A robot and its lever-type variable stiffness joint with customizable stiffness curve

Abstract

This invention discloses a robot and its lever-type variable stiffness joint with customizable stiffness curves, including a drive motor assembly, a stiffness adjustment assembly, an encoder, a stiffness adjustment motor, and an output link. The stiffness adjustment assembly consists of an input assembly and an output assembly, with the output assembly located inside the input assembly. Both are coaxial and can rotate relative to each other. The input assembly is fixed to the output portion of the joint motor assembly. The housing of the stiffness adjustment motor is fixed to the output assembly, and the output link is fixed to the housing of the stiffness adjustment motor. The encoder consists of a magnetic ring and a reading head; the magnetic ring is fixed to the housing of the stiffness adjustment motor, and the reading head is fixed to the input assembly. This invention achieves customized joint stiffness curves by designing different cam curves. By replacing the cam, different joint stiffness curves can be quickly customized to suit different application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, specifically relating to a lever-type variable stiffness joint with a customizable stiffness curve. Background Technology

[0002] With the development of robotics technology, robots need to interact with their surroundings and humans. High-stiffness drive joints and structural designs struggle to achieve robot compliance, leading to the development of flexible series elastic actuators. However, the stiffness of these actuators is fixed, resulting in a trade-off between force control bandwidth and force control resolution (lower stiffness leads to higher resolution and lower bandwidth, while higher stiffness results in lower resolution and higher bandwidth). To balance force control resolution and bandwidth, variable stiffness joints have emerged.

[0003] In practical applications, existing leaf spring-type variable stiffness joints with customizable stiffness curves present a contradiction between strength and stiffness. When the leaf spring thickness is large, the stiffness adjustment range decreases; when the leaf spring thickness is small, breakage is more likely. Within a small stiffness range, the maximum torque it can withstand does not always increase with increasing stiffness (up to the maximum load torque), which increases the difficulty of control and reduces reliability.

[0004] Existing lever-type variable fulcrum position variable stiffness joints have the advantage of a large stiffness adjustment range. However, when the lever fulcrum position remains unchanged, the joint stiffness curve (stiffness-deformation angle function) is only related to its structure. Therefore, it cannot be changed and cannot meet the stiffness variation requirements of certain application scenarios, thus limiting its application scope. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a lever-type variable stiffness joint with a customizable stiffness curve.

[0006] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0007] A lever-type variable stiffness joint with a customizable stiffness curve includes a drive motor assembly, a stiffness adjustment assembly, an encoder, a stiffness adjustment motor, and an output link. The stiffness adjustment assembly consists of an input assembly and an output assembly, with the output assembly located inside the input assembly. The two assemblies are coaxial and rotatable relative to each other. The input assembly is fixed to the output portion of the drive motor assembly. The housing of the stiffness adjustment motor is fixed to the output assembly, and the output link is fixed to the housing of the stiffness adjustment motor. The encoder consists of a magnetic ring and a reading head. The magnetic ring is fixed to the housing of the stiffness adjustment motor, and the reading head is fixed to the input assembly. The encoder recognizes the difference between the angle output by the drive motor assembly and the angle of the output link, and this difference is used to calculate the load torque of the variable stiffness joint.

[0008] In the above technical solution, the input component includes a first housing, a cam, and a second housing, wherein the cam is fixed between the first housing and the second housing.

[0009] In the above technical solution, the output component includes an output component support frame, an output component linear guide rail, an output component first slider, an output component rolling bearing, an output component spring guide rod, an output component spring, an output component second slider, an output component lever, an output component lever fulcrum, and an output component stiffening cam. The output component linear guide rail is fixed in the output component support frame. The two output component first sliders are centrally symmetrically arranged and slide on the two tracks of the output component linear guide rail, respectively. Output component rolling bearings are respectively installed on the cylinders at the outer ends of the output component first sliders, and the rolling bearings contact the inner side of the input component cam. The two output component spring guide rods are respectively fixed in the output component support frame and located in the output group. On both sides of the linear guide rail, two output component springs are installed on each output component spring guide rod, and the second output component slider is sleeved between the two output component springs; the small cylinder at the upper part of the second output component slider is engaged in the slide groove at the bottom of the output component lever, and the circular hole at the lower end of the output component lever is connected to the cylinder at the inner end of the first output component slider; the upper end of the output component fulcrum is engaged in the spiral groove of the output component adjusting cam, the upper half of the lower end of the output component fulcrum is engaged in the strip groove in the upper part of the output component support frame, and the lower half of the lower end of the output component fulcrum is engaged in the groove at the upper end of the output component lever; the output component adjusting cam is installed on the upper part of the output component support frame through the third output component bearing.

