Finger posture determination method, dexterous hand and robot

Abstract

The invention provides a finger posture determination method, a dexterous hand and a robot, and relates to the field of robots. The finger posture determination method is applied to the situation that a finger is powered on again after power failure and comprises the following steps that when a driving motor of the finger is powered on again after power failure, the driving motor is controlled to drive the finger to execute a holding action, so that the finger is held from the re-powered-on posture to the maximum holding posture of the finger; an incremental encoder of the driving motor is used for recording the first number of turns corresponding to the situation that the finger is held from the re-power-on posture to the maximum holding posture; a second number of turns is obtained by subtracting the first number of turns from the maximum number of turns (the maximum number of turns is the number of turns recorded by the incremental encoder when the finger is held from the original zero position posture to the maximum holding posture) of the incremental encoder, and the second number of turns can represent the number of turns when the finger is held from the original zero position posture to the re-electrification posture. And the incremental encoder needs to rotate the number of turns.

Description

Technical Field

[0001] This application relates to the field of robotics, and more specifically, to a method for determining finger posture, a dexterous hand, and a robot. Background Technology

[0002] As an important component of humanoid robots, the dexterous hand is mainly used to grasp objects.

[0003] There are many types of dexterous hands, such as linkage-type dexterous hands and rope-driven dexterous hands. Taking a rope-driven dexterous hand as an example, each finger is pulled by the rotation of a drive motor to bend the tendon rope, thereby realizing the dexterous hand's gripping action and grasping objects. In this dexterous hand, torsion springs can be set between the knuckles of each finger. Through the reset action of the torsion springs, the stretched and bent fingers can be extended and reset. In this way, the gripping and releasing action of the dexterous hand can be realized, thereby completing the corresponding grasping and releasing action.

[0004] In some rope-driven dexterous hands, the incremental encoders of the drive motors are typically incremental encoders. When the dexterous hand is performing an action and experiences a sudden power outage and subsequent power restoration, the values ​​of each incremental encoder will reset to 0. However, at this time, the dexterous hand's fingers may have already performed a partial bending motion. This means that after the dexterous hand is powered back on, the controller does not know the angle of the fingers' bending; that is, the controller cannot obtain the current true position information of each finger. The controller will only determine that the dexterous hand is in a zero-position state. Obviously, this situation of sudden power outage and power restoration is extremely detrimental to the control of the dexterous hand. If the dexterous hand is to continue performing actions... To perform the corresponding actions, the dexterous hand must undergo zero-position calibration after power-on; otherwise, it cannot accurately execute the corresponding grasping operations. However, current rope-driven dexterous hands using incremental encoders are helpless when faced with a sudden power outage and subsequent power-on, struggling to recalibrate the fingers' zero position. This is why current rope-driven dexterous hands use absolute encoders. However, absolute encoders are not only expensive, but their errors also gradually increase with the rapid increase in mechanical wear of the dexterous hand, leading to a sharp drop in control accuracy. Moreover, the sampling rate of absolute encoders is much lower than that of incremental encoders, which is one of the reasons why some rope-driven dexterous hands have abandoned absolute encoders in favor of incremental encoders. Therefore, solving the zero-position calibration problem of dexterous hands using incremental encoders after power failure is of profound significance for the application and promotion of robots, especially humanoid robots. Summary of the Invention

[0005] The purpose of this application is to provide a finger posture determination method, a dexterous hand, and a robot. The finger posture determination method can determine the current posture information of the finger when it is powered on again after a power outage (which can be deduced by the number of revolutions of an incremental encoder), thereby providing a precise reference for the subsequent control of the finger.

[0006] In a first aspect, embodiments of this application provide a method for determining finger posture, applied to situations where the finger has been powered off and then re-energized, comprising the following steps: When the drive motor of the finger is powered on again after a power outage, the drive motor is controlled to drive the finger to perform a gripping action, so that the finger is gripping from the power-on posture to the maximum gripping posture of the finger; The incremental encoder of the drive motor records the first number of revolutions from when the drive motor of the finger is re-energized to when the finger is in its maximum gripping posture. The second number of revolutions is obtained by subtracting the first number of revolutions from the maximum number of revolutions of the incremental encoder; Wherein, the maximum number of revolutions of the incremental encoder is the number of revolutions recorded by the incremental encoder when the finger is gripped from its original zero position to its maximum grip position; the second number of revolutions represents the number of revolutions that the incremental encoder needs to make when the finger is gripped from the original zero position to the re-powered position.

[0007] In some embodiments, the maximum number of revolutions of the incremental encoder is pre-stored.

