Low-energy-consumption hexapod robot based on nonlinear rope geometric constraint and foot end linearization compensation method thereof

Abstract

The invention discloses a low-energy-consumption hexapod robot based on nonlinear rope geometric constraint and a foot end linearization compensation method thereof, and relates to the field of robot design. The problems that legs of a robot do circular motion with a hip joint as the circle center, foot ends transversely move, and the motion precision of the robot is affected are solved. Six leg mechanisms are arranged on the two sides of a robot body in a bilateral symmetry mode, the three leg mechanisms on the same side are sequentially arranged from front to back and comprise a front leg, a middle leg and a rear leg, each leg mechanism comprises a thigh, a shank and a foot, the thighs, the shanks and the feet are sequentially connected, the thighs are rotationally installed on the robot body through hip joint shafts, and the thighs are rotationally installed on the robot body through hip joint shafts. The thigh and the shank are rotationally connected through a knee joint shaft and form an inverted V shape, and the shank is a telescopic leg; the hip joint driving mechanism can drive the thigh to rotate around the Z axis so as to control the thigh to swing back and forth; the knee joint driving mechanism can transmit power in the front-back swinging process of the thigh, and the rotating motion of the thigh is converted into the unfolding and folding motion of the shank so as to correct the motion trail of the foot end.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of robot design, and in particular to a low-energy consumption hexapod robot based on nonlinear rope geometric constraints and a foot end linearization compensation method thereof. BACKGROUND

[0002] Multi-legged robots have attracted much attention due to their superior motion performance in unstructured environments. However, traditional hexapod robots usually face the contradiction between complex structure and motion efficiency. Among them, full-DOF robots are equipped with 3 or more motors per leg, and the control algorithm is extremely complex, and the motor self-weight leads to low energy efficiency. In order to reduce the motor, the single-DOF hip joint drive is often used for robots with simplified configuration. This results in that the leg can only make circular arc motion with the hip joint as the center. When the foot end contacts the ground, this "circular arc trajectory" will produce a transverse displacement perpendicular to the forward direction. This transverse displacement will cause the foot end to produce severe transverse friction with the ground, not only increasing the energy consumption, but also easily causing the robot to slip left and right on the smooth road surface, which cannot maintain a straight course, seriously affecting the load capacity and motion accuracy of the robot. SUMMARY

[0003] Therefore, the present application provides a low-energy consumption hexapod robot based on nonlinear rope geometric constraints and a foot end linearization compensation method thereof. Through the rotational motion of the upper thigh, combined with rope transmission, the inner and outer spread of the lower thigh is driven, so that the vertical distance between the foot end and the body is kept constant. The composite motion compensates for the transverse displacement of the foot end caused by the circular motion of the upper thigh, so that the projection trajectory of the foot end on the ground is approximately a straight line parallel to the forward direction of the robot, solving the problems of large transverse friction and easy slipping caused by the circular arc trajectory of the foot end.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0005] In a first aspect, the present application provides a low-energy consumption hexapod robot based on nonlinear rope geometric constraints, which comprises a body, a leg mechanism, a hip joint driving mechanism and a knee joint driving mechanism. The leg mechanism is arranged on both sides of the body in a left-right symmetrical manner, and three leg mechanisms on the same side are arranged from front to back as front legs, middle legs and rear legs. Each leg mechanism comprises a thigh, a lower leg and a foot connected in sequence. The thigh is rotatably mounted on the body through a hip joint shaft, and the thigh and the lower leg are rotatably connected through a knee joint shaft, forming an inverted "V" shape. The lower leg is a telescopic leg. The hip joint driving mechanism can drive the thigh to rotate around the Z-axis to control the forward and backward swing of the thigh. The knee joint driving mechanism can transmit power during the forward and backward swing of the thigh to convert the rotational motion of the thigh into the spread and contraction motion of the lower leg to correct the foot end motion trajectory.

[0006] Further, the knee joint driving mechanism is provided with six, each corresponding to a leg mechanism; each knee joint driving mechanism comprises a rope and a reset torsion spring, and a threading hole is formed on the upper thigh; one end of the rope is fixed on the body, and the other end is fixed on the lower leg after passing through the threading hole on the upper thigh, and is used for restraining the lower leg; the reset torsion spring is sleeved on the knee joint shaft, and the feet at both ends of the reset torsion spring are connected to the upper thigh and the lower leg respectively, and is used for driving the lower leg to spread out; during the process that the hip joint driving mechanism drives the upper thigh to swing forward, the rope is gradually loosened, and the reset torsion spring drives the lower leg to gradually spread out, so as to compensate for the inward movement of the foot end caused by the circular motion of the upper thigh; during the process that the hip joint driving mechanism drives the upper thigh to swing backward, the rope is gradually tightened and generates a pulling force on the lower leg, and the lower leg gradually folds inward, so as to compensate for the outward movement of the foot end caused by the circular motion of the upper thigh.

[0007] Further, each knee joint driving mechanism further comprises a rope end fixing plate and a guide wheel, the rope end fixing plate is installed on the body, and the guide wheel is installed on the upper thigh; the rope is fixed on the body through the rope end fixing plate, and abuts against the guide wheel before passing through the threading hole on the upper thigh.

[0008] Further, the hip joint driving mechanism is provided with two and arranged on the left and right sides in the body, each corresponding to three leg mechanisms on the same side; each hip joint driving mechanism comprises a first driving unit and a second driving unit, the first driving unit corresponds to the front leg and is used for controlling the swing of the front leg; the second driving unit corresponds to the middle leg and the rear leg on the same side and is used for controlling the swing of the middle leg and the rear leg.