[0010] In the above technical solution, a rolling bearing fixing piece for the output component is fixed on the cylinder at the outer end of the first slider of the output component to prevent the rolling bearing of the output component from falling off.

[0011] In the above technical solution, the upper and lower ends of the output component fulcrum are separated by a circular boss.

[0012] In the above technical solution, the output component further includes an output component frame connector for connecting the stiffness adjustment motor; the output component frame connector is fixed to the top of the output component support frame and located above the output component stiffness adjustment cam.

[0013] In the above technical solution, the output component frame connector is connected to the input component second housing via the output component second bearing, and the output component support frame is connected to the input component first housing via the output component first bearing.

[0014] In the above technical solution, the stiffness curve of the lever-type variable stiffness joint is customized by designing the curve of the input component cam.

[0015] In the above technical solution:

[0016] Given the spring stiffness of the output component and the position of the lever fulcrum, the axis of the lever fulcrum is located between the cylindrical axis of the inner end of the first slider of the output component and the axis of the spring guide rod. If the functional relationship f(θ) between the variable stiffness joint load torque T and the joint deformation angle θ is given, then... U1=2kΔx 2 U1 = U2 Find the trajectory curve ρ(θ) of the axis of the output component rolling bearing on the first slider of the output component and the deformation angle θ of the variable stiffness joint. The cam curve is the envelope of the output component rolling bearing surface when the axis of the output component rolling bearing moves on the trajectory curve. Where: U2 is the work done by the joint load torque T on the joint deformation angle θ, U1 is the energy change when the output component spring is deformed, k is the stiffness of the output component spring, Δx is the deformation of the output component spring, L1 is the distance between the axis of the output component lever fulcrum and the plane M, L2 is the distance between the axis of the output component lever fulcrum and the axis of the output component spring guide rod, and M is the swept plane formed by the cylindrical axis of the inner end of the first slider of the output component on the linear guide rail of the output component.

[0017] Given the position of the lever fulcrum of the output component, if the stiffness variation function g(θ) of the variable stiffness joint is given, the relationship between the stiffness of the variable stiffness joint and the load torque is as follows: Therefore, by integrating g(θ) over θ, f(θ) can be obtained, and the cam curve can be further calculated.

[0018] Once the cam curve is determined, the stiffness curve of the variable stiffness joint at that given fulcrum position can be determined.

[0019] When the position of the lever fulcrum of the output component is changed, the stiffness curve of the joint becomes K′=k′g(θ), where the value of k′ is related to the position of the lever fulcrum, and its range is from a minimum value close to 0 to positive infinity. When the lever fulcrum of the output component is close to the cylinder at the inner end of the first slider of the output component, the value of k′ increases, and vice versa.

[0020] A robot comprising the aforementioned lever-type variable stiffness joint with customizable stiffness curves.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) This invention, based on a lever and cam mechanism, designs a novel variable stiffness joint that combines active and passive variable stiffness. When the lever fulcrum is in a certain position, different joint stiffness curves (stiffness K as a function of the joint deformation angle θ, g(θ)) can be achieved by customizing different cam curves. The stiffness function g(θ) can be an increasing function, a fixed value, or a decreasing function, and different stiffness curves are suitable for different application scenarios. When the lever fulcrum is in different positions, although the stiffness of the variable stiffness joint changes, the change law of its stiffness curve remains unchanged. The stiffness curve function of the joint is K′=k′g(θ), where the value of k′ is related to the position of the lever fulcrum, and its range is from a minimum value close to 0 to positive infinity.

[0023] (2) The present invention connects the stiffening motor in series with the output component (the axis of the stiffening motor coincides with the output axis of the joint output component), which reduces the rotational inertia of the joint, and the encoder and output linkage are installed on the basis of the stiffening motor housing, which increases the structural compactness.

[0024] (3) The present invention achieves customized stiffness curve by designing cam curve. The cam is installed in the output component, and the input component and the output component are separated from each other. Therefore, different customized stiffness curves can be quickly replaced by quick disassembly.

