Flexible control end face ratchet active rotation locking mechanism and flexible control method thereof

Abstract

The invention discloses a compliant control end face ratchet active rotation locking mechanism and a compliant control method thereof.End face ratchets are distributed on the opposite sides of a fixed ratchet and a sliding ratchet and used for limiting rotation in the direction when the fixed ratchet and the sliding ratchet are meshed with each other, and round holes are formed in the center of the fixed ratchet and the center of the sliding ratchet; a hole is formed in the center of the motor, mounting surfaces are positioned on two sides of the motor, one side is matched with the output connecting rod, the other side is matched with the sleeve connecting rod, and the output connecting rod and the sleeve connecting rod form a rotating mechanism through the motor; square sliding grooves are formed in the two sides of the sleeve connecting rod, a round through hole is formed in the upper surface, and a round hole is formed in the center of the bottom. A protrusion is arranged on the end face of the end cover and matched with a groove in the end face of the sleeve connecting rod, and fixing is achieved. The structure is simple, the response speed is high, and the effects of compliant control and rotation locking can be achieved under the small size limitation.

Description

Technical Field

[0001] The invention belongs to the technical field of robots, and in particular relates to a compliant control end face ratchet active rotation locking mechanism and a compliant control method thereof. Background Art

[0002] Motor-driven joint rotation is a very important design in the field of robotics. Different stiffnesses need to be set for the rotational joints to meet different mission objectives, which can be achieved by designing a compliant control algorithm. The joint locking mechanism is a common mechanical design used to lock or release the joint when needed, which can save energy and reduce joint wear. This mechanism is widely used in engineering, medical equipment, sports equipment and other fields. Currently, most common technologies use friction, ball pins, gears or hydraulic mechanisms for locking. Friction locking can cause wear of friction parts, high energy consumption and low precision after long-term use; ball pin locking has limited reliability, is prone to gaps or looseness after long-term use, and has poor flexibility; gear locking has a complex structure, occupies a large space, and has high design and processing costs; hydraulic systems have high manufacturing and maintenance costs, and the complex system has the risk of oil leakage, which affects reliability and environmental safety. The heavy weight is not suitable for applications with high lightweight requirements. Summary of the Invention

[0003] The object of the present invention is to provide a compliant control end face ratchet active rotation locking mechanism and a compliant control method thereof, which realizes the active compliant control rotation and locking functions of the joint and reduces the space occupancy rate.

[0004] In order to achieve the purpose of the present invention, on the one hand, the present invention provides a compliant control end face ratchet active rotation locking mechanism, wherein end face ratchets are distributed on the opposite side of the fixed ratchet and the sliding ratchet, which are used to limit the rotation in the direction when they are engaged with each other, and circular holes are provided in the centers of the fixed ratchet and the sliding ratchet; the motor has a hole in the center, and the mounting surfaces are located on both sides of the motor, one side of which cooperates with the output connecting rod and the other side cooperates with the sleeve connecting rod, and a rotation mechanism is formed between the output connecting rod and the sleeve connecting rod through the motor;

[0005] The sleeve connecting rod has square slots on both sides, a circular through hole on the upper surface, and a circular hole in the center of the bottom;

[0006] There is a protrusion on the end surface of the end cover, and a circular through hole is opened in the center of the protrusion, which cooperates with the groove on the end surface of the sleeve connecting rod to achieve fixation.

[0007] When the arcuate end face ratchet of the sliding ratchet is meshed with the arcuate end face ratchet of the fixed ratchet, a gap is left in the center of the sliding ratchet and the fixed ratchet for fixing the memory alloy spring.

[0008] One end of the first memory alloy spring is fixed to the circular hole in the center of the end cover, and the other end is fixed to the circular hole in the center of the sliding ratchet; one end of the second memory alloy spring is fixed to the circular hole in the center of the sliding ratchet, and the other end is fixed to the circular hole in the center of the fixed ratchet, and it is ensured that the end face ratchets on the surfaces of the sliding ratchet and the fixed ratchet can engage with each other when the memory alloy spring contracts.

