Robot center of mass motion planning method, device and biped robot

Abstract

The present application provides a robot center of mass motion planning method, device and bipedal robot, the method comprising: calculating the expected periodic trajectory of the robot's single gait based on the dynamic equation constructed by the simplified model of the robot; correcting the expected periodic trajectory according to the feedback of the robot's center of mass state, and generating the expected center of mass trajectory of the robot using the corrected expected periodic trajectory; and controlling the robot's motion according to the center of mass expected trajectory. The method performs trajectory planning and trajectory correction on a single gait cycle, and then combines them to obtain the expected center of mass trajectory. Compared with the traditional center of mass planning method, the method is simpler and faster, and is also convenient for real-time trajectory correction according to new task requirements.

Description

Technical Field

[0001] The present application relates to the field of robot control technology, and in particular to a robot center of mass motion planning method, device and bipedal robot. Background Art

[0002] When a bipedal humanoid robot walks, the trajectory of the center of mass is a very important factor affecting the walking stability. In existing technologies, complex motion equations or curves are usually constructed according to task requirements to pre-plan the trajectory of the center of mass during the robot's movement. When the task needs to be modified, the trajectory of the center of mass must be re-planned, which is often a complex and time-consuming process. Summary of the invention

[0003] In view of this, embodiments of the present application provide a robot center of mass motion planning method, device and bipedal robot.

[0004] In a first aspect, an embodiment of the present application provides a robot center of mass motion planning method, comprising:

[0005] Calculating the expected periodic trajectory of a single gait of the robot based on the dynamic equations constructed based on the simplified model of the robot;

[0006] Correcting the desired periodic trajectory according to the feedback robot center of mass state;

[0007] Generating an expected center of mass trajectory of the robot using the corrected expected periodic trajectory;

[0008] The robot movement is controlled according to the desired trajectory of the center of mass.

[0009] In some embodiments, the dynamic equation of the robot is obtained by simplifying the robot into a linear inverted pendulum model and making the zero moment point of the robot consistent with the fulcrum of the linear inverted pendulum.

[0010] In some embodiments, the center of mass state includes an actual center of mass position, and the correcting the expected periodic trajectory according to the fed-back robot center of mass state includes:

[0011] Calculating the error between the actual center of mass position fed back by the robot at the end of the previous gait cycle and the expected center of mass position at the initial moment of the current gait cycle;

[0012] Based on the error and the boundary conditions satisfied by the center of mass state of the robot, a correction term of the center of mass trajectory of the robot is constructed by fitting a cubic polynomial curve;

[0013] The expected periodic trajectory and the correction term are superimposed to obtain a corrected expected periodic trajectory.

[0014] In some embodiments, the boundary conditions satisfied by the center of mass state of the robot include:

[0015] In a single gait cycle, the correction amounts of the center of mass position at the initial moment and the end moment are the error and zero respectively, and the correction amounts of the center of mass velocity at the initial moment and the end moment are both zero.

[0016] In some embodiments, the kinetic equation is expressed as follows:

[0017] in,

[0018] In the formula, x and are the center of mass position and center of mass acceleration of the linear inverted pendulum in the forward direction, y and are respectively the center of mass position and center of mass acceleration of the linear inverted pendulum along the lateral direction, z is the height of the center of mass of the linear inverted pendulum from the ground, and g is the acceleration due to gravity.

[0019] In some embodiments, the expression of the desired center of mass trajectory of the robot is as follows:

[0020]

[0021] In the formula, x d (t) and y d (t) represents the desired center of mass trajectory of the robot in the forward and lateral directions, cosh() and sinh() represent the hyperbolic cosine and sine, respectively, S and D represent the step length and step width of the robot, respectively, and They represent the center of mass velocity of the robot in the forward direction and the lateral direction at the initial moment of a gait cycle, respectively, and f x (t) and f y (t) represent the correction components of the desired periodic trajectory in the forward direction and the lateral direction respectively.

[0022] In some embodiments, the robot center of mass motion planning method further includes:

[0023] The expected periodic trajectory is corrected according to the fed-back robot center of mass state and the task requirements received in real time to obtain the corrected expected periodic trajectory.

