Universal motion modeling method and system for three-dimensional gaits of snakelike robot

Abstract

The invention relates to the technical field of snakelike robot autonomous motion control, and discloses a snakelike robot three-dimensional gait general motion modeling method and system, and the method comprises the following steps: obtaining parameters, decomposing the motion of a snakelike robot into two main components: a backbone curve motion component and a motion component of the snakelike robot along a backbone curve, according to the parameters, a backbone curve motion component and a motion component of the snake-shaped robot along the backbone curve are calculated, the backbone curve motion component and the motion component vector of the snake-shaped robot along the backbone curve are summed, a universal motion model for the three-dimensional gait of the snake-shaped robot is constructed, and the three-dimensional gait of the snake-shaped robot is obtained through the model. Displacement and speed of various gaits generated by splicing different curves during different control inputs can be calculated, and the method is suitable for various gaits of the snake-shaped robot and is high in accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of autonomous motion control of snake robots, and particularly to a general motion modeling method and system for three-dimensional gait of snake robots. Background Art

[0002] As a bionic robot, a snake robot is composed of alternately connected pitch and yaw joints, and can form various motion gaits and configurations through its own configuration changes to adapt to various environments. Among them, a three-dimensional snake robot without passive wheels can achieve bionic functions such as climbing trees, passing through ruins, crossing pipelines and adapting to various terrains, so as to perform tasks such as reconnaissance, search and rescue, and exploration. At present, the motion ability of snake robots on the ground has been gradually improved, and there are various gaits to cope with various terrain environments, such as the lateral serpentine gait for deserts and sandy soils, the spiral rolling gait for climbing pipelines and trees, and the lateral undulating gait for underwater motion. However, the current research results mainly focus on the artificial planning and design of special gaits and motions. In terms of autonomous motion, due to the lack of a general motion modeling method for these various gaits, it is impossible to predict the motion of the snake robot according to the input control quantity and environmental information, so automatic control is difficult to achieve.

[0003] There are few achievements in the method of establishing the motion model of snake robots. There are mainly three difficulties: First, there are various gait generation methods for snake robots, such as common curve splicing methods, wave function methods, and Central Pattern Generator methods. The mathematical descriptions of these gait generation methods vary greatly, making it difficult to find a general motion modeling method. Second, as a highly redundant robot, snake robots have many ground contact points during movement, and the contact situation changes very complexly, increasing the difficulty of motion modeling. Finally, some uncontrollable factors during movement, such as slipping and errors caused by actuator performance, will affect the accuracy of motion modeling. The existing motion modeling achievements mainly analyze individual modules during the movement process, lacking a consideration of the overall robot, resulting in relatively complex final results, general generalizability, and low accuracy. At the same time, it can only be applied to gaits with relatively simple shapes.In recent years, some researchers have tried data-driven methods (see Y. Hwang, M. Ishikawa, Generative locomotion model of snake robot with hierarchical networks for topological representation, in Proc. Int. Conf. Agents Artif. Intell., 2020, 194202. (Y.Hwang and M. Ishikawa, Generative locomotion model of snake robot with hierarchical networks for topological representation, in Proc. Int. Conf. Agents Artif. Intell., 2020, 194202.)), (R. Wang, W. Xi, X. Guo, and Y. Fang, Path following for snake robot using crawler gait based on path integral reinforcement learning, in Proc. IEEE 6th Int. Conf. Adv. Robot. Mechatronics, 2021, 192198. (R. Wang, W. Xi, X. Guo, and Y. Fang, Path following for snake robot using crawler gait based on path integral reinforcement learning, in Proc. IEEE 6th Int. Conf. Adv. Robot. Mechatronics, 2021, 192198.)) or methods combining action fuzzy mapping with controllers (see A.H.Chang, P.A.Vela, Shape-centric modeling for control of traveling wave rectilinear locomotion on snake-like robots, Robot. Auton. Syst., vol. 124, (2020), Art. no. 103406 (A. H. Chang and P. A. Vela, Shape-centric modeling for control of traveling wave rectilinear locomotion on snake-like robots, Robot. Auton. Syst., vol. 124, 2020, Art. no. 103406)).Although autonomous behavior has been achieved to a certain extent, the deficiencies are also obvious: First, the data collection process is cumbersome and repetitive, and attention needs to be paid to the diversity and representativeness of the data, which is highly difficult; Second, the resulting motion model is extremely sensitive to gait and the physical environment, and due to its low interpretability, it is difficult to make subsequent adjustments and modifications; Finally, these methods are only applicable to gaits with simple shapes and lack generalization, and are not applicable to gaits with three-dimensional complex configurations.