[0008] In some embodiments, the maximum number of revolutions of the incremental encoder is pre-stored in a controller electrically connected to the incremental encoder.

[0009] In some embodiments, the controller is connected to the incremental encoder via a wired connection.

[0010] In some embodiments, the first number of revolutions is sent by the incremental encoder to the controller.

[0011] In some embodiments, the second number of revolutions is calculated by the controller.

[0012] In some embodiments, the controller includes a microcontroller.

[0013] In some embodiments, the finger performs a gripping action under the driving action of the forward rotation of the drive motor, and under the driving action of the reverse rotation of the drive motor, the finger returns to its initial state by the reset action of its elastic reset member.

[0014] In a second aspect, embodiments of this application also provide a dexterous hand, including at least one finger, wherein the finger is determined using the aforementioned finger posture determination method.

[0015] In a third aspect, embodiments of this application also provide a robot, including the dexterous hand described above. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the external structure of the index finger of a dexterous hand provided in an embodiment of this application; Figure 2 for Figure 1 Functional module diagram of the middle and index finger control section; Figure 3 This is an application scenario diagram of a finger posture determination method provided in an embodiment of this application, which shows the change in the number of revolutions of the incremental encoder of the index finger when the finger (e.g., the index finger) is performing posture determination. Figure 4 for Figure 3 A flowchart of the method for determining the posture of the middle and index fingers.

[0018] Icons: 1-Controller; 2-Incremental encoder; 3-Drive motor; 4-Index finger; 41-Knuckle; 42-Torsion spring; 43-Tendon chord. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] Please refer to Figures 1 to 2 This embodiment provides a finger posture determination method applicable to situations where the finger has been powered off and then re-energized. "Power off" means the finger's drive motor suddenly loses power, and the finger will maintain the posture it held at the time of power failure. "Power re-energization" means the finger's drive motor is powered on again and can continue to drive the finger. Specifically, this finger posture determination method can be applied to situations where a robot's dexterous hand experiences a sudden power failure during pre-grasping, and also to situations when the robot has just started up. This dexterous hand can be, for example, a tethered dexterous hand.

[0025] First, you can learn about the structure and operating mechanism of the rope-driven dexterous hand.

[0026] like Figure 1As shown, a common rope-driven dexterous hand includes several fingers, usually five. The mainstream dexterous hand adopts a human-like finger form, which generally includes the thumb, index finger, middle finger, ring finger, and little finger. The following explanation uses the index finger 4 as an example. The index finger 4 generally includes three sequentially hinged knuckles 41. An elastic restoring element, such as a torsion spring 42, is provided between two knuckles 41. The forward rotation of the drive motor 3 drives the winch on the output shaft of the drive motor 3 to rotate, thereby stretching the tendon rope 43 wound around the winch. The tendon rope 43 passes through each knuckle 41, applying forward tension to each knuckle 41 to force them to bend relative to each other, thus achieving the gripping action of the index finger 4. When the knuckles 41 are bent relative to each other, the torsion spring 42 accumulates elastic potential energy. The desired bending state of the index finger 4 can be controlled by the drive motor 3 that stretches the tendon rope 43. Under the reverse rotation of the drive motor 3, the index finger 4 releases its elastic potential energy through the torsion spring 42, generating a restoring effect that allows the index finger 4 to return to its initial state, which can be the straightened state of the index finger 4 (e.g., the torsion spring 42). Figure 3 (The original zero position of the middle index finger 4). In addition, as disclosed in patent CN119036492A, a dexterous hand thumb mechanism and its control method are provided, which elaborates on the configuration of tendon rope and torsion spring in the rope-driven finger. It will not be repeated here. The focus of this embodiment is on the description of the finger control method. It is worth emphasizing that an important difference between the dexterous hand in this embodiment and the existing dexterous hand is that the encoder used is an incremental encoder, rather than the common absolute encoder.