[0009] Further, the first driving unit is a first driving motor, the first driving motor is arranged in the body, and the motor shaft of the first driving motor is connected to the hip joint shaft of the front leg, so as to drive the upper thigh to rotate through the hip joint shaft.

[0010] Further, the second driving unit comprises a second driving motor, a first bevel gear, a second bevel gear and a gear shaft, the first bevel gear is provided with two and is sleeved on the hip joint shaft of the middle leg and the rear leg respectively, the second bevel gear is provided with two and is sleeved on the two ends of the gear shaft, and the two second bevel gears are meshed and connected with the two first bevel gears respectively; the second driving motor is installed in the body, the motor shaft of the second driving motor is connected with the hip joint shaft of the middle leg or the rear leg, and can control the rotation of the hip joint shaft of the middle leg or the rear leg.

[0011] Further, the lower leg comprises an upper leg rod, a lower leg rod and a leg rod driving electric cylinder, one end of the upper leg rod is connected with the upper thigh through the knee joint shaft, the leg rod driving electric cylinder is installed on the other end of the upper leg rod, and the lower leg rod is slidingly connected with the upper leg rod and can be driven by the leg rod driving electric cylinder to move up and down.

[0012] Furthermore, the fuselage includes a front fuselage section, a rear fuselage section, and a pitch motor. The front fuselage section and the rear fuselage section are arranged front to back and are rotatably connected by a pitch joint shaft. The front fuselage section is keyed to the pitch joint shaft. The housing of the pitch motor is fixed to the rear fuselage section, and the motor shaft of the pitch motor is keyed to the pitch joint shaft, and can drive the front fuselage section to perform pitch movement through the pitch joint shaft.

[0013] Secondly, the present invention provides a method for straightening the foot end of a low-energy hexapod robot based on nonlinear rope geometric constraints. Specifically, for the low-energy hexapod robot based on nonlinear rope geometric constraints described in the first aspect, this method adjusts the installation position of the rope end fixing plate (…). , The compensation effect of the control rope constraint makes the foot trajectory approximately linear, that is, to achieve linearization compensation of the foot.

[0014] Preset according to the width limitation of the fuselage The value is based on the radius of rotation of the guide wheel on the thigh relative to the center of the hip joint. and work area The support trajectory is determined according to the following general analytical formula. :

[0015] ,

[0016] ,

[0017] ,

[0018] in, , Intermediate variable, constant The elongation provided for the fuselage section rope length, ( , () represents the coordinates of the rope end fixing plate in the XY plane.

[0019] Further, determine The general analytical formula for the support trajectory is obtained through the following steps:

[0020] The target abduction angle of the lower leg is determined by equidistantly balancing the starting and ending points of the support along the Y-axis. The required rope length variation is then determined by calculating this target abduction angle. Finally, the second rope segment is determined based on the principle of rope length conservation. The change is equal to that of the first rope segment The change in;

[0021] Determine based on the relationship between the rope end fixing plate, guide wheel, and lower leg rope node during the movement. The expression, combined The change amount is equal to The relationship of the change amount is finally determined The general analytical formula of the support trajectory;

[0022] The calf target abduction angle Wherein The hip joint rotation angle, The straight line distance from the knee joint axis to the foot end touch point, The thigh rotation radius, The Y-axis coordinate of the foot end The constant corresponding constant.

[0023] The beneficial effects generated by the present application compared with the prior art are:

[0024] 1、The hexapod robot of the present application adopts a triangle gait walking mode, which can make the six-legged robot body supported by three leg mechanisms located on different sides at the same time, and the remaining three leg mechanisms perform stepping actions synchronously. Through the cyclic alternation of the two groups of triangle supports, the robot realizes stable and continuous forward movement.

[0025] 2、The knee joint driving mechanism of the present application is driven by the rotation of the thigh, combined with the rope transmission, to drive the calf abduction and adduction, so as to keep the vertical distance between the foot end and the body constant. The composite motion compensates for the transverse displacement of the foot end caused by the circular motion of the thigh, so that the projection trajectory of the foot end on the ground is approximately a straight line parallel to the forward direction of the robot. This design not only makes the robot structure compact and walking stable, but also solves the problems of large transverse friction and easy sliding of the existing simplified hexapod robot due to the circular arc shape of the foot end trajectory. In addition, the abduction and adduction of the calf is completely realized by the rotation of the thigh, without the use of knee joint motor, thereby reducing the complexity of joint control. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are part of the present application and serve to provide a further understanding of the present application.

[0027] Figure 1 It is a structural schematic diagram of a low-energy consumption hexapod robot based on nonlinear rope geometric constraints of the present application.

[0028] Figure 2 It is a top view of a low-energy consumption hexapod robot based on nonlinear rope geometric constraints of the present application.

[0029] Figure 3 It is a structural schematic diagram of a low-energy consumption hexapod robot based on nonlinear rope geometric constraints of the present application (without the body shell).

[0030] Figure 4A structure schematic view (bottom angle) of a low-energy consumption hexapod robot based on nonlinear rope geometric constraint of the present application.

[0031] Figure 5 An assembly view of the left leg mechanism, the hip joint driving mechanism and the knee joint driving mechanism.

[0032] Figure 6 A structure schematic view (top angle) of a low-energy consumption hexapod robot based on nonlinear rope geometric constraint of the present application. Figure 5 A local enlarged view at A in the figure.