[0004] In summary, in order to achieve safe and stable autonomous movement of the snake robot, there is an urgent need to design a general motion modeling method that is applicable to various gaits and has high precision. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a general motion modeling method and system for the three-dimensional gait of a snake robot, which can be used for motion modeling of snake robots with various gaits.

[0006] The present invention provides a general motion modeling method for the three-dimensional gait of a snake robot, including the following steps: S1. Obtain parameters: the contact points of the snake robot with the ground, the control input quantity, the backbone curve parameters of the snake robot, the length of the snake robot joint module, and the position of the current snake head on the backbone curve S h0 ; The control input quantity refers to the transfer length of the gait; S2. Decompose the motion of the snake robot into two main components: the backbone curve motion component and the motion component of the snake robot along the backbone curve; The backbone curve is a variety of gait curves generated by the curve splicing method; The backbone curve motion component refers to the displacement caused by the change of the contact points of the snake robot with the ground; The motion component of the snake robot along the backbone curve refers to the displacement caused by the change of the snake robot's own configuration; S3. Calculate the backbone curve motion component according to the contact points of the snake robot backbone curve with the ground, the control input quantity, the snake robot backbone curve parameters, and the length of the snake robot joint module; S4. According to the snake robot backbone curve parameters, the control input quantity, and the position of the current snake head on the backbone curve S h0 , calculate the motion component of the snake robot along the backbone curve; S5. Vectorially add the backbone curve motion component and the motion component of the snake robot along the backbone curve to construct a general motion model for the three-dimensional gait of the snake robot.

[0007] Further, in S1, the method for determining the contact points of the snake robot with the ground includes: Taking the starting point of the backbone curve of the snake robot as the coordinate origin O, the X-axis is parallel to the connection line from the starting point to the ending point of the smallest repeating unit in the backbone curve of the snake robot, the Z-axis is perpendicular to the horizontal plane upward, and the Y-axis is determined by the right-hand rule to establish a three-dimensional coordinate system; The contact point of the snake robot with the ground refers to the point with the smallest Z-axis coordinate value in the three-dimensional coordinates.

[0008] Further, in S1, the parameters of the backbone curve of the snake robot specifically include: The geometric parameters of each curve segment of the gait curve, including: segment ordinal number, segment shape, segment parameters, and the twist angle at the connection with the previous segment .

[0009] Further, in S1, the position of the current snake head on the backbone curve S h0 The determination method includes: Calculating the position of the current snake head on the backbone curve according to the starting point of the backbone curve and the historical control input amount S h0 .

[0010] Further, in S3, according to the contact points of the snake robot with the ground, the control input amount, the parameters of the backbone curve of the snake robot, and the lengths of the joint modules of the snake robot, calculating the motion components of the backbone curve specifically includes: Assuming that there is no slipping phenomenon between the snake robot and the ground during the movement; Calculating the magnitude of the motion components of the backbone curve according to the control input amount, and the calculation formula is as follows: ; Wherein, is the magnitude of the motion components of the backbone curve, is the control input amount, that is, the transmission length of the gait; Calculating the direction of the motion components of the backbone curve according to the contact points of the backbone curve of the snake robot with the ground, the lengths of the joint modules, and the parameters of the backbone curve of the snake robot; Determining the motion components of the backbone curve according to the magnitude and direction of the motion components of the backbone curve.