[0027] However, when the index finger 4 uses an incremental encoder 2 to record the number of rotations of its drive motor 3, the value of the incremental encoder 2 is recorded as 0 when the drive motor 3 is in its initial state. The data recorded by the incremental encoder 2 can be synchronously sent to the controller 1, so that the controller 1 records the number of rotations of the drive motor 3 of the index finger 4 as 0. As the dexterous hand with the index finger 4 performs the gripping action, the number of rotations of the drive motor 3 also increases. However, when the dexterous hand suddenly loses power, all fingers of the dexterous hand (including the index finger 4) will maintain the bent posture of the fingers at the time of power failure. At this time, the value of the incremental encoder 2 of the index finger 4 will return to zero. However, when the power is restored to the dexterous hand after troubleshooting and the interrupted gripping action is attempted to continue, the value of the incremental encoder 2 of the index finger 4 returns to zero, but the index finger 4 is not in its original zero position posture. This will cause the posture information of the index finger 4 recorded by the controller 1 to differ from the current actual posture of the index finger 4. The state information is mismatched. That is to say, the grip posture information (i.e., the number of revolutions recorded by the incremental encoder 2) of the index finger 4 recorded by the controller 1 before the power is cut off is zeroed, but the position of the index finger 4 is not zeroed. If the index finger 4 is not corrected and the dexterity gripping work continues, the controller 1 will judge that the number of revolutions recorded by the incremental encoder 2 of the index finger 4 is 0. If the index finger 4 is directly controlled to perform a full-stroke gripping action, such as performing a gripping action from the original zero position posture of the index finger 4 to the maximum gripping posture, there will inevitably be excessive gripping action. This may cause the tendon 43 to be overstretched or even broken, and may also cause the drive motor 3 to be overloaded and burned. Therefore, after the index finger 4 is powered on again, the current position of the index finger 4 must be determined first. The controller 1 needs to determine the true grip posture of the index finger 4 after the second power-on (i.e., the number of revolutions that the incremental encoder 2 has turned) before the subsequent gripping action of the index finger 4 can be executed accurately.

[0028] To address the aforementioned issues, the solution provided in this implementation is to obtain the position and posture information of the dexterous hand when it suddenly loses power through controller 1. Based on this information, controller 1 can recalibrate the incremental encoder 2 to continue executing the unfinished grasping action.

[0029] Please combine Figure 3 and Figure 4 As shown, this embodiment uses the following method to solve the problem: The index finger 4 posture determination method provided in this embodiment is applied to the case where the index finger 4 is powered off and then powered on again. The method includes the following steps: Step S1: When the drive motor 3 of the index finger 4 is powered on again after being powered off, control the drive motor 3 to drive the index finger 4 to perform a gripping action, so that the index finger 4 is gripped from the power-off posture / power-on posture to the maximum gripping posture of the index finger 4; at this time, the drive motor 3 stops rotating.

[0030] like Figure 3 As shown, during the process of index finger 4 moving from the power-off posture / power-on posture (the power-off posture and power-on posture of index finger 4 are the same physical posture, the difference being whether the drive motor 3 is powered on) to the maximum grip posture, when index finger 4 is in the power-off posture, the number of rotations R of its corresponding incremental encoder 2 relative to the original zero position posture of index finger 4 is... x It is unknown, this R x Essentially, this is the desired result of this embodiment, wherein the initial number of revolutions R0 recorded by the incremental encoder 2 of the index finger 4 in its original zero position posture can be set to zero.

[0031] When index finger 4 is re-energized, its drive motor 3 rotates forward and pulls the tendon ligament 43. The forward rotation of the drive motor 3 causes index finger 4 to perform a gripping action and bend until index finger 4 is gripped to its maximum bending state. Figure 3 The maximum gripping posture of the index finger 4 is shown. At this time, the drive motor 3 will stop rotating. Simultaneously, when the knuckles 41 of the index finger 4 are bent relative to each other, the torsion spring 42 between two adjacent knuckles 41 can accumulate elastic potential energy, which drives the two adjacent knuckles 41 to return to the original zero-position posture of the index finger 4 after bending. When the controller 1 detects that the drive motor 3 of the index finger 4 has stopped rotating, the tendon 43 is also in a state of maximum tension. The controller 1 can be, for example, a microcontroller unit (MCU), such as a single-chip microcomputer.

[0032] Step S2: The incremental encoder 2 of the drive motor 3 records the first number of revolutions R1 corresponding to the index finger 4 from the power-on posture to the maximum grip posture.

[0033] During the process of the index finger 4 moving from a power-off gripping position to the maximum gripping position, the drive motor 3 will rotate forward from a stationary state and then stop rotating when the tendon 43 is also at its maximum tension. Correspondingly, the incremental encoder 2 will record the number of rotations of the drive motor 3, denoted as the first rotation number R1. The first rotation number R1 will be synchronously sent by the incremental encoder 2 to the controller 1 so that the controller 1 can perform subsequent calculations. The incremental encoder 2 can be electrically connected to the controller 1 via wired or wireless means. To ensure no signal delay, this implementation uses a wired connection.

