Self-adaptive control method for hand joints of humanoid robot

Abstract

The invention discloses a self-adaptive control method for hand joints of a humanoid robot. The method comprises the following steps: firstly, determining a position vector of a geometric center point of a grabbing surface by using pressure sensors mounted at the tail ends of fingers; calculating expected pressure and actual pressure vectors of the tail ends of the fingers; and calculating a finger end point position correction vector by using the contact elastic coefficient matrix to realize self-adaptive correction of the end point position. The method has the advantages that objects can be grabbed in a self-adaptive mode according to the set contact elastic coefficient only through the pressure sensors installed at the tail ends of the fingers, the flexibility is adjustable, the algorithm is simple, and the method is suitable for various humanoid robots with different finger numbers.

Description

Technical Field

[0001] The present invention relates to the field of robotics and automation, and in particular to an adaptive control method for hand joints of a humanoid robot. Background Art

[0002] Humanoid robots belong to a class of robotic systems with highly complex kinematic models and interactions with the environment. As the number of fingers increases, position control becomes increasingly complex and it is difficult to adjust the contact force with the environment. Therefore, an adaptive control method for humanoid robot hand joints is urgently needed to achieve dual control of the position and force of each finger. Summary of the invention

[0003] The problem to be solved by the present invention is to provide an adaptive control method for the hand joints of a humanoid robot.

[0004] In order to solve the above problems, the present invention provides an adaptive control method for the hand joints of a humanoid robot. In order to achieve the above objectives, the technical solution adopted by the present invention to solve the technical problems is:

[0005] An adaptive control method for a humanoid robot hand joint comprises: step S1: closing the palm; step S2: calculating the position vector of the geometric center point of the grasping surface; step S3: calculating the expected pressure and the actual pressure vector of the end of each finger in the palm; step S4: calculating the correction vector of the position of the end point of the finger; step S5: compensating the correction vector to the control system;

[0006] The center point of the rotation joint connecting the i-th finger and the palm of the humanoid robot hand in step S1 is A. i (i=1,2,…,n), the end point of the i-th finger is B i , the palm center defines the coordinate system O-xyz, n represents the number of fingers; given the end point B of the i-th finger i The expected position instruction The expected rotation angle of each finger driving joint motor is calculated by position inverse solution, and closed-loop control is implemented to make the palm perform a closing movement;

[0007] Step S2 includes installing at each finger end point B during the execution of step S1. i The pressure sensor collects pressure signals in real time And use the following formula to calculate the judgment factor λ:

[0008]

[0009] As a further improvement of the present invention, step S3 is to determine the gravity f of the grasped object. gThe expected pressure vector at the end point of the i-th finger is given by the friction coefficient μ with the surface of the grasped object. The actual pressure vector for:

[0010]

[0011] As a further improvement of the present invention, step S4 sets the contact elasticity coefficient matrix K of the finger end point according to actual needs, and then calculates the contact elasticity coefficient matrix K of the i-th finger end point B using the following formula: i Correction vector for position:

[0012]

[0013] As a further improvement of the present invention, step S5 uses the following formula to calculate the end point B of the i-th finger: i Corrected position vector:

[0014]

[0015] The position calculation result of the above formula is inversely solved to calculate the expected rotation angle of each finger driving joint motor, and closed-loop control is implemented to enable the palm to adaptively grasp the object.

[0016] As a further improvement of the present invention, in step S2, when λ=0 is satisfied, step S1 is continued to be executed; when λ≠0 is satisfied, the position correct solution is used to calculate the end point of the i-th finger as B i The position vector is r Bi , and then use the following formula to calculate the position vector of the geometric center point C of the grasping surface:

[0017]

[0018] As a further improvement of the present invention, in step S4, k x , k y , k z Represents the contact elastic coefficient along the three directions of the coordinate system O-xyz.

[0019] The beneficial effects of adopting the above-mentioned technical solution of the present application include: only using the pressure sensor installed at the end of the finger to adaptively grasp the object according to the set contact elasticity coefficient, flexible and adjustable, simple algorithm, and suitable for various types of humanoid robots with different numbers of fingers. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a schematic diagram of robot hand joints and grasping positions according to an embodiment of the present invention;

[0022] Figure 2 It is an adaptive control block diagram of an implementation mode of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with specific embodiments:

[0024] The present invention provides an adaptive control method for a humanoid robot hand joint, comprising the following steps:

[0025] Step S1: Implement palm closure.