[0033] Explanation of reference signs:

[0034] 1, body; 11, front body section; 12, rear body section; 13, pitch joint shaft; 14, pitch motor; 2, leg mechanism; 21, upper leg; 211, horizontal part; 212, diagonal strut part; 213, threading hole; 22, lower leg; 221, upper leg rod; 222, lower leg rod; 23, leg rod driving electric cylinder; 24, foot; 25, hip joint shaft; 26, knee joint shaft; 3, hip joint driving mechanism; 31, first driving motor; 32, second driving motor; 33, first bevel gear; 34, second bevel gear; 35, gear shaft; 36, support seat; 4, knee joint driving mechanism; 41, rope end fixing plate; 42, rope; 43, guide wheel. DETAILED DESCRIPTION

[0035] The present application will be described in detail below in combination with the drawings and specific examples.

[0036] Example 1:

[0037] Reference is made to Figure 1The low-energy consumption hexapod robot based on nonlinear rope geometric constraint comprises a body 1, leg mechanisms 2, hip joint driving mechanisms 3 and knee joint driving mechanisms 4. The leg mechanisms 2 are symmetrically arranged on the left and right sides of the body 1, and three leg mechanisms 2 on the same side are arranged from front to back. The three leg mechanisms 2 on the left side of the body 1 are sequentially arranged as a left front leg, a left middle leg and a left rear leg from front to back, and the three leg mechanisms 2 on the right side of the body 1 are sequentially arranged as a right front leg, a right middle leg and a right rear leg from front to back. The hip joint driving mechanisms 3 are symmetrically arranged in the body 1, and each hip joint driving mechanism 3 can drive the three leg mechanisms 2 on the same side to swing forward and backward. The front leg and the rear leg on the same side and the middle leg on the opposite side form a coordinated motion unit, that is, there are two coordinated motion units in total, the three leg mechanisms 2 in each coordinated motion unit have the same stepping direction, and the two coordinated motion units have opposite stepping directions. Specifically, the left front leg, the left rear leg and the right middle leg form a group, and the right front leg, the right rear leg and the left middle leg form a group. The left hip joint driving mechanism 3 drives the left front leg and the left rear leg to swing forward / backward and drives the left middle leg to swing backward / forward, and the right hip joint driving mechanism 3 drives the right front leg and the right rear leg to swing backward / forward and drives the right middle leg to swing forward / backward, so as to realize three-point support. Figure 1 and Figure 2 The knee joint driving mechanisms 4 are provided for the six leg mechanisms 2, and each knee joint driving mechanism 4 can transmit power in the process of swinging the thigh 21 forward and backward, convert the rotary motion of the thigh 21 into the extension and retraction motion of the shank 22, correct the motion trajectory of the foot end and avoid the problem of foot end slipping.

[0038] During the forward movement of the robot, the three leg mechanisms 2 in one coordinated motion unit are driven by the hip joint driving mechanism 3 to swing forward, and at the same time, the shanks 22 in the three leg mechanisms 2 are driven by the corresponding knee joint driving mechanisms 4 to extend outward and lift upward, and the three leg mechanisms 2 in the other coordinated motion unit are driven by the hip joint driving mechanism 3 to swing backward, and at the same time, the shanks 22 in the three leg mechanisms 2 support the ground. Under the reaction force of the ground, the body 1 moves forward. The two coordinated motion units alternately perform the stepping action in opposite directions to form a triangular gait walking mode. In this way, the six leg mechanisms 2 on different sides can support the body 1 at the same time, and the remaining three leg mechanisms 2 can perform the stepping action synchronously. Through the cyclic alternation of the two triangular supports, the robot can stably and continuously move forward.

[0039] Referring to Figure 1In the embodiment, each leg mechanism 2 comprises a thigh 21, a shank 22 and a foot 24 connected in sequence. The thigh 21 is in the form of a bent rod structure, specifically formed by a horizontal portion 211 and a diagonal strut portion 212. The end of the horizontal portion 211 is rotatably mounted to the body 1 by a hip joint shaft 25, and the diagonal strut portion 212 extends obliquely upward. The shank 22 mainly comprises an upper leg rod 221, a lower leg rod 222 and a leg rod drive electric cylinder 23. One end of the upper leg rod 221 is rotatably connected to the extended end of the thigh 21 by a knee joint shaft 26, thereby forming a knee joint of the leg. The other end of the upper leg rod 221 extends obliquely downward, and the upper leg rod 221 and the diagonal strut portion 212 of the thigh 21 form a deployable "V" shape structure, so that the overall leg shape is similar to a "spider leg". The other end of the upper leg rod 221 is also slidably connected to the lower leg rod 222. The leg rod drive electric cylinder 23 is mounted to the other end of the upper leg rod 221, and the driving end of the leg rod drive electric cylinder 23 is fixedly connected to the lower leg rod 222 for driving the lower leg rod 222 to extend or retract relative to the upper leg rod 221. The bottom end of the lower leg rod 222 is fixedly connected to the foot 24.

[0040] Referring to Figure 1 In the embodiment, each knee joint drive mechanism 4 is designed by using a rope drive. The power generated by the swing of the thigh 21 can be transmitted to the shank 22 through the rope 42, so that the shank 22 performs a deployment movement, thereby adjusting the vertical distance between the foot end and the body 1, adjusting the movement trajectory of the foot end of the robot, and avoiding the robot from slipping. Specifically, the knee joint drive mechanism 4 of the embodiment comprises a rope end fixing plate 41, a rope 42, a guide wheel 43 and a reset torsional spring (not shown in the figure). The rope end fixing plate 41 is mounted to the upper surface of the body 1 and close to the thigh 21. The guide wheel 43 is rotatably mounted to the horizontal portion 211 of the thigh 21 by a support. A threading hole 213 is formed in the thigh 21. One end of the rope 42 is fixed to the rope end fixing plate 41, and the other end of the rope 42 passes through the guide wheel 43 and then is fixed to the upper leg rod 221 of the shank 22. The rope 42 is used to constrain the shank 22. The connection point of the rope 42 and the rope end fixing plate 41 is marked as point A, the guide point of the guide wheel 43 to the rope 42 is marked as point B, and the rope segment between point A and point B is marked as a first rope segment The connection point of the rope 42 and the upper leg rod 221 is marked as point C, and the rope segment between point B and point C is marked as a second rope segment The reset torsional spring is sleeved at the knee joint shaft 26, and the legs of the reset torsional spring are connected to the thigh 21 and the shank 22 respectively, for driving the shank 22 to abduct.