[0011] Further, in S4, according to the parameters of the backbone curve of the snake robot, the control input amount, and the position of the current snake head on the backbone curve S h0 , calculating the motion components of the snake robot along the backbone curve specifically includes: Determine the direction of the motion component of the snake robot along the backbone curve according to the tangent direction of each point on the backbone curve, and the position of each point on the backbone curve depends on the position of the current snake head on the backbone curve; Perform a line integral based on the control input and the new position from the current snake head position along the backbone curve to the position after adding the gait transfer length to the current snake head position, and calculate the magnitude of the motion component of the robot along the backbone curve. The calculation formula is as follows: ; Among them, is the magnitude of the motion component of the snake robot along the backbone curve in the x direction; is the magnitude of the motion component of the snake robot along the backbone curve in the y direction; is the unit vector in the x direction, is the unit vector in the y direction, is the control input, that is, the transfer length of the gait; S h0 is the position of the current snake head on the backbone curve; Determine the motion component of the snake robot along the backbone curve according to the direction and magnitude of the motion component of the snake robot along the backbone curve.

[0012] The present invention also provides a three-dimensional gait general motion modeling system for a snake robot, which is used to execute the three-dimensional gait general motion modeling method for a snake robot, and is characterized by including the following modules: A data acquisition module, which is used to extract the contact points of the snake robot with the ground and the control input, the backbone curve parameters of the snake robot, the lengths of the joint modules of the snake robot, and the position of the current snake head on the backbone curve S h0 information; A motion decomposition module, which is connected to the data acquisition module and is used to decompose the motion of the snake robot into two main components: the backbone curve motion component and the motion component of the snake robot along the backbone curve; the backbone curve is a variety of gait curves generated by the curve splicing method; the backbone curve motion component refers to the displacement caused by the change of the contact points of the snake robot with the ground; the motion component of the snake robot along the backbone curve refers to the displacement caused by the change of the self-configuration of the snake robot; A calculation module, which is connected to the motion decomposition module and is used to calculate the backbone curve motion component and the motion component of the snake robot along the backbone curve. According to the contact points of the snake robot with the ground, the control input, the backbone curve parameters of the snake robot, and the lengths of the joint modules of the snake robot, calculate the backbone curve motion component; according to the backbone curve parameters of the snake robot, the control input, and the position of the current snake head on the backbone curve S h0, calculate the motion components of the snake robot along the backbone curve; A model establishment module, connected to the calculation module, is configured to vectorially sum the backbone curve motion components and the motion components of the snake robot along the backbone curve to construct a general motion model for the three-dimensional gait of the snake robot.

[0013] The embodiments of the present invention have the following technical effects: A general motion modeling method for the three-dimensional gait of a snake robot provided by the present invention is based on regarding the backbone curve of the snake robot as a movable entity, decomposing the motion of the snake robot into: the backbone curve motion components and the motion components of the robot along the backbone curve, and obtaining the motion model of the snake robot through vectorial summation. It can be applied to the motion modeling of various gaits of the snake robot, and can more accurately understand and predict the motion behavior of the snake robot, which helps to achieve more precise motion control and enables the robot to perform tasks more stably and efficiently in complex environments. Description of the Drawings

[0014] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 Schematic diagram of a general motion modeling framework for the three-dimensional gait of a snake robot according to the present invention; Figure 2 Schematic diagram of the structure of the snake robot; Figure 3 Schematic diagram of the present invention decomposing the motion into the backbone curve motion components and the motion components of the snake robot along the backbone curve; Figure 4 Schematic diagram of the configuration change of the snake robot during motion; Figure 5 Snake robot platform used when the present invention conducts experimental verification; Figure 6 Schematic diagram of the lateral undulating gait of the snake robot; Figure 7 Schematic diagram of the instantaneous switching analysis of the contact points with the ground during the lateral undulating gait motion of the snake robot; Figure 8 Motion process diagram of the lateral undulating gait of the snake robot; Figure 9 Comparison diagram of the predicted trajectory of the snake head and the actually collected snake head trajectory during the lateral undulating gait motion of the snake robot; Figure 10 Schematic diagram of the tracked gait of a snake robot Figure 11 Motion process diagram of the tracked gait of a snake robot Figure 12 Comparison diagram of the predicted trajectory of the snake head and the actually collected snake head trajectory during the tracked gait movement of a snake robot Figure 13 Schematic diagram of the S-shaped foot wave gait of a snake robot Figure 14 Motion process diagram of the S-shaped foot wave gait of a snake robot Figure 15 Comparison diagram of the predicted trajectory of the snake head and the actually collected snake head trajectory during the S-shaped foot wave gait movement of a snake robot Specific implementation mode

[0016] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope protected by the present invention.

