A biped robot step time regulation method, device, terminal and storage medium

Abstract

The application discloses a biped robot step time regulation method, device, terminal and storage medium, comprising: simulating the motion of the biped robot by using an equivalent reduced order model, and establishing an equivalent reduced order model based on a foot end Cartesian coordinate system; calculating the actual position of the current time centroid relative to the landing foot and the actual system angular momentum according to the current state of the system; obtaining the expected forward speed and the expected lateral speed at the current time based on the robot motion path, and calculating the expected angular momentum according to the equivalent reduced order model; solving the remaining step time according to the actual angular momentum and the expected angular momentum values; determining the final step time according to the system step time constraint, and analytically calculating the final landing point position according to the final step time. The step time regulation method can prevent the step deviation of the biped robot, and improve the tracking reliability and stability of the biped robot along the given motion path.

Description

Technical Field

[0001] The present invention relates to the technical field of robot motion control, and in particular to a method, device, terminal and storage medium for controlling the stepping time of a bipedal humanoid robot. Background Art

[0002] Bipedal humanoid robots, a key branch of mobile robotics, typically feature humanoid legs and feet. During locomotion, these robots typically require control over step timing and foot placement to achieve leg alternation and stable movement.

[0003] Due to the complex structure and strong nonlinearity of the system, the control of bipedal humanoid robots is difficult. Generally, bipedal humanoid robots are reduced in order;

[0004] In the existing technology, the foothold position of bipedal humanoid robots is controlled according to a given step time. Due to factors such as model uncertainty, disturbance, noise, and foot slippage, the foothold of the bipedal humanoid robot will swing significantly and randomly, deviating from the expected motion path. Especially when walking in crowded or narrow passages, uncontrolled lateral movement can easily lead to dangerous accidents.

[0005] Therefore, how to provide a method for controlling the steps of a bipedal humanoid robot along a motion path is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method, device, terminal, and storage medium for controlling the stride time of a bipedal humanoid robot, which are used to overcome or at least partially resolve the above problems. The method uses a fixed foothold position to control the stride time of a bipedal humanoid robot.

[0007] The present invention provides the following scheme:

[0008] A method for controlling the stepping time of a bipedal humanoid robot, comprising:

[0009] The equivalent reduced-order model is used to simulate the motion of a bipedal humanoid robot and an equivalent reduced-order model based on the Cartesian coordinate system of the foot end is established.

[0010] Calculate the actual position of the center of mass relative to the grounded foot and the actual system angular momentum at the current moment based on the current state of the system;

[0011] Obtaining the expected forward velocity and expected lateral velocity at the current moment based on the robot's motion path, and calculating the expected angular momentum according to the equivalent reduced-order model;

[0012] Calculating a remaining step time based on the actual angular momentum and the expected angular momentum;

[0013] A final step time is determined according to a system step time constraint, and a final footfall position is analytically calculated based on the final step time.

[0014] As a further improvement of the above technical solution, the equivalent reduced-order model is expressed by the following formula:

[0015]

[0016] The solution of the equivalent reduced-order model is expressed as follows:

[0017]

[0018] Where: and is the forward or lateral position and velocity of the center of mass relative to the foot end, L y / x and is the rate of change of the lateral or forward angular momentum and angular momentum of the center of mass, m is the total mass of the robot, g is the acceleration due to gravity, z is the height of the center of mass, is the forward or sideways foot slip speed, T step is the expected step cycle, t is the current step time, and V s y / x (t) is the lateral or forward angular momentum offset caused by the foot slip velocity.

[0019] As a further improvement of the above technical solution, the current center of mass relative to the actual position p of the grounded foot st (t) is represented by the following formula:

[0020] p st (t) = p CoM (t)-p st,w (t)

[0021] The actual angular momentum L(t) is the angular momentum of the system relative to the position of the grounded foot, which is expressed by the following formula:

[0022]

[0023] Where: p st,w (t) represents the absolute position of the foot touching the ground at the current moment t, p CoM (t) with Indicates the center of mass position and center of mass velocity at the current time t; L CoM (t) represents the angular momentum of the system relative to the center of mass at the current moment t, and ∧ represents the vector cross product.

[0024] As a further improvement of the above technical solution, the desired angular momentum can be expressed as:

[0025] Desired forward angular momentum: The desired angular momentum is calculated based on the left and right leg step widths and the desired lateral velocity:

[0026]

[0027] Desired lateral angular momentum: The desired lateral angular momentum can be calculated based on the desired forward velocity Calculation yields:

[0028]

[0029] Where: W is the desired stride width, is the expected lateral velocity The corresponding angular momentum.