[0041] Figure 1 and Figure 2 The state shown in FIG. 1 is the initial state of the hexapod robot. The state shown in FIG. 2 is the state of the hexapod robot in which the shanks 22 are in the maximum abduction state. Figure 1 Figure 2 ​It can be seen that the left front leg, the left rear leg and the right middle leg of the hexapod robot are in the limit position of backward swing (the reset torsion spring in this limit position is in the energy storage state), the right front leg, the right rear leg and the left middle leg are in the limit position of forward swing, that is, the leg mechanisms 2 on the left and right sides are not symmetrical in the initial state, but are in the respective limit positions. In this state, the shank 22 of the leg mechanism 2 swinging forward is the longest, and the shank 22 of the leg mechanism 2 swinging backward is the shortest, so that the hexapod robot is in a stable state of supporting the ground. Since the gaits of the left front leg, the left rear leg and the right middle leg are consistent, and the gaits of the right front leg, the right rear leg and the left middle leg are consistent, the left front leg and the right front leg are taken as examples to illustrate the entire movement process of the leg mechanism 2 in this embodiment:

[0042] When the hexapod robot moves forward in a straight line, the left hip joint driving mechanism 3 drives the left front leg to rotate counterclockwise around the Z axis, the thigh 21 swings forward, and the guide wheels 43 on the thigh 21 gradually approach the rope end fixing plate 41. At this time, the rope 42 gradually loosens, and the rope segment between the A point and the B point gradually shortens, that is, the first rope segment gradually shortens. Since the total length of the rope 42 is constant, the rope segment between the B point and the C point gradually increases in length, that is, the second rope segment gradually lengthens, so that the second rope segment loosens the constraint on the shank 22; the reset torsion spring releases energy and drives the shank 22 to lift and extend outward, and the shank 22 gradually moves away from the body 1. Since the shank 22 extends outward, the foot end of the left front leg does not slip off the ground. When the left front leg moves to the limit position, the leg rod driving electric cylinder 23 drives the lower leg rod 222 to extend, and the foot end of the left front leg is supported on the ground. At the same time, the right hip joint driving mechanism 3 drives the right front leg to swing backward, and the guide wheels 43 on the thigh 21 gradually move away from the rope end fixing plate 41. The rope 42 gradually tightens, and the rope segment between the A point and the B point gradually lengthens, that is, the first rope segment gradually lengthens. Since the total length of the rope 42 is constant, the rope segment between the B point and the C point gradually shortens in length, that is, the second rope segment gradually shortens, so that the second rope segment constrains the shank 22, and the rope 42 pulls the shank 22 inward to make the shank 22 gradually approach the body 1. Since the foot end of the right front leg is always in contact with the ground, the body 1 moves forward under the action of the reverse force, thereby realizing the straight forward movement of the hexapod robot. When the right front leg moves to the limit position of backward swing, the leg rod driving electric cylinder 23 drives the lower leg rod 222 to retract the upper leg rod 221, so that the right front leg returns to the initial state when it swings backward to the limit position. After the first gait cycle is completed, the left hip joint driving mechanism 3 starts to drive in the reverse direction, and the right hip joint driving mechanism 3 drives in the forward direction, so that the robot enters the next gait cycle, and the forward movement of the hexapod robot is realized by the reciprocating driving.

[0043] When the right front leg swings backward, it rotates counterclockwise around the Z axis. If the calf 22 is not driven inward by the rope 42 at this time, the vertical distance between the foot end and the body 1 will gradually increase, which is easy to cause the foot end to slip. Therefore, in this embodiment, the rotation of the thigh 21 is converted into the power for driving the calf 22 inward by the transmission of the rope 42, so that the vertical distance between the foot end and the body 1 remains constant, effectively avoiding the slipping phenomenon. This compound motion compensates for the lateral outward displacement of the foot end caused by the circumferential motion of the thigh 21, so that the projection trajectory of the foot end on the ground is approximately a straight line parallel to the forward direction of the robot. This design not only makes the hexapod robot compact and stable in walking, but also solves the problems of large lateral friction and easy slipping caused by the circular arc trajectory of the foot end of the existing simplified hexapod robot. It should be noted that the inward and outward extension of the calf 22 is entirely realized by the rotation of the thigh 21, without the need for a knee joint motor, thereby reducing the complexity of joint control. In addition, the rope 42 used in this embodiment is designed to be fixed in length and inelastic, so that the rope 42 will not interfere with the motion trajectory of the foot end due to length problems.