[0025] (4) The present invention proposes a design method for cam curves. By giving the variable stiffness joint load torque curve (load torque T as a function of deformation angle θ f(θ)) or joint stiffness curve (stiffness K as a function of deformation angle g(θ)), the cam curve can be derived. Attached Figure Description

[0026] Figure 1 This is a diagram of the lever-type variable stiffness joint structure with customizable stiffness curves described in this invention.

[0027] Figure 2 This is an exploded view of the lever-type variable stiffness joint with customizable stiffness curve described in this invention.

[0028] Figure 3 This is a cross-sectional view of the drive motor assembly described in this invention;

[0029] Figure 4 This is an isometric view of the input component described in this invention;

[0030] Figure 5 This is an exploded view of the output component described in this invention;

[0031] Figure 6 This is a schematic diagram of the variable stiffness principle of the variable stiffness joint described in this invention;

[0032] Figure 7 This is a diagram illustrating the variable stiffness principle (fulcrum adjustment principle) described in this invention.

[0033] Figure 8 A partial sectional view of the output component lever fulcrum installation;

[0034] Figure 9 To output the isometric view of the component lever;

[0035] In the diagram: 100-Drive motor assembly, 200-Stiffness adjustment assembly, 300-Encoder, 400-Stiffness adjustment motor, 500-Output linkage, 210-Input assembly, 220-Output assembly, 101-Drive motor end cover, 102-Drive motor encoder reading head, 103-Drive motor encoder magnetic column, 104-Drive motor first bearing, 105-Drive motor first housing, 106-Drive motor stator, 107-Drive motor rotor, 108-Drive motor output shaft, 109-Drive motor second bearing, 110-Harmonic reducer generator mounting component, 111-Harmonic reducer, 112-Harmonic reducer wave generator, 113-Harmonic reducer rigid wheel, 114-Harmonic reducer flexible wheel, 115-Drive motor second housing 116 - Drive motor third bearing cover, 117 - Drive motor third bearing, 211 - Input component first housing, 212 - Input component cam, 213 - Input component second housing, 221 - Output component first bearing, 222 - Output component second bearing, 223 - Output component support frame, 224 - Output component linear guide, 225 - Output component first slider, 226 - Output component rolling bearing, 227 - Output component rolling bearing fixing piece, 228 - Output component spring guide rod, 229 - Output component spring, 230 - Output component second slider, 231 - Output component lever, 232 - Output component lever fulcrum, 233 - Output component frame connector, 234 - Output component stiffening cam, 235 - Output component third bearing. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0037] like Figure 1 , 2As shown, this invention discloses a lever-type variable stiffness joint with a customizable stiffness curve, comprising a drive motor assembly 100, a stiffness adjustment assembly 200, an encoder 300, a stiffness adjustment motor 400, and an output link 500. The stiffness adjustment assembly 200 consists of an input assembly 210 and an output assembly 220, with the output assembly 220 located inside the input assembly 210. They are coaxial and can rotate relative to each other. The encoder 300 consists of a magnetic ring and a reading head. The housing of the stiffness adjustment motor 400 is fixed to the output assembly 220, the output link 500 is fixed to the housing of the stiffness adjustment motor 400, the magnetic ring is fixed to the housing of the stiffness adjustment motor 400, and the reading head is fixed to the input assembly 210. The input assembly 210 is fixed to the output portion of the drive motor assembly 100. The angle recognized by the encoder 300 is the difference between the angle output by the drive motor assembly 100 and the angle of the output link 500 (this difference is generated by the flexibility of the joint). The load torque of the variable stiffness joint can be calculated based on this difference.