[0024] In a second aspect, an embodiment of the present application further provides a robot center of mass motion planning device, comprising:

[0025] A periodic trajectory solving module, used for calculating the expected periodic trajectory of a single gait of the robot based on the dynamic equations constructed by the simplified model of the robot;

[0026] A trajectory correction module, used to correct the desired periodic trajectory according to the feedback of the robot's center of mass state;

[0027] A center-of-mass trajectory generating module, used for generating an expected center-of-mass trajectory of the robot using the corrected expected periodic trajectory;

[0028] A motion control module is used to control the motion of the robot according to the expected trajectory of the center of mass.

[0029] In a third aspect, an embodiment of the present application further provides a bipedal robot, comprising a processor and a memory, wherein the memory stores a computer program, and the processor is used to execute the computer program to implement the above-mentioned robot center of mass motion planning method.

[0030] In a fourth aspect, an embodiment of the present application further provides a readable storage medium storing a computer program, which, when executed on a processor, implements the above-mentioned robot center of mass motion planning method.

[0031] The embodiments of the present application have the following beneficial effects:

[0032] The robot center of mass motion planning method proposed in the embodiment of the present application splits the robot's walking into multiple separate gait cycles to achieve trajectory planning for a single gait cycle. At the same time, considering that there is often an error between the single gait cycle trajectory and the actual center of mass trajectory due to interference, the calculated periodic trajectory is compensated to obtain the final expected center of mass trajectory for controlling the robot movement. Compared with the traditional center of mass planning method, the method is simpler and faster, and can also facilitate real-time trajectory correction according to new task requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 related drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of a robot according to an embodiment of the present application is shown;

[0035] Figure 2 A first flow chart of a robot center of mass motion planning method according to an embodiment of the present application is shown;

[0036] Figure 3 A schematic diagram showing a robot according to an embodiment of the present application simplified as a linear inverted pendulum;

[0037] Figure 4A schematic diagram showing an expected periodic trajectory of a single gait of a robot based on a linear inverted pendulum according to an embodiment of the present application is shown;

[0038] Figure 5 A flow chart showing the correction of the expected periodic trajectory according to an embodiment of the present application is shown;

[0039] Figure 6 A schematic diagram showing an error between the center of mass planning and the periodic trajectory of the robot in an embodiment of the present application is shown;

[0040] Figure 7 A schematic diagram showing the desired centroid planning obtained after compensating the periodic trajectory according to an embodiment of the present application is shown;

[0041] Figure 8 A second flow chart of the robot center of mass motion planning method according to an embodiment of the present application is shown;

[0042] Fig. 9 A schematic structural diagram of a robot center of mass motion planning device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0044] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various 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 claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0045] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0046] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0047] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0048] Please refer to Figure 1 , is a structural diagram of a robot 10 proposed in an embodiment of the present application, specifically, a bipedal robot. Exemplarily, the bipedal robot 10 may include a processor 11, a memory 12, and a sensing unit 13, wherein the memory 12 and the sensing unit 13 are both connected to the processor 11, the memory 12 stores a corresponding computer program, and the processor 11 is used to execute the computer program to implement the robot center of mass motion planning method in the embodiment of the present application, thereby effectively solving the problems in the prior art that the center of mass trajectory of the robot during walking needs to be planned in advance and is difficult to modify in real time.

[0049] Among them, the processor 11 can be an integrated circuit chip with signal processing capabilities. The processor 11 can be a general-purpose processor, including a central processing unit (CPU), a graphics processing unit (GPU), a network processor (NP), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or at least one of other programmable logic devices, discrete gates or transistor logic devices, and discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc., which can implement or execute the disclosed methods, steps and logic block diagrams in the embodiments of the present application.

[0050] The memory 12 may be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), etc. The memory 12 is used to store a computer program, and the processor 11 may execute the computer program accordingly after receiving an execution instruction.