[0009] When the first memory alloy spring is energized, the first memory alloy spring contracts, the fixed ratchet and the end face ratchet on the sliding ratchet surface are separated, and the rotating shaft can rotate freely; when the second memory alloy spring is energized, the second memory alloy spring contracts, the fixed ratchet and the end face ratchet on the sliding ratchet surface are engaged, limiting the rotation of the rotating shaft in the force direction.

[0010] The output connecting rod has a protruding shaft and a small hole at its center. During installation, the protruding shaft passes through the center of the motor and the hole at the bottom of the sleeve connecting rod, and cooperates with the fixed ratchet mounting surface.

[0011] The protruding shaft end is provided with a groove, which cooperates with the protrusion in the fixing ratchet mounting groove to achieve fixation.

[0012] The sliding ratchet cooperates with the sliding groove of the sleeve connecting rod through the square sliding blocks on both sides to achieve axial movement in the sleeve.

[0013] On the other hand, the present invention also provides a method for compliantly controlling an end face ratchet active rotation locking mechanism, comprising the following steps:

[0014] Step 1: Obtain angle data and torque data through real-time feedback from the motor sensor;

[0015] Step 2: Input the angle data and the torque data into an admittance controller to obtain a desired angle error value;

[0016] Step 3: Input the calculated actual target angle into the PID position controller to complete the position control of the motor.

[0017] Compared with the prior art, the significant improvements of the present invention are: (1) the active rotation locking mechanism provided by the present invention has a compact structure and low space occupancy; it is easy to install, simple to use, and more portable; (2) the present invention drives the slider to move in two directions through two memory alloy springs to achieve the engagement and separation of the ratchet teeth, thereby achieving the purpose of locking the rotation and saving energy; (3) the present invention has a simple structure and a fast response speed, and can achieve smooth control and locking rotation effects within a smaller size limit.

[0018] In order to more clearly illustrate the functional characteristics and structural parameters of the present invention, further description is given below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 It is a combination diagram of the present invention;

[0021] Figure 2 It is an exploded structural diagram of the present invention;

[0022] Figure 3 2 is a schematic diagram of the output connecting rod structure of the present invention;

[0023] Figure 4 It is a schematic diagram of the motor structure of the present invention;

[0024] Figure 5 It is a schematic diagram of the sleeve connecting rod structure of the present invention;

[0025] Figure 6 It is a schematic diagram of the fixed ratchet structure of the present invention;

[0026] Figure 7 It is a schematic diagram of the sliding ratchet structure of the present invention;

[0027] Figure 8 It is a schematic diagram of the end cover structure of the present invention;

[0028] Figure 9 It is a block diagram of the compliant control method of the present invention.

[0029] The reference numerals in the figure are: 1-output connecting rod, 2-motor, 3-sleeve connecting rod, 4-fixed ratchet, 5-sliding ratchet, 6-end cover. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] The present invention is a flexible control end face ratchet active rotation locking mechanism, combined with Figure 1 and Figure 2 , the fixed ratchet 4 and the sliding ratchet 5 are provided with end face ratchets on the opposite side, which are used to limit the rotation direction when they are engaged with each other, and the centers of the fixed ratchet 4 and the sliding ratchet 5 are provided with circular holes;

[0032] Combine Figure 4 The motor 2 is hollow and is used to protrude the shaft through the output connecting rod. The motor mounting surface is located on both sides of itself, which are respectively connected to the output connecting rod and the sleeve connecting rod. The rotation of the motor drives the entire joint mechanism to rotate. One side cooperates with the output connecting rod 1 and the other side cooperates with the sleeve connecting rod 3. The output connecting rod 1 and the sleeve connecting rod 3 form a rotating mechanism through the motor.

[0033] Combine Figure 5 The sleeve connecting rod 3 has square grooves on both sides, a circular through hole on the upper surface, and a circular hole in the center of the bottom. Figure 8 There is a protrusion on the end face of the end cover 6, and a circular through hole is opened in the center of the protrusion, which is used to fix one end of the first memory alloy spring and also serves as a lead, cooperating with the groove on the end face of the sleeve connecting rod 3 to achieve fixation.

