CN-121995946-A - Load sensing method and system for heavy foot type carrying platform

CN121995946ACN 121995946 ACN121995946 ACN 121995946ACN-121995946-A

Abstract

The invention discloses a load sensing method and a system for a heavy foot-type carrying platform, wherein the method comprises the steps of establishing a dynamic model of each active leg system, designing a nonlinear disturbance observer based on the dynamic model, and observing space equipotential forces in real time by utilizing driving motor parameters of the active leg systems; the method comprises the steps of establishing a dynamic model of a fuselage, acquiring inertial measurement unit data of the fuselage, calculating the inertial force and the inertial moment of the fuselage, calculating the acting force of a load on the fuselage by combining the inertial force of the fuselage and the moment balance relation according to the observed space equipotency of each active leg system on the fuselage, and calculating the acting position of the load on the fuselage by moment balance. According to the invention, on the premise of not additionally arranging a force sensor and fully considering the dynamic influence of the large mass leg, the dual sensing of the high-precision load force and the load position of the heavy foot type carrying platform in a complex environment is realized, the system cost is effectively reduced, and the control stability of the platform is improved.

Inventors

CHEN SHOUYUAN
QIAN TIANWEI
YE CHENGZHENG
LIU SHAOXUN

Assignees

上海交通大学

Dates

Publication Date: 20260508
Application Date: 20260403

Claims (9)