[0026] Let the center point of the rotation joint connecting the i-th finger and the palm of the humanoid robot be A i (i=1,2,…,n), the end point of the i-th finger is B i , the palm center defines the coordinate system O-xyz, n represents the number of fingers. Given the end point B of the i-th finger i The expected position instruction The expected rotation angles of the motors of each finger driving joint are calculated through position inverse solution, and closed-loop control is implemented to make the palm perform a closing movement.

[0027] Step S2: Calculate the position vector of point C, the geometric center of the grasping surface.

[0028] During the execution of step S1, the finger end point B is installed i The pressure sensor collects pressure signals in real time And use the following formula to calculate the judgment factor λ:

[0029]

[0030] When λ=0 is satisfied, continue to execute step S1; when λ≠0 is satisfied, use the position solution to calculate the end point of the i-th finger as B i The position vector is r Bi , and then use the following formula to calculate the position vector of the geometric center point C of the grasping surface:

[0031]

[0032] Step S3: Calculate the expected pressure and actual pressure vector at the end of each finger.

[0033] Given the known gravity f on the grasped object g The expected pressure vector at the end point of the i-th finger is given by the friction coefficient μ with the surface of the grasped object. The actual pressure vector for:

[0034]

[0035] Step S4: Calculate the correction vector of the finger end point position.

[0036] Set the contact elastic coefficient matrix K of the finger end point according to actual needs, and then calculate the i-th finger end point B using the following formula: i Correction vector for position:

[0037]

[0038] In the formula, k x , k y , k z Represents the contact elastic coefficient along the three directions of the coordinate system O-xyz.

[0039] Step S5: Compensate the correction vector to the control system.

[0040] The end point B of the i-th finger is calculated using the following formula: i Corrected position vector:

[0041]

[0042] The position calculation result of the above formula is inversely solved to calculate the expected rotation angle of each finger driving joint motor, and closed-loop control is implemented to enable the palm to adaptively grasp the object.

[0043] like Figure 1 As shown, the palm includes five fingers, each of which is a double-link mechanism hinged to each other. One end of each finger is hinged to the palm surface.

[0044] like Figure 2 As shown, the position inverse algorithm drives the joint motor to the desired rotation angle, and then uses the PID feedback controller, servo drive, motor in sequence to finally drive the joint of the manipulator.

[0045] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. An adaptive control method for a humanoid robot hand joint, characterized in that: include: Step S1; Implement palm closure; Step S2; Calculate the position vector of the geometric center point of the grasping surface; Step S3: Calculate the expected pressure and actual pressure vector at the end of each finger in the palm; Step S4: Calculate the correction vector of the finger end point position; Step S5: Compensating the correction vector to the control system; Wherein, the center point of the rotation joint connecting the i-th finger of the humanoid robot hand and the palm in step S1 is A i (i=1,2,…,n), the end point of the i-th finger is B i , the center of the palm defines the coordinate system O-xyz, n represents the number of fingers; Given the end point B of the i-th finger i The expected position instruction The expected rotation angle of each finger driving joint motor is calculated by position inverse solution, and closed-loop control is implemented to make the palm perform a closing movement; The step S2 includes installing at each finger end point B during the execution of step S1. i The pressure sensor collects pressure signals in real time And use the following formula to calculate the judgment factor λ:

2. The method for adaptive control of hand joints of a humanoid robot according to claim 1, characterized in that: In step S3, when the gravity f of the grasped object is known, g The expected pressure vector at the end point of the i-th finger is given by the friction coefficient μ with the surface of the grasped object. The actual pressure vector for:

3. The adaptive control method for the hand joints of a humanoid robot according to claim 2, characterized in that: The step S4 sets the contact elastic coefficient matrix K of the finger end point according to actual needs, and then calculates the contact elastic coefficient matrix K of the i-th finger end point B using the following formula: i Correction vector for position:

4. The adaptive control method for the hand joints of a humanoid robot according to claim 3, characterized in that: The step S5 calculates the end point B of the ith finger using the following formula: i Corrected position vector: The position calculation result of the above formula is inversely solved to calculate the expected rotation angle of each finger driving joint motor, and closed-loop control is implemented to enable the palm to adaptively grasp the object.

5. The adaptive control method for the hand joints of a humanoid robot according to claim 1, characterized in that: In step S2, when λ=0 is satisfied, step S1 is continued; when λ≠0 is satisfied, the position correct solution is used to calculate the end point of the i-th finger as B i The position vector is r Bi , and then use the following formula to calculate the position vector of the geometric center point C of the grasping surface:

6. The method for adaptive control of hand joints of a humanoid robot according to claim 3, characterized in that: In the step S4, k x , k y , k z Represents the contact elastic coefficient along the three directions of the coordinate system O-xyz.

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