CN-121979265-A - Gait self-adaptive control method for four-foot robot based on active anti-interference

CN121979265ACN 121979265 ACN121979265 ACN 121979265ACN-121979265-A

Abstract

The invention belongs to the technical field of robot motion control, and discloses a four-foot robot gait self-adaptive control method based on active anti-interference, which comprises the steps of realizing a foot drop fixed track through a swing phase foot drop compensation strategy, introducing an improved EID estimator to estimate system disturbance in real time and obtain compensation quantity meeting the constraint condition of the four-foot robot to the sole force of a support phase, thereby improving the anti-interference capability of the four-foot robot in the foot drop fixed state and ensuring the stable body posture; and only when the disturbance exceeds the redundant bearing range of the machine body, temporarily switching the foot drop point follow-up mode to ensure the safety of the whole machine, and finally realizing the stable and high-precision motion control of the four-foot robot in an extreme operation scene.

Inventors

WU XIANG
YIN SHUAI
HUANG GUANGPU
JIA YU
DONG HUI
LIANG DINGKUN
WU MINCHENG
GUO FANGHONG
ZHANG WENAN

Assignees

浙江工业大学

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (8)

1. The gait self-adaptive control method of the four-foot robot based on active anti-interference is characterized by comprising the following steps of: Acquiring the position of the centroid at the current moment of the quadruped robot under a world coordinate system and the leg state, and obtaining the expected centroid position at the current moment by using a centroid planner; Aiming at the leg with the leg state being a swinging phase, judging whether the quadruped robot is disturbed by external force larger than a disturbance threshold according to the position of the centroid at the current moment under a world coordinate system, the expected centroid position at the current moment and the expected centroid position at the last moment; if the four-foot robot is disturbed by external force larger than a disturbance threshold, determining the position of the foot drop point of the leg at the current moment by adopting a centroid follow-up mode, otherwise, determining the position of the foot drop point of the leg at the current moment by adopting an expected centroid position compensation mode; For the leg with the leg state as the supporting phase, an improved equivalent input disturbance estimator is adopted to estimate external disturbance, and an external disturbance estimated value acts on the foot end contact force of the leg to compensate, so as to obtain the compensated foot end contact force, wherein the improved equivalent input disturbance estimator is obtained by replacing the generalized inverse of the B matrix in the equivalent input disturbance estimator with a quadratic programming method.
2. The adaptive control method for gait of the four-foot robot based on active anti-interference of claim 1, wherein the determining whether the four-foot robot is disturbed by an external force greater than a disturbance threshold according to the position of the centroid at the current moment in the world coordinate system, the expected centroid position at the current moment and the expected centroid position at the last moment comprises: If the expected centroid position at the current moment is equal to the expected centroid position at the last moment and the absolute value of the difference between the position of the centroid at the current moment under the world coordinate system and the expected centroid position at the current moment is smaller than the disturbance threshold, the four-foot robot is not disturbed by external force larger than the disturbance threshold, otherwise, the four-foot robot is disturbed by external force larger than the disturbance threshold.
3. The adaptive control method for gait of four-foot robot based on active anti-interference as claimed in claim 1, wherein the determining the position of the landing point of the leg at the current moment by adopting the centroid following mode comprises: And calculating the foot drop position of the leg at the current moment according to the position of the centroid at the current moment under the world coordinate system, the centroid speed, the centroid expected speed and the phase moment of the leg swing at the current moment and the heuristic foot drop planning mode.
4. The adaptive control method for gait of the four-foot robot based on active anti-interference according to claim 1, wherein the determining the position of the landing point of the leg at the current moment by adopting the expected centroid position compensation mode comprises the following steps: According to the circular motion radius and azimuth angle of the leg foot end on the plane, respectively determining the world coordinate system of the leg foot drop point Shaft and method for producing the same A projection component in an axial direction; Using world coordinate systems Shaft and method for producing the same Desired centroid positions in axial direction are respectively set on world coordinate system for leg foot drop points Shaft and method for producing the same The projection component in the axial direction is compensated to obtain the world coordinate system of the falling foot point of the leg at the current moment Shaft and method for producing the same A position in the axial direction.
5. The adaptive control method for the gait of the four-foot robot based on active anti-interference according to claim 1, wherein foot end track planning is performed through a Bezier curve according to the foot drop position of the leg at the current moment, so as to obtain continuous foot end positions in each control period.
6. The adaptive control method for gait of a four-foot robot based on active anti-interference of claim 1, wherein said estimating external disturbances using an improved equivalent input disturbance estimator comprises: Constructing a three-dimensional single rigid body model of the four-foot robot, and obtaining a state space model of the four-foot robot; defining an observation residual error and designing a state observer according to the system state, the input of the controller and the observation output; amplifying the observation residual error through the gain of the state observer, and converting the dimension of the amplified observation residual error into force and moment through a conversion matrix to obtain a disturbance force acting on the mass center; according to barycenter dynamics, a mapping relation between foot-end compensation force and disturbance force acting on barycenter is established, a quadratic programming problem is constructed based on the mapping relation, and the quadratic programming problem is solved to obtain foot-end compensation force; and (3) passing the foot compensation force through a filter, and obtaining an external disturbance estimated value based on the output of the filter.
7. The adaptive control method for gait of the four-legged robot based on active anti-interference according to claim 6, wherein the transformation matrix comprises two rows and two columns of elements, wherein the elements of the first row and the first column are the ratio of the inertial tensor to the control period under the world coordinate system of the four-legged robot, the elements of the first row and the second column and the first column are zero matrices, and the elements of the second row and the second column are the ratio of the product of the mass of the four-legged robot and the identity matrix to the control period.
8. The adaptive control method for gait of a four-foot robot based on active anti-interference of claim 6, wherein the construction quadratic programming problem is as follows: ; In the formula, As a matrix of parameters, Is that The foot end at the moment compensates the force, Is that The disturbing force acting on the centroid at any time, For the leg index of a four-legged robot, For the leg set with the current leg state of the four-foot robot being the swing phase, For the leg set with the current leg state of the four-legged robot as the supporting phase, The constraint condition of the friction cone is indicated, Representing the function of the friction cone constraint, Representing the friction cone constraint threshold value, 、 Is the upper and lower bounds of the normal force; Is shown in Time of day (time) The foot end of the strip leg contacts the force, Is that Time of day (time) The foot ends of the strip legs compensate for the force, Representing foot contact force In the component of the normal direction, Compensating force for foot end A component in the normal direction.

