Disclosure of Invention
In view of the problems existing in the background art, the present invention aims to provide a spatial three-dimensional large-scale kinematics simulation system and method, which can realize the simulation of the relative motion between aircrafts in a large-scale three-dimensional space in a limited ground experimental space, increase the flexibility of the simulation system, reduce the complexity of the problems, and reduce the construction cost of the whole simulation system.
In order to achieve the above object, in a first aspect, the present invention provides a spatial three-dimensional large-scale kinematics simulation system, which includes an experimental site, a target aircraft simulation mechanism, and a mission aircraft simulation mechanism; the target aircraft simulation mechanism comprises a target aircraft and a first industrial mechanical arm, wherein a base of the first industrial mechanical arm is fixed on an experimental field, and the tail end of the first industrial mechanical arm is connected to the target aircraft; the task aircraft simulation mechanism comprises a task aircraft, a second industrial mechanical arm and an all-directional mobile platform, wherein a base of the second industrial mechanical arm is fixed on the all-directional mobile platform, the tail end of the second industrial mechanical arm is connected to the task aircraft, and the all-directional mobile platform is arranged on an experimental site and can move on the experimental site.
In one embodiment, the spatial three-dimensional large-scale kinematic simulation system further comprises: and the positioning system is arranged on the omnibearing mobile platform and is used for acquiring the relative pose of the omnibearing mobile platform relative to the base of the first industrial mechanical arm in real time.
In order to achieve the above object, in a second aspect, the present invention provides a method for simulating spatial three-dimensional large-scale kinematics, which performs simulation based on the spatial three-dimensional large-scale kinematics simulation system of the first aspect, and includes: establishing a fixed coordinate system F of the target aircraft
T,F
TThe origin point of the target aircraft is the mass center of the target aircraft, and a target aircraft orbit coordinate system F is established
W,F
WThe origin point of the target aircraft is the mass center of the target aircraft, and a task aircraft fixed coordinate system F is established
SEstablishing a coordinate system F of the experimental site
eA first industrial robot base coordinate system F
TbAnd a second industrial robot base coordinate system F
SbWherein, the translation of the target aircraft along the space orbit is not considered, and only the relative motion relation between the target aircraft and the mission aircraft in the space is considered; in a coordinate system F
T、F
W、F
SThen, based on the initial angular velocity vector value of the given target aircraft and according to the calculation of space dynamics, the fixed point motion track T of the target aircraft in the space environment is obtained
2(T), wherein T
2(t) is the target aircraft's trajectory of rotation about the center of mass; in a coordinate system F
T、F
W、F
SThen, aiming at the control strategy of the mission aircraft, the mission aircraft is controlled to move relative to the target aircraft, and the motion trail T of the mission aircraft in the space environment is directly obtained according to the flight route of the mission aircraft
1(T), wherein T
1(t) is the fixed coordinate system F of the mission aircraft
SRelative orbit coordinate system F
WRelative movement track of, T
1(t) is represented by a series of dense discrete points; and (3) performing motion planning on the relative motion of the target aircraft on the space in an experimental field by the mission aircraft: dividing the relative motion between the mission aircraft and the target aircraft into a first virtual motion and a second virtual motion, wherein the first virtual motion is F
TAround F
WThe second virtual motion is F
SRelative to F
WThe second virtual motion is F
SRelative to F
Sb、F
SbRelative to F
e、F
eRelative to F
Tb、F
TbRelative to F
WThe continuous motion chain is virtualized to be a super-redundant mechanical arm, and a base coordinate system of the super-redundant mechanical arm is F
WThe tail end of the super-redundant mechanical arm is a fixed coordinate system F of the mission aircraft
S(ii) a According to the given movement locus T of the mission aircraft
1(t) performing motion planning and trajectory planning based on the virtual kinematics model of the super-redundant mechanical arm, and calculating to obtain the motion trajectory of each joint of the super-redundant mechanical arm, namely the motion trajectory of each joint of the second industrial mechanical arm
i∈[1,N
S]Wherein N is
SIs the number of joints of the second industrial robot arm; movement locus of each degree of freedom of omnibearing mobile platform
i∈[x,y,θ](ii) a And each joint motion track of the first industrial mechanical arm
i∈[1,N
TT]Wherein N is
TTIs the number of joints of the first industrial robot arm; according to the motion track Tra of each joint of the first industrial mechanical arm
TTi(t) calculating to obtain the end F of the first industrial robot arm
WRelative base F
TbIs Tra
T(t)=[x
T(t) y
T(t) z
T(t) rx
T(t) ry
T(t) rz
T(t)]
T(ii) a Attaching a first industrial robot end F
WIs Tra
T(T) a movement locus T around the center of mass with the target aircraft
2(t) fusing to obtain the end F of the first industrial robot
TAt F
TbDown motion trajectory, then based on F
TAt F
TbThe movement track of the final joint closing movement of the first industrial mechanical arm is obtained
i∈[1,N
T]Wherein N is
TIs the number of joints of the first industrial robot arm; and simulating the relative motion of the mission aircraft relative to the target aircraft according to the track planning result of each joint.
