End effector with force feedback and grabbing control method

Abstract

The invention provides an end effector with force feedback and a grabbing control method. The end effector comprises an arc-shaped seat, a palm is arranged at the center of the bottom end of the arc-shaped seat, and a laser distance measuring sensor is arranged on the side portion of the palm; two or more circular guide rails are fixed to the side portion of the arc-shaped base, and the surfaces of the circular guide rails are slidably connected with a left sliding block and a right sliding block. A steering engine is arranged on the side portion of the arc-shaped base and connected with the left sliding block and the right sliding block through a linkage assembly. The steering engine drives the left sliding block and the right sliding block to be separated or close through the linkage assembly. A left finger is arranged at the bottom end of the left sliding block, and a right finger is arranged at the bottom end of the right sliding block; the left finger and the right finger have the same structure, and the right finger comprises a finger body and a force sensor; a force sensor is arranged on the side portion of the finger body. According to the invention, the laser ranging sensor and the force sensor are simultaneously adopted to detect the target position grabbed by the fingers and the clamping force, so that the grabbing action of the gripper can be accurately controlled, and the picking quality and efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of end effectors, and in particular to an end effector with force feedback and a grasping control method. Background Art

[0002] The end effector, commonly known as a manipulator or robot hand, is a tool or device mounted at the end of a robot arm to perform specific tasks such as grasping, handling, assembly, welding, painting, cutting, inspection, etc. The design and function of the end effector are very diverse, ranging from simple grippers to complex multi-finger dexterous hands. Their flexibility and adaptability are key components of the robotic system. With the development of agriculture, various manipulators are applied to the sowing and picking processes of agriculture. Using manipulators to pick mushrooms is one of the important applications.

[0003] Existing manipulators are generally driven by hydraulic cylinders, pneumatic cylinders, etc., and there are also motors that drive the opening and closing of the manipulators. However, mushrooms are fragile and easily damaged. When using a manipulator to pick mushrooms, excessive force can easily damage the mushrooms, and too little force can make it difficult to successfully complete the picking of mushrooms. Existing manipulator drive components are too rigid and have limited accuracy during use, which can easily cause damage to the mushrooms, and the picking efficiency is low. Therefore, there is an urgent need for an end effector for mushroom picking to pick mushrooms. Summary of the invention

[0004] In view of the deficiencies in the prior art, an object of the present invention is to provide an end effector with force feedback and a grasping control method, which can solve the existing problems.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] The present invention is realized by the following technical scheme: comprising an arc seat, a palm is arranged at the center of the bottom end of the arc seat, and a laser distance sensor is arranged on the side of the palm; the laser distance sensor is used to detect the distance between the target object and the actuator; two or more circular guide rails are fixed on the side of the arc seat, and the surface of the circular guide rails is slidably connected with a left sliding block and a right sliding block; a steering engine is arranged on the side of the arc seat, and the steering engine connects the left sliding block and the right sliding block through a linkage component; the steering engine drives the left sliding block and the right sliding block to be separated or close to each other through the linkage component; a left finger is arranged at the bottom end of the left sliding block, and a right finger is arranged at the bottom end of the right sliding block; the left finger and the right finger have the same structure, and the right finger includes a finger body and a force sensor; a force sensor is arranged on the side of the finger body, and the force sensor is used to monitor the clamping force of the clamped target object.

[0007] Furthermore, the finger body adopts an inward-concave structure, and the finger body includes a flexible silicone finger sleeve, a lower end of the finger and an upper end of the finger; the inner side of the upper end of the finger is connected to the lower end of the finger through a force sensor, and the lower end of the finger is connected to the flexible silicone finger sleeve; the flexible silicone finger sleeve adopts an arc spoon shape.

[0008] Furthermore, fixing holes are provided at both ends of the force sensor, and the force sensor is connected to the lower end of the finger and the upper end of the finger through the fixing holes and the fixing bolts.