Description

Gait self-adaptive control method for four-foot robot based on active anti-interference Technical Field The invention belongs to the technical field of robot motion control, and particularly relates to a gait self-adaptive control method of a four-foot robot based on active anti-interference. Background The quadruped robot has good terrain adaptability and exercise flexibility, and has wide application prospects in conventional inspection, field search and rescue, outdoor operation, special protection and various unstructured extreme operation scenes. The method is characterized in that part of extreme operation scenes are high-risk area fixed-point operation (such as field thunder area explosion elimination, nuclear radiation area fixed-point detection and toxic and harmful environment sampling), narrow limited space passing (such as underground roadway, pipeline corridor and collapse building gap) and the like, and strict requirements are put forward on motion control of the quadruped robot, wherein when sudden disturbance is received, leg motion amplitude needs to be strictly controlled, large position deviation cannot occur, foot drop points need to be precisely fixed at preset points, and the situation that the robot is unstable, scene danger is triggered or operation precision is damaged due to leg follow-up and foot drop point deviation is avoided, for example, the explosion is mistakenly touched in the thunder area, the narrow space is blocked and turned on one's side, and the like. The conventional four-foot robot generally adopts periodic gait to perform motion control, the gait period can be divided into a supporting phase and a swinging phase, wherein the supporting phase is communicated with plantar ground reaction force distribution to realize body support and posture stabilization, and the swinging phase is communicated with foot end track generation and foot drop point planning to realize speed tracking and motion direction adjustment. Under the general working condition, the swing phase foot drop planning usually adopts a heuristic method or an on-line adjustment strategy based on a stability index, so that the foot drop is changed along with the mass center state or the speed error, and the disturbed recovery capacity is improved. However, in the above extreme working scenario, the drop foot needs to be fixed in a preset point or a limited area, and the conventional control logic of the drop foot follow-up adjustment has a fundamental conflict with the extreme working requirement, that is, even if a small disturbance occurs, the existing drop foot follow-up strategy may drive the drop foot to deviate from the preset point, resulting in reduced working accuracy and induced safety risk. On the other hand, under the locking constraint of the falling foot points, when the supporting phase only depends on the conventional model predictive control to distribute plantar force, the supporting phase is limited by constraints such as friction cone, normal force range, joint moment saturation and the like, and the problems of insufficient posture recovery, increased body fluctuation and even instability can occur in the face of larger external force disturbance. Therefore, a need exists for a gait self-adaptive control method of a quadruped robot, which adapts to an extreme operation scene, so as to solve the technical defects that the prior art cannot ensure that the foot end track is fixed, the foot drop point is not deviated, and disturbance cannot be effectively resisted on the premise of the foot end track is fixed, and break the application limit of the quadruped robot in extreme working conditions. Disclosure of Invention The invention aims to overcome the problems that in the prior art, under an extreme operation scene, a four-foot robot cannot meet the core precondition requirement of a foot drop fixing track, and the disturbance rejection capability is insufficient and the instability of a machine body is easy to cause when the foot end track is fixed, and provides a gait self-adaptive control method of the four-foot robot based on active disturbance rejection, which comprises the steps of firstly realizing the foot drop fixing track through a swing phase foot drop compensation strategy, then introducing an improved Equivalent Input Disturbance (EID) estimator to estimate the system disturbance in real time and obtain a compensation quantity meeting the constraint condition of the four-foot robot to the plantar force of a support phase, so that the disturbance rejection capability of the four-foot robot in the foot drop fixing state is improved, and the stability of the machine body posture is ensured; and only when the disturbance exceeds the redundant bearing range of the machine body, temporarily switching the foot drop point follow-up mode to ensure the safety of the whole machine, and finally realizing the stable and high-precision motion control of the four-foot robot in an extreme op