JP2013233614A - Robot hand, and robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To retain an appropriate gripping force by correcting a temporal change of the gripping force of a robot hand without using a force sensor.SOLUTION: A current value is controlled so that the rotational speed of a driving motor for driving a plurality of finger parts may increase and decrease. Moreover, at least two pairs of the rotational speed of the driving motor and the current value are measured as a movement information during the movement of a finger part, and an upper limit current value of the driving motor is corrected based on a measured movement information. When the finger part comes into contact with an object to detect a decrease in the rotational speed of the driving motor, the object is gripped by making the current value of the driving motor an upper limit current value. In so doing, an appropriate gripping force can be retained by correcting a temporal change of the gripping force.

Description

  The present invention relates to a robot hand or a robot that grips an object using a plurality of fingers.

  Due to recent advances in robot technology, many robots are used in industrial product manufacturing sites. In addition, a robot hand capable of gripping an object using a plurality of fingers has been developed, and a robot equipped with a robot hand is used for assembling and transporting products and various parts. Such a robot hand needs to grip an object with an appropriate force so as to reliably grip the object and not damage the object. However, if a force sensor such as a pressure-sensitive element is attached to the finger portion in order to detect a force (gripping force) for grasping an object in real time, it is difficult to reduce the size and weight of the robot hand.

  Thus, the following technique has been proposed for a robot hand that does not have a force sensor (Patent Document 1). First, the current value (moving current value) of the drive motor is controlled so as to increase or decrease the rotational speed of the drive motor that moves the finger portion, and the finger portion is moved toward the object. When the finger part comes into contact with the object and a decrease in the rotational speed of the drive motor is detected, the object is controlled by controlling the current value (gripping current value ≧ moving current value) predetermined according to a predetermined gripping force. Hold the grip. In the proposed technique, it is possible to grip an object with a predetermined gripping force without using a force sensor by appropriately determining a gripping current value in advance.

JP 2002-178281 A

  However, in the proposed technology, even if the sliding resistance (static friction) increases with time change due to the use of the robot hand and the gripping force is lower than the initial setting (even if the assumed gripping force is not generated) Since the force sensor is not provided, there is a problem that it is difficult to accurately detect the shortage of the gripping force and correct the gripping force (grip current value). In addition, if the reduced gripping force is detected by the force sensor, there is no point in performing control for gripping the object without using the force sensor as described above.

  The present invention has been made to solve at least a part of the above-described problems of the prior art, and is appropriate by correcting the change with time of the gripping force of the robot hand without using a force sensor. An object is to provide a technique capable of maintaining a gripping force.

In order to solve at least a part of the problems described above, the robot hand of the present invention employs the following configuration. That is,
A robot hand that grips an object using a plurality of fingers,
A drive motor for driving the fingers;
A movement control unit for controlling the current value of the drive motor so as to increase or decrease the rotation speed of the drive motor, and for moving the finger unit relative to the object;
An upper limit current value correcting unit that measures at least two sets of the rotational speed and current value of the drive motor as movement information while the finger is moving, and corrects the upper limit current value based on the measured movement information;
When the finger is in contact with the object and a decrease in the rotation speed of the drive motor is detected, the gripping force of the finger on the object is determined by setting the current value of the drive motor as the upper limit current value. A grip control unit for holding
It is characterized by providing.

  In the robot hand of the present invention having such a configuration, the finger portion can be brought closer to the object by controlling the current value of the drive motor so that the rotational speed of the drive motor increases or decreases. When the finger part comes into contact with the object, the rotational speed of the drive motor decreases, so that it is possible to detect that the finger part has contacted the object. After the finger touches the target object in this way, the current value of the drive motor is controlled to the upper limit current value corresponding to the target gripping force, thereby gripping the target object with the target gripping force without using a force sensor. It is possible. However, the upper limit current value is set on the premise of the sliding resistance (static friction) at the initial setting, and when the sliding resistance increases due to the change over time due to use, the current is consumed by the increase ( The gripping force is reduced due to insufficient current value. The influence of the increase in sliding resistance due to changes over time also appears in the control of the current value of the drive motor while the finger is moving. It is necessary to add the current value of. Therefore, during the movement of the finger part, at least two pairs of the rotational speed and current value of the drive motor are measured as movement information, and the increase in sliding resistance is estimated based on the measured movement information. By correcting the upper limit current value in consideration of the increase in sliding resistance, the target gripping force can be maintained without using a force sensor.