[0009] Furthermore, the linkage assembly includes a straight rudder arm, a right-side arc-shaped connecting rod and a left-side arc-shaped connecting rod; the servo shaft of the servo is connected to the center of the straight rudder arm, and connecting holes are provided on the surface of the straight rudder arm; the two sides of the straight rudder arm are rotatably connected to the right-side arc-shaped connecting rod and the left-side arc-shaped connecting rod through the connecting holes; the right-side arc-shaped connecting rod is connected to the right sliding block, and the left-side arc-shaped connecting rod is connected to the left sliding block.

[0010] Furthermore, a plurality of connecting holes are provided on both sides of the surface of the straight rudder arm, and the connecting holes on the surface of the straight rudder arm are connected to the right arc connecting rod and the left arc connecting rod through an axis; a right connecting rod is fixed to the side of the right sliding block, and the right connecting rod is rotatably connected to the right arc connecting rod through an axis; a left connecting rod is fixed to the side of the left sliding block, and the left connecting rod is rotatably connected to the left arc connecting rod through an axis.

[0011] Furthermore, the arc seat adopts a semi-disc structure, and the top end of the arc seat extends upward to form a mounting plate; two extending plates are vertically provided on the side of the arc seat, and two circular guide rails are fixed between the two extending plates.

[0012] Furthermore, a fixing rod is provided on the side of the arc seat, and the steering gear shaft of the steering gear is rotatably connected to the fixing rod; the bottom end of the fixing rod is fixed to the palm, and the palm adopts a rectangular top and a disc structure at the bottom; a fixing groove is opened on the side of the palm, and a laser ranging sensor is installed in the fixing groove; a detection hole passes through the inside of the palm, and the detection part of the laser ranging sensor passes through the detection hole.

[0013] A grasping control method of an end effector with force feedback, the method comprising:

[0014] S1. Setting the parameters of the end effector, including: setting the initial angle a of the servo, the maximum setting angle b of the servo, the minimum setting angle c of the servo, the actuator finger opening and closing trigger distance x, the closing trigger distance y, the minimum clamping force i, the maximum clamping force j, and the servo at the initial angle a;

[0015] S2. The actuator moves downward from the top to approach the target object to be clamped, and the laser ranging sensor measures the digital distance between the finger and the target object in real time;

[0016] S3, when the laser ranging sensor detects for the first time that the digital value of the distance between the finger and the target object is less than or equal to the finger trigger distance x, the servo is controlled to rotate counterclockwise to the initial angle (a+2);

[0017] S4. When the laser ranging sensor detects for the second time that the digital value of the distance between the finger and the target object is greater than or equal to the closed trigger distance y, the servo is controlled to rotate clockwise to control the left and right fingers to contract inward. During the contraction process, the force sensors on the sides of the two fingers detect the clamping force in real time and measure the digital quantity. When the clamping force is less than the minimum clamping force value i, the servo is controlled to rotate clockwise by an angle of 2. When the clamping force is greater than the maximum clamping force value j, the servo is controlled to rotate counterclockwise by an angle of 2. The clamping force is adjusted to between the minimum clamping force value i and the maximum clamping force value j to complete the grasping.

[0018] Compared with the prior art, the beneficial effects of the present invention include:

[0019] The end effector of the present invention utilizes a servo motor to drive two sliding blocks to move through a linkage component, thereby driving the left and right fingers to move and open. The linkage component is used to convert the rotational force into a driving force for left and right movement, which is highly accurate and gentler, and can clamp the mushrooms and complete the picking without causing damage to the mushrooms. The present invention has the characteristics of simple structure and high picking efficiency, and at the same time, a TOF laser ranging sensor and a force sensor are used to detect the target position and clamping force of the fingers, which can accurately control the grasping action of the claws and improve the picking quality and efficiency. In addition, the left and right fingers of the present invention adopt arc-shaped inner grooves and spoon-shaped tips, which can reduce damage to the mushrooms, and can be inserted into the gaps of dense mushrooms to realize human-like picking of dense mushrooms, with high picking quality and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them:

[0021] Figure 1 It is a schematic diagram of the overall structure of the end effector with force feedback of the present invention;

[0022] Figure 2 It is a structural schematic diagram of another state of the end effector with force feedback in an embodiment of the present invention;

[0023] Figure 3 It is a schematic diagram of the side structure of an implementation case of the present invention.