[0038] like Figure 3As shown, the drive motor assembly 100 consists of a drive motor end cover 101, a drive motor encoder reading head 102, a drive motor encoder magnetic column 103, a drive motor first bearing 104, a drive motor first housing 105, a drive motor stator 106, a drive motor rotor 107, a drive motor output shaft 108, a drive motor second bearing 109, a harmonic reducer generator fixing component 110, a harmonic reducer 111, a drive motor second housing 115, a drive motor third bearing cover 116, and a drive motor third bearing 117. The drive motor encoder reading head 102 is installed inside the drive motor end cover 101, the drive motor encoder magnetic column 103 is installed at the bottom of the drive motor output shaft 108, the drive motor stator 106 is installed in the housing composed of the drive motor first housing 105 and the drive motor end cover 101, the drive motor rotor 107 is located inside the drive motor stator 106 and fixed on the drive motor output shaft 108, and the drive motor output shaft 108 is connected to the housing through the drive motor first bearing 104 and the drive motor second bearing 109. Harmonic reducer 111 consists of harmonic reducer wave generator 112, harmonic reducer rigid wheel 113, and harmonic reducer flexible wheel 114. The harmonic reducer wave generator 112 is the input of harmonic reducer 111, and the harmonic reducer rigid wheel 113 is the output of harmonic reducer 111. The harmonic reducer wave generator 112 is fixed to the output shaft 108 of the drive motor via a harmonic reducer generator fixing member 110. The harmonic reducer wave generator 112 is located inside the harmonic reducer flexible wheel 114, which is fixed to the top of the first housing 105 of the drive motor. The reducer flexible wheel 114 is located inside the harmonic reducer rigid wheel 113. The harmonic reducer rigid wheel 113 is fixed inside the drive motor second housing 115. The drive motor second housing 115 serves as the output of the drive motor assembly 100. The drive motor first housing 105 is also connected to the drive motor second housing 115 through the drive motor third bearing 117. The drive motor third bearing cover 116 is fixed on the drive motor second housing 115, pressing the outer ring of the drive motor third bearing 117. The drive motor third bearing cover 116 is used to prevent the drive motor third bearing 117 from falling off.

[0039] like Figure 4 As shown, the input component 210 consists of an input component first housing 211, an input component cam 212, and an input component second housing 213. The input component first housing 211 is connected to the drive motor second housing 115. The reading head of the encoder 300 is fixed above the input component second housing 213. The input component cam 212 is fixed between the input component first housing 211 and the input component second housing 213. The input component cam 212 contacts the output component rolling bearing 226.

[0040] like Figure 5As shown, the output component 220 consists of an output component first bearing 221, an output component second bearing 222, an output component support frame 223, an output component linear guide rail 224, an output component first slider 225, an output component rolling bearing 226, an output component rolling bearing fixing piece 227, an output component spring guide rod 228, an output component spring 229, an output component second slider 230, an output component lever 231, an output component lever fulcrum 232, an output component frame connector 233, an output component stiffening cam 234, and an output component third bearing 235. The output component frame connector 233 is fixed to the top of the output component support frame 223. The output component frame connector 233 is installed into the input component 210 through the output component second bearing 222. The output component support frame 223 is installed into the input component 210 through the output component first bearing 221. The output component second bearing 222 is connected to the input component second housing 213, and the output component first bearing 221 is connected to the input component first housing 211. The stiffness adjustment motor 400 is connected to the input component second housing 233. The remaining components are installed on the output component support frame 223. Specifically, the output component linear guide rail 224 is fixed in the output component support frame 223, and the two output component first sliders 225 are centrally symmetrically arranged and slide on the two tracks of the output component linear guide rail 224 respectively. The length of the output component first slider 225 is less than the track length of the output component linear guide rail 224. Output component rolling bearings 226 are respectively installed on the cylinder at the outer end of the output component first slider 225, and the output component rolling bearing fixing piece 227 is fixed on the cylinder at the outer end of the output component first slider 225 to prevent the output component rolling bearings 226 from falling off. Two output component spring guide rods 228 are respectively fixed in the output component support frame 223 and located on both sides of the output component linear guide rail 224. Two output component springs 229 are mounted on each output component spring guide rod 228. The output component second slider 230 is sleeved between the two output component springs 229 and can slide on the output component spring guide rod 228 to compress the output component springs 229. A small cylinder ( ) is located on the upper part of the output component second slider 230. Figure 6 ) is snapped into the slide groove at the bottom of the output component lever 231, and the lower end of the output component lever 231 has a circular hole ( Figure 9 ) and the cylinder at the inner end of the first slider 225 of the output component ( Figure 5 ) connection; the output component adjusting cam 234 has two centrally symmetrical helical grooves. Figure 7 Two slots are provided in the upper part of the output component support frame 223. Figure 5 The upper end of the output component lever fulcrum 232 is engaged in the spiral groove, the upper half of the lower end of the output component lever fulcrum 232 is engaged in the strip groove, and the lower half of the lower end of the output component lever fulcrum 232 is engaged in the groove at the upper end of the output component lever 231. Figure 9The groove is located above the plane where the lower and middle circular holes are located. The upper and lower ends of the output component lever fulcrum 232 are connected via... Figure 5 The circular bosses shown are separated; the output component stiffening cam 234 is mounted on the upper part of the output component support frame 223 via the third bearing 235 of the output component, and is located below the output component frame connector 233.