  In the robot hand of the present invention described above, the current value at the time when the rotational speed of the drive motor is zero from the movement information (two or more sets of the rotational speed and current value of the drive motor) measured during the movement of the finger. As estimating (stop current value), the correction amount of the upper limit current value may be determined based on the estimated stop current value.

  For example, if two sets of the rotational speed and current value of the drive motor while the finger is moving are measured, a straight line connecting the two sets of measured values in the graph showing the relationship between the rotational speed of the drive motor and the current value. The current value (stop current value) at the time when the rotational speed of the drive motor is zero can be obtained from the intersection (intercept) between the current value axis and the current value axis. This stop current value represents the magnitude of the load due to the sliding resistance. Therefore, when the stop current value increases due to changes over time due to use, it can be determined that the sliding resistance has increased, and by determining the correction amount of the upper limit current value from the increase amount of the stop current value, It becomes possible to hold the target gripping force. Note that the accuracy of correction can be increased by increasing the measured values of the rotational speed and current value of the drive motor to three or more sets and obtaining the stop current value from the approximate straight line based on those measured values.

  In the robot hand of the present invention, the following may be performed. First, when power is turned on to the robot hand, the finger is moved to the reference position and the origin is adjusted. And while moving a finger | toe part to a reference position, movement information (The rotational speed and current value of a drive motor and 2 sets or more) is measured, and an upper limit electric current value is correct | amended.

  In general, the origin of the finger portion is adjusted by fixing the robot hand in a predetermined posture. Therefore, if the movement information is measured during the origin adjustment (while the finger is moved to the reference position), it is more affected by the posture of the robot hand, etc. than during the general movement (the movement of gripping the object with the finger). The fluctuation of the sliding resistance is small and the correction accuracy can be increased.

Moreover, this invention can also be grasped | ascertained in the following aspects. That is,
A robot having a robot hand that grips an object using a plurality of fingers,
A movement control unit that controls the current value of the drive motor so as to increase or decrease the rotational speed of the drive motor that drives the finger unit, and moves the finger unit relative to the object;
An upper limit current value correcting unit that measures at least two sets of the rotational speed and current value of the drive motor as movement information while the finger is moving, and corrects the upper limit current value based on the measured movement information;
When the finger is in contact with the object and a decrease in the rotation speed of the drive motor is detected, the gripping force of the finger on the object is determined by setting the current value of the drive motor as the upper limit current value. A grip control unit for holding
Can be grasped as a robot characterized by being provided in the hand / arm control unit of the robot.

  In the robot according to the present invention, it is possible to correct the change with time of the gripping force of the robot hand and maintain an appropriate gripping force. Moreover, since no force sensor is required, the robot can be reduced in size and weight.

  In the above-described robot of the present invention, the current value at the time when the rotational speed of the drive motor is zero based on the movement information measured during the movement of the finger (two or more rotational speeds and current values of the drive motor) ( As the estimation of the stop current value, the correction amount of the upper limit current value may be determined based on the estimated stop current value.

  If the stop current value increases, it can be determined that the sliding resistance has increased due to changes over time due to use. By determining the correction amount for the upper limit current value from the increase amount of the stop current value, the robot hand It is possible to hold the target gripping force.

  In the robot of the present invention, the following may be performed. First, when power is turned on to the robot hand, the finger is moved to the reference position and the origin is adjusted. And while moving a finger | toe part to a reference position, movement information (The rotational speed and current value of a drive motor and 2 sets or more) is measured, and an upper limit electric current value is correct | amended.

  The origin of the finger is usually adjusted with the robot hand fixed in a predetermined posture. If the movement information is measured during the origin adjustment (while the finger is moved to the reference position), the normal operation (finger Compared with the operation of gripping the object by the part), the variation of the sliding resistance due to the influence of the posture of the robot hand and the like is small, so that the correction accuracy can be improved.

