (hydraulic pressure command value) for the fluid actuators M1 to M6 and the lower limit current Imin to the required current Ireq. As a result, it is possible to suppress the detection error of the current detection unit 125 from accumulating in the integral term of the feedback calculation when the demand for hydraulic pressure is eliminated while responding to the demand for hydraulic pressure for the fluid actuators M1-M6.

Further, the valve drive control units 120a to 120f fill the tubes T of the plurality of fluid actuators M1 to M6 (artificial muscles) with hydraulic oil in a predetermined order as preparation for starting work of the robot device 1. The required current Ireq to the electromagnetic portion 15e of the corresponding linear solenoid of the fluid actuator in the waiting state is set to the lower limit current Imin. As a result, it is possible to suppress the accumulation of the detection error of the current detection unit 125 in the integral term in the feedback control of the linear solenoid valve corresponding to the fluid actuator in the turn waiting state, and the work start preparation can be completed early. becomes possible.

The hand portion 4 also has a fluid actuator M7 and a spring 4sp (elastic body) as operating members for operating the pair of gripping claws 4ca and 4cb. target) is being operated, the required current Ireq to the electromagnetic portion 15e of the corresponding linear solenoid valve 157 of the fluid actuator M7 is set to the lower limit current Imin. As a result, when the pair of gripping claws 4ca and 4cb (actuation targets) are actuated by the biasing force of the spring 4sp, the current detection unit 125 is applied to the integral term in the feedback control of the corresponding linear solenoid valve 157 of the fluid actuator M7. Accumulation of detection errors can be suppressed, and the hand portion 4 (the pair of gripping claws 4ca and 4cb) can be operated quickly.

Further, the invention of the present disclosure is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the present disclosure.

For example, in the above-described embodiment, the fluid supply device 10 functions as a fluid adjustment valve (fluid adjustment unit), for example, the fluid actuator M1 that adjusts the fluid pressure (fluid pressure) detected by the pressure sensor to the required pressure. - May include a flow control valve to control the flow of liquid (fluid) to M6. The fluid supply device 10 may supply liquid other than working oil such as water or gas such as air to the fluid actuators M1 to M7.

Furthermore, the robot apparatus 1 may include only one joint, or may include only one or two fluid actuators as artificial muscles. Further, the robot device 1 is not limited to one including the robot arm 2 having at least one fluid actuator M1 or the like and the hand portion 4, and at least one fluid actuator and a tool such as a drill bit or a switch can be pressed. It may also include a robot arm to which elements other than the hand unit 4, such as a pressing member, are attached to the hand. Furthermore, the robot device 1 may be a walking robot, a wearable robot, or the like.

Further, the robot arm 2 of the robot device 1 may include a swing motor (for example, a swing motor that rotates the base (wrist) of the hand portion 4) as a fluid actuator that drives the arm 3. FIG. That is, the robot main body of the robot apparatus 1 may include at least one of a fluid actuator as an artificial muscle and a swing motor. Further, the robot arm 2 of the robot device 1 may include fluid pressure cylinders such as air cylinders and hydraulic cylinders as fluid actuators. Further, it is not always necessary to provide a plurality of pairs of fluid actuators (artificial muscles) M for all of the two arms 3 etc. connected via the joints J1-J3. Alternatively, one or more fluid actuators may be connected to an elastic body such as a spring or rubber material arranged to oppose the fluid actuators. Additionally, in the robot device 1 , the tank 11 may be supported by a robot body such as the robot arm 2 .

Furthermore, in the above embodiment, the fluid actuators M1 to M7 as artificial muscles are provided with a tube T that radially expands and axially contracts in response to an increase in the hydraulic pressure inside the fluid actuators M1 to M7 supplied with hydraulic oil. , and a braided sleeve S covering the tube T, the configuration of the fluid actuators M1 to M7 in the robot device 1 is not limited to this. That is, the fluid actuators M1 to M7 may include a tube that expands in the radial direction and contracts in the axial direction when supplied with fluid. Axial fiber reinforced axial fiber reinforced body comprising an outer tubular member formed by a body and coaxially disposed outside the inner tubular member; and a fiber layer disposed between the inner tubular member and the outer tubular member. It may be a fluid actuator (see, for example, JP-A-2011-137516).

INDUSTRIAL APPLICABILITY The invention of the present disclosure can be used in industries such as the manufacturing industry of robotic devices including at least one artificial muscle that operates when supplied with fluid.

REFERENCE SIGNS LIST 1 robot device 2 robot arm 3 arm 4 hand part (tip) 4ca, 4cb grasping claw (operation target) 4sp spring (elastic body) 10 fluid supply device 13 pump (fluid supply source) 15e Electromagnetic part 16 Control valve 100 Control device (control part) 111 Lower limit guard processing part 120a, 120b, 120c, 120d, 120e, 120f, 120g Valve drive control part 151, 152, 153, 154, 155, 156 , 157 linear solenoid valves, J1, J2, J3 joints, M1, M2, M3, M4, M5, M6, M7 fluid actuators (artificial muscles).

Claims (4)

A robotic device comprising at least one artificial muscle that operates when supplied with a fluid, and a fluid supply device that supplies and discharges the fluid to and from the artificial muscle,
The fluid supply device
a source of the fluid;
a fluid adjustment unit that adjusts and outputs the pressure or flow rate of the fluid from the supply source side to the artificial muscle by driving a linear solenoid valve;
a current detector that detects current flowing through the electromagnetic part of the linear solenoid valve;
generating a PWM signal based on a feedback calculation including an integral term based on a difference between a current detected by the current detection unit and a required current required by the electromagnetic unit of the linear solenoid valve; a control unit that controls energization of the unit;
with
When the supply of the fluid to the artificial muscle is not requested, the control section sets the requested current to the electromagnetic section of the linear solenoid valve to a predetermined value greater than 0 within a range in which the linear solenoid valve does not operate. set to current,
robotic device. The robot device according to claim 1,
The control unit sets the required current with the predetermined current as a lower limit according to the pressure or flow rate of the fluid for the artificial muscle.
robotic device. The robot device according to claim 1 or 2,
The at least one artificial muscle includes a plurality of artificial muscles to which the fluid is supplied by driving the corresponding linear solenoid valves,
The control unit controls energization of the electromagnetic unit of each linear solenoid so that the fluid is supplied to the plurality of artificial muscles in a predetermined order in preparation for starting the operation of the robot device. and setting the required current for the electromagnetic part of the linear solenoid corresponding to the artificial muscle in the waiting state to the predetermined current;
robotic device. The robot device according to any one of claims 1 to 3,
an elastic body arranged so as to be paired with the artificial muscle and biased in a direction opposite to contraction force acting on the artificial muscle when supplied with the fluid, wherein the biasing force of the elastic body and the artificial muscle an actuating member that actuates an object to be actuated by contraction force of muscles;
The control unit sets the required current for the electromagnetic unit of the linear solenoid valve corresponding to the artificial muscle to the predetermined current when the actuating target is actuated by the biasing force of the elastic body.
robotic device.

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