[0017] Figure 1 Schematic diagram of a general motion modeling framework for the three-dimensional gait of a snake robot, describing each step of the motion modeling method proposed by the present invention Figure 2 Schematic diagram of the structure of a snake robot, composed of pitch joints and yaw joints with orthogonally alternating joint axes Figure 4 Schematic diagram of the configuration change of a snake robot during movement, where the position of the snake head on the backbone curve is s h0 , as the snake head moves along the backbone curve, the entire snake robot forms the shape of the corresponding backbone curve segment. According to Figure 1 , Figure 2 and Figure 4 shown, a general motion modeling method for the three-dimensional gait of a snake robot is described as follows: S1. Obtain parameters: the contact points of the snake robot with the ground, the control input quantity, the backbone curve parameters of the snake robot, the length of the joint modules of the snake robot, and the current position of the snake head on the backbone curve S h0 .

[0018] Specifically, the control input quantity refers to the transfer length of the gait

[0019] The method for determining the contact points of the snake robot with the ground includes: Taking the starting point of the backbone curve of the snake robot as the coordinate origin O, the X-axis is parallel to the line connecting the starting point to the ending point of the smallest repeating unit in the backbone curve of the snake robot, the Z-axis is perpendicular to the horizontal plane and points upward, and the Y-axis is determined by the right-hand rule to establish a three-dimensional coordinate system; The contact point of the snake robot with the ground refers to the point with the smallest Z-axis coordinate value in the three-dimensional coordinates.

[0020] The parameters of the backbone curve of the snake robot specifically include the geometric parameters of each curve segment of the gait curve. The geometric parameters include: segment ordinal number, segment shape, segment parameters, and the twist angle at the connection with the previous segment .

[0021] Exemplarily, the geometric parameters of the track gait curve are shown in Table 1, where the segment parameters include the straight-line length , the radius of the arc , the semi-arc spacing , and the twist angle are all set as needed when designing the gait.

[0022] Table 1 Geometric parameters of the track gait curve

[0023] The current position of the snake head on the backbone curve S h0 The determination method includes: calculating the current position of the snake head on the backbone curve according to the starting point of the backbone curve and the historical control input S h0 .

[0024] S2. Decompose the movement of the snake robot into two main components: the backbone curve movement component and the movement component of the snake robot along the backbone curve.

[0025] Specifically, the backbone curve is a variety of gait curves generated by the curve splicing method; the backbone curve movement component refers to the displacement caused by the change of the contact point of the snake robot with the ground; the movement component of the snake robot along the backbone curve refers to the displacement caused by the change of the self-configuration of the snake robot.

[0026] S3. Calculate the backbone curve movement component according to the contact point of the backbone curve of the snake robot with the ground, the control input, the parameters of the backbone curve of the snake robot, and the length of the joint module of the snake robot.

[0027] Specifically, assume that there is no slipping phenomenon between the snake robot and the ground during the movement; if there is a slipping phenomenon between the snake robot and the ground during the movement, errors will occur. Therefore, assume that there is no slipping phenomenon between the snake robot and the ground during the movement.

[0028] Calculate the magnitude of the motion component of the backbone curve according to the control input quantity. The calculation formula is as follows: ; Wherein, is the magnitude of the motion component of the backbone curve, is the control input quantity, that is, the transfer length of the gait. The transfer length of the gait is set as required, and each input can be the same or different.

