Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a wheel type mobile platform motion track preview tracking control system and a wheel type mobile platform motion track preview tracking control method. For a given reference path, the pre-aiming pose deviation of the wheeled mobile platform relative to the reference curve can be calculated according to a parameter equation of the reference curve, the current pose and the pre-aiming distance of the wheeled mobile platform, and then the pre-aiming pose deviation is transmitted to a track tracking control system of the wheeled mobile platform, so that the walking control precision of the wheeled mobile platform is improved.
The invention is realized by the following technical scheme:
a wheel type mobile platform motion trail preview tracking control system comprises a vehicle-mounted preview control device and an actuating mechanism unit, wherein the vehicle-mounted preview control device and the actuating mechanism unit are arranged on a wheel type mobile platform;
the vehicle-mounted pre-aiming control equipment comprises a vehicle-mounted positioning device, a motion reference curve generator, a pre-aiming amount regulator, a processor, a data memory and a program memory, wherein the vehicle-mounted positioning device is used for measuring the current pose of the wheeled mobile platform, the motion reference curve generator is used for generating a path which can be executed by the wheeled mobile platform, the pre-aiming amount regulator is used for dynamically regulating the aiming distance according to the linear speed of the wheeled mobile platform, the program memory stores a pre-aiming point pose error resolving and control program, the data memory is used as an intermediate data carrier generated in the running process of the pre-aiming point pose error resolving and control program, and the program memory and the data memory are both in communication connection with the processor so as to calculate the current pre-aiming point pose error, control line speed and control angular speed of the wheeled mobile platform; the processor is connected with the execution mechanism unit, and the execution mechanism unit drives the wheel type mobile platform to move according to the control linear velocity and the control angular velocity output by the processor.
In the technical scheme, the processor comprises a pre-aiming point pose error calculation unit, a motion control unit, a speed planning unit and a speed feedback unit, wherein the pre-aiming point pose error calculation unit is used for calculating the pre-aiming point pose error of the wheel type mobile platform according to the wheel type mobile platform positioning pose provided by the vehicle-mounted positioning device, the path curve equation provided by the motion reference curve generator and the adjustment data provided by the pre-aiming amount adjuster; the speed feedback unit is used for feeding the current speed data of the wheel type mobile platform back to the speed planning unit; the speed planning unit plans the linear speed and the angular speed of the current point on the basis of the current speed data fed back by the speed feedback unit according to the remaining distance between the wheeled mobile platform and the target point; and the motion control unit calculates the track control data of the counter wheel type moving platform according to the pre-aiming point pose error and the planned linear velocity and angular velocity, and transmits the track control data to the actuating mechanism unit.
In the above technical solution, the vehicle-mounted positioning device outputs the current pose of the wheel-type moving platform center point P: p ═ a, b, θ, where a is the abscissa of the wheel center point P in the absolute coordinate system XOY, b is the ordinate of the wheel center point P in the absolute coordinate system XOY, and θ is X of the following coordinate system0The angle between the axis (i.e. the forward direction of the wheeled mobile platform) and the X-axis of the absolute coordinate system.
In the technical scheme, the motion reference curve generator outputs a curve equation F (t) of a feasible path of the wheel type mobile platform in an absolute coordinate system,
α refers to the upper bound of t, β refers to the lower bound of t.
In the technical scheme, the pre-aiming amount regulator outputs the pre-aiming adjustment amount delta L of the wheel type moving platform, wherein the delta L is the arc length from a point Q to a point R, the point Q is the closest point of the center point P of the wheel type moving platform on a distance curve equation, and the point R is the pre-aiming point on the curve equation.