1. A load sensing method for a heavy foot-type carrying platform, comprising: Establishing a dynamic model of each active leg system, wherein the dynamic model describes the space equivalent force of the active leg system at a connection point with a fuselage in the motion process, designing a nonlinear disturbance observer based on the dynamic model, and observing the space equivalent force in real time by using the driving motor parameters of the active leg system; Establishing a dynamic model of the airframe in an inertial coordinate system, acquiring inertial measurement unit data of the airframe, and calculating the inertial force and the inertial moment of the airframe; Calculating the acting force of the load on the airframe through a force balance relation by combining the airframe inertia force according to the observed space equivalent force of each active leg system on the airframe; And calculating the position of the load relative to the fuselage through a moment balance relation according to the observed space equivalent force of each active leg system on the fuselage and the inertia moment of the fuselage.
2. The load sensing method of claim 1, wherein establishing a kinetic model of the active leg system comprises: respectively establishing a ground contact stage dynamics model and a swing stage dynamics model according to the movement stage of the active leg system; In the ground contact stage, the active leg system is regarded as a mechanical arm fixed on the ground, an inertial coordinate system is established at a ground contact point of a foot end based on the assumption that the foot end is in contact with the ground point and has no relative sliding, and a kinetic equation comprising an inertial matrix, a Coriolis force matrix, a gravity matrix, electric cylinder active force, friction force and the space equivalent force of the active leg system is constructed; in the swing stage, a non-inertial coordinate system is established at the joint of the active leg system and the airframe, and a corresponding kinetic equation is established; The electric cylinder main power is obtained through calculation of a motor-electric cylinder coupling dynamics model according to electromagnetic torque of a driving motor, electric cylinder transmission ratio, inertial parameters, damping parameters and rigidity parameters of the motor and the electric cylinder.
3. The load sensing method of claim 2, wherein the method of calculating the master power of the electric cylinder comprises: Establishing a dynamic model of the driving motor, wherein the model comprises motor electromagnetic torque, output shaft load torque, rotor rotational inertia, damping coefficient and association relation between rotor rotating speed and angular acceleration; Establishing an electric cylinder dynamics model considering equivalent mass of a rotor, wherein the model comprises a transmission ratio from a motor to an electric cylinder, screw rotational inertia, electric cylinder push rod mass and association relation among push rod position, speed, acceleration, an electric cylinder damping coefficient, a rigidity coefficient, electric cylinder main power and friction force; substituting the dynamic model of the driving motor into the electric cylinder dynamic model, deducing an associated expression of the electric cylinder main power, the motor electromagnetic torque, the motor and the electric cylinder structural parameters and the motion parameters, and acquiring the electric cylinder main power corresponding to the big and small legs of the active leg system based on the expression.
4. The load sensing method of claim 2, wherein the designing a nonlinear disturbance observer based on the dynamics model comprises: combining the equivalent damping of a motor electric cylinder, the rigidity of the electric cylinder and disturbance items in the system in the dynamic model of the active leg system into a model uncertainty item, and simplifying the dynamic model to obtain an active leg system dynamic equation containing equivalent expression of the space equivalent force on the electric cylinder; when the space equivalent force is zero in the variation quantity in a single sampling period and the model uncertainty item is negligible compared with the main power of a motor and the space equivalent force ratio, constructing a basic observation model of the nonlinear disturbance observer based on the simplified dynamic equation of the active leg system; Introducing an intermediate variable, defining a Lyapunov function of the space equivalent effect observation error, designing a gain matrix of the nonlinear disturbance observer, ensuring the convergence of the observer, and forming a complete nonlinear disturbance observer; And inputting parameters of the driving motor of the driving leg system to the nonlinear disturbance observer to obtain an equivalent expression of the space equivalent force on the electric cylinder, and obtaining an observed value of the space equivalent force at the position of the connecting point of the driving leg system and the airframe through jacobian matrix conversion from the connecting point of the driving leg system and the airframe to a generalized variable.
5. The load sensing method of claim 1, wherein the modeling of dynamics of the fuselage in an inertial coordinate system comprises: Defining generalized variables of the airframe as vectors containing position components and attitude components of the airframe in an inertial coordinate system, wherein the attitude components are roll, pitch and yaw angles of the airframe, and establishing an airframe dynamics core equation based on the generalized variables, wherein the core equation meets the balance relation between an airframe inertia matrix, a coriolis force matrix and a gravity matrix and the total external force born by the airframe; determining the composition of the total external force born by the airframe, wherein the composition comprises the supporting force of each active leg system on the airframe and the acting force of the load on the airframe, the supporting force of each active leg system on the airframe is equal to and opposite to the space equivalent force corresponding to the connection point of the active leg system and the airframe, and the supporting force is converted into an expression form in the generalized space of the airframe through a jacobian matrix from the airframe to the hinge point of the active leg system and the airframe; Based on the space mechanics principle of an inertial coordinate system, the airframe dynamics core equation is unfolded into a three-way force balance equation of the airframe along the X, Y, Z axis and a three-way moment balance equation of the airframe around the X, Y, Z axis, so as to form an airframe dynamics unfolding model for calculating the load acting force and the load position.