[0051] Among them, the perception unit 13 mainly refers to the sensors set on the robot, which are used to transmit necessary external information and self-state information to the robot's control system, thereby providing necessary conditions for the robot's decision-making. In some cases, these sensors can be divided into internal sensors and external sensors, wherein the internal sensors are functional elements used to measure the robot's own state, and their function is to measure kinematic quantities and mechanical quantities, which are used for the robot to perceive its own motion state, so that the robot can move according to the specified parameters such as position, trajectory and speed. For example, in this embodiment, the robot's center of mass position, center of mass velocity, center of mass acceleration and other motion states can be fed back through these internal sensors. Exemplarily, these internal sensors include but are not limited to position or angle sensors, six-dimensional force sensors, pressure sensors, etc., which are set at corresponding joints or torsos. The external sensors mainly perceive the mutual information between the robot itself and the environment, such as visual information, and specifically include but are not limited to proximity sensors, visual sensors, etc. It should be understood that the above-mentioned sensors can be selectively set according to the actual application scenario of the robot.

[0052] In the present application, the robot 10 has two leg structures that imitate human walking, and is used to perform alternating movements of the left and right legs when walking. Like humans, the movement gait of the bipedal robot is periodic. In the periodic gait, the center of mass of the robot moves from the rear side of the supporting foot to the front side of the supporting foot, and the lateral position of the center of mass gradually approaches the supporting foot in the early stage of the current gait cycle, and then gradually moves away, thus completing the walking of a gait cycle of the bipedal robot. It can be understood that by planning and combining multiple single gait cycles, the robot can also complete the desired walking task.

[0053] Based on the above robot structure, the embodiment of the present application proposes a robot center of mass motion planning method, which splits the robot's walking process into multiple individual gait cycle units, performs trajectory planning for individual gait cycles, and then combines them to obtain the desired center of mass motion trajectory, thereby completing the center of mass motion trajectory planning. Compared with the traditional solution of planning the motion trajectory of the entire route in advance, this method is simpler and faster. Since each gait cycle is planned separately, the trajectory can be corrected in real time according to new task requirements.

[0054] Please refer to Figure 2 This embodiment proposes a robot center of mass motion planning method. Exemplarily, the robot center of mass motion planning method includes steps S110 to S140:

[0055] S110, calculating the expected periodic trajectory of a single gait of the robot based on the dynamic equations constructed by the simplified model of the robot.

[0056] In order to facilitate the study and analysis of the robot's motion characteristics, the robot model is simplified here. In this application, the linear inverted pendulum model (abbreviated as LIPM) will be used to simplify the entire model of the bipedal robot. The basic principle of the linear inverted pendulum is as follows: Figure 3 As shown, the linear inverted pendulum includes a center of mass and a telescopic rod connected to the center of mass, wherein the component of the force generated by the telescopic rod in the vertical direction can just compensate for the gravity.

[0057] In this embodiment, the supporting leg of the robot in the walking state is regarded as the telescopic rod, and the center of mass (trunk) of the robot is regarded as the center of mass of the linear inverted pendulum. To facilitate the description of the direction of movement, the coordinate system is established on the horizontal plane where the ankle joint of the supporting leg is located, the origin of the coordinate system is located at the ankle joint of the supporting leg, the x-axis points to the front direction of the robot (also called the forward direction), the y-axis points to the side direction of the robot, and the z-axis points to the direction perpendicular to the ground. It can be understood that the walking planning of the robot needs to meet the following requirements: the center of mass can smoothly transition from the initial position to the initial position of the next step, and the pressure center point of the supporting leg can be kept within the supporting polygon during this transition, thereby ensuring the stable walking of the robot. Among them, the pressure center is also called the zero moment point (ZMP), and it is assumed here that the ZMP position of the robot is [0, 0]. After setting the step length, step width and walking cycle for the robot, the characteristics of the linear inverted pendulum can be used to plan the center of mass trajectory of the robot.