[0034] When the end face ratchet of the sliding ratchet 5 is engaged with the end face ratchet of the fixed ratchet 4 , a gap is left in the center of the sliding ratchet 5 and the fixed ratchet 4 for fixing the memory alloy spring.

[0035] Combine Figure 6 The fixed ratchet 4 is provided with an arc-shaped end face ratchet that meshes with the end face ratchet of the sliding ratchet 5 to achieve a locking function. One end of a first memory alloy spring is fixed to the circular hole in the center of the end cap 6, and the other end is fixed to the circular hole in the center of the sliding ratchet 5. One end of a second memory alloy spring is fixed to the circular hole in the center of the sliding ratchet 5, and the other end is fixed to the circular hole in the center of the fixed ratchet 4. When the memory alloy spring contracts, the end face ratchet of the sliding ratchet 5 and the end face ratchet of the fixed ratchet 4 can mesh with each other.

[0036] When the first memory alloy spring is energized, it contracts, the end face ratchets on the surfaces of the fixed ratchet 4 and the sliding ratchet 5 are separated, and the rotating shaft can rotate freely; when the second memory alloy spring is energized, it contracts, the end face ratchets on the surfaces of the fixed ratchet 4 and the sliding ratchet 5 are engaged, limiting the rotation of the rotating shaft in the direction of force.

[0037] Combine Figure 3 The output connecting rod 1 has a protruding shaft and a small hole in the center. During installation, the protruding shaft passes through the center of the motor 2 and the bottom hole of the sleeve connecting rod 3, and cooperates with the mounting surface of the fixed ratchet 4.

[0038] The protruding shaft end is provided with a groove, which cooperates with the protrusion in the mounting groove of the fixed ratchet 3 to achieve fixation.

[0039] Combine Figure 7Furthermore, the surface of the sliding ratchet 5 is provided with an arc-shaped end face ratchet, and a memory alloy spring fixing hole is opened in the center. The sliding ratchet 5 cooperates with the sliding groove of the sleeve connecting rod 3 through the square sliders on both sides to realize axial movement in the sleeve.

[0040] The present invention also provides a flexible control method for a flexible control end face ratchet active rotation locking mechanism, combined with Figure 9 , including the following steps:

[0041] Step 1: Obtain angle data and torque data through real-time feedback from the motor sensor;

[0042] Step 2: Input the angle data and the torque data into an admittance controller to obtain a desired angle error value;

[0043] The dynamic model of the admittance controller is:

[0044]

[0045] Among them, M is the mass parameter, which describes the inertia of the system; B is the damping parameter, which describes the damping characteristics of the system; K is the stiffness parameter, which describes the elastic characteristics of the system; θ, are joint angle, joint angular velocity and joint angular acceleration respectively; T is the external torque of the joint;

[0046] Discretize the above equation according to the time interval of Δt, rewrite the admittance related parameters, and determine the discrete form model of the admittance controller:

[0047]

[0048] Among them, k and k-1 represent the discrete time steps. and Δθ k Respectively represent the angular acceleration, angular velocity and angular error value at time k;

[0049] The error value is generated by the external torque T of the joint, that is, the actual target angle θ k The angle from the original expectation The relationship is as follows:

[0050]

[0051] Step 3: Input the calculated actual target angle into the PID position controller to complete the position control of the motor.

[0052] Example

[0053] A driving method for a compliantly controlled end face ratchet active rotation locking mechanism is as follows:

[0054] Shape memory alloys are driven by electric current, and the heat comes from the thermal effect of the current. The relationship model between the current, the temperature of the shape memory alloy spring, and the ambient temperature is as follows:

[0055]

[0056] Where I is the current, R is the resistance of the shape memory alloy, h is the convection heat transfer coefficient, T1 is the shape memory alloy temperature, T0 is the ambient temperature, T2 is the metal wire temperature, R λ is the contact thermal resistance between the shape memory alloy and the metal conductor. The shape memory alloy used has a phase transition temperature of 60°C. The model calculates the required drive current based on the ambient temperature, enabling real-time corrections at different ambient temperatures to ensure the performance of the shape memory alloy.