It is explanatory drawing which showed the rough structure of the robot hand of a present Example. It is explanatory drawing which showed the operation | movement which the robot hand of a present Example hold | grips a target object. It is the time chart which showed the flow until it sets the electric current value of a finger drive motor and hold | grips a target object with a finger part. It is the flowchart which showed the first half part of the origin adjustment process performed with a robot hand. It is the flowchart which showed the latter half part of the origin adjustment process performed with a robot hand. It is the graph which showed the relationship between the rotation speed of a finger drive motor, and an electric current value. It is the graph which showed the relationship between the grip force by a finger | toe part, and the electric current value of a finger drive motor. It is explanatory drawing which shows the robot carrying the robot hand of a present Example. It is the block diagram which showed the circuit structure which controls the arm which is the main structures of a robot, a palm part, and a finger part.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. The structure of the robot hand of this embodiment:
B. Object gripping motion:
C. Gripping force correction:
D. Application example:

A. The structure of the robot hand of this embodiment:
FIG. 1 is an explanatory diagram showing a rough structure of the robot hand 100 of the present embodiment. First, FIG. 1A shows the appearance of a robot hand. As shown in FIG. 1A, the robot hand 100 according to the present embodiment includes four fingers 10 for gripping an object and palms provided between the four fingers 10. It comprises a base 12 provided with a portion 14 and an arm 16 that supports the base 12. Four fingers 10 are provided so as to face each other around the palm 14. A mechanism for driving the four finger portions 10 and the palm portion 14 is provided inside the base 12.

  FIG. 1B shows a driving mechanism for the four fingers 10. As shown in FIG. 1B, the base 12 of the robot hand 100 has two moving members 20 built in, and two of the four fingers 10 provided in the same direction. The finger portions 10 are erected from the same moving member 20. Each moving member 20 has rack gears 22 extending on the sides facing each other, and these rack gears 22 mesh with pinion gears 24 provided between the two moving members 20. The base 12 incorporates a finger drive motor 28, and the power of the finger drive motor 28 is transmitted to the pinion gear 24 via the gear box 26. For this reason, when the finger drive motor 28 is driven, the pinion gear 24 rotates, and the two moving members 20 move in the opposite directions by the same distance by the rack and pinion mechanism. As a result, the finger parts 10 facing each other approach or move away. The finger drive motor 28 of this embodiment corresponds to the “drive motor” of the present invention.

  FIG. 1C shows a drive mechanism for the palm 14. As shown in FIG. 1C, the palm portion 14 is formed of a plate-like member, and a rack gear 32 suspended from the lower surface side (side facing the base 12) of the palm portion 14 includes: It meshes with a pinion gear 34 provided inside the base 12. The base 12 has a built-in palm drive motor 38, and the power of the palm drive motor 38 is transmitted to the pinion gear 34 through the gear box 36. Therefore, when the palm drive motor 38 is driven, the pinion gear 34 rotates, and the palm portion 14 protrudes or retracts from the base 12 by the rack and pinion mechanism.

B. Object gripping action:
FIG. 2 is an explanatory diagram illustrating an operation in which the robot hand 100 of the present embodiment grips the object W. As described above, the robot hand 100 according to the present embodiment can drive the finger drive motor 28 so that the distance between the finger portions 10 facing each other in the four finger portions 10 can be made closer or farther away. Further, by driving the palm drive motor 38, the palm portion 14 can be protruded or retracted from the base 12. The driving of the finger drive motor 28 and the palm drive motor 38 is controlled by the control unit 50.

  When gripping the target object W, first, as shown in FIG. 2A, the robot hand 100 is aligned with the target object W so that the target object W is positioned in the middle of the finger portions 10 facing each other. . Next, the control unit 50 controls the driving of the finger drive motor 28 and the palm drive motor 38 so that the interval between the finger units 10 facing each other is reduced, and the palm unit 14 is projected toward the object W. . As a result, as shown in FIG. 2 (b), the robot hand 100 has the finger 10 facing the object W sandwiching the object W from both sides, and the palm 14 from the direction intersecting the holding direction by the finger 10. The object W can be gripped by coming into contact with W. By bringing the palm part 14 into contact with the object W in this way, the number of contact points with the object W is increased as compared with the case where both sides of the object W are sandwiched between the finger parts 10, thereby improving the gripping stability. be able to.