[0044] Referring to Figure 1 , the hip joint driving mechanism 3 of this embodiment includes a first driving unit and a second driving unit arranged front and back, the first driving unit corresponds to the front leg and is used to control the swing of the front leg; the second driving unit corresponds to the same side of the middle leg and the rear leg and is used to control the swing of the middle leg and the rear leg. In combination with Figure 1 , the first driving unit of this embodiment is a first driving motor 31, which is fixed in the body 1 through a motor seat, and the motor shaft of the first driving motor 31 is connected to the hip joint shaft 25 of the front leg to control the rotation of the thigh 21 around the Z axis. In combination with Figure 3 and Figure 4 , the second driving unit of this embodiment includes a second driving motor 32, a first bevel gear 33, a second bevel gear 34, a gear shaft 35 and a support seat 36; the first bevel gear 33 is provided with two and is sleeved on the hip joint shaft 25 of the middle leg and the rear leg respectively; the gear shaft 35 is horizontally rotatably installed in the body 1 through the support seat 36, and the second bevel gear 34 is provided with two and is sleeved on both ends of the gear shaft 35, the two second bevel gears 34 are respectively meshed and connected with the two first bevel gears 33; the second driving motor 32 is fixed in the body 1 through a motor seat, wherein the motor shaft of the second driving motor 32 in the left second driving unit is fixedly connected with the hip joint shaft 25 of the left rear leg. The motor shaft of the second driving motor 32 in the right second driving unit is fixedly connected with the hip joint shaft 25 of the right middle leg.

[0045] When the hexapod robot moves straight forward, the two first driving motors 31 on the left and right sides drive the corresponding large thighs 21 to rotate anticlockwise around the Z axis, the left front leg swings forward and the right front leg swings backward. The second driving motor 32 on the left side drives the left rear leg to rotate anticlockwise around the Z axis through the hip joint shaft 25 of the left rear leg, the left rear leg swings forward, the first bevel gear 33 on the hip joint shaft 25 of the left rear leg rotates anticlockwise, and drives the first bevel gear 33 on the hip joint shaft 25 of the middle leg to rotate clockwise through the transmission cooperation of the second bevel gear 34 and the gear shaft 35, the middle leg is driven to rotate clockwise around the Z axis through the hip joint shaft 25, and the middle leg swings backward. Similarly, the second driving motor 32 on the right side drives the middle leg to rotate anticlockwise through the hip joint shaft 25, the middle leg swings forward, the first bevel gear 33 on the hip joint shaft 25 of the middle leg rotates anticlockwise, and drives the first bevel gear 33 on the hip joint shaft 25 of the rear leg to rotate clockwise through the transmission cooperation of the second bevel gear 34 and the gear shaft 35, the rear leg is driven to rotate clockwise around the Z axis through the hip joint shaft 25, and the rear leg swings backward.

[0046] Obviously, the embodiment can control the movement of the six leg mechanisms 2 through the transmission cooperation of the four driving motors and gears, realize the straight movement of the hexapod robot, reduce the number of motors, reduce the control complexity of the robot, and make the robot meet the low energy consumption requirement.

[0047] Referring to Figure 1 The body 1 of the embodiment is provided with two sections, and the robot can climb a slope through the bending of the two sections of the body 1. Specifically, the body 1 includes a front body section 11, a rear body section 12, and a pitch motor 14, the front body section 11 and the rear body section 12 are arranged in front of and behind each other and are rotationally connected through a pitch joint shaft 13, the front body section 11 is keyed to the pitch joint shaft 13, the housing of the pitch motor 14 is fixed to the rear body section 12, the motor shaft of the pitch motor 14 is connected to the pitch joint shaft 13 and can drive the front body section 11 to perform pitch movement through the pitch joint shaft 13. The left front leg and the right front leg are arranged on the left and right sides of the front body section 11, the left middle leg and the left rear leg are arranged on the left side of the rear body section 12, and the right middle leg and the right rear leg are arranged on the right side of the rear body section 12. The first driving unit is arranged in the front body section 11, and the second driving unit is arranged in the rear body section 12.

[0048] When the hexapod robot needs to climb a slope, the pitch motor 14 drives the front body section 11 to pitch upward according to the angle of the slope surface, so that the left front leg and the right front leg can be vertically supported on the slope surface, avoiding the slipping of the left front leg and the right front leg and causing the failure of the robot to climb the slope.

[0049] Working principle of the hexapod robot:

[0050] Straight advancing process: when the hexapod robot moves straight forward, the first driving motor 31 on the left side drives the hip joint shaft 25 of the left front leg to rotate anticlockwise around the Z axis, and the left front leg swings forward. The second driving motor 32 on the left side drives the left rear leg to rotate anticlockwise around the Z axis through the hip joint shaft 25 of the left rear leg, and the left rear leg swings forward; the first bevel gear 33 on the hip joint shaft 25 of the left rear leg rotates anticlockwise, and drives the first bevel gear 33 on the hip joint shaft 25 of the left middle leg to rotate clockwise through the transmission cooperation of the second bevel gear 34 and the gear shaft 35, and the first bevel gear 33 drives the left middle leg to rotate clockwise around the Z axis through the hip joint shaft 25 of the left middle leg, and the left middle leg swings backward. At the same time, the first driving motor 31 on the right side drives the hip joint shaft 25 of the right front leg to rotate anticlockwise around the Z axis, and the right front leg swings backward. The second driving motor 32 on the right side drives the right middle leg to rotate anticlockwise through the hip joint shaft 25 of the right middle leg, and the right middle leg swings forward, and the first bevel gear 33 on the hip joint shaft 25 of the right middle leg rotates anticlockwise, and drives the first bevel gear 33 on the hip joint shaft 25 of the right rear leg to rotate clockwise through the transmission cooperation of the second bevel gear 34 and the gear shaft 35, and the right rear leg rotates clockwise around the Z axis through the hip joint shaft 25 of the right rear leg, and the right rear leg swings backward.