In the above technical solution, the method for solving the pre-aiming point pose error is as follows:
suppose 1, the equation parameter corresponding to point Q on curve equation F (t) is tQ;
Suppose 2, the equation parameter corresponding to the point R on the curve equation F (t) is tR;
Assume 3 that, for curve equation F (t), the arc length between any two points is represented as L (t)1,t2),L(t1,t2) The gaussian-legendre integration method is applied to calculate the following:
in the formula, ωiIs the integral coefficient, τiIs a Gaussian point, t1,t2∈[α,β]。
A first derivative vector of a reference curve is represented,
2 norm, which represents the first derivative vector, is understood to be
By iterating continuously on the parameter t
QAnd t
RSo that
And L (t)
Q,t
R)≈ΔL,
Is a vector pointing the line between P and point Q, F (t)
Q) ' refers to the tangent vector at point Q: f (t)
Q)′=[x′(t
Q),y′(t
Q)];
Then, the parameter t can be obtained
QAnd t
RExpressed as
And
therefore, the calculation formula of the pre-aiming point pose error is as follows:
wherein:
EPRis a pre-aiming point pose error representation, EPR=(xe,ye,θe),xeIs the abscissa deviation value y from the current wheel type moving platform center point P to the pre-aiming point R on the motion reference curve in the absolute coordinate systemeIs the vertical coordinate deviation amount theta from the current wheel type moving platform center point P to the pre-aiming point R on the motion reference curve in the absolute coordinate systemeThe angular deviation value between the angular pose of the current wheeled mobile platform and the direction angle of the vector of the R-cut pre-aiming point on the motion reference curve in the absolute coordinate system;
is a pose representation of the pre-aiming point R on the motion reference curve,
x
Ris the abscissa, y, of the pre-aiming point R in an absolute coordinate system
RIs the ordinate, theta, of the pre-aiming point R in an absolute coordinate system
RIs the angle between the tangential direction of the collimation point R in the absolute coordinate system and the X-axis of the absolute coordinate system (i.e., θ)
RIs the tangent vector direction angle of the pre-aiming point R in the absolute coordinate system);
p is the current pose representation of the wheel center point P, where a is the abscissa of the wheel center point P in the absolute coordinate system XOY, and b is the ordinate of the wheel center point P in the absolute coordinate system XOYAnd theta is X of the following coordinate system0The angle between the axis (i.e. the forward direction of the wheeled mobile platform) and the X-axis of the absolute coordinate system.
In the above technical solution, the position and pose of the wheel-type mobile platform is regulated according to the position and pose error of the pre-aiming point, and the obtained control law of the wheel-type mobile platform is as follows:
in the formula, vrIs the planned linear speed value of the robot, which is obtained by the distance from the point Q to the terminal point T and the speed constraint, omegarIs the planned angular velocity, omega, of the robotrBy vrMultiplied by the curvature of the Q point, [ v, [ omega ]]TIs the linear and angular velocity control quantity, the control parameter k1>0,k2>0,k3>0。
A motion trail preview tracking control method comprises the following steps:
s100: loading the positioning pose of the vehicle-mounted positioning device, a path equation of the motion reference curve generator and the adjustment data of the pre-aiming quantity adjuster, and inputting the data into the processor;
s200: calculating the pre-aiming point position error of the wheel type mobile platform by using the positioning position, the path equation and the adjustment data;
s300: planning the linear velocity and the angular velocity of the current point by using the remaining distance between the wheeled mobile platform and the target point;
s400: calculating a control linear velocity and a control angular velocity of the motion of the wheeled mobile platform according to the pointing position error of the pre-pointing point, the planned linear velocity and the planned angular velocity;
s500: and the control linear velocity and the control angular velocity are used as current control values of the wheel type mobile platform and are input to the execution mechanism unit, and the pose of the wheel type mobile platform is adjusted to achieve the target pose.
The invention has the advantages and beneficial effects that:
the invention calls a prealignment point pose error resolving and controlling program in the program memory through the processor, thereby calculating the prealignment point pose error, the control linear velocity and the control angular velocity of the wheel type mobile platform at the current position. The processor takes the control linear velocity and the control angular velocity as the current control values of the wheel type mobile platform, inputs the current control values to the execution mechanism unit, adjusts the pose of the wheel type mobile platform, achieves the target pose, and improves the control precision of the walking of the wheel type mobile platform.
Detailed Description
In order to make the technical solution of the present invention better understood, the technical solution of the present invention is further described below with reference to specific examples.