[0024] Explanations in the figure: 1. Right finger; 101. Flexible silicone finger sleeve; 102. Lower end of finger; 103. Force sensor; 104. Upper end of finger; 2. Right sliding block; 201. Right connecting rod; 3. Right arc-shaped connecting rod; 4. Straight rudder arm; 401. Connecting hole; 5. Arc seat; 501. Extension plate; 502. Mounting plate; 6. Left arc-shaped connecting rod; 7. Fixed rod; 8. Left sliding block; 801. Left connecting rod; 9. Palm; 901. Fixed groove; 902. Detection hole; 10. Laser ranging sensor; 11. Circular guide rail; 12. Servo; 13. Left finger. DETAILED DESCRIPTION

[0025] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the present invention.

[0026] An end effector with force feedback, for example, Figure 1 , Figure 2 and Figure 3 As shown, it includes an arc seat 5, a palm 9 is provided at the center of the bottom end of the arc seat 5, and a laser distance sensor 10 is provided on the side of the palm 9; specifically, a fixing rod 7 is provided on the side of the arc seat 5, and the steering gear shaft of the steering gear 12 is rotatably connected to the fixing rod 7; the bottom end of the fixing rod 7 fixes the palm 9, and the palm 9 adopts a rectangular top and a disc bottom structure; a fixing groove 901 is opened on the side of the palm 9, and the laser distance sensor 10 is installed in the fixing groove 901; the inside of the palm 9 passes through the detection hole 902, and the detection part of the laser distance sensor 10 passes through the detection hole 902; so that the laser distance sensor 10 completes the distance detection through the detection hole 902, and the laser distance sensor 10 adopts a TOF (Time of Flight) laser distance sensor; the laser distance sensor 10 is used to detect the distance between the target object and the actuator;

[0027] Two or more circular guide rails 11 are fixed to the side of the arc seat 5. Specifically, the arc seat 5 adopts a semi-disc structure, and the top of the arc seat 5 extends upward to form a mounting plate 502. A hole is opened on the mounting plate 502 to facilitate the connection of the actuator as a whole with external equipment; two outrigger plates 501 are vertically arranged on the side of the arc seat 5, and two circular guide rails 11 are fixed between the two outrigger plates 501. The surface of the circular guide rail 11 penetrates and is slidably connected with the left sliding block 8 and the right sliding block 2;

[0028] A steering engine 12 is provided on the side of the arc seat 5, and the steering engine 12 is connected to the left sliding block 8 and the right sliding block 2 through a linkage assembly; the steering engine 12 drives the left sliding block 8 and the right sliding block 2 to be separated or close to each other through the linkage assembly; specifically, the linkage assembly includes a straight rudder arm 4, a right arc connecting rod 3 and a left arc connecting rod 6; the steering engine shaft of the steering engine 12 is connected to the center of the straight rudder arm 4, and connecting holes 401 are provided on the surface of the straight rudder arm 4; the two sides of the straight rudder arm 4 are rotatably connected to the right arc connecting rod 3 and the left arc connecting rod 6 through the connecting holes 401; the right arc connecting rod 3 is connected to the right sliding block 2, and the left arc connecting rod 6 is connected to the left sliding block 8. Exemplarily, a plurality of connecting holes 401 are provided on both sides of the surface of the straight rudder arm 4, and the connecting holes 401 on the surface of the straight rudder arm 4 are connected to the right arc connecting rod 3 and the left arc connecting rod 6 through an axis; a right connecting rod 201 is fixed to the side of the right sliding block 2, and the right connecting rod 201 is connected to the right arc connecting rod 3 through an axis rotation; a left connecting rod 801 is fixed to the side of the left sliding block 8, and the left connecting rod 801 is connected to the left arc connecting rod 6 through an axis rotation.