In one embodiment, a first industrial robot end F is positioned
WIs Tra
T(T) a movement locus T around the center of mass with the target aircraft
2(t) the specific steps of performing fusion include: establishing a positive kinematic equation P
Tm=X(q
Tm) Equation of inverse kinematics q
Tm=Y(P
Tm) Wherein P is
TmShowing the first industrial robot arm end at F
TbPosition attitude vector of lower, q
TmRepresenting angle vectors of respective joints of the first industrial robot arm in joint space; end F of super redundant mechanical arm
WRelative base F
TbPlanning the obtained movement track Tra
T(t) is represented by a homogeneous transformation matrix as
Moving track T of target aircraft around centroid
2(t) expansion into homogeneous transformation matrices
According to
The first industrial robot end F can be calculated
TAt F
TbUnderlying homogeneous transformation matrix
Then based on
Inverse kinematics equation q by first Industrial robot arm
Tm=Y(P
Tm) Solving the position of each joint, calculating the speed and the acceleration of each joint through a difference method, and finally obtaining a first industrial mechanical arm combined motion planning result
In one embodiment, during the final step of executing, the method for the ground simulation system to simulate the approach of the mission aircraft to the target aircraft in the space further comprises: the omnibearing mobile platform according to the measured data track
i∈[x,y,θ]Establishing a PID feedback control system to follow the expected motion track of each degree of freedom of the omnibearing mobile platform
i∈[x,y,θ]。
The invention has the following beneficial effects: by the spatial three-dimensional large-scale kinematics simulation method, the limitation of a ground experiment environment is broken through by combining the second mechanical arm and the omnibearing mobile platform, kinematics simulation in a larger range is realized, and the flexibility of a simulation system is increased; in addition, the super-redundant mechanical arm is established, the complex collaborative planning problem of a plurality of actuating mechanisms is integrated into the planning problem of the super-redundant mechanical arm, and the complexity of the problem is reduced; moreover, by defining a track coordinate system, and abstracting a virtual super-redundant mechanical arm and a fixed point motion structure, the problem of motion planning of a plurality of systems in the prior art is converted into the problem of collaborative planning of two independent virtual motion mechanisms, so that the complexity of the problem is reduced.
Detailed Description
The following describes a spatial three-dimensional large-scale kinematics simulation system and method according to the present invention in detail with reference to the accompanying drawings.
Referring to fig. 1 and 2, the spatial three-dimensional large-scale kinematics simulation system according to the present invention includes an experimental site 1, a target aircraft simulation mechanism 2, a mission aircraft simulation mechanism 3, and a positioning system 4.
The target aircraft simulation mechanism 2 comprises a target aircraft 21 and a first industrial mechanical arm 22, wherein the base of the first industrial mechanical arm 22 is fixed on the experimental site 1, and the tail end of the first industrial mechanical arm 22 is connected to the target aircraft 21. The first industrial robot arm 22 adjusts the movement of the target aircraft 21 by adjusting the tip position attitude. It should be added that the first industrial robot arm 22 is mainly composed of a joint and a connecting rod, and the joint is composed of a motor, a harmonic reducer, an absolute position sensor, a joint torque sensor, a joint controller, and the like.
In one embodiment, the target aircraft 21 is connected to the first industrial robot arm 22 by a connecting flange.
In one embodiment, the first industrial robot 22 is a six-axis robot, but not limited thereto, and the first industrial robot 22 may have more or less degrees of freedom according to actual situations to better meet the use requirements.