[0051] The guide wheels 43 on the thighs 21 of the left front leg, the left rear leg and the right middle leg gradually approach the rope end fixing plate 41, at this time the rope 42 gradually loosens, the length of the rope 42 between the points A and B gradually shortens, and the length of the rope 42 between the points B and C gradually increases, so that the constraint of the rope 42 on the shanks 22 is loosened; the reset torsional spring releases energy and drives the shanks 22 to lift up and stretch outwards, the shanks 22 gradually move away from the body 1, and the foot end of the left front leg does not slip when the left front leg, the left rear leg and the right middle leg move to the limit position, the leg rod driving electric cylinder 23 drives the lower leg rod 222 to extend out, and the foot end of the left front leg, the left rear leg and the right middle leg is supported on the ground. At the same time, the guide wheels 43 on the thighs 21 of the right front leg, the right rear leg and the left middle leg gradually move away from the rope end fixing plate 41, the rope 42 gradually tightens, the length of the rope 42 between the points A and B gradually increases, and the length of the rope 42 between the points B and C gradually shortens, so that the rope 42 generates a constraint force on the shanks 22, the rope 42 pulls the shanks 22 inwards to make the shanks 22 gradually close to the body 1. Since the foot end of the right front leg, the right rear leg and the left middle leg always touches the ground, the body 1 is subjected to a reverse force to move forward, thereby realizing the straight forward movement of the hexapod robot. When the right front leg, the right rear leg and the left middle leg move to the limit position of the backward swing, the leg rod driving electric cylinder 23 drives the lower leg rod 222 to partially retract into the upper leg rod 221, so that the right front leg returns to the initial state when the right front leg moves to the limit position of the backward swing. After the first gait cycle is completed, the left hip joint driving mechanism 3 starts to drive in the reverse direction, and the right hip joint driving mechanism 3 drives in the forward direction, so that the robot enters the next gait cycle, and the forward movement of the hexapod robot is realized through the reciprocating driving.

[0052] Turning process: The turning movement of the hexapod robot is realized by controlling the speed difference of the left and right first driving motors 31 and the second driving motors 32. Since the left first driving motor 31 and the second driving motor 32 control the reciprocating leg frequency of the left three legs, and the right first driving motor 31 and the second driving motor 32 control the reciprocating leg frequency of the right three legs, when the speed of the left and right driving motors is different, the step speed of the leg mechanisms 2 on the two sides will be different, thereby causing the hexapod robot to realize differential speed turning. When the speed of the left first driving motor 31 and the second driving motor 32 is higher than that of the right first driving motor 31 and the second driving motor 32, the robot turns right; otherwise, the robot turns left.

[0053] Terrain adaptation control: When the hexapod robot needs to climb a slope, the pitch motor 14 drives the front body section 11 to tilt upwards according to the angle of the slope surface, so that the left front leg and the right front leg can be vertically supported on the slope surface to avoid slipping of the left front leg and the right front leg.

[0054] Embodiment 2:

[0055] This embodiment presents a method for straightening the feet of a low-energy hexapod robot based on nonlinear rope geometric constraints. The overall idea for achieving foot straightening is to constrain the "support start position" and "support end position" to make the distance in the Y-axis direction of the foot equal, thereby determining the installation position of the rope end fixing plate 41. In other words, by controlling the installation position of the rope end fixing plate 41... , This is to compensate for the straightening of the foot end.

[0056] In determining the installation position of the rope end fixing plate 41, the distance in the Y-axis direction of the foot end is made equal by constraining the "support starting point position" and the "support ending point position", and the target abduction angle of the lower leg required for the "rotation support process" is calculated; then, the required length of rope change (that is, the constraint length of rope 42, because the second rope segment) is determined by calculating the target abduction angle of the lower leg. The length of the rope constrains the abduction angle of the lower leg target; then, according to the principle of rope length conservation, it is possible to determine... The decrease = The increase in quantity; because the three points of "rope end fixing plate", "guide wheel" and "lower leg rope node" are approximately on the same horizontal reference plane during the movement, therefore =The formula for the distance between the two points, "fixed point" and "thigh guide point", makes The change equals The change in the quantity of change ultimately yields the coordinates of the rope end fixing plate 41. , To clarify the motion mechanism of the hexapod robot in this embodiment and to determine the coordinates of the rope end fixing plate 41 (). , Based on the value rules of ), this embodiment establishes a kinematic vector model of a single-leg system and derives a general analytical formula for realizing the linear support trajectory of the foot.

[0057] S1. Coordinate system definition and mechanism kinematic parameters:

[0058] Establish a spatial rectangular coordinate system: Let the center of rotation of the hip joint be the origin O (0,0,0); the X-axis is the forward direction along the robot body 1, with forward being positive; the Y-axis is the horizontal direction along the body 1, with outward being positive; and the Z-axis is the vertical direction, with upward being positive.

[0059] The key geometric parameters are defined as follows:

[0060] (Hip joint rotation angle): The angle between the horizontal projection axis of thigh 21 and the Y-axis. Defined when thigh 21 is perpendicular to the side of fuselage 1. =0, forward swing is positive. The range of motion of the support phase is defined as follows: .

[0061] (Thigh 21 rotation radius): The projected length of the distance from the hip joint axis to the knee joint axis on the XY plane.

[0062] (22 effective bar lengths for the lower leg): The straight-line distance from the knee joint axis to the point of contact with the foot.

[0063] (Lower leg 22 abduction angle): Lower leg 22 effective link The angle between the angle and the vertical direction (-Z) is defined as positive when it extends outward.