[0058] Exemplarily, the dynamic equation of the robot can be obtained by simplifying the robot into a LIPM in advance and making the zero moment point (ZMP) of the robot consistent with the fulcrum of the linear inverted pendulum, which is also the dynamic equation of the linear inverted pendulum. Specifically, the dynamic equation of the linear inverted pendulum is as follows:

[0059] in,

[0060] In the formula, x and are the center of mass position and center of mass acceleration of the linear inverted pendulum along the forward direction, y and are the center of mass position and center of mass acceleration of the linear inverted pendulum along the lateral direction, z is the height of the center of mass of the linear inverted pendulum from the ground, and g is the acceleration due to gravity.

[0061] Then, according to the expected walking cycle and the expected center of mass height, the expected cycle trajectory of the robot in a single gait cycle can be calculated through the dynamic equation. It can be understood that when the set walking cycle is larger, the center of mass trajectory amplitude of the linear inverted pendulum is larger, but the center of mass of the linear inverted pendulum will always pass through the point (S / 2, D / 2), such as Figure 4 shown.

[0062] In one embodiment, when the center of mass height z remains unchanged, the above dynamic equation is solved to obtain the following expected periodic trajectory of the robot in a single gait cycle:

[0063]

[0064]

[0065] Where x(t) and y(t) are the expected periodic trajectories of the robot in the forward and lateral directions at time t, cosh() and sinh() represent the hyperbolic cosine and sine, respectively, and S and D represent the step length and step width of the robot, respectively. and They represent the center of mass velocity of the robot in the forward and lateral directions at the initial moment of a gait cycle.

[0066] Furthermore, taking the first-order derivative of the above expected periodic trajectory, we have:

[0067]

[0068]

[0069] In the formula, and are the speeds of the robot in the forward and lateral directions, respectively; x0 and y0 represent the center of mass positions in the forward and lateral directions at the initial moment of a gait cycle, respectively.

[0070] As an optional solution, for periodic trajectories, under ideal conditions (without interference), it is expected that at the end of a gait cycle T, the velocity magnitude and direction of the center of mass in the forward direction (corresponding to the x-axis direction) are the same as those at the initial moment, and the velocity magnitude and direction in the lateral direction (corresponding to the y-axis direction) are opposite to those at the initial moment, that is, the following constraints are satisfied:

[0071]

[0072] Therefore, for the calculated expected periodic trajectory, combined with the above constraints, it can be calculated:

[0073]

[0074] In the formula, and are the initial speed values ​​of the reference periodic trajectory, that is, in the absence of interference, the robot will move at [-S / 2, D / 2, ] as the initial values ​​of the center of mass position and center of mass velocity, and the expected periodic trajectory of a single gait cycle solved above is used as the ideal center of mass trajectory planning.

[0075] However, in actual situations, due to the existence of various interference factors such as model errors, friction coefficients, structural gaps, external forces, etc., the robot cannot guarantee that the step length and step width exactly meet the set S and D at the end of each gait cycle, and the forward and lateral positions of the center of mass cannot be exactly S / 2 and D / 2. Therefore, it is necessary to consider the center of mass trajectory planning when there is interference.

[0076] Exemplarily, during walking, the robot controls the joints of the robot to move according to the center of mass trajectory calculated in the real-time gait cycle, and then collects the actual motion state of the robot to feedback after the movement, so as to determine whether it moves according to the expected trajectory. In this embodiment, based on the expected cycle trajectory of each gait cycle calculated, the actual center of mass state of the previous step is used for compensation to achieve the purpose of correcting the expected center of mass trajectory calculated in the current step.

[0077] S120, correcting the expected periodic trajectory according to the fed-back robot center of mass state.

[0078] The robot's center of mass state may include one or more of the position, velocity, and acceleration of the robot's center of mass, and the above parameters may be directly collected or indirectly calculated by corresponding sensors disposed in the robot's torso. In this embodiment, the center of mass trajectory of the previous step is mainly used to correct the center of mass trajectory of the current step.

[0079] In one embodiment, Figure 5 As shown, step S120 includes the following sub-steps:

[0080] S210, calculating the error between the actual center of mass position fed back by the robot at the end of the previous gait cycle and the expected center of mass position at the initial moment of the current gait cycle.