Task aircraft simulation mechanism 3 includes task aircraft 31, second industry arm 32 and all direction movement platform 33, and on the base of second industry arm 32 was fixed in all direction movement platform 33, the end-to-end connection of second industry arm 32 in task aircraft 31, all direction movement platform 33 set up on experimental area 1 and can move on experimental area 1.
In one embodiment, mission aircraft 31 is connected to second industrial robot arm 32 via a connecting flange.
In one embodiment, the second industrial robot 32 is a six-axis robot, and similarly, the second industrial robot 32 may have more or less degrees of freedom depending on the actual situation to better meet the use requirement. It should be added that the second industrial robot arm 32 is mainly composed of a joint and a connecting rod, and the joint is composed of a motor, a harmonic reducer, an absolute position sensor, a joint torque sensor, a joint controller and the like.
The omni-directional mobile platform 33 is an omni-directional mobile AGV, such as an omni-directional mobile cart based on multiple sets of Mecanum wheels or an omni-directional mobile cart based on multiple sets of steerable wheels. The omnibearing movable platform 33 moves in the experimental site 1, the translation of X, Y and the rotation of the Z axis can be realized, and meanwhile, the second industrial mechanical arm 32 adjusts the pose of the task aircraft 31 at the tail end and controls the motion of the task aircraft 31 together with the omnibearing movable platform 33. Compared with the prior art, the omnibearing mobile platform 33 greatly increases the motion range of the mission aircraft 31, avoids the constraint of a guide rail on a motion mechanism, and meets the requirement of space large-scale three-dimensional motion simulation; in addition, the simulation system can increase the number of simulated objects, for example, two task aircrafts can be arranged to track the target aircraft, thereby increasing the flexibility of the simulation system.
In one embodiment, as shown in FIG. 1, the positioning system 4 is disposed on the omni-directional
mobile platform 33. Of course, the positioning system 4 may be disposed at other positions, and may be disposed according to specific needs. The positioning system 4 is used to monitor in real time the base F of the omni-directional
mobile platform 33 relative to the first
industrial robot 22
TbThen calculates the real-time motion track of the omni-directional
mobile platform 33 according to the relative pose
i∈[x,y,θ]Wherein, in the step (A),
for real-time angles of the i-axis direction of the omni-directional
mobile platform 33 at a certain time,
for real-time angular velocity of the omni-directional
mobile platform 33 in the i-axis direction at a certain moment,
a PID feedback control system is established for the real-time angular acceleration of the omni-directional
mobile platform 33 in the i-axis direction at a certain moment, so that the pose of the omni-directional
mobile platform 33 is continuously adjusted until the pose is adjusted to be described laterExpected motion trajectory
i∈[x,y,θ]Wherein q is
Vi(t) is a desired angle of the i-axis direction of the omni-directional
mobile platform 33 at a certain time,
for a desired angular velocity of the omni-directional
mobile platform 33 in the i-axis direction at a certain time,
the desired angular acceleration of the omni-directional
mobile platform 33 in the i-axis direction at a certain time is obtained, thereby improving the positioning accuracy of the omni-directional
mobile platform 33. It should be noted that the expected movement trace Tra
ViEach data in (T) is based on T in the experimental field
1(t) theoretical data obtained by calculation. The positioning system 4 may be a camera positioning system, a high precision lidar positioning system, or an indoor GPS or high precision motion capture system, etc. The positioning process of the positioning system is specifically explained by taking a high-precision laser radar as an example: under the condition that the first industrial
mechanical arm 22 is fixedly installed on the experiment site 1, the omni-directional
mobile platform 33 provided with the high-precision laser radar is placed in the experiment site 1, the movement of the omni-directional
mobile platform 33 is controlled, the laser radar is used for scanning the surrounding environment to obtain a point cloud picture of the surrounding environment, and meanwhile, a slam algorithm (such as mapping, cartographer and the like) is used for drawing the surrounding environment according to the self-milemeter information of the omni-directional
mobile platform 33 until a global environment map with higher precision is obtained; in the simulation process, the laser radar scans the surrounding environment of the current position to generate a local point cloud map of the current position, matches the local point cloud map with the global environment map, and uses the matched position as the real-time position of the current omni-directional mobile platform 33 (i.e., the omni-directional
mobile platform 33 is relative to the base F of the first
industrial robot 22 as described above)
TbRelative pose). The space positioning problem of the omnibearing moving
platform 33 is solved by adopting a high-precision positioning system, so that the mechanism such as a large-stroke guide rail is not adoptedUnder the condition, the spatial pose of the omnibearing
mobile platform 33 is accurately measured, and the motion simulation range and the simulation precision are met.