[0030] As a further improvement of the above technical solution, the remaining step time t remain It can be obtained by numerically solving the simultaneous equations, which is expressed as follows:

[0031]

[0032] Where, is the forward or lateral angular momentum relative to the foot’s landing position at the end of the current step, V s x / y It is the forward or sideways angular momentum offset caused by the foot slip speed.

[0033] As a further improvement to the above technical solution, when the remaining step time is less than the minimum step time or greater than the maximum step time, the final step time and the final foothold position are expressed by the following formula:

[0034]

[0035] A bipedal humanoid robot stepping time control device, comprising:

[0036] Modeling module: used to build the state space equations of the reduced-order model of the bipedal humanoid robot;

[0037] State estimation module: used to obtain the relative position of the center of mass and the foot end at the current moment, and the forward and lateral angular momentum of the system;

[0038] Expected angular momentum module: used to calculate the expected angular momentum of the expected landing point or velocity;

[0039] Numerical solution module: used to numerically solve the remaining step time based on the expected foot landing point position;

[0040] Step control module: used to analyze the expected step time and the expected step landing point.

[0041] A terminal includes a memory and a processor, wherein the memory is used to store a computer program, and the processor executes the computer program to enable the terminal to implement any of the above-mentioned methods for controlling the stepping time of a bipedal humanoid robot.

[0042] A computer-readable storage medium stores the computer program executed by the terminal.

[0043] The beneficial effects of the present invention are:

[0044] (1) Based on the robot's expected motion speed and stepping point, the expected angular momentum is calculated using an equivalent reduced-order model; the remaining step time is numerically solved based on the actual angular momentum of the system at the current moment and the expected angular momentum; the step time and the position of the foothold are obtained by considering the system's stepping time constraint, which can solve the problem of the bipedal humanoid robot deviating from the expected motion path and ensure its safety when passing through narrow passages;

[0045] (2) Compared with the traditional motion control with a fixed step cycle, the present invention has a simple structure and high computational efficiency. It can consider both the step cycle and the step landing point at the same time, and the control is more flexible. At the same time, the present invention considers the change in angular momentum caused by foot slippage, which can ensure that the motion path can be followed more stably after slipping, and has higher robustness and practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0047] Figure 1 A schematic flow chart of a method for controlling the stepping time of a bipedal humanoid robot provided in Example 1 of the present invention;

[0048] Figure 2 A schematic diagram of the motion of an equivalent reduced-order model provided in Example 1 of the present invention;

[0049] Figure 3 A schematic diagram of solving the expected speed based on the motion path provided in Example 1 of the present invention;

[0050] Figure 4 A schematic diagram of the structure of a bipedal humanoid robot stepping time control device provided in Example 2 of the present invention;

[0051] Figure 5 This is a schematic diagram of the structure of a terminal provided in Example 3 of the present invention.

[0052] Description of main component symbols:

[0053] 100 - bipedal humanoid robot stepping time control device, 110 - modeling module, 120 - state estimation module, 130 - expected angular momentum module, 140 - numerical solution module, 150 - stepping control module, 200 - terminal, 210 - memory, 220 - processor, 230 - input unit, 240 - display unit. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0055] The following specifically explains the application scenarios of the bipedal humanoid robot provided in the embodiments of the present application and the working conditions of the bipedal humanoid robot in such scenarios.

[0056] See also Figure 1 This embodiment provides a method for controlling the stepping time of a bipedal humanoid robot, the method comprising the following steps:

[0057] Step A: Use the equivalent reduced-order model to simulate the motion of the bipedal humanoid robot and establish an equivalent reduced-order model based on the Cartesian coordinate system of the foot end.

[0058] See also Figure 2 , exemplary, step A includes:

[0059] Step A1: Establish a foot-end Cartesian coordinate system {o} at the foot's landing position. This Cartesian coordinate system {o} has an orthogonal x-axis, y-axis, and z-axis. The x-axis is a horizontal axis, representing the forward and backward direction of the humanoid robot; the y-axis is another horizontal axis perpendicular to the x-axis, representing the lateral movement direction of the humanoid robot; and the z-axis is a vertical axis, representing the vertical direction.

[0060] Step A2: In a bipedal humanoid robot, establishing the equivalent reduced-order model based on the Cartesian coordinate system of the foot end from the position of the grounded foot to the center of mass, wherein the equivalent reduced-order model is a linear inverted pendulum model;

[0061] Step A3: In one example, the equivalent reduced-order model can be expressed as:

[0062]

[0063] The solution of the equivalent reduced-order model is expressed as follows:

[0064]

[0065] Where: and is the forward or lateral position and velocity of the center of mass relative to the foot end, L y / x and is the rate of change of the lateral or forward angular momentum and angular momentum of the center of mass, m is the total mass of the robot, g is the acceleration due to gravity, z is the height of the center of mass, is the forward or sideways foot slip speed, T step is the expected step cycle, t is the current step time, and V s y / x (t) is the lateral or forward angular momentum offset caused by the foot slip velocity.