[0081] like Figure 6 As shown in the figure, in the coordinate system established with the position of the supporting leg of the i-th step, the i-th step periodic trajectory under the ideal state (i.e., the expected periodic trajectory mentioned above) can be calculated by the above dynamic equation. However, when there is interference, at the initial moment of the gait cycle, there will be a position error between the i-1-th step center of mass trajectory at the end moment and the i-th step center of mass trajectory at the initial moment, which is denoted as [δx,δy], where δx and δy are the center of mass position errors in the forward and lateral directions, respectively.

[0082] S220, constructing a correction term for the robot's center of mass trajectory through cubic curve fitting based on the error and the boundary conditions satisfied by the robot's center of mass state.

[0083] In one embodiment, the boundary conditions satisfied by the center of mass state of the robot may include but are not limited to: within a single gait cycle, the correction amounts of the center of mass position at the initial moment and the final moment are the above-calculated error and zero, respectively, and the correction amounts of the center of mass velocity at the initial moment and the final moment are both zero. Specifically, if described by an expression, then:

[0084] f x (0) = δx, f x (T) = 0;

[0085]

[0086] f y (0) = δy, f y (T) = 0;

[0087]

[0088] Where, T represents the gait period; f x (0) and They represent the corrections of the center of mass position and center of mass velocity along the forward direction at the initial moment, respectively, x (T) and They represent the corrections of the center of mass position and center of mass velocity along the forward direction at the end time respectively; f y (0) and They represent the corrections of the center of mass position and center of mass velocity along the lateral direction at the initial moment, respectively. y (T) and They respectively represent the correction amount of the mass center position and mass center velocity along the lateral direction at the end time. It can be understood that the above boundary conditions are only an example. For example, boundary conditions such as constraints on mass center acceleration can also be added, which are not limited here.

[0089] Then, the robot's center of mass trajectory is compensated respectively by a cubic polynomial curve that satisfies the boundary conditions, that is, the above-mentioned expected periodic trajectory is corrected. It can be understood that by using a cubic polynomial to correct the calculated periodic trajectory, the smoothness of the center of mass movement when the supporting leg is switched can be ensured. For example, the cubic curve used for fitting may include but is not limited to a cubic general polynomial curve, a cubic S-shaped curve, a cubic sample curve, etc. The cubic sample curve may be a cubic Hermite curve or a cubic Bezier curve, etc., which is not limited here.

[0090] Taking the above boundary conditions satisfied by the center of mass position and velocity in a single gait cycle as an example, using a general cubic polynomial curve, the following polynomial expression can be obtained:

[0091]

[0092]

[0093] In the formula, f x (t) and f y (t) represent the correction components of the expected periodic trajectory in the forward direction and the lateral direction respectively.

[0094] S230, superimposing the expected periodic trajectory and the correction term to obtain a corrected expected periodic trajectory.

[0095] Exemplarily, after obtaining the correction term, the calculated expected periodic trajectory and the correction term may be added to obtain the final periodic trajectory. Taking the above polynomial expression as an example, the expression of the corrected expected periodic trajectory is as follows:

[0096]

[0097] In the formula, x d (t) and y d (t) represents the desired center of mass trajectory of the robot along the forward and sideways directions.

[0098] S130, generating an expected center of mass trajectory of the robot using the corrected expected periodic trajectory.

[0099] Exemplarily, the compensated periodic trajectories of each gait cycle may be combined to serve as the planned desired center of mass trajectory. Figure 7As shown, for the i-th step, after calculating the expected periodic trajectory of the i-th step and the correction term of the i-th step, the corrected expected periodic trajectory can be used as the expected trajectory of the center of mass of the i-th step. For each gait cycle, this method is used to determine the expected trajectory of the center of mass of the corresponding step, and the entire expected center of mass trajectory of the robot can be obtained.

[0100] S140, controlling the movement of the robot according to the expected trajectory of the center of mass.

[0101] Demonstratively, after the final center of mass trajectory is determined, the control quantities of each joint of the robot, such as joint angles, joint angular velocities, etc., can be solved through the inverse kinematics equations; the calculated joint control quantities are then sent to the corresponding joint motors to drive the motors to rotate, so that the robot can walk along the desired center of mass trajectory and achieve the expected task.