[0041] The working principle of the lever-type variable stiffness joint with customizable stiffness curve of the present invention is as follows:

[0042] The output section of the drive motor assembly 100—the second housing 115 of the drive motor—inputs rotational motion into the input assembly 210. The input assembly cam 212 in the input assembly 210 drives the output assembly 220 to rotate by pressing the output assembly rolling bearing 226. The output link 500 is fixed to the output assembly support frame 223 via the stiffness adjustment motor 400 housing. This ensures that the rotation angles of the output link 500, the stiffness adjustment motor 400 housing, and the output assembly 220 are consistent. However, because the output assembly 220 contains a flexible device (output assembly spring 229), the rotation angles of the input assembly 210 and the output assembly 220 are not equal; the angle difference is the deformation angle of the variable stiffness joint.

[0043] When the drive motor assembly 100 is in operation, the drive motor rotor 107 drives the harmonic reducer wave generator 112 to rotate via the drive motor output shaft 108 and the harmonic reducer wave generator fixing member 110, thereby causing the harmonic reducer rigid wheel 113 to rotate, which in turn drives the second housing 115 of the drive motor to rotate around the first housing 105 of the drive motor.

[0044] For the stiffness adjustment component 200, when the input component 210 is driven by the second housing 115 of the drive motor, the driving torque of the input component 210 is transmitted to the output component 220 because the input component cam 212 is in contact with the output component rolling bearing 226, and further to the stiffness adjustment motor 400 and the output link 500, causing the output link 500 to move. Due to the flexibility of the output component spring 229, the output component rolling bearing 226 will move on the output component linear guide 224 based on the output component first slider 225, thereby forcing the input component 210 and the output component 220 to generate a relative rotation angle, which is the deformation angle of the variable stiffness joint. The specific reason for the joint flexibility is that when the output component first slider 225 moves on the output component linear guide 224, the cylinder at the inner end of the output component first slider 225 pushes the output component lever 231 to rotate around the output component lever fulcrum 232, thereby causing the output component lever 231 to compress the output component spring 229 through the output component second slider 230, thus causing the spring to deform. By designing the cam curve in the input component cam 212, different stiffness curves (stiffness-deformation angle functions) can be customized, thereby realizing the predefined stiffness characteristics of the variable stiffness joint and increasing the application scenarios of the variable stiffness joint.

[0045] The present invention discloses a cam curve design method for a lever-type variable stiffness joint with customizable stiffness curve:

[0046] Let the deformation angle of the variable stiffness joint be θ, the stiffness of the output component spring 229 be k, and the functional relationship between the movement distance of the axis of the output component rolling bearing 226 on the output component linear guide 224 and the deformation angle θ of the variable stiffness joint be ρ(θ). Let M be the swept plane formed by the movement of the cylindrical axis at the inner end of the first slider 225 of the output component on the output component linear guide 224, and let L1 be the distance between the axis of the output component lever fulcrum 232 and plane M. Figure 6 The distance between the axis of the output component lever fulcrum 232 and the axis of the output component spring guide rod 228 is L2. Figure 6 When the position of the lever fulcrum 232 of the output component remains unchanged, the values ​​of L1 and L2 do not change. It should be noted that: Figure 6 In the middle, the output component first slider 225 in the upper left corner and the output component spring guide rod 228 and the output component lever fulcrum 232 to its left form a group, and the output component first slider 225 in the lower right corner and the output component spring guide rod 228 and the output component lever fulcrum 232 to its right form a group. The above L1 and L2 refer to the distance between the two components in the same group.

[0047] The following describes the design steps of the cam curve when given the stiffness k of the output component spring, the position of the output component lever fulcrum 232 (the axis of the lever fulcrum is between the cylindrical axis of the inner end of the first slider 225 of the output component and the axis of the spring guide rod 228 of the output component), and the function f(θ) of the joint load torque T and the joint deformation angle θ or the function g(θ) of the joint stiffness K:

[0048] The relationship between the deformation Δx of the output component spring 229 and ρ(θ) is as follows:

[0049] When the output component spring 229 deforms, its energy change is: U1=2kΔx 2 ;

[0050] The work done by the joint load torque T on the joint deformation θ is:

[0051] According to the law of conservation of energy, the work done by the joint load torque T on the joint deformation angle θ is the same as the energy change of the spring, that is, U1 = U2.