  Further, the robot hand 100 needs to grip the object W with an appropriate force so as not to damage the object W, and the control unit 50 mounted on the robot hand 100 according to the present embodiment is provided with the finger drive motor 28. By appropriately setting the current value, the force with which the finger 10 grips the object W (gripping force) is controlled.

  FIG. 3 is a time chart showing a flow from setting the current value of the finger drive motor 28 to gripping the object W with the finger unit 10. FIG. 3A shows a time change of the current value, and FIG. 3B shows a time change of the rotation speed of the finger drive motor 28. First, in order to move the finger part 10 toward the object W, the current value is increased to accelerate the rotation of the finger driving motor 28. When the rotation speed of the finger drive motor 28 reaches a predetermined speed, the current value is controlled so as to maintain the predetermined speed. Thereby, the finger part 10 approaches the target object W at a constant speed. The control unit 50 according to the present embodiment that controls the current value so as to increase or decrease the rotation speed of the finger drive motor 28 corresponds to the “movement control unit” of the present invention.

  Thus, when the finger 10 that moves at a constant speed comes into contact with the object W, the finger 10 stops moving, and the rotation speed of the finger drive motor 28 rapidly decreases accordingly. However, since the current value is controlled so that the rotation speed of the finger drive motor 28 is maintained even after the finger 10 comes into contact with the object W, the current value rapidly increases and a gripping force is generated. The control unit 50 can detect that the finger unit 10 is in contact with the object W from such a rapid increase in the current value of the finger drive motor 28 (decrease in the rotation speed).

  Then, after detecting that the finger unit 10 has contacted the object W, when the current value of the finger drive motor 28 reaches the upper limit value, control is performed to maintain the upper limit value. This upper limit value is set in advance according to a target gripping force suitable for the object W (a gripping force that does not damage the object W). For this reason, in the robot hand 100 of the present embodiment, even if the force sensor such as a pressure sensitive element is not provided, the current value of the finger drive motor 28 is controlled to the upper limit value, so that the object W is moved with the target gripping force. It is possible to grip. Note that the control unit 50 of this embodiment that performs control to maintain the upper limit value of the current value of the finger drive motor 28 corresponds to the “gripping control unit” of the present invention.

  As described above, in the robot hand 100 that controls the gripping force by setting the upper limit value of the current value of the finger drive motor 28 without using the force sensor, the gripping force may be reduced with time. This is because the sliding resistance (static friction) increases from the initial setting due to the change over time due to the use of the robot hand 100, and the assumed gripping force (target gripping force) is reduced because the current value is insufficient by that amount. This is because it does not occur. Therefore, in the robot hand 100 according to the present embodiment, the time-dependent change of the gripping force is corrected as the origins (reference positions) of the finger unit 10 and the palm unit 14 are matched when the power is turned on. .

C. Gripping force correction:
4 and 5 are flowcharts showing the origin matching process performed by the robot hand 100. FIG. This process is executed by the control unit 50 when the robot hand 100 is powered on. As shown in the drawing, in the origin alignment process, first, the interval between the finger portions 10 facing each other is opened to the limit (step S100). At this time, the rotation speed of the finger drive motor 28 is controlled to be a predetermined speed, and the finger unit 10 moves at a constant speed. In the robot hand 100 of the present embodiment, the rotation speed of the finger drive motor 28 is set in advance instead of the rotation speed of the finger drive motor 28. When the finger unit 10 is opened in step S100, the finger drive motor 28 is set. The number of rotations is controlled to be 2000 rpm. And if the finger part 10 contacts the case (refer FIG. 1A) which comprises the outer frame of the base 12, the finger drive motor 28 will be stopped as what the finger part 10 opened to the limit. When the finger part 10 is opened to the limit in this way, the origin of the finger part 10 is once reset (step S102).