[0029] A left finger 13 is provided at the bottom end of the left sliding block 8, and a right finger 1 is provided at the bottom end of the right sliding block 2; the left finger 13 and the right finger 1 have the same structure, and the right finger 1 includes a finger body and a force sensor 103; a force sensor 103 is provided on the side of the finger body, and the force sensor 103 is used to monitor the clamping force of the clamped target object. Among them, the finger body adopts a concave structure, and the finger body includes a flexible silicone finger sleeve 101, a finger lower end 102 and a finger upper end 104; the inner side of the finger upper end 104 is connected to the finger lower end 102 through the force sensor 103, and the finger lower end 102 is connected to the flexible silicone finger sleeve 101; the flexible silicone finger sleeve 101 adopts an arc spoon shape. Fixing holes are provided at both ends of the force sensor 103, and the force sensor 103 is connected to the finger lower end 102 and the finger upper end 104 through the fixing holes and the fixing bolts.

[0030] The end effector of the present invention has force feedback. When in use, the laser distance sensor 10 is first used to detect the distance between the actuator and the target mushroom, and the actuator is controlled to move downward from the upper end to continuously approach the mushroom according to the detected distance. After the laser distance sensor 10 detects that the first preset distance has been reached, the steering gear 12 is started to rotate counterclockwise. When the steering gear 12 rotates counterclockwise, it can drive the straight rudder arm 4 to rotate counterclockwise, thereby pushing the right sliding block 2 and the left sliding block 8 away from each other, so that the right finger 1 and the left finger 13 are away from each other. After the laser distance sensor 10 detects that the distance between the actuator and the target mushroom has reached the second preset distance, the left finger 13 and the right finger 1 are on both sides of the mushroom, and the steering gear 12 is started again to make the left finger 13 and the right finger 1 move away from each other. The servo 12 rotates clockwise. When the servo 12 rotates clockwise, it can drive the rudder arm 4 to rotate clockwise, thereby pulling the right sliding block 2 and the left sliding block 8 closer to each other, so that the right finger 1 and the left finger 13 are closer to each other. The right finger 1 and the left finger 13 are closer to each other to clamp the mushroom. During the clamping process, the force sensor 103 provided on the side of the right finger 1 and the left finger 13 is used to detect the clamping force, and the clamping force is adjusted according to the detected clamping force. For example, when the clamping force is less than the preset minimum clamping force value, the servo 12 is controlled to rotate clockwise by an angle of 2. When the clamping force is greater than the preset maximum clamping force value, the servo 12 is controlled to rotate counterclockwise by an angle of 2, and the clamping force is adjusted to a value between the preset minimum clamping force value i and the maximum clamping force value j to complete the grasping.

[0031] The end effector of the present invention utilizes a servo motor to drive two sliding blocks to move through a linkage component, thereby driving the left and right fingers to move and open. The linkage component is used to convert the rotational force into a driving force for left and right movement, which is highly accurate and gentler, and can clamp the mushrooms and complete the picking without causing damage to the mushrooms. The present invention has the characteristics of simple structure and high picking efficiency, and at the same time, a TOF laser ranging sensor and a force sensor are used to detect the target position and clamping force of the fingers, which can accurately control the grasping action of the claws and improve the picking quality and efficiency. In addition, the left and right fingers of the present invention adopt arc-shaped inner grooves and spoon-shaped tips, which can reduce damage to the mushrooms, and can be inserted into the gaps of dense mushrooms to realize human-like picking of dense mushrooms, with high picking quality and high efficiency.