The following describes the spatial three-dimensional large-scale kinematics simulation method of the present invention.
The simulation method of the space three-dimensional large-scale kinematics, which is based on the simulation system of the space three-dimensional large-scale kinematics, comprises the following steps: establishing a fixed coordinate system F of the target aircraft 21T,FTIs the center of mass of the target aircraft 21, and establishes an orbit coordinate system F of the target aircraft 21WTaking FWIs the center of mass, F, of the target aircraft 21WPoints to the tangent and normal directions of the space orbit to establish a fixed coordinate system F of the mission aircraft 31SEstablishing a coordinate system F of the experimental site 1eFirst industrial robot 22 base coordinate system FTb(FTbAnd FeCoincident) and second industrial robot 32 base coordinate system FSbWherein only the relative motion relationship between target vehicle 21 and mission vehicle 31 in space is considered, regardless of the translational motion of target vehicle 21 along the trajectory of space. It should be noted that F is the target vehicle 21 that does not account for the translation along the trajectory of spaceWThe origin of (a) is stationary.
In a coordinate system F
T、F
W、F
SThen, based on the initial angular velocity vector value of the given
target aircraft 21 and according to the calculation of space dynamics, the fixed point motion track T of the
target aircraft 21 in the space environment is obtained
2(T), wherein T
2(t) is the trajectory of the
target aircraft 21 around the center of mass. Specifically, the movement locus of the
target aircraft 21 is divided into the translational locus T of the centroid of the
target aircraft 21 according to the calculation result of the space dynamics
t(T) and the locus T of rotation of the
target aircraft 21 about the center of mass
r(T), T, since the translation of
target vehicle 21 along the trajectory of space is not taken into account during the simulation, T
2(t)=T
r(t), the spatial dynamics calculation process is as follows: vector of angular velocity
Wherein Ω ═ C ω
sAnd C is a constant related to the inertial parameter of the target aircraft. Omega
sIs a self-rotation angular velocity and is a constant, omega
nIs the lateral angular velocity, is a constant,
the initial deflection angle is the angular velocity and is constant. The initial value omega is given as required
x0,ω
y0,ω
z0Can calculate ω
s,ω
n,
The three constants are:
ω
s=ω
z0;
the deflection angle can be obtained by integrating the angular velocity vector:
wherein R is
0,Y
0,P
0Is an initial angle set as required. The angle of rotation and the speed of the
target aircraft 21 at any given time can thus be determined from the above equations. And for the obtained Euler angles R, P and Y, directly converting into a homogeneous transformation matrix according to a formula. Fixed point motion trajectory T
2(t) can be described by a dense series of discrete points, where any one discrete point contains the time and location of the point.