  Subsequently, the palm 14 is contracted to the limit (step S104). At this time, the rotation speed of the palm drive motor 38 is controlled to be 300 rpm, and the palm portion 14 moves toward the base 12 at a constant speed. Further, the current value A at the constant speed of the palm drive motor 38 is measured (step S106), and it is determined whether or not the measured value is not more than a failure threshold value (step S108). If the measured value is larger than the failure threshold value (step S108: no), it is determined that some trouble has occurred in the drive mechanism of the palm 14 and a warning is issued (step S110). finish.

  On the other hand, when the measured value is equal to or less than the failure threshold value (step S108: yes), when the palm part 14 comes into contact with the case of the base 12, the palm drive motor 38 is stopped and the palm part 14 is assumed to have shrunk to the limit. Is reset (step S112). Thereby, the state where the palm part 14 is contracted to the limit becomes the origin of the palm part 14. After the origin of the palm part 14 is thus adjusted, the palm part 14 is then moved to the standby position (step S114). In the robot hand 100 of the present embodiment, the position where the palm portion 14 protrudes 5 mm from the origin is set as the standby position of the palm portion 14, and when the palm portion 14 is moved to the standby position, the palm drive motor 38 The rotation speed is controlled to 2000 rpm.

  When the palm portion 14 is stopped at the standby position, the finger portion 10 is closed until the fingertip interval between the facing finger portions 10 becomes 10 mm (step S116). Note that the reference position (origin) of the finger 10 at this time is the position where the reset is performed in step S102 (a state where the finger 10 is opened to the limit). When the finger unit 10 is closed in step S116, the rotation speed of the finger drive motor 28 is controlled to be 2000 rpm, and the current value B1 when the finger drive motor 28 is at a constant speed is measured (step S118). Then, it is determined whether or not the measured value is equal to or less than the failure threshold (step S120). If the measured value is larger than the failure threshold (step S120: no), it is determined that some trouble has occurred in the driving mechanism of the finger unit 10, so a warning is issued (step S110), and the origin is aligned. finish.

  On the other hand, when the measured value is equal to or less than the failure threshold (step S120: yes), the finger unit 10 is further closed to the limit (step S122). At this time, the number of rotations of the finger drive motor 28 is decreased and controlled to be 300 rpm. Further, the current value B2 at the constant speed of the finger drive motor 28 is measured (step S124), and it is determined whether or not the measured value is equal to or less than a failure threshold value (step S126). If the measured value is larger than the failure threshold value (step S126: no), it is determined that some trouble has occurred in the driving mechanism of the finger unit 10, so a warning is issued (step S110), and the origin is aligned. finish.

  On the other hand, when the measured value is equal to or less than the failure threshold (step S126: yes), when the fingertips of the opposing finger parts 10 come into contact with each other, the finger driving motor 28 is stopped, assuming that the finger parts 10 are closed to the limit. The origin of the unit 10 is reset (step S128). Thereby, the state where the finger part 10 is closed to the limit becomes the origin of the finger part 10. When the origin of the finger part 10 is thus aligned, the finger part 10 is moved to the standby position (step S130). In the robot hand 100 according to the present embodiment, the position where the fingertip interval between the facing finger portions 10 is 10 mm is set as the standby position of the finger portion 10, and when the finger portion 10 is moved to the standby position, the finger drive motor 28. Is controlled to 2000 rpm.

  When the finger unit 10 is stopped at the standby position in this way, a process for correcting the gripping force (a gripping force correction process) is performed (step S132), and the origin adjustment is completed. The gripping force is corrected based on the current value B1 measured in step S118 and the current value B2 measured in step S124, and estimating the current value when the finger drive motor 28 is stopped (rotation speed is zero) as follows. And do it.

  FIG. 6 is a graph showing the relationship between the number of rotations of the finger drive motor 28 and the current value. First, in the robot hand 100 of the present embodiment, the current value is measured while changing the number of rotations of the finger drive motor 28 at the time of manufacture (or the number of rotations is measured while changing the current value), and a plurality of measured rotation numbers and currents are measured. The value is stored as an initial value. In FIG. 6, the approximate straight line drawn based on the initial value is shown by a solid line. Here, in FIG. 6 showing the relationship between the rotation speed of the finger drive motor 28 and the current value, a point where the approximate straight line of the initial value intersects the current value axis (horizontal axis) (when the rotation speed of the finger drive motor 28 is zero) ) Represents the magnitude of the load due to the sliding resistance (static friction) in the initial stage (at the start of use). Hereinafter, the current value when the rotation speed of the finger drive motor 28 is zero is referred to as a “stop current value”.