6. The load sensing method of claim 5, wherein the acquiring inertial measurement unit data of the fuselage, calculating inertial forces and moments of inertia of the fuselage comprises: Acquiring three-axis real-time linear acceleration and three-axis real-time angular acceleration acquired by the body inertia measurement unit and preset structural parameters of the body, wherein the preset structural parameters comprise the integral mass of the body and the rotational inertia of the body around the three axes of an inertia coordinate system X, Y, Z; Based on Newton's second law, multiplying the whole mass of the airframe by the real-time linear accelerations of X, Y, Z three axes in an inertial coordinate system respectively to obtain inertial force components of the airframe along the three axes of the inertial coordinate system X, Y, Z, and synthesizing the inertial force of the airframe by the inertial force components of the three axes; Based on the principle of rigid body rotation dynamics, the moment of inertia of the machine body around the three axes of the inertial coordinate system X, Y, Z is multiplied by the real-time angular acceleration of the corresponding axis respectively to obtain the moment of inertia components of the machine body around the three axes of the inertial coordinate system X, Y, Z, and the moment of inertia components of the machine body are synthesized by the three axes of the moment of inertia components.
7. The method of claim 6, wherein calculating the force of the load on the fuselage from the force balance relationship based on the observed spatial equipotential forces of each of the active leg systems to the fuselage in combination with the fuselage inertial forces comprises: Converting the space equivalent force of each active leg system at the connection point of the active leg system and the machine body into a supporting force of the corresponding active leg system on the machine body, wherein the supporting force is equal to the space equivalent force in size and opposite in direction, extracting three-axis components of each supporting force in an inertial coordinate system X, Y, Z, and respectively calculating to obtain the sum of the supporting force components of X, Y, Z three axes in the inertial coordinate system; acquiring the inertial force components of the fuselage on the X, Y, Z three axes under an inertial coordinate system, and simultaneously determining a gravity value of the fuselage, wherein the gravity only acts on the Z-axis direction of the inertial coordinate system; According to a three-way force balance principle of the machine body under an inertial coordinate system, respectively calculating components of load force on X, Y, Z three axes, wherein an X-axis load force component is the sum of an X-axis inertial force component of the machine body minus an X-axis supporting force component, a Y-axis load force component is the sum of a Y-axis inertial force component of the machine body minus a Y-axis supporting force component, and a Z-axis load force component is the sum of a Z-axis inertial force component of the machine body minus a Z-axis supporting force component and then minus the gravity of the machine body; and synthesizing the calculated triaxial components of the load force X, Y, Z to obtain the total acting force of the load on the machine body.
8. The method of claim 7, wherein calculating the position of the load relative to the fuselage from the torque balance relationship in combination with the fuselage moment of inertia based on the observed spatial equipotency of each of the active leg systems to the fuselage comprises: converting the space equivalent force of each active leg system at the connection point of the active leg system and the fuselage into a supporting force of the corresponding active leg system on the fuselage, wherein the supporting force is equal to the space equivalent force in size and opposite in direction, extracting three-axis components of each supporting force in an inertial coordinate system X, Y, Z, respectively calculating the supporting moment of each supporting force on the fuselage center of mass around the X, Y, Z three axes by combining the position coordinates of each active leg system and the fuselage hinge point relative to the fuselage center of mass, and summing to obtain the total supporting moment of the fuselage around the X, Y, Z three axes under the inertial coordinate system; Acquiring the moment of inertia components of the machine body around the three axes of an inertial coordinate system X, Y, Z, and respectively calculating load moment components of the load on the machine body around the three axes X, Y, Z according to the moment balance principle of the machine body around the three axes, wherein the single-axis load moment components are the moment of inertia components of corresponding axes minus the total supporting moment components of the axes; Extracting the roll, pitch and yaw angles of the airframe calculated by the airframe inertia measurement unit, deducing a rotation matrix of the airframe relative inertia system based on the angles, and converting the relative distance between the load and the airframe mass center from an inertia coordinate system to an expression form under the airframe coordinate system; Neglecting the contact deformation between the load and the machine body, and assuming point contact, determining that the vertical distance between the load and the machine body is half of the thickness of the machine body, reducing the dimension of a load moment balance equation in a three-dimensional space to an X-Y plane of a machine body coordinate system, and eliminating a vertical position unknown quantity; Based on the X-Y plane moment balance relation after dimension reduction, a corresponding coefficient matrix and moment vector are constructed, the coefficient matrix is calculated with the moment vector after inversion, X, Y position components of the load relative to the mass center of the machine body under a machine body coordinate system are obtained, and the known vertical position components are combined to obtain the complete position coordinates of the load relative to the mass center of the machine body.
9. A load sensing system for a heavy foot-type carrying platform comprising a fuselage and a plurality of active leg systems, comprising: the model building module is used for building a dynamic model of each active leg system and building a dynamic model of the airframe in an inertial coordinate system; The data acquisition module is used for acquiring driving motor parameters of the driving leg system and acquiring inertial measurement unit data of the airframe; The nonlinear disturbance observer module is connected with the model construction module and the data acquisition module, and is used for observing the space equipotential force of the active leg system at the position of the connection point with the machine body in the motion process in real time based on the dynamic model design of the active leg system by utilizing the driving motor parameters; The inertial force and moment calculation module is connected with the data acquisition module and calculates the inertial force and moment of inertia of the airframe according to the data of the inertial measurement unit; The load force resolving module is respectively connected with the nonlinear disturbance observer module and the inertia force and moment calculating module, and calculates the acting force of the load on the airframe through a force balance relation according to the observed space equivalent force of each active leg system on the airframe and the airframe inertia force; The load position calculating module is respectively connected with the nonlinear disturbance observer module and the inertia force and moment calculating module, and calculates the position of the load relative to the airframe through a moment balance relation according to the observed space equivalent force of each active leg system on the airframe and the airframe inertia moment; and the output module is used for outputting the acting force of the load on the machine body and the position of the load relative to the machine body.