In a coordinate system FT、FW、FSThen, aiming at the control strategy of the mission aircraft 31, the mission aircraft 31 is controlled to move relative to the target aircraft 21, and the motion track T of the mission aircraft 31 in the space environment is directly obtained according to the flight route of the mission aircraft (31)1(T), wherein T1(t) is the fixed coordinate system F of mission aircraft 31SRelative orbit coordinate system FWIs described by a known series of closely spaced discrete points,any one discrete point contains the time and location of the point. It is supplementary that the control strategy of mission aircraft 31 is the mission execution strategy to be tested, and the control strategy has various implementation forms, for example, a remote control mode through ground teleoperation; as another example, the spatial trajectory that mission aircraft 31 will produce, i.e., the rigid coordinate system F of mission aircraft 31, is based on the current control strategy based on the corresponding movements of the aircraft's own sensors via the sensing environment and planningSRelative to the orbital coordinate system FWTrack T of1(t)。
The mission aircraft 31 carries out simulation planning on the relative motion of the target aircraft 21 in space in an experimental field: the relative motion between mission aircraft 31 and target aircraft 21 is divided into a first virtual motion and a second virtual motion, the first virtual motion being FTAround FWThe second virtual motion is FSRelative to FWThe second virtual motion is FSRelative to FSb(FSRelative to FSbN by the second industrial robot arm 32SIndividual joint realization), FSbRelative to Fe(FSbRelative to FeRealized by three joints of a virtual arm m described below), FeRelative to FTb(mutual pose is fixed), FTbRelative to FW(FTbRelative to FWN by the first industrial robot 22TRealizing each joint), and virtualizing the continuous motion chain into a super-redundant mechanical arm R, wherein the base coordinate system of the super-redundant mechanical arm R is FWThe tail end of the super-redundant mechanical arm R is a fixed coordinate system F of the mission aircraft 31S. It should be noted that, in order to establish the super-redundant manipulator R, a virtual manipulator m (as shown in fig. 2) is constructed between the omni-directional mobile platform 33 and the experimental site 1, and unlike the first industrial manipulator 22 and the second industrial manipulator 32, the virtual manipulator m has only three degrees of freedom, which are respectively translation in x and y directions and rotation around z direction on the experimental site 1, and here, the three degrees of freedom of the virtual manipulator m can be abstracted into three joints.Therefore, the super-redundant mechanical arm R is formed by connecting the first industrial mechanical arm 22, the virtual mechanical arm m and the second industrial mechanical arm 32 in series, and the target aircraft 21 winds the base F of the super-redundant mechanical arm RWAnd performing fixed-point motion.
According to the given movement trajectory T of mission aircraft 31
1(t) performing motion planning and trajectory planning based on the kinematic model of the virtual super-redundant mechanical arm R, and calculating the motion trajectory of each joint of the super-redundant mechanical arm R, namely the motion trajectory of each joint of the second industrial mechanical arm 32
i∈[1,N
S]Wherein N is
SIs the number of joints, q, of the second industrial robot arm 32
Si(t) is the angle of a certain joint of the second
industrial robot arm 32 at a certain moment,
the angular velocity of a certain joint of the second
industrial robot arm 32 at a certain moment,
angular acceleration of a certain joint of the second
industrial robot arm 32 at a certain moment; movement locus of each degree of freedom of the omni-directional mobile platform 33
i∈[x,y,θ](ii) a And the respective joint movement trajectories of the first industrial robot arm 22
i∈[1,N
TT]Wherein N is
TTIs the number of joints of the first
industrial robot arm 22.
In the case of a constructed super redundant robot arm R according to the first industrial robot arm 22, at FWThe movement track Tra of each joint calculated for the base coordinate systemTTi(t) calculating and deriving the end F of the first industrial robot 22WRelative base FTbIs TraT(t)=[xT(t) yT(t) zT(t) rxT(t) ryT(t) rzT(t)]T。
End F of first
industrial robot 22
WIs Tra
T(T) a trajectory T with the
target aircraft 21 about the center of mass
2(t) fusion to obtain the end F of the first
industrial robot 22
TAt F
TbDown motion trajectory, then based on F
TAt F
TbThe movement locus of the first
industrial robot arm 22, and the joint movement locus of the final joint movement of the first industrial robot arm 22
i∈[1,N
T]Wherein N is
TIs the number of joints of the first industrial robot arm (22). It should be noted that the motion trajectory Tra
T(t) is the end F of the first
industrial robot arm 22
WRelative base F
TbThe motion trajectory of (1) is a result calculated by the second virtual motion, and if the first
industrial robot arm 22 is supposed to perform spatial simulation on the
target aircraft 21, the first virtual motion is considered, and the first virtual motion and the Tra are combined
T(t) are synthesized so that the joint locus Tra of the combined motion of the first
industrial robot arm 22 can be obtained
Ti(t)。
Based on the result of the trajectory planning for each joint, the simulation of the relative motion of the mission aircraft 31 with respect to the target aircraft 21 is performed.
By the space three-dimensional large-scale kinematics simulation method, the limitation of a ground experimental environment is broken through by combining the second mechanical arm 32 and the omnibearing moving platform 33, kinematics simulation in a larger range is realized, and the flexibility of a simulation system is increased; in addition, the super-redundant mechanical arm R is established, the complex collaborative planning problem of a plurality of actuating mechanisms is integrated into the planning problem of the super-redundant mechanical arm R, and the complexity of the problem is reduced; furthermore, by defining an orbital coordinate system FWAnd the abstracted virtual super-redundant mechanical arm R and a fixed-point motion structure convert the problem of respectively carrying out motion planning on a plurality of systems in the prior art into two independent virtual motion mechanisms (the first virtual motion mechanism is described above)And a second virtual motion), reducing the complexity of the problem.