[0052] According to the above formula, when given the functional relationship f(θ) between the joint load torque T and the deformation angle θ of the variable stiffness joint, ρ(θ) can be obtained, which is the trajectory curve of the axis movement distance of the output component rolling bearing 226 and the deformation angle θ. The curve of the input component cam 212 is the envelope of the output component rolling bearing surface when the axis of the output component rolling bearing 226 moves on the trajectory curve.

[0053] Due to the stiffness of variable stiffness joints Therefore, given the stiffness variation function g(θ) of the variable stiffness joint, we can first integrate to find f(θ) and then further find the cam curve.

[0054] Once the cam curve is determined, the stiffness curve of the variable stiffness joint at that given fulcrum position can be determined.

[0055] When the position of the lever fulcrum 232 of the output component is changed, the values ​​of L1 and L2 change, and the stiffness of the variable stiffness joint changes. However, the stiffness remains unchanged as a function of the deformation angle θ (the stiffness change law is determined by the cam curve). That is, when the position of the lever fulcrum changes, the stiffness curve of the joint becomes K′=k′g(θ), where the value of k′ is related to the position of the lever fulcrum and its range is from a minimum value close to 0 to positive infinity. When the lever fulcrum 232 of the output component is close to the cylinder at the inner end of the first slider 225 of the output component, the value of k′ increases, and vice versa.

[0056] When a variable stiffness joint is in actual operation, it will deform due to the presence of load torque. This angle can be measured by encoder 300. The load torque value of the variable stiffness joint can be calculated based on the joint deformation angle.

[0057] Figure 7 , 8 The diagram illustrates the principle of fulcrum position change: The upper end of the output component lever fulcrum 232 is embedded in the helical groove of the output component stiffening cam 234, the upper half of the lower end is embedded in the strip groove of the output component support frame 223, and the lower half of the lower end is embedded in the upper groove of the output component lever 231, forming the fulcrum of the lever. The position of the output component lever fulcrum 232 is jointly determined by the helical groove in the output component stiffening cam 234 and the strip groove of the output component support frame 223. Specifically, the position of the output component lever fulcrum 232 is the overlapping position of the helical groove in the output component stiffening cam 234 and the strip groove of the output component support frame 223. When the output component stiffening cam 234 is driven by the output shaft of the stiffness adjustment motor 400 to rotate around its centerline, the helical groove also rotates, and the overlapping part of the helical groove and the strip groove of the output component support frame 223 changes, that is, the position of the fulcrum changes.

[0058] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A lever-type variable stiffness joint with customizable stiffness curve, characterized in that, It includes a drive motor assembly (100), a stiffness adjustment assembly (200), an encoder (300), a stiffness adjustment motor (400), and an output linkage (500); the stiffness adjustment assembly (200) consists of an input assembly (210) and an output assembly (220), the output assembly (220) being located inside the input assembly (210), the two being coaxial and rotatable relative to each other; the input assembly (210) is fixed to the output part of the drive motor assembly (100); the stiffness adjustment motor (400) is externally... The housing is fixed on the output assembly (220), and the output link (500) is fixed on the housing of the stiffness adjustment motor (400); the encoder (300) consists of a magnetic ring and a reading head, the magnetic ring is fixed on the housing of the stiffness adjustment motor (400), and the reading head is fixed on the input assembly (210); the angle recognized by the encoder (300) is the difference between the angle output by the drive motor assembly (100) and the angle of the output link (500), and the load torque of the variable stiffness joint is calculated based on the difference; The input component (210) includes an input component first housing (211), an input component cam (212), and an input component second housing (213), wherein the input component cam (212) is fixed between the input component first housing (211) and the input component second housing (213); The output component (220) includes an output component support frame (223), an output component linear guide rail (224), an output component first slider (225), an output component rolling bearing (226), an output component spring guide rod (228), an output component spring (229), an output component second slider (230), an output component lever (231), an output component lever fulcrum (232), and an output component stiffening cam (234). The output component linear guide rail (224) is fixed in the output component support frame (223). The two output component first sliders (225) are centrally symmetrically arranged and slide on the two tracks of the output component linear guide rail (224). The output component rolling bearings (226) are respectively installed on the cylinders at the outer ends of the output component first sliders (225). The output component rolling bearings (226) are in contact with the inner side of the input component cam (212). The two output component spring guide rods (228) are respectively fixed in the output component support frame (223) and located in the center of the cylinder. On both sides of the linear guide rail (224) of the output component, two output component springs (229) are installed on each output component spring guide rod (228). The second slider (230) of the output component is sleeved between the two output component springs (229). The small cylinder at the upper part of the second slider (230) of the output component is engaged in the groove at the bottom of the lever (231) of the output component. The circular hole at the lower end of the lever (231) of the output component is connected to the cylinder at the inner end of the first slider (225) of the output component. The upper end of the output component lever fulcrum (232) is engaged in the spiral groove of the output component stiffening cam (234), the upper half of the lower end of the output component lever fulcrum (232) is engaged in the strip groove in the upper part of the output component support frame (223), and the lower half of the lower end of the output component lever fulcrum (232) is engaged in the groove at the upper end of the output component lever (231); the output component stiffening cam (234) is installed on the upper part of the output component support frame (223) through the third bearing (235) of the output component; The stiffness curve of the lever-type variable stiffness joint can be customized by designing the curve of the input component cam (212).