Description

Load sensing method and system for heavy foot type carrying platform Technical Field The invention relates to the technical field of foot robots, in particular to a load sensing method and a system for a heavy foot type carrying platform. Background Foot drives exhibit significant terrain adaptability advantages over traditional wheel drives in complex non-structural environments. The foot-type platform can effectively cope with uneven ground and dense barriers through a flexible movement mode and a variable gait strategy, so that the foot-type platform is widely focused and applied in the high-difficulty operation fields of rescue, detection, military reconnaissance and the like. To meet heavy duty mission requirements, heavy foot platforms are typically equipped with active leg systems (ACTIVE LEG SYSTEM, ALS) having a large dead weight. However, the introduction of high mass ALS causes the system to exhibit significant model uncertainty and causes moment and position response delays, making it difficult for conventional wheeled vehicles and stable control methods of lightweight foot robots to migrate directly to such platforms. At present, robust control research on heavy-duty foot platforms in complex environments still faces a plurality of challenges, particularly in the key technical fields of floating base ground force observation, load sensing and the like. Due to the cost bottleneck of the wide-range and high-precision multidimensional force sensor and the complexity of the ALS structure, the existing research is urgent to explore a load sensing method under the condition of a foot-less contact sensor so as to improve the control performance and stability of the platform under the conditions of load disturbance, ground impact and environmental disturbance. Modeling methods for heavy foot-type carrying platforms generally consider them as floating bases with attached touchdown or swing ALS, and build an overall kinetic model by stacking generalized variables of each ALS with the pose of the fuselage. However, the integral modeling method has inherent defects that firstly, the angular acceleration of ALS is difficult to directly and accurately measure, if a high-precision sensor is added to acquire the parameter, the system cost is obviously increased, and secondly, the modeling mode causes the system to present overdetermined characteristics, and even if the angular acceleration of ALS can be accurately acquired, the ground acting force is difficult to be reversely pushed out only through the inertial force and the moment of the airframe which are solved by the IMU sensor. On the other hand, the light foot type robot usually adopts a simplified modeling method, ignores the influence of inertial force and moment of legs in the movement process on the robot body, and simplifies the problem into that the ground force directly acts on the robot body. However, this method is not suitable for heavy foot-type carrying platforms equipped with high mass ALS, because the inertial effects of the high mass legs are not negligible, and if a simplified model is used, significant errors will be introduced, affecting the control accuracy and stability of the platform. Based on this, a new solution is needed. Disclosure of Invention In view of the above, embodiments of the present invention provide a load sensing method and system for a heavy foot-type carrying platform, so as to at least solve the problems in the prior art. The embodiment of the invention provides the following technical scheme: The embodiment of the invention provides a load sensing method for a heavy foot-type carrying platform, which comprises the following steps: Establishing a dynamic model of each active leg system, wherein the dynamic model describes the space equivalent force of the active leg system at a connection point with a fuselage in the motion process, designing a nonlinear disturbance observer based on the dynamic model, and observing the space equivalent force in real time by using the driving motor parameters of the active leg system; Establishing a dynamic model of the airframe in an inertial coordinate system, acquiring inertial measurement unit data of the airframe, and calculating the inertial force and the inertial moment of the airframe; Calculating the acting force of the load on the airframe through a force balance relation by combining the airframe inertia force according to the observed space equivalent force of each active leg system on the airframe; And calculating the position of the load relative to the fuselage through a moment balance relation according to the observed space equivalent force of each active leg system on the fuselage and the inertia moment of the fuselage. Preferably, establishing the dynamic model of the active leg system includes: respectively establishing a ground contact stage dynamics model and a swing stage dynamics model according to the movement stage of the active leg system; In the ground