Referring to fig. 1 and fig. 2, the wheel type mobile platform motion trajectory preview tracking control system disclosed by the invention comprises a vehicle-mounted preview control device and an execution mechanism unit 7 which are arranged on the wheel type mobile platform.
The vehicle-mounted pre-aiming control equipment comprises a vehicle-mounted positioning device 1, a motion reference curve generator 2, a pre-aiming amount regulator 3, a processor 4, a data memory 5 and a program memory 6, wherein the vehicle-mounted positioning device 1 is used for measuring the current pose of the wheeled mobile platform, the motion reference curve generator 2 is used for generating a path which can be executed by the wheeled mobile platform, the pre-aiming amount regulator 3 is used for dynamically adjusting the aiming distance according to the linear speed of the wheeled mobile platform, the program memory 6 is stored with a pre-aiming point pose error resolving and control program, the data memory 5 is used as an intermediate data carrier generated in the running process of the pre-aiming point pose error resolving and control program, and the program memory 6 and the data memory 5 are both in communication connection with the processor 4, calculating the current pre-aiming point pose error, control linear velocity and control angular velocity of the wheel type mobile platform; the processor 4 is connected with an actuator unit 7, and the actuator unit 7 can drive the wheel type mobile platform to move according to the control linear velocity and the control angular velocity output by the processor 5.
To explain the motion of the wheeled mobile platform, the concepts of an absolute coordinate system and a following coordinate system need to be introduced, referring to fig. 3, the absolute coordinate system is an XOY plane, and the following coordinate system X is a following coordinate system0PY0Taking the central point P of the wheel type moving platform as the origin, and establishing X in the forward direction of the wheel type moving platform0Axes on which Y is established according to the right-hand rule0The axes form a coordinate system.
The vehicle-mounted positioning device 1 outputs the position and posture of the central point P of the wheel type moving platform: p ═ a, b, θ, where a is the abscissa of the wheel center point P in the absolute coordinate system, b is the ordinate of the wheel center point P in the absolute coordinate system, and θ is X0The angle between the axis (i.e. the forward direction of the wheeled mobile platform) and the X-axis of the absolute coordinate system.
The motion reference curve generator 2 outputs a curve equation F (t) of the feasible path of the wheel type mobile platform in the absolute coordinate system,
α refers to the upper bound of t, β refers to the lower bound of t.
The pre-aiming quantity regulator 3 outputs a pre-aiming regulating quantity delta L of the wheel type moving platform, wherein the delta L is the arc length from a point Q to a point R, the point Q is the closest point of the center point P of the wheel type moving platform to the curve equation, and the point R is the pre-aiming point on the curve equation.
Then, the method for solving the pre-aiming point pose error is as follows:
suppose 1, the equation parameter corresponding to point Q on curve equation F (t) is tQ;
Suppose 2, the equation parameter corresponding to the point R on the curve equation F (t) is tR;
Assume 3 that, for curve equation F (t), the arc length between any two points is represented as L (t)1,t2),L(t1,t2) The gaussian-legendre integration method is applied to calculate the following:
in the formula, ωiIs the integral coefficient, τiIs a Gaussian point, parameter t1,t2Represents the parameters corresponding to two endpoints of the arc on the curve and t1,t2∈[α,β]。
A first derivative vector of a reference curve is represented,
2 norm, which represents the first derivative vector, is understood to be
By iterating continuously on the parameter t
QAnd t
RSo that
And L (t)
Q,t
R)≈ΔL,
Is a vector pointing the line between P and point Q, F (t)
Q) ' refers to the tangent vector at point Q: f (t)
Q)′=[x′(t
Q),y′(t
Q)];
Then, the parameter t can be obtained
QAnd t
RExpressed as
And
therefore, the calculation formula of the pre-aiming point pose error is as follows:
wherein: e
PRIs a pre-aiming point pose error representation, E
PR=(x
e,y
e,θ
e),x
eIs the abscissa deviation value y from the current wheel type moving platform center point P to the pre-aiming point R on the motion reference curve in the absolute coordinate system
eIs the vertical coordinate deviation amount theta from the current wheel type moving platform center point P to the pre-aiming point R on the motion reference curve in the absolute coordinate system
eThe angular deviation value from the current wheel type moving platform center point P to the pre-aiming point R on the motion reference curve in the absolute coordinate system;
is a pose representation of the pre-aiming point R on the motion reference curve,
x
Ris the abscissa, y, of the pre-aiming point R in an absolute coordinate system
RIs the ordinate, theta, of the pre-aiming point R in an absolute coordinate system
RIs the included angle between the tangential direction of the pre-aiming point R in the absolute coordinate system and the X axis of the absolute coordinate system; p is the current pose representation of the wheel type mobile platform central point P, and P is equal to(a, b, theta), wherein a is the abscissa of the center point P of the wheel-type moving platform in the absolute coordinate system XOY, b is the ordinate of the center point P of the wheel-type moving platform in the absolute coordinate system XOY, and theta is X of the following coordinate system
0The angle between the axis (i.e. the forward direction of the wheeled mobile platform) and the X-axis of the absolute coordinate system.