2. The lever-type variable stiffness joint with customizable stiffness curve according to claim 1, characterized in that, The output component rolling bearing fixing piece (227) is fixed on the cylinder at the outer end of the first slider (225) of the output component to prevent the output component rolling bearing (226) from falling off.

3. The lever-type variable stiffness joint with customizable stiffness curve according to claim 1, characterized in that, The upper and lower ends of the output component lever fulcrum (232) are separated by a circular boss.

4. The lever-type variable stiffness joint with customizable stiffness curve according to claim 1, characterized in that, The output component (220) also includes an output component frame connector (233) for connecting a stiffness adjustment motor (400); the output component frame connector (233) is fixed on the top of the output component support frame (223) and located above the output component stiffness adjustment cam (234).

5. The lever-type variable stiffness joint with customizable stiffness curve according to claim 4, characterized in that, The output component frame connector (233) is connected to the input component second housing (213) via the output component second bearing (222), and the output component support frame (223) is connected to the input component first housing (211) via the output component first bearing (221).

6. The lever-type variable stiffness joint with customizable stiffness curve according to claim 1, characterized in that: Given the stiffness of the output component spring (229) and the position of the output component lever fulcrum (232), the axis of the output component lever fulcrum (232) is located between the cylindrical axis of the inner end of the first slider (225) of the output component and the axis of the output component spring guide rod (228). If a variable stiffness joint load torque is given... Deformation angle of the joint The functional relationship f(θ) is given by , , , Calculate the distance the axis of the rolling bearing (226) of the output component moves along the first slider (225) of the output component and the deformation angle of the variable stiffness joint. trajectory curve The cam curve is the surface envelope of the output component rolling bearing (226) when the axis of the output component rolling bearing (226) moves on the trajectory curve, where: U2 is the joint load torque T acting on the joint deformation angle. The work done on the output component spring (229) is U1, which is the energy change when the spring (229) deforms. To output the stiffness of the spring (229) of the component, L1 is the deformation of the spring (229) of the output component, L2 is the distance between the axis of the lever fulcrum (232) of the output component and the plane M, L2 is the distance between the axis of the lever fulcrum (232) of the output component and the axis of the spring guide rod (228) of the output component, and plane M is the sweep plane formed by the cylindrical axis of the inner end of the first slider (225) of the output component on the linear guide rail (224) of the output component; Given the position of the output component lever fulcrum (232), if the stiffness variation function g(θ) of the variable stiffness joint is given, since the relationship between the stiffness of the variable stiffness joint and the load torque is... Therefore, through right Integrate to obtain f(θ), then further calculate the cam curve; Once the cam curve is determined, the stiffness curve of the variable stiffness joint at that given fulcrum position can be determined. If the position of the lever fulcrum (232) of the output component is changed, the stiffness curve of the joint becomes ,in The value is related to the position of the lever fulcrum, and its range is from a minimum value close to 0 to positive infinity. When the lever fulcrum (232) of the output component is close to the cylinder at the inner end of the first slider (225) of the output component, The value increases, and vice versa. The value decreases.

7. A robot, characterized in that, Including the lever-type variable stiffness joint with customizable stiffness curve as described in any one of claims 1-6.

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