[0102] As an optional solution, considering that a new task may need to be temporarily performed during the robot's movement, the robot's center of mass trajectory also needs to be adjusted accordingly. In this regard, the present embodiment can also make real-time corrections to the expected periodic trajectory calculated based on the dynamic equation according to the task requirements received in real time, and then adjust the center of mass trajectory in real time without having to re-plan the entire center of mass trajectory, which is fast and simple.

[0103] For example, Figure 8 As shown, for the above step S120, when the expected periodic trajectory is corrected, the robot center of mass motion planning method further includes:

[0104] S121, correcting the expected periodic trajectory according to the fed-back robot center of mass state and the task requirements received in real time to obtain a corrected expected periodic trajectory.

[0105] For example, the task requirement may include but is not limited to performing a following operation. In real-time planning of the center of mass trajectory, in addition to considering the interference of the robot itself, this embodiment also considers the temporary receipt of new tasks, which can improve the response efficiency of the robot in performing new tasks. Exemplarily, the corresponding error can be calculated through the feedback of the robot center of mass state, and then a total correction term is calculated using the error and the boundary conditions of the task requirements to be executed, and then the periodic trajectory is corrected using the total correction term.

[0106] The center of mass motion planning method proposed in this embodiment splits the walking process into multiple separate gait cycles, and plans a periodic trajectory for each gait cycle based on the dynamic equation constructed based on the simplified linear inverted pendulum model of the robot, and then combines multiple periodic trajectories as the center of mass trajectory of the robot. This is simpler and faster than the traditional center of mass planning method, and can be corrected in real time according to new task requirements; and using cubic curves to correct the calculated periodic trajectory can maintain the smoothness of the center of mass motion when the supporting foot switches.

[0107] Please refer to Fig. 9 Based on the method of the above embodiment, this embodiment proposes a robot center of mass motion planning device 100. Exemplarily, the robot center of mass motion planning device 100 includes:

[0108] The periodic trajectory solving module 110 is used to calculate the expected periodic trajectory of a single gait of the robot based on the dynamic equation constructed by the simplified model of the robot.

[0109] The dynamic equation of the robot is obtained by simplifying the robot into a linear inverted pendulum model and making the zero moment point of the robot consistent with the fulcrum of the linear inverted pendulum.

[0110] The trajectory correction module 120 is used to correct the expected periodic trajectory according to the feedback of the robot's center of mass state.

[0111] The center-of-mass trajectory generating module 130 is used to generate the expected center-of-mass trajectory of the robot using the corrected expected periodic trajectory.

[0112] The motion control module 140 is used to control the motion of the robot according to the expected trajectory of the center of mass.

[0113] Among them, the trajectory correction module 120 includes an error calculation submodule, a curve fitting submodule and a correction superposition submodule. Specifically, the error calculation submodule is used to calculate the error between the actual center of mass position of the robot at the end moment of the previous gait cycle feedback and the expected center of mass position calculated to the initial moment of the current gait cycle; the curve fitting submodule is used to construct a correction term of the robot's center of mass trajectory through cubic polynomial curve fitting based on the error and the boundary conditions satisfied by the center of mass state of the robot; the correction superposition submodule is used to superimpose the expected periodic trajectory and the correction term to obtain a corrected expected periodic trajectory.

[0114] Furthermore, the trajectory correction module 120 is further used to correct the expected periodic trajectory according to the fed-back robot center of mass state and the task requirements received in real time to obtain the corrected expected periodic trajectory.

[0115] It can be understood that the device of this embodiment corresponds to the method of the above embodiment, and the options in the above embodiment are also applicable to this embodiment, so they will not be described repeatedly here.

[0116] The present application also provides a readable storage medium for storing the computer program used in the above-mentioned bipedal robot.