  Further, as described above, in the robot hand 100 of the present embodiment, in the origin matching process, the current value B1 when the rotation speed of the finger drive motor 28 is 2000 rpm (step S118 in FIG. 4) and the rotation of the finger drive motor 28. The current value B2 when the number is 300 rpm (step S124 in FIG. 5) is measured. In FIG. 6, an approximate straight line drawn based on the measured value is indicated by a one-dot chain line. The current value (stop current value) at the point where the approximate straight line of the measured value intersects the current value axis (horizontal axis) is greater than the stop current value on the approximate straight line of the initial value. The difference between the stop current values represents a change (increase) in load due to sliding resistance (static friction). Therefore, the difference between the measured current value and the initial value is set as a correction value. Since the process of setting the correction value is performed by the control unit 50, the control unit 50 of this embodiment corresponds to the “upstream current value correction unit” of the present invention.

  FIG. 7 is a graph showing the relationship between the gripping force by the finger unit 10 and the current value of the finger drive motor 28. As described above, the robot hand 100 of this embodiment does not have a force sensor, and the solid line in FIG. 7 indicates that the current value of the finger drive motor 28 is changed experimentally using an external force sensor at the time of manufacture. It is an approximate straight line drawn based on the measured gripping force (initial value). Moreover, the dashed-dotted line in FIG. 7 has shown the estimated value of the time-dependent change of the gripping force. If the sliding resistance (static friction) increases from the initial setting due to the change over time due to the use of the robot hand 100, the current is consumed (the current value is insufficient) and the gripping force decreases. . For this reason, if the current value of the finger drive motor 28 is maintained at the initial upper limit current value set in advance according to the target gripping force, the target gripping force is not actually generated, and the object W Grasping becomes unstable. Therefore, in the robot hand 100 of the present embodiment, the upper limit current value is obtained by adding the correction value obtained as the difference between the above measured value and the initial value (FIG. 6) to the initial upper limit current value. Perform the correction. Then, by controlling the current value of the finger drive motor 28 to the corrected upper limit current value, the target gripping force can be held without using a force sensor.

  In the robot hand 100 of the present embodiment, the gripping force correction by the finger unit 10 is performed in the origin matching process when the power is turned on, but the rotation speed and current value of the finger driving motor 28 during the movement of the finger unit 10 are. , The gripping force can be corrected based on the measured value, and is not necessarily limited to the case of performing the origin adjustment process. For example, the rotation speed and current value of the finger drive motor 28 may be measured during the movement of the finger unit 10 in the general operation of gripping the object W, and the gripping force may be corrected based on the measured value. However, the origin matching process is usually performed with the robot hand 100 fixed in a predetermined posture. If the gripping force is corrected in the origin matching process, the robot hand 100 is compared with the case where it is performed during a general operation. The variation in sliding resistance (static friction) due to the influence of the posture of the head is small, and the correction accuracy can be increased.

  In the description using FIG. 6, the stop current value ((2) when the rotation speed of the finger drive motor 28 is 2000 rpm and the current value B2 when the rotation speed of the finger drive motor 28 is 300 rpm. The current value when the rotation speed of the finger drive motor 28 is zero) is calculated, but the stop current value does not necessarily have to be calculated explicitly. For example, a lookup table in which correction values are set in advance using various combinations of the current values B1 and B2 is prepared, and correction values corresponding to the measured current value B1 and current value B2 pairs are prepared. May be read from the lookup table.

D. Application example:
As described above, the robot hand 100 according to the present embodiment can correct a change in grip force with time and can maintain an appropriate grip force, and does not require a force sensor, so that the size and weight can be reduced. Can be achieved. For this reason, as shown in FIG. 8, if the robot hand 100 of the present embodiment is mounted, it is possible to hold an appropriate gripping force, and to realize a small and lightweight robot 200. .