[0064] (Inner angle of the knee joint): The interior angle of the triangle formed by the guide point of the thigh 21, the axis of the knee joint, and the rope node of the lower leg 22. Its angle is different from the abduction angle of the lower leg 22. There exists a fixed linear mapping relationship: ,in This is the inherent installation angle determined by the mechanical structure.

[0065] S2, Target constraint equation for the straight trajectory of the foot:

[0066] To eliminate lateral slippage of the robot's support phase, the trajectory of its feet in the horizontal plane should be a straight line parallel to the X-axis. That is, at any angle of the support phase... Below, the Y-axis coordinate of the foot It should be constant. .

[0067] Establish the kinematic equations for the foot position:

[0068] ,

[0069] make = The abduction angle function of the lower leg 22 target, which is required to maintain a straight trajectory, can be solved inversely. :

[0070] ,

[0071] This indicates that: with the hip joint rotation angle The increase ( (Reduce), lower leg 22 target abduction angle Nonlinear scaling is required to compensate for the circumferential adduction effect of the hip joint.

[0072] S3, Rope-Knee Joint Transmission Model:

[0073] This embodiment utilizes the geometric constraints of a fixed-length rope 42 to drive knee joint movement. The side lengths of the transmission triangle at the knee joint are defined as follows: Distance from the guide wheel 43 to the knee joint axis; Cable node for the lower leg 22 Distance to the knee joint axis; Cable node for the lower leg 22 Length of the cable between the guide wheel 43 and the cable node for the lower leg 22 (i.e. the second cable segment ).

[0074] According to the cosine theorem, the relationship between the second cable segment and the internal angle of the knee joint is established:

[0075] ,

[0076] Substituting and obtained from , the function of the second cable segment required to satisfy the straight line trajectory with the change of the hip joint angle is obtained:

[0077] .

[0078] S4, the solving model of the coordinates of the cable end fixing plate 41:

[0079] Let the total length of the cable 42 be a constant value . According to the principle of cable length conservation, the first cable segment must satisfy:

[0080] ,

[0081] On the other hand, the expression form of is constructed from the geometric spatial position:

[0082] Let ( , ) be the coordinates of the cable end fixing plate 41 in the XY plane to be solved; is the turning radius of the guide wheel 43 relative to the center of the hip joint. The coordinates of the guide wheel 43 change with as:

[0083] ,

[0084] This embodiment sets that the three points of "cable end fixing plate 41", "guide wheel 43" and "cable node for the lower leg 22" are approximately on the same horizontal reference plane during the movement. Then the geometric distance equation of the first cable segment is:

[0085] .

[0086] S5, Analytical solution formula for the coordinates of the rope end fixing plate 41:

[0087] In order to determine the coordinates of the rope end fixing plate 41 ( , This embodiment uses the feature point matching method. The endpoint of the support phase is selected ( =0) and the starting point ( = Establish constraint equations.

[0088] S5.1 Define the rope length compensation constant required for a straight trajectory. :

[0089] Based on the goal of "straightening the foot," first calculate the distance at the knee joint (second rope segment). The necessary change in length. Let... To satisfy the ideal abduction angle of the lower leg of 22 required for a straight trajectory.

[0090] Define constants The first rope segment Required elongation:

[0091] ,

[0092] in:

[0093] ,

[0094] .

[0095] S5.2 Establish the constraint equations for the coordinates of the rope end fixing plate 41:

[0096] Based on the geometric relationship of rope length, the first rope segment The change should be equal to :

[0097] ,

[0098] Substituting into the geometric coordinate formula: At that time, the coordinates of the guide point 21 on the thigh were (0, ).exist At that time, the coordinates of the guide point 21 on the thigh were... .

[0099] Get about , The core equation:

[0100] .

[0101] S5.3, Coordinates of rope end fixing plate 41 about Analytical expression of

[0102] Since the above equation contains two unknowns, in engineering design, the value of is usually preset according to the width limit of the fuselage 1, so as to solve .

[0103] In order to simplify the expression, let

[0104] , , ,

[0105] The core equation is moved and squared to simplify and derive a quadratic equation about :

[0106] ,

[0107] The expression of the coefficient of each term is:

[0108] Quadratic term coefficient:

[0109] ,

[0110] Linear term coefficient:

[0111] ,

[0112] The finally derived analytical solution expression of :

[0113] Let the intermediate variable be:

[0114] ,

[0115] ,

[0116] Then can be obtained by solving the following equation:

[0117] ,

[0118] According to the root formula , since the rope end fixing plate 41 must be located in front of the hip joint ( > 0), take the positive root:

[0119] .

[0120] Through the above analytical formula, given the mechanical size of the robot ( , , , , ) and working interval (W) ) and working interval (W) Therefore, not only the horizontal position of the foot end at the start and stop moments is strictly coincident, but also the residual error of the trajectory during the whole continuous movement is small, because the inboard compensation curve generated by the geometric constraint of the rope 42 and the outboard displacement curve generated by the hip rotation have similar nonlinear curvature characteristics in the working interval, so that the foot end moves approximately along a straight line, and the horizontal swing of the foot end is greatly reduced.

[0121] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application.

Claims

1. A low-energy consumption hexapod robot based on nonlinear cable geometry constraints, characterized in that, The robot comprises a body, leg mechanisms, hip joint driving mechanisms and knee joint driving mechanisms. The leg mechanisms are symmetrically arranged on both sides of the body. The three leg mechanisms on the same side are arranged from front to back as front legs, middle legs and rear legs. Each leg mechanism comprises a thigh, a shank and a foot connected in sequence. The thigh is rotatably mounted on the body through a hip joint shaft. The thigh and the shank are rotatably connected through a knee joint shaft, and form an inverted "V" shape. The shank is a telescopic leg.