[0029] Calculate the direction of the motion component of the backbone curve according to the contact point of the backbone curve of the snake robot with the ground, the length of the joint module, and the backbone curve parameters of the snake robot; Define a direction angle for the direction of the motion component of the backbone curve , as shown in Figure 3 , wherein is the unit vector in the y direction, indicating the angle between this component and the axis. When calculating this direction angle, it is necessary to analyze the contact point of the gait curve with the ground. The direction of the component is the tangent direction of the gait backbone curve at the ground contact point. Since the snake robot is moving continuously and each joint is alternately in contact with the ground, directly analyzing the motion of each module is cumbersome and inefficient. However, after the gait design is completed, the shape of the backbone curve will not change, and the positions on the curve that will contact the ground will also remain unchanged, that is, the tangent directions of these ground contact points will not change during the motion. According to the contact point of the backbone curve of the snake robot with the ground, the length of the joint module, and the backbone curve parameters of the snake robot, the cumbersome and repetitive motion analysis of the joint module is effectively avoided.

[0030] Determine the motion component of the backbone curve according to the magnitude and direction of the motion component of the backbone curve.

[0031] S4. According to the backbone curve parameters of the snake robot, the control input quantity, and the current position of the snake head on the backbone curve S h0 , calculate the motion component of the snake robot along the backbone curve.

[0032] Specifically, determine the direction of the motion component of the snake robot along the backbone curve according to the tangent direction of each point on the backbone curve. The positions of each point on the backbone curve depend on the current position of the snake head on the backbone curve; Perform a line integral according to the control input quantity and the new position from the current snake head position to the position after adding the gait transfer length along the backbone curve to calculate the magnitude of the motion component of the robot along the backbone curve. The calculation formula is as follows: ; Wherein, is the magnitude of the motion component of the snake robot along the backbone curve in the direction; is the magnitude of the motion component of the snake robot along the backbone curve in the direction; is the unit vector in the direction, is the unit vector in the S h0 is the position of the current snake head on the backbone curve; Determine the motion component of the snake robot along the backbone curve according to the direction and magnitude of the motion component of the snake robot along the backbone curve.

[0033] S5. Vectorially add the backbone curve motion component and the motion component of the snake robot along the backbone curve to construct a general motion model of the three-dimensional gait of the snake robot.

[0034] Exemplarily, in order to verify the accuracy of a method for general motion modeling of the three-dimensional gait of a snake robot proposed by the present invention, a snake robot is built. The snake robot has a total of 16 joints, a total length of 1.5 m, a cross-sectional diameter of 0.08 m, and weighs about 5 kg. The motors are divided into two groups. The axes of the servos in the same group are parallel to each other and face the same direction, and the axes of adjacent servos are perpendicular to each other. A self-designed connecting piece is used between the servos, and a resin shell and a rubber sleeve are installed outside for protection. It receives the angles calculated by the PC end through the control line and then distributes them to each servo through the bus. There is a marking point on the head of the robot to facilitate the motion capture system to collect the motion trajectory; build a three-dimensional snake robot platform with a standard structure, as Figure 5 shown.

[0035] Exemplarily, Figure 6 is a schematic diagram of the lateral undulating gait of the snake robot, Figure 7 is a schematic diagram of the instantaneous switching analysis of the contact points with the ground during the lateral undulating gait motion of the snake robot, Figure 8 is a motion process diagram of the lateral undulating gait of the snake robot. According to Figures 6 - 8 shown, when the snake robot performs the lateral undulating gait motion, through the modeling method proposed by the present invention, a motion model of the snake robot at any time and for any control input can be established as follows: ; wherein, is the control input, is the length of the joint module of the snake robot, is the segment parameter of the lateral undulating gait, S h1 is the position of the snake head on the backbone curve of the snake robot at the start of the motion, It is the direction of the backbone curve motion component obtained from the switching of the contact points between the snake robot and the ground.

[0036] Furthermore, since the gait is periodic, for the convenience of practical use, the motion model of the snake robot for one period is calculated, that is, when the control input makes the snake head advance along the backbone curve of the snake robot for one gait period, the displacement generated by the snake robot is: ; where is the length of the joint module of the snake robot, is the segment parameter of the lateral undulating gait, is the twist angle at the connection with the previous segment, is the direction of the backbone curve motion component obtained from the switching of the contact points between the snake robot and the ground.