[0034] Step S3: Using the pre-stored maximum number of revolutions R of the incremental encoder 2 max Subtract the first number of revolutions R1 to obtain the second number of revolutions R2. Here, the maximum number of revolutions R of the incremental encoder 2 is... maxThe second number of revolutions R2 is the number of revolutions recorded by the incremental encoder 2 when the index finger 4 is gripped from the original zero position to the maximum grip position. This second number of revolutions R2 can represent the number of revolutions that the incremental encoder 2 needs to make when the index finger 4 is gripped from the original zero position to the power-off position.

[0035] Controller 1 can pre-store the maximum stroke of the drive motor 3 in the forward direction when the index finger 4 moves from the original zero position to the maximum grip position, which is also the maximum number of revolutions of the incremental encoder 2, i.e., the aforementioned R. max Based on this, after controller 1 obtains the first revolution count R1, it sets the maximum revolution count R of incremental encoder 2. max By subtracting the difference obtained from the first number of revolutions R1, which is the second number of revolutions R2 mentioned above, we can deduce the number of revolutions that the incremental encoder 2 has made in the process of the index finger 4 in the power-off posture relative to the original zero posture, and thus deduce the posture information maintained by the index finger 4 in the power-off posture.

[0036] As described above, it can be seen that regardless of the index finger 4's posture when power is suddenly lost, as long as power is restored to the index finger 4, firstly, the controller 1 controls the drive motor 3 to drive the index finger 4 from the power-off posture to the maximum grip posture, thus obtaining the first number of revolutions R1. Then, the maximum number of revolutions R1 of the incremental encoder pre-stored in the controller 1 is obtained. max Subtracting the first rotation number R1 allows us to calculate the number of rotations the incremental encoder 2 needs to make when the index finger 4 moves from its original zero-position grip to a power-off position, i.e., R2. This allows us to determine the bending posture of the index finger 4 when the power is off. Thus, regardless of when or how many times the index finger 4 is powered off, once the power is restored, this method can always be used to calculate the actual number of rotations the incremental encoder 2 should have recorded for the index finger 4 in its power-off position, providing a reliable and accurate position reference for subsequent index finger 4 control. Although this embodiment uses the index finger 4 as an example for illustration, it can be understood that the other fingers of the dexterous hand can also use the above method to determine the finger posture after power failure and power restoration. When all the fingers of the dexterous hand adopt this finger posture determination method, no matter when or how many times the dexterous hand is powered off, as long as the power is restored, the dexterous hand can always smoothly complete the unfinished grasping action. When robots, especially humanoid robots, adopt this dexterous hand, it will be beneficial to the application and promotion of the robot.

[0037] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining finger posture, characterized in that, The application to the situation where the finger is powered off and then powered on again includes the following steps: When the drive motor of the finger is powered on again after a power outage, the drive motor is controlled to drive the finger to perform a gripping action, so that the finger is gripping from the power-on posture to the maximum gripping posture of the finger; The incremental encoder of the drive motor records the number of rotations of the finger from the power-on posture to the maximum grip posture. The second number of revolutions is obtained by subtracting the first number of revolutions from the maximum number of revolutions of the incremental encoder; Wherein, the maximum number of revolutions of the incremental encoder is the number of revolutions recorded by the incremental encoder when the finger is gripped from its original zero position to its maximum grip position; the second number of revolutions represents the number of revolutions that the incremental encoder needs to make when the finger is gripped from the original zero position to the re-powered position.

2. The finger posture determination method according to claim 1, characterized in that, The maximum number of revolutions of the incremental encoder is pre-stored.

3. The finger posture determination method according to claim 2, characterized in that, The maximum number of revolutions of the incremental encoder is pre-stored in the controller electrically connected to the incremental encoder.

4. The finger posture determination method according to claim 3, characterized in that, The controller is connected to the incremental encoder via a wired connection.

5. The finger posture determination method according to claim 3, characterized in that, The first number of revolutions is sent to the controller by the incremental encoder.

6. The finger posture determination method according to claim 3 or 5, characterized in that, The second number of revolutions is calculated by the controller.

7. The finger posture determination method according to claim 1, characterized in that, The controller includes a microcontroller.

8. The finger posture determination method according to claim 1, characterized in that, The finger performs the gripping action under the driving action of the forward rotation of the drive motor, and under the driving action of the reverse rotation of the drive motor, the finger returns to its initial state by the reset action of its elastic reset member.

9. A dexterous hand, characterized in that, It includes at least one finger, wherein the finger is determined using the finger posture determination method as described in any one of claims 1-8.

10. A robot, characterized in that, Including the dexterous hand as described in claim 9.

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