  FIG. 9 is a block diagram showing a circuit configuration for controlling the arm 16, palm 14, and finger 10, which is the main configuration of the robot 200. In FIG. 9, as an example, an arm drive circuit 301 that drives the arm 16, a palm part drive circuit 302 that drives the palm part 14, and a finger part drive circuit 303 that drives the finger part 10. Is in control. The “movement control unit”, “upper limit current correction unit”, and “gripping control unit” of the present invention may be included in the hand / arm control unit 310.

  Although the robot hand and the robot according to the present embodiment have been described above, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof.

  For example, in the above-described embodiment, the current value B1 when the rotation speed of the finger drive motor 28 is 2000 rpm and the current value B2 when the rotation speed of the finger drive motor 28 is 300 rpm are measured. Three or more points may be measured. Thus, by increasing the number of measurement points and calculating the correction value from the approximate straight line based on them, the correction accuracy can be increased.

  In the above-described embodiment, the rotation speed and current value of the finger drive motor 28 measured at the time of manufacturing the robot hand 100 are stored as initial values. However, the rotation of the finger drive motor 28 is performed in the origin matching process when the power is turned on. The initial value is overwritten (updated) every time the number and current value are measured, and the difference between the current measurement value and the initial value (previous measurement value) is set as the correction value to the previous upper limit current value. You may correct | amend an upper limit electric current value by adding.

10 ... finger part, 12 ... base, 14 ... palm part,
16 ... Arm, 28 ... Finger drive motor, 38 ... Palm drive motor,
50 ... Control unit, 100 ... Robot hand, 200 ... Robot,
310: Hand arm control unit, W: Object

Claims (6)

A robot hand that grips an object using a plurality of fingers,
A drive motor for driving the fingers;
A movement control unit for controlling the current value of the drive motor so as to increase or decrease the rotation speed of the drive motor, and for moving the finger unit relative to the object;
An upper limit current value correcting unit that measures at least two sets of the rotational speed and current value of the drive motor as movement information while the finger is moving, and corrects the upper limit current value based on the measured movement information;
When the finger is in contact with the object and a decrease in the rotation speed of the drive motor is detected, the gripping force of the finger on the object is determined by setting the current value of the drive motor as the upper limit current value. A grip control unit for holding
A robot hand characterized by comprising: The robot hand according to claim 1,
The upper limit current value correction unit estimates a stop current value that is a current value at a time when the rotational speed of the drive motor is zero from the movement information measured during the movement of the finger, and the estimated stop current value A correction amount for the upper limit current value is determined based on the robot hand. The robot hand according to claim 1 or 2,
When the power is turned on to the robot hand, the movement control unit moves the finger unit to a reference position to adjust the origin,
The upper limit current value correcting unit measures the movement information while the finger unit moves to the reference position, and corrects the upper limit current value. A robot having a robot hand that grips an object using a plurality of fingers,
A movement control unit that controls the current value of the drive motor so as to increase or decrease the rotational speed of the drive motor that drives the finger unit, and moves the finger unit relative to the object;
An upper limit current value correcting unit that measures at least two sets of the rotational speed and current value of the drive motor as movement information while the finger is moving, and corrects the upper limit current value based on the measured movement information;
When the finger is in contact with the object and a decrease in the rotation speed of the drive motor is detected, the gripping force of the finger on the object is determined by setting the current value of the drive motor as the upper limit current value. A grip control unit for holding
The robot is characterized in that it is equipped in the robot's hand arm control unit. The robot according to claim 4,
The upper limit current value correction unit estimates a stop current value that is a current value at a time when the rotational speed of the drive motor is zero from the movement information measured during the movement of the finger, and the estimated stop current value A correction amount of the upper limit current value is determined based on the robot. The robot according to claim 4 or 5, wherein
When the power is turned on to the robot hand, the movement control unit moves the finger unit to a reference position to adjust the origin,
The robot is characterized in that the upper limit current value correction unit measures the movement information while the finger unit moves to the reference position, and corrects the upper limit current value.

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