[0037] Figure 9 is based on the actual snake head motion trajectory captured by the motion capture system and the predicted snake head motion trajectory according to the motion model. Refer to Figure 9 , when the control input is 3 gait periods, it can be obtained that the motion modeling method provided by the present invention has more accurate prediction, the predicted snake head motion trajectory and the actual snake head motion trajectory are basically coincident, and both also show three periods, with an error of 1.8% in the X direction (expected 2.64m, actual 2.69m) and an error of 2.4% in the Y direction (expected 0.81m, actual 0.79m). A small amount of error comes from the fitting error, measurement error and error caused by ground slippage during gait generation.

[0038] Exemplarily, Figure 10 is the schematic diagram of the track gait of the snake robot, Figure 11 is the motion process diagram of the track gait of the snake robot. According to Figures 10 - 11 shown, when the snake robot moves in the track gait, through the modeling method proposed by the present invention, the motion model of the snake robot at any time with any control input can be established as follows: ; where is the control input quantity, S h1 is the position of the snake head on the backbone curve of the snake robot at the start of the motion, is the direction of the backbone curve motion component obtained from the switching of the contact points between the snake robot and the ground.

[0039] Furthermore, since the gait is periodic, for the convenience of practical use, the motion model of the snake robot for one period is calculated, that is, when the control input makes the snake head advance along the backbone curve of the snake robot for one gait period, the displacement generated by the snake robot is: ; Among them, are the segment parameters of the crawler gait.

[0040] Figure 12 Based on the actual snake head movement trajectory captured by the motion capture system and the snake head movement trajectory predicted according to the motion model, with the control input being 2 gait cycles, it can be obtained that the motion modeling method provided by the present invention has more accurate prediction, the predicted snake head movement trajectory and the actual snake head movement trajectory are basically coincident, and both also show two cycles. There is an error of 3.3% in the X direction (expected 2.96m, actual 2.86m). The expected motion direction is along the X-axis, and there is an error angle of 1.7 between the actual motion direction and the X-axis. A small amount of error comes from the fitting error during gait generation, the measurement error, and the error caused by ground slippage.

[0041] Exemplarily, Figure 13 is a schematic diagram of the S-shaped foot wave gait of the snake robot, Figure 14 is a motion process diagram of the S-shaped foot wave gait of the snake robot. According to Figures 13 - 14 shown, when the snake robot moves in the S-shaped foot wave gait, through the modeling method proposed by the present invention, a motion model of the snake robot at any time with any control input can be established as follows: ; Among them, is the control input quantity, is the position of the snake head on the backbone curve of the snake robot at the start of the motion, is the direction of the backbone curve motion component obtained from the switching situation of the contact points between the snake robot and the ground.

[0042] Furthermore, since the gait is periodic, for the convenience of actual use, when calculating the motion model of the snake robot for one cycle, that is, when the control input makes the snake head advance one gait cycle along the backbone curve of the snake robot, the displacement generated by the snake robot is: ; Among them, are the segment parameters of the S-shaped foot wave gait, and β is the twist angle at the connection with the previous segment.

[0043] Figure 15Based on the actual snake head movement trajectory captured by the motion capture system and the predicted snake head movement trajectory according to the motion model, with a control input of 3 gait cycles, it can be obtained that the motion modeling method provided by the present invention has a more accurate prediction. The predicted snake head movement trajectory and the actual snake head movement trajectory basically coincide, and also show three cycles. There is an error of 1.9% in the X direction (expected 2.52m, actual 2.47m). The expected movement direction is along the X-axis, and the actual movement direction has an error angle of 2.2 with the X-axis. A small amount of error comes from the fitting error during gait generation, measurement error, and error caused by ground slippage.

[0044] A three-dimensional gait general motion modeling method for a snake-shaped robot provided by the present invention is based on regarding the backbone curve of the snake-shaped robot as a movable entity, and decomposing the movement of the snake-shaped robot into: the backbone curve movement component and the movement component of the robot along the backbone curve. The movement model of the snake-shaped robot is obtained through vector addition. This modeling method can be applied to all gaits generated by the snake-shaped robot through the curve splicing method, and can more accurately predict the movement behavior of the snake-shaped robot, which helps to achieve more precise movement control.