[0066] When the foot contacts the ground without slipping, And V s y / x (t)=0.

[0067] Step B: Calculate the actual position of the center of mass relative to the grounded foot and the actual system angular momentum at the current moment based on the current state of the system.

[0068] The actual position p of the center of mass relative to the grounded foot at the current moment st (t) is represented by the following formula:

[0069] p st (t) = p CoM (t)-p st,w (t)

[0070] The actual angular momentum L(t) is the angular momentum of the system relative to the position of the grounded foot, which is expressed by the following formula:

[0071]

[0072] Where: p st,w (t) represents the absolute position of the foot touching the ground at the current moment t, p CoM (t) with Indicates the center of mass position and center of mass velocity at the current time t; L CoM (t) represents the angular momentum of the system relative to the center of mass at the current moment t, and ∧ represents the vector cross product.

[0073] Step C: Obtain the current expected forward speed and expected lateral speed based on the robot's motion path.

[0074] See also Figure 3 , the expected forward velocity at the current moment can be expressed as

[0075]

[0076] Where, is the desired velocity vector in the xy plane of the world coordinate system at the current moment, which can be obtained by differentiating the robot motion path. θ is the angle between the desired velocity vector and the x-axis of the world coordinate system.

[0077] The desired forward angular momentum: The desired angular momentum is calculated based on the left and right leg step widths and the desired lateral speed. Calculation yields:

[0078]

[0079] The desired lateral angular momentum: The desired lateral angular momentum can be calculated based on the desired forward velocity Calculation yields:

[0080]

[0081] Where: W is the desired stride width, is the expected lateral velocity The corresponding angular momentum.

[0082] Step D: Calculating the remaining step time based on the actual angular momentum and the expected angular momentum.

[0083] The remaining step time t remain It can be obtained by numerically solving the simultaneous equations, which is expressed as follows:

[0084]

[0085] Where, is the forward or lateral angular momentum relative to the foot’s landing position at the end of the current step, V s x / y It is the forward or sideways angular momentum offset caused by the foot slip speed.

[0086] Step E: Determine the final step time according to the system step time constraint, and analytically calculate the final footfall position based on the final step time.

[0087] The final step time and the final foothold position, when the remaining step time is less than the minimum step time or greater than the maximum step time, the final step time and the final foothold position are expressed by the following formula:

[0088]

[0089] Example 2

[0090] See also Figure 4 This embodiment provides a bipedal humanoid robot stepping time control device 100, which includes:

[0091] Modeling module 110: for establishing state space equations of a reduced-order model of a bipedal humanoid robot in Cartesian space at the foot end;

[0092] State estimation module 120: used to obtain the relative position of the center of mass and the foot end at the current moment, and the forward and lateral angular momentum of the system;

[0093] Expected angular momentum module 130: used to calculate the expected angular momentum of the expected landing point or velocity;

[0094] Numerical solution module 140: used for numerically solving the remaining step time based on the expected foot landing point position;

[0095] The step control module 150 is used to analyze the expected step time and the expected step landing point.

[0096] Example 3

[0097] See also Figure 5 This embodiment provides a terminal 200, which includes a memory 210 and a processor 220. The memory 210 is used to store a computer program, and the processor 220 executes the computer program to enable the terminal 200 to implement any of the above-mentioned methods for controlling the stepping time of a bipedal humanoid robot.

[0098] The terminal 200 includes terminal devices that do not have mobile communication capabilities (such as computers, servers, etc.), and also includes mobile terminals (such as smart phones, tablets, car computers, smart wearable devices, etc.).

[0099] Memory 210 may include a program storage area and a data storage area. The program storage area may store applications required for at least one operating system function (e.g., sound playback, image playback, etc.); the data storage area may store data generated based on the use of terminal 200 (e.g., operating data, backup files, etc.). Memory 210 may also include high-speed random access memory and non-volatile memory (e.g., at least one disk storage device, flash memory device, or other volatile solid-state memory device).

[0100] Preferably, the terminal 200 further includes an input unit 230 and a display unit 240. The input unit 230 is used to receive various user input commands or parameters (including a preset scrolling mode, a preset time interval, and a preset number of scrolling times), and may include a mouse, keyboard, touch panel, or other input devices. The display unit 240 is used to display various output information of the terminal 200 (including web pages, parameter configuration interfaces, etc.), and may include a display panel.