[0057] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0058] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A compliant control end face ratchet active rotation locking mechanism, characterized in that: End face ratchets are distributed on the opposite side of the fixed ratchet (4) and the sliding ratchet (5) for limiting the rotation in a certain direction when they are meshed with each other. Circular holes are provided in the centers of the fixed ratchet (4) and the sliding ratchet (5); The motor (2) has a hole in the center, and mounting surfaces are located on both sides of the motor (2), one side of which cooperates with the output connecting rod (1), and the other side cooperates with the sleeve connecting rod (3), and a rotating mechanism is formed between the output connecting rod (1) and the sleeve connecting rod (3) through the motor; The sleeve connecting rod (3) has square sliding grooves on both sides, a circular through hole on the upper surface, and a circular hole at the center of the bottom; The end surface of the end cover (6) is provided with a protrusion, the center of which is provided with a circular through hole, which cooperates with the groove on the end surface of the sleeve connecting rod (3) to achieve fixation.

2. A compliant control end face ratchet active rotation locking mechanism according to claim 1, characterized in that: When the arc-shaped end face ratchet of the sliding ratchet (5) meshes with the arc-shaped end face ratchet of the fixed ratchet (4), a gap is left in the center of the sliding ratchet (5) and the fixed ratchet (4) for fixing the memory alloy spring.

3. A compliant control end face ratchet active rotation locking mechanism according to claim 2, characterized in that: One end of the first memory alloy spring is fixed to the circular hole in the center of the end cover (6), and the other end is fixed to the circular hole in the center of the sliding ratchet (5); one end of the second memory alloy spring is fixed to the circular hole in the center of the sliding ratchet (5), and the other end is fixed to the circular hole in the center of the fixed ratchet (4), and it is ensured that the end face ratchets on the surfaces of the sliding ratchet (5) and the fixed ratchet (4) can mesh with each other when the memory alloy spring contracts.

4. A compliant control end face ratchet active rotation locking mechanism according to claim 3, characterized in that: When the first memory alloy spring is energized, the first memory alloy spring contracts, the end face ratchets on the surfaces of the fixed ratchet (4) and the sliding ratchet (5) are separated, and the rotating shaft can rotate freely; when the second memory alloy spring is energized, the second memory alloy spring contracts, the end face ratchets on the surfaces of the fixed ratchet (4) and the sliding ratchet (5) are engaged, and the rotation of the rotating shaft in the force direction is restricted.

5. The compliant control end face ratchet active rotation locking mechanism according to claim 1, characterized in that: The output connecting rod (1) has a protruding shaft and a small hole at its center. During installation, the protruding shaft passes through the center of the motor (2) and the bottom hole of the sleeve connecting rod (3) and cooperates with the mounting surface of the fixed ratchet (4).

6. A compliant control end face ratchet active rotation locking mechanism according to claim 5, characterized in that: The protruding shaft end is provided with a groove, which cooperates with the protrusion in the mounting groove of the fixed ratchet (3) to achieve fixation.

7. The compliant control end face ratchet active rotation locking mechanism according to claim 1, characterized in that: The sliding ratchet (5) cooperates with the sliding groove of the sleeve connecting rod (3) through the square sliding blocks on both sides to achieve axial movement in the sleeve.

8. A compliant control method for a compliant control end face ratchet active rotation locking mechanism based on any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Obtain angle data and torque data through real-time feedback from the motor sensor; Step 2: input the angle data and the torque data into an admittance controller to obtain a desired angle error value; Step 3: Input the calculated actual target angle into the PID position controller to complete the position control of the motor.

9. A method for compliantly controlling a compliant end face ratchet active rotation locking mechanism according to claim 8, characterized in that: The dynamic model of the admittance controller is: Among them, M is the mass parameter, which describes the inertia of the system; B is the damping parameter, which describes the damping characteristics of the system; K is the stiffness parameter, which describes the elastic characteristics of the system; θ, are joint angle, joint angular velocity and joint angular acceleration respectively; T is the external torque of the joint; Determine the discrete form model of the admittance controller: Among them, Δt represents the time interval, k and k-1 represent the discrete time steps, With Δθ k Respectively represent the angular acceleration, angular velocity and angular error value at time k; Actual target angle θ k The angle with the original expectation The relationship is shown as follows:

Images