[0045] The present invention also provides a three-dimensional gait general motion modeling system for a snake-shaped robot, which is used to execute the three-dimensional gait general motion modeling method for a snake-shaped robot. It is characterized by including the following modules: A data acquisition module, which is used to extract the contact points between the snake-shaped robot and the ground and the control input quantity, the backbone curve parameters of the snake-shaped robot, the lengths of the joint modules of the snake-shaped robot, and the position of the current snake head on the backbone curve S h0 information; A motion decomposition module, connected to the data acquisition module, which is used to decompose the movement of the snake-shaped robot into two main components: the backbone curve movement component and the movement component of the snake-shaped robot along the backbone curve; the backbone curve is a variety of gait curves generated by the curve splicing method; the backbone curve movement component refers to the displacement caused by the change of the contact points between the snake-shaped robot and the ground; the movement component of the snake-shaped robot along the backbone curve refers to the displacement caused by the change of the self-configuration of the snake-shaped robot; A calculation module, connected to the motion decomposition module, which is used to calculate the backbone curve movement component and the movement component of the snake-shaped robot along the backbone curve. According to the contact points between the snake-shaped robot and the ground, the control input quantity, the backbone curve parameters of the snake-shaped robot, and the lengths of the joint modules of the snake-shaped robot, calculate the backbone curve movement component; according to the backbone curve parameters of the snake-shaped robot, the control input quantity, and the position of the current snake head on the backbone curve S h0 , calculate the movement component of the snake-shaped robot along the backbone curve; The model establishment module, connected to the calculation module, is used to establish a general motion model for the three-dimensional gait of the snake robot, and vectorially add the motion components of the backbone curve and the motion components of the snake robot along the backbone curve.

[0046] It should be noted that the terms used in the present invention are only for describing specific embodiments and do not limit the scope of the present application. As shown in the specification of the present invention, unless the context clearly indicates otherwise, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include the plural. The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method or device including the said element.

[0047] It should also be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. Unless otherwise clearly specified and defined, terms such as "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or equivalently replace some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A general motion modeling method for three-dimensional gait of a snake-like robot, characterized in that: The steps include: S1. Obtaining parameters: The parameters include the contact point between the snake robot and the ground, the control input, the backbone curve parameters of the snake robot, the length of the snake robot joint module, and the current position of the snake head on the backbone curve. S h0 ; The control input refers to the transfer length of the gait; S2, decomposing the motion of the snake robot into two main components: the backbone curve motion component and the motion component of the snake robot along the backbone curve; The backbone curve is a variety of gait curves generated by a curve splicing method; The backbone curve motion component refers to the displacement caused by the change of the contact point between the snake-like robot and the ground; The movement component of the snake-like robot along the backbone curve refers to the displacement caused by the change in the configuration of the snake-like robot itself; S3, calculating the backbone curve motion component according to the contact point between the backbone curve of the snake-like robot and the ground, the control input, the backbone curve parameters of the snake-like robot, and the length of the joint module of the snake-like robot; S4. According to the backbone curve parameters of the snake robot, control the input amount and the current position of the snake head on the backbone curve S h0 , calculate the motion components of the snake robot along the backbone curve; S5. Add the backbone curve motion component and the motion component of the snake-like robot along the backbone curve vector to construct a three-dimensional gait universal motion model of the snake-like robot.

2. A three-dimensional gait universal motion modeling method for a snake-like robot according to claim 1, characterized in that: In S1, the method for determining the contact point between the snake-like robot and the ground includes: The starting point of the backbone curve of the snake-like robot is taken as the coordinate origin O, the X-axis is parallel to the line connecting the minimum repeating unit from the starting point to the end point in the backbone curve of the snake-like robot, the Z-axis is perpendicular to the horizontal plane and upward, and the Y-axis is determined by the right-hand rule to establish a three-dimensional coordinate system; The contact point between the snake-like robot and the ground refers to the point with the smallest Z-axis coordinate value in the three-dimensional coordinates.