[0101] A computer-readable storage medium is also provided herein, which stores the computer program executed by the terminal.

[0102] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and structure diagrams in the accompanying drawings show the possible implementation architectures, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the process or block diagram can represent a module, program segment or part of the code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical functions.

[0103] It should also be noted that, in alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in the opposite order, depending on the functions involved.

[0104] It should also be noted that each box in the structure diagram and / or flowchart, and combinations of boxes in the structure diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0105] In addition, the functional modules or units in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0106] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a smart phone, a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0107] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not limiting, and thus other examples of the exemplary embodiments may have different values.

[0108] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0109] The above-described embodiments merely illustrate several embodiments of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for controlling the stepping time of a bipedal humanoid robot, characterized in that: The steps include: The equivalent reduced-order model is used to simulate the motion of a bipedal humanoid robot and an equivalent reduced-order model based on the Cartesian coordinate system of the foot end is established. Calculate the actual position of the center of mass relative to the grounded foot and the actual system angular momentum at the current moment based on the current state of the system; Obtaining the expected forward velocity and expected lateral velocity at the current moment based on the robot's motion path, and calculating the expected angular momentum according to the equivalent reduced-order model; Calculating a remaining step time based on the actual angular momentum and the expected angular momentum; A final step time is determined according to a system step time constraint, and a final footfall position is analytically calculated based on the final step time.

2. A method for controlling the stepping time of a bipedal humanoid robot according to claim 1, characterized in that The equivalent reduced-order model is expressed as follows: The solution of the equivalent reduced-order model is expressed as follows: Where: and is the forward or lateral position and velocity of the center of mass relative to the foot end, L y / x and is the rate of change of the lateral or forward angular momentum and angular momentum of the center of mass, m is the total mass of the robot, g is the acceleration due to gravity, z is the height of the center of mass, is the forward or sideways foot slip speed, T step is the expected step cycle, t is the current step time, and It is the lateral or forward angular momentum offset caused by the foot slip speed.

3. The method for controlling the stepping time of a bipedal humanoid robot according to claim 1, wherein The actual position p of the center of mass relative to the grounded foot at the current moment st (t) is represented by the following formula: p st (t)=p CoM (t)-p st,w (t) The actual angular momentum L(t) is the angular momentum of the system relative to the position of the grounded foot, which is expressed by the following formula: Where: p st,w (t) represents the absolute position of the foot touching the ground at the current moment t, p CoM (t) with Indicates the center of mass position and center of mass velocity at the current time t; L CoM (t) represents the angular momentum of the system relative to the center of mass at the current moment t, and ∧ represents the vector cross product.

4. A method for controlling the stepping time of a bipedal humanoid robot according to claim 1, characterized in that The desired angular momentum can be expressed as: Desired forward angular momentum: The desired angular momentum is calculated based on the left and right leg step widths and the desired lateral velocity: Desired lateral angular momentum: The desired lateral angular momentum can be calculated based on the desired forward velocity Calculation yields: Where: W is the desired stride width, is the expected lateral velocity The corresponding angular momentum.

5. The method for controlling the stepping time of a bipedal humanoid robot according to claim 1, wherein The remaining step time t remain It can be obtained by numerically solving the simultaneous equations, which is expressed as follows: Where, is the forward or lateral angular momentum relative to the foot's landing position at the end of the current stride, It is the forward or sideways angular momentum offset caused by the slipping speed of the foot.

6. The method for controlling the stepping time of a bipedal humanoid robot according to claim 1, wherein The final step time and the final foothold position, when the remaining step time is less than the minimum step time or greater than the maximum step time, the final step time and the final foothold position are expressed by the following formula:

7. A bipedal humanoid robot stepping time control device, referring to the bipedal humanoid robot stepping time control method according to claim 1, characterized in that include: Modeling module: used to build the state space equations of the reduced-order model of the bipedal humanoid robot; State estimation module: used to obtain the relative position of the center of mass and the foot end at the current moment, and the forward and lateral angular momentum of the system; Expected angular momentum module: used to calculate the expected angular momentum of the expected landing point or velocity; Numerical solution module: used to numerically solve the remaining step time based on the expected foot landing point position; Step control module: used to analyze the expected step time and the expected step landing point.

8. A terminal comprising a memory and a processor, wherein the memory is used to store a computer program, and the processor executes the computer program to enable the terminal to implement the method for controlling the stepping time of a bipedal humanoid robot according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer program executed by the terminal according to claim 8 is stored therein.

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