2. The low-energy consumption hexapod robot based on nonlinear rope geometric constraints according to claim 1, characterized in that, The knee joint driving mechanisms are arranged on both sides of the body. Each knee joint driving mechanism corresponds to one leg mechanism. Each knee joint driving mechanism comprises a rope and a reset torsion spring. A threading hole is arranged on the thigh. One end of the rope is fixed on the body, and the other end of the rope is fixed on the shank through the threading hole on the thigh, and is used for restraining the shank. The reset torsion spring is sleeved on the knee joint shaft, and the two ends of the reset torsion spring are connected to the thigh and the shank respectively, and are used for driving the shank to spread out. During the process that the hip joint driving mechanism drives the thigh to swing forward, the rope is gradually loosened, and the reset torsion spring drives the shank to gradually spread out, so as to compensate for the inward movement of the foot end caused by the circular motion of the thigh. During the process that the hip joint driving mechanism drives the thigh to swing backward, the rope is gradually tightened and generates a pulling force on the shank, and the shank is gradually folded inward, so as to compensate for the outward movement of the foot end caused by the circular motion of the thigh.

3. The low-energy consumption hexapod robot based on nonlinear cable geometry constraints according to claim 2, characterized in that, Each knee joint driving mechanism further comprises a rope end fixing plate and a guide wheel. The rope end fixing plate is mounted on the body, and the guide wheel is mounted on the thigh. The rope is fixed on the body through the rope end fixing plate, and abuts against the guide wheel through the threading hole on the thigh.

4. The low-energy consumption hexapod robot based on nonlinear cable geometry constraints according to claim 1, wherein, The hip joint driving mechanisms are arranged on both sides of the body. Each hip joint driving mechanism corresponds to three leg mechanisms on the same side. Each hip joint driving mechanism comprises a first driving unit and a second driving unit. The first driving unit corresponds to the front leg, and is used for controlling the swing of the front leg. The second driving unit corresponds to the middle leg and the rear leg on the same side, and is used for controlling the swing of the middle leg and the rear leg.

5. The low-energy consumption hexapod robot based on nonlinear cable geometry constraints according to claim 4, characterized in that, The first driving unit is a first driving motor. The first driving motor is arranged in the body, and the motor shaft of the first driving motor is connected to the hip joint shaft of the front leg, so as to drive the thigh to rotate through the hip joint shaft.

6. The low-energy consumption hexapod robot based on nonlinear cable geometry constraints according to claim 5, wherein, The second driving unit comprises a second driving motor, first bevel gears, second bevel gears and a gear shaft. The first bevel gears are sleeved on the hip joint shafts of the middle leg and the rear leg. The second bevel gears are sleeved on the two ends of the gear shaft, and are meshed with the first bevel gears. The second driving motor is arranged in the body, and the motor shaft of the second driving motor is connected to the hip joint shaft of the middle leg or the rear leg, so as to control the rotation of the hip joint shaft of the middle leg or the rear leg.

7. The low-energy consumption hexapod robot based on nonlinear cable geometry constraints according to claim 1, wherein, The shank comprises an upper leg rod, a lower leg rod and a leg rod driving electric cylinder. One end of the upper leg rod is connected to the thigh through the knee joint shaft. The leg rod driving electric cylinder is mounted on the other end of the upper leg rod. The lower leg rod is slidably connected to the upper leg rod, and is driven by the leg rod driving electric cylinder to move up and down.

8. The low-energy consumption hexapod robot based on nonlinear cable geometry constraints according to claim 1, characterized in that, The fuselage comprises a front fuselage section, a rear fuselage section and a pitching motor, the front and rear fuselage sections are arranged in front and back and are connected by a pitching joint shaft, the front fuselage section is keyed to the pitching joint shaft; the housing of the pitching motor is fixed to the rear fuselage section, the motor shaft of the pitching motor is connected to the pitching joint shaft and can drive the front fuselage section to make pitching motion through the pitching joint shaft.

9. A foot end linearization compensation method for a low-energy consumption hexapod robot based on nonlinear cable geometry constraints, characterized in that, The low-energy consumption six-legged robot based on nonlinear rope geometric constraint according to claim 3 controls the compensation effect of the rope constraint by adjusting the installation position of the rope end fixing plate , ) to make the foot end trajectory approximate linear motion, that is, to realize foot end linearization compensation. According to the fuselage width limit preset value, based on the turning radius of the guide wheels on the upper thighs relative to the hip joint center and the working range , determined according to the following general analytical formula of the support trajectory : ， ， ， wherein, , is an intermediate variable, constant is the elongation provided by the fuselage segment rope length, , is the coordinate of the rope end fixing plate in the XY plane.

10. The foot end linearization compensation method of a low-energy consumption hexapod robot based on nonlinear rope geometry constraints according to claim 9, characterized in that, determining The general analytical formula of the support trajectory is obtained by the following steps: The target abduction angle of the lower leg is determined by equidistantly balancing the starting and ending points of the support along the Y-axis. The required rope length variation is then determined by calculating this target abduction angle. Finally, the second rope segment is determined based on the principle of rope length conservation. The change is equal to that of the first rope segment The change in; According to the relationship among the rope end fixing plate, the guide wheel and the lower leg rope node in the movement process The expression of The change amount is equal to The relationship of the change amount, finally determine The general analytical formula of the support trajectory; The shank target abduction angle wherein is the hip joint rotation angle, is the straight line distance from the knee joint axis to the foot end contact point, is the thigh turning radius, is the Y axis coordinate of the foot end is a constant corresponding constant.

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