[0117] In several embodiments provided in the present 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 architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in an alternative implementation, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the structure diagram and / or the flow diagram, and the combination of boxes in the structure diagram and / or the flow diagram, can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0118] In addition, the functional modules or units in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0119] If the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art, and the computer software product is stored in a storage medium, including several instructions for a computer device (which can be a smart phone, a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. 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 disk or an optical disk.

[0120] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A robot center of mass motion planning method, characterized in that: include: Calculating the expected periodic trajectory of a single gait of the robot based on the dynamic equations constructed by the simplified model of the robot; Calculating the error between the actual center of mass position fed back by the robot at the end of the previous gait cycle and the expected center of mass position at the initial moment of the current gait cycle; Based on the error and the boundary conditions satisfied by the center of mass state of the robot, a correction term of the center of mass trajectory of the robot is constructed by fitting a cubic polynomial curve; wherein the boundary conditions include: within a single gait cycle, the correction amount of the center of mass position at the initial moment and the end moment is the error and zero respectively, and the correction amount of the center of mass velocity at the initial moment and the end moment is zero; Superimposing the expected periodic trajectory and the correction term to obtain a corrected expected periodic trajectory; Generating an expected center of mass trajectory of the robot using the corrected expected periodic trajectory; The robot movement is controlled according to the desired trajectory of the center of mass.

2. The robot center of mass motion planning method according to claim 1, characterized in that: The dynamic equation of the robot is obtained by simplifying the robot into a linear inverted pendulum model and making the zero moment point of the robot consistent with the fulcrum of the linear inverted pendulum.

3. The robot center of mass motion planning method according to claim 2, characterized in that: The expression of the kinetic equation is as follows: in, In the formula, x and are the center of mass position and center of mass acceleration of the linear inverted pendulum in the forward direction, y and are respectively the center of mass position and center of mass acceleration of the linear inverted pendulum along the lateral direction, z is the height of the center of mass of the linear inverted pendulum from the ground, and g is the acceleration due to gravity.

4. The robot center of mass motion planning method according to claim 3, characterized in that: The expression of the desired center of mass trajectory of the robot is as follows: In the formula, x d (t) and y d (t) represents the desired center of mass trajectory of the robot in the forward and lateral directions, cosh() and sinh() represent the hyperbolic cosine and sine, respectively, S and D represent the step length and step width of the robot, respectively, and They represent the center of mass velocity of the robot in the forward direction and the lateral direction at the initial moment of a gait cycle, respectively, and f x (t) and f y (t) represent the correction components of the desired periodic trajectory in the forward direction and the lateral direction respectively.

5. The robot center of mass motion planning method according to any one of claims 1 to 4, characterized in that: Also includes: The expected periodic trajectory is corrected according to the fed-back robot center of mass state and the task requirements received in real time to obtain the corrected expected periodic trajectory.

6. A robot center of mass motion planning device, characterized in that: include: A periodic trajectory solving module, used for calculating the expected periodic trajectory of a single gait of the robot based on the dynamic equations constructed by the simplified model of the robot; A trajectory correction module is used to calculate the error between the actual center of mass position of the robot fed back at the end of the previous gait cycle and the expected center of mass position at the initial moment of the current gait cycle; based on the error and the boundary conditions satisfied by the center of mass state of the robot, a correction term of the robot's center of mass trajectory is constructed by fitting a cubic polynomial curve; The expected periodic trajectory and the correction term are superimposed to obtain a corrected expected periodic trajectory; wherein the boundary conditions include: within a single gait cycle, the correction amounts of the center of mass position at the initial moment and the end moment are the error and zero respectively, and the correction amounts of the center of mass velocity at the initial moment and the end moment are both zero; A center-of-mass trajectory generating module, used for generating an expected center-of-mass trajectory of the robot using the corrected expected periodic trajectory; A motion control module is used to control the motion of the robot according to the expected trajectory of the center of mass.

7. A bipedal robot, characterized in that: The biped robot comprises a processor and a memory, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the robot center of mass motion planning method according to any one of claims 1 to 5.

8. A readable storage medium, characterized in that: The computer program is stored therein, and when the computer program is executed on a processor, the robot center of mass motion planning method according to any one of claims 1 to 5 is implemented.

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