It should be added that the specific steps for establishing the super-redundant mechanical arm R include: f is to beSbRelative to FeAbstract as a virtual robot m (as shown in fig. 2), the three degrees of freedom of the virtual robot m are assumed as three joints, and the first industrial robot 22, the virtual robot m, and the second industrial robot 32 may be connected in series to form a super-redundant robot R.
Kinematics model and spatial motion trajectory T for virtual super-redundant mechanical arm R
1(t), the specific process of determining the motion trajectory of each joint is as follows: according to the Jacobian matrix of the virtual super-redundant mechanical arm R, the space velocity of each joint can be obtained
And super redundant end of arm velocity
The relationship of (1):
wherein J
AIs a Jacobian matrix. Defining the weighting matrix W ═ diag [ omega ]
1,ω
2,…,ω
N]Wherein N is N
S+N
V+N
TN is the number of degrees of freedom of the super-redundant mechanical arm R,
h (q) is an objective function to be optimized, and optimization performance indexes comprise the motion flexibility, obstacle avoidance, joint angle limit and the like of the mechanical arm. Under the action of the weighting matrix, defining a weighted Jacobian matrix
And weighting joint angular velocities
Based on the weighted Jacobian matrix and the weighted joint angular velocity, have
From this, a weighted joint angular velocity can be determined
Wherein the content of the first and second substances,
further get the formula (I)
Will be provided with
Into formula (I) and further to obtain
Track T
1(t) is comprised of a series of discrete points with respect to time, the time interval between adjacent points being Δ t, the ultra-redundant robotic arm tip speed being based on
Is calculated, from which it can be calculated
Further, the joint angle at the current moment can be calculated according to the joint angular velocity at the previous moment
According to the calculated joint angle q (t), aiming at any single joint, the speed and acceleration values are calculated by adopting a cubic polynomial interpolation mode, and therefore, the planning result of the super-redundant mechanical arm, namely, the motion track of each joint of the second industrial mechanical arm 32 can be finally obtained
i∈[1,N
S](ii) a Movement locus of each degree of freedom of the omni-directional mobile platform 33
i∈[x,y,θ](ii) a And the respective joint movement trajectories of the first industrial robot arm 22
i∈[1,N
TT]。
End F of first
industrial robot 22
WIs Tra
T(T) a trajectory T with the
target aircraft 21 about the center of mass
2(t) the specific steps of performing fusion include: establishing a positive kinematic equation P
Tm=X(q
Tm) Equation of inverse kinematics q
Tm=Y(P
Tm) Wherein P is
TmShowing the end of the first
industrial robot 22 at F
TbPosition attitude vector of lower, q
TmAn angle vector representing each joint of the first
industrial robot arm 22 in joint space; end F of super redundant mechanical arm
WRelative base F
TbPlanning the obtained movement track Tra
T(t) is represented by a homogeneous transformation matrix as
Locus T of motion of
target aircraft 21 around centroid
2(t) expansion into homogeneous transformation matrices
According to
The end F of the first
industrial robot 22 may be calculated
TAt F
TbUnderlying homogeneous transformation matrix
Then based on
Inverse kinematics equation q through the first
industrial robot arm 22
Tm=Y(P
Tm) The position of each joint is solved, the velocity and acceleration of each joint are calculated through a difference method, and finally the plan of the combined motion of the first industrial
mechanical arm 22 is obtainedResults
i∈[1,N
T]。
The first and second
industrial robots 22, 32 are provided with joint controllers themselves so that they can accurately follow the planned motion trajectory (i.e., Tra) during the simulation process
Si(t) and Tra
Ti(t)). The omni-directional
mobile platform 33 can precisely adjust the pose thereof through the high-precision positioning system 4, thereby precisely following the planned motion trajectory, specifically, the omni-directional
mobile platform 33 follows the actual measurement data trajectory
i∈[x,y,θ]The PID feedback control system is established to follow the expected motion trajectory of the respective degrees of freedom of the omni-directional
mobile platform 33