3. A three-dimensional gait universal motion modeling method for a snake-like robot according to claim 1, characterized in that: In S1, the backbone curve parameters of the snake-like robot specifically include: The geometric parameters of each curve segment of the gait curve include: segment number, segment shape, segment parameters, and the torsion angle at the connection with the previous segment.

4. The method for modeling a three-dimensional gait of a snake-like robot according to claim 1, characterized in that: In S1, the position of the current snake head on the backbone curve S h0 Methods for determination include: According to the starting point of the backbone curve and the historical control input, calculate the current position of the snake head on the backbone curve S h0 .

5. The method for general motion modeling of three-dimensional gait of a snake-like robot according to claim 1, characterized in that: In the above S3, the backbone curve motion component is calculated according to the contact point between the snake-like robot and the ground, the control input, the backbone curve parameters of the snake-like robot, and the length of the joint module of the snake-like robot, specifically including: Assume that there is no slippage between the snake robot and the ground during movement; The size of the backbone curve motion component is calculated based on the control input. The calculation formula is as follows: ； in, is the magnitude of the motion component of the backbone curve, is the control input quantity, i.e., the transfer length of the gait; According to the contact point between the backbone curve of the snake robot and the ground, the length of the joint module and the backbone curve parameters of the snake robot, the direction of the movement component of the backbone curve is calculated; The backbone curve motion component is determined according to the magnitude of the backbone curve motion component and the direction of the backbone curve motion component.

6. A three-dimensional gait universal motion modeling method for a snake-like robot according to claim 1, characterized in that: In S4, the input amount and the current position of the snake head on the backbone curve are controlled according to the backbone curve parameters of the snake robot. , calculate the motion components of the snake-like robot along the backbone curve, including: Determine the direction of the movement component of the snake-like robot along the backbone curve according to the tangent direction of each point on the backbone curve, wherein the position of each point on the backbone curve depends on the current position of the snake head on the backbone curve; According to the control input and the line integral from the current snake head position to the new position after the current position of the snake head plus the gait transfer length along the backbone curve, the size of the motion component of the snake robot along the backbone curve is calculated. The calculation formula is as follows: ； in, is the magnitude of the motion component of the snake robot along the backbone curve in the x direction; is the magnitude of the y-direction of the motion component of the snake robot along the backbone curve; is the unit vector in the x direction, is the unit vector in the y direction, is the control input quantity, i.e., the transfer length of the gait; S h0 is the current position of the snake head on the backbone curve; The movement component of the snake-like robot along the backbone curve is determined according to the direction of the movement component of the snake-like robot along the backbone curve and the size of the movement component of the snake-like robot along the backbone curve.

7. A snake-like robot three-dimensional gait universal motion modeling system, used to execute a snake-like robot three-dimensional gait universal motion modeling method according to any one of claims 1 to 6, characterized in that: Includes the following modules: Data acquisition module, used to extract the contact points between the snake robot and the ground and the control input, the backbone curve parameters of the snake robot, the length of the snake robot joint module, and the current position of the snake head on the backbone curve S h0 information; A motion decomposition module is connected to the data acquisition module and is used to decompose the motion of the snake-like robot into two main components: a backbone curve motion component and a motion component of the snake-like robot along the backbone curve; the backbone curve is a plurality of gait curves generated by a curve splicing method; the backbone curve motion component refers to the displacement caused by the change of the contact point between the snake-like robot and the ground; the motion component of the snake-like robot along the backbone curve refers to the displacement caused by the change of the configuration of the snake-like robot itself; The calculation module is connected to the motion decomposition module and is used to calculate the backbone curve motion component and the motion component of the snake-like robot along the backbone curve. The backbone curve motion component is calculated according to the contact point between the snake-like robot and the ground, the control input, the backbone curve parameters of the snake-like robot, and the length of the snake-like robot joint module; the backbone curve motion component is calculated according to the backbone curve parameters and control input of the snake-like robot, and the current position of the snake head on the backbone curve. S h0 , calculate the motion components of the snake robot along the backbone curve; The model building module is connected to the calculation module and is used to add the backbone curve motion component and the motion component vector of the snake-like robot along the backbone curve to construct a universal motion model of the three-dimensional gait of the snake-like robot.

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