[0032] In the present invention, TOF (Time of Flight) laser ranging sensor is a sensor that measures distance based on the principle of light flight time. This sensor emits a pulse light signal and receives the light signal reflected from the target object. By calculating the time difference of the light signal going back and forth, the distance between the sensor and the target object is calculated. A servo motor, also known as a servo motor, is a closed-loop controlled motor system that is mainly used to provide precise rotation angle or position control. It consists of a motor, a reduction gear set, a position feedback element (usually a potentiometer or encoder) and a control circuit.

[0033] The present invention also provides a grasping control method of an end effector with force feedback, the method comprising the following steps:

[0034] Step 1, setting the parameters of the end effector, including: setting the initial angle a of the servo 12, the maximum setting angle b of the servo 12, the minimum setting angle c of the servo 12, the actuator finger opening and closing trigger distance x, the closing trigger distance y, the minimum clamping force i, the maximum clamping force j, and the servo 12 is at the initial angle a;

[0035] Step 2: The actuator as a whole moves downward from the top to approach the target object to be clamped, and the laser ranging sensor 10 measures the digital value of the distance between the finger and the target object in real time;

[0036] Step 3, when the laser ranging sensor 10 detects for the first time that the digital value of the distance between the finger and the target object is less than or equal to the finger trigger distance x, it controls the servo 12 to rotate counterclockwise to the initial angle a+2; (Note: The initial setting value of a certain angle is composed of a variable (a) plus 2 degrees. Here, (a) can represent any known or unknown angle value, and "(a+2)" means that 2 degrees are added on this basis).

[0037] Step 4. When the laser ranging sensor 10 detects for the second time that the digital value of the distance between the finger and the target object is greater than or equal to the closed trigger distance y, the servo 12 is controlled to rotate clockwise to control the left finger 13 and the right finger 1 to contract inward. During the contraction process, the force sensors 103 on the sides of the two fingers detect the clamping force in real time and measure the digital quantity. When the clamping force is less than the minimum clamping force value i, the servo 12 is controlled to rotate clockwise by an angle of 2. When the clamping force is greater than the maximum clamping force value j, the servo 12 is controlled to rotate counterclockwise by an angle of 2. The clamping force is adjusted to between the minimum clamping force value i and the maximum clamping force value j to complete the grasping.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0039] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0041] The technical scope of the present invention is not limited to the contents in the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. An end effector with force feedback, characterized in that: The invention comprises an arc seat (5), wherein a palm (9) is provided at the center of the bottom end of the arc seat (5), and a laser distance sensor (10) is provided on the side of the palm (9); the laser distance sensor (10) is used to detect the distance between the target object and the actuator; two or more circular guide rails (11) are fixed on the side of the arc seat (5), and the surface of the circular guide rail (11) is slidably connected with a left sliding block (8) and a right sliding block (2); a steering engine (12) is provided on the side of the arc seat (5), and the steering engine (12) is connected to the left sliding block (8) through a linkage component. 8) and a right sliding block (2); the servo (12) drives the left sliding block (8) and the right sliding block (2) to move away from or closer to each other through a linkage assembly; a left finger (13) is provided at the bottom end of the left sliding block (8), and a right finger (1) is provided at the bottom end of the right sliding block (2); the left finger (13) and the right finger (1) have the same structure, and the right finger (1) includes a finger body and a force sensor (103); a force sensor (103) is provided on the side of the finger body, and the force sensor (103) is used to monitor the clamping force of the clamped target object.

2. The end effector with force feedback according to claim 1, characterized in that: The finger body adopts an inward concave structure, and the finger body comprises a flexible silicone finger sleeve (101), a finger lower end (102) and a finger upper end (104); the inner side of the finger upper end (104) is connected to the finger lower end (102) via a force sensor (103), and the finger lower end (102) is connected to the flexible silicone finger sleeve (101); the flexible silicone finger sleeve (101) adopts an arc spoon shape.