Further, the processor 4 includes a pre-aiming point pose error calculation unit, a motion control unit, a velocity planning unit, and a velocity feedback unit (see fig. 1). The pre-aiming point position error calculation unit is used for calculating the wheel type mobile platform pre-aiming point position error E according to the wheel type mobile platform positioning position provided by the vehicle-mounted positioning device 1, the path curve equation provided by the motion reference curve generator 2 and the adjustment data provided by the pre-aiming amount adjuster 3PR(ii) a The speed feedback unit is used for feeding the current speed data of the wheel type mobile platform back to the speed planning unit; the speed planning unit plans the linear speed and the angular speed of the current point on the basis of the current speed information fed back by the speed feedback unit according to the remaining distance between the wheeled mobile platform and the target point; the motion control unit is used for carrying out pose regulation and control on the wheel type mobile platform according to the pose error of the pre-aiming point, is a core unit for realizing the accurate tracking of the wheel type mobile platform on a reference curve, and obtains the control law of the wheel type mobile platform according to the kinematics law and the Lyapunov stability theorem as follows:
in the formula, vrIs the planned linear speed value of the robot, which is obtained by the distance from the point Q to the terminal point T and the speed constraint, omegarIs the planned angular velocity, omega, of the robotrBy vrMultiplied by the curvature of the Q point, [ v, [ omega ]]TIs the linear and angular velocity control quantity, the control parameter k1>0,k2>0,k3Is greater than 0. Will EPR、[vr,ωr]TAnd (4) carrying the above formula, obtaining the track control data of the wheel type mobile platform, and transmitting the track control data to the actuating mechanism unit.
Referring to fig. 4, a method for controlling a preview tracking of a motion trajectory according to the present invention includes the following steps:
s100: and loading the positioning pose of the vehicle-mounted positioning device 1, the path equation of the motion reference curve generator 2 and the adjustment data of the pre-aiming quantity adjuster 3, and inputting the data into the processor 4.
S200: and calculating the pre-aiming point position error of the wheel type mobile platform by using the positioning position, the path equation and the adjustment data.
S300: and planning the linear speed and the angular speed of the current point by using the remaining distance between the wheeled mobile platform and the target point.
S400: and calculating the control linear velocity and the control angular velocity of the motion of the wheeled mobile platform according to the pointing position error of the pre-pointing point, the planned linear velocity and the planned angular velocity.
S500: the control linear velocity and the control angular velocity are used as current control values of the wheel type moving platform and input to the execution mechanism unit 7, and the pose of the wheel type moving platform is adjusted to achieve the target pose.
The invention also discloses a computer readable storage medium, on which a computer program is stored, wherein the computer program is a preview point pose error resolving and controlling program, and when the computer program is executed by the processor 4, the preview tracking control method of the motion trail of the wheeled mobile platform disclosed by the invention can be realized.
Spatially relative terms, such as "upper," "lower," "left," "right," and the like, may be used in the embodiments for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatial terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "lower" can encompass both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Moreover, relational terms such as "first" and "second," and the like, may be used solely to distinguish one element from another element having the same name, without necessarily requiring or implying any actual such relationship or order between such elements.
The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.