3. The end effector with force feedback according to claim 2, characterized in that: Fixing holes are provided at both ends of the force sensor (103), and the force sensor (103) is connected to the lower end (102) of the finger and the upper end (104) of the finger through the fixing holes and the fixing bolts.

4. The end effector with force feedback according to any one of claims 1 to 3, characterized in that: The linkage assembly comprises a straight rudder arm (4), a right side arc-shaped connecting rod (3) and a left side arc-shaped connecting rod (6); the rudder shaft of the servo (12) is connected to the center of the straight rudder arm (4), and the surface of the straight rudder arm (4) is provided with connection holes (401); the two sides of the straight rudder arm (4) are rotatably connected to the right side arc-shaped connecting rod (3) and the left side arc-shaped connecting rod (6) through the connection holes (401); the right side arc-shaped connecting rod (3) is connected to the right sliding block (2), and the left side arc-shaped connecting rod (6) is connected to the left sliding block (8).

5. The end effector with force feedback according to claim 4, characterized in that: A plurality of connection holes (401) are provided on both sides of the surface of the straight rudder arm (4), and the connection holes (401) on the surface of the straight rudder arm (4) are connected to a right arc-shaped connecting rod (3) and a left arc-shaped connecting rod (6) via an axis; a right connection rod (201) is fixed to the side of the right sliding block (2), and the right connection rod (201) is connected to the right arc-shaped connecting rod (3) via an axis; a left connection rod (801) is fixed to the side of the left sliding block (8), and the left connection rod (801) is connected to the left arc-shaped connecting rod (6) via an axis.

6. The end effector with force feedback according to any one of claims 1 to 3, characterized in that: The arc seat (5) adopts a semi-circular disc structure, and the top end of the arc seat (5) extends upward to form a mounting plate (502); two extending plates (501) are vertically arranged on the side of the arc seat (5), and two circular guide rails (11) are fixed between the two extending plates (501).

7. The end effector with force feedback according to any one of claims 1 to 3, characterized in that: A fixing rod (7) is provided on the side of the arc seat (5), and the steering gear shaft of the steering gear (12) is rotatably connected to the fixing rod (7); a palm (9) is fixed at the bottom end of the fixing rod (7), and the palm (9) has a rectangular top and a disc-shaped bottom; a fixing groove (901) is provided on the side of the palm (9), and a laser distance sensor (10) is installed in the fixing groove (901); a detection hole (902) is passed through the inside of the palm (9), and a detection part of the laser distance sensor (10) passes through the detection hole (902).

8. A grasping control method for an end effector with force feedback, characterized in that: The method comprises: S1, setting parameters of the end effector, including: setting the initial angle a of the servo (12), the maximum setting angle b of the servo (12), the minimum setting angle c of the servo (12), the actuator finger opening and closing trigger distance x, the closing trigger distance y, the minimum clamping force i, the maximum clamping force j, and the servo (12) being at the initial angle a; S2, the actuator as a whole moves downward from the top to approach the target object to be clamped, and the laser distance sensor (10) measures the digital value of the distance between the finger and the target object in real time; S3, when the laser distance measuring sensor (10) detects for the first time that the digital value of the distance between the finger and the target object is less than or equal to the finger trigger distance x, the steering engine (12) is controlled to rotate counterclockwise to the initial angle (a+2); S4. When the laser distance sensor (10) detects for the second time that the digital value of the distance between the finger and the target object is greater than or equal to the closed trigger distance y, the steering engine (12) is controlled to rotate clockwise to control the left finger (13) and the right finger (1) to retract inward. During the retraction process, the force sensors (103) on the sides of the two fingers detect the clamping force in real time and measure the digital quantity. When the clamping force is less than the minimum clamping force value i, the steering engine (12) is controlled to rotate clockwise by an angle of 2. When the clamping force is greater than the maximum clamping force value j, the steering engine (12) is controlled to rotate counterclockwise by an angle of 2. The clamping force is adjusted to between the minimum clamping force value i and the maximum clamping force value j, thereby completing the grasping.

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