Disclosure of Invention
The invention provides a ground variable-centroid zero-gravity simulation device and a ground variable-centroid zero-gravity simulation method, aiming at the problem that the performance of a space device is influenced by the existing microgravity simulation device.
The invention relates to a ground variable-centroid zero-gravity simulation device and a simulation method, wherein the device comprises a base 1, a lower platform 2, a spherical air bearing pedestal 3, a spherical air bearing rotor 24, a middle platform 5, a Z-direction movement module, a linear module fixing platform 25, an XY-direction movement module, an upper platform 17, a centroid sensing element 18, a mechanical arm connecting rod and a controller;
the spherical air bearing pedestal 3 is fixed on the base 1, the spherical air bearing rotor 24 is arranged on the spherical air bearing pedestal 3, the middle platform 5 is positioned above the spherical air bearing rotor 24, and air floatation can be formed between the middle platform 5 and the spherical air bearing rotor 24;
the lower platform 2 is positioned below the middle platform 5, the lower platform 2 is fixedly connected with the middle platform 5 through a support rod 23, the Z-direction movement module is arranged on the lower platform 2, the linear module fixing platform 25 is arranged on the Z-direction movement module, and the Z-direction movement module is used for driving the linear module fixing platform 25 to move in the vertical direction;
the XY direction movement module is arranged on the linear module fixing platform 25, the upper platform 17 is arranged on the XY direction movement module, and the XY direction movement module is used for driving the upper platform 17 to move on a horizontal plane;
the centroid sensing element 18 and the mechanical arm connecting rod are arranged on the upper platform 17 and are an integral piece;
the signal output end of the centroid sensing element 18 is connected with the signal input end of the controller, and the X, Y direction motion control signal output end of the controller is connected with the X, Y direction motion control signal input end of the XY direction motion module;
the Z-direction motion control signal output end of the controller is connected with the Z-direction motion control signal input end of the Z-direction motion module; the air injection control signal output end of the controller is connected with the air injection control signal input end of the spherical air bearing rotor 24.
In the simulation process, the controller controls the XY-direction motion module, the Z-direction motion module and the spherical air bearing rotor 24 to inject air according to the change of the center of mass detected by the center-of-mass sensing element 18, so that the center of mass of the integrated piece moves to the center of the spherical air bearing rotor 24, and the center of mass adjustment is realized.
Preferably, the mechanical arm connecting rod comprises a first section connecting rod 19, a second section connecting rod 20, a third section connecting rod 30 and a fourth section connecting rod 29;
the mechanical arm connecting rod comprises a first section of connecting rod 19, a second section of connecting rod 20, a third section of connecting rod 30 and a fourth section of connecting rod 29;
the first section of connecting rod 19, the second section of connecting rod 20, the third section of connecting rod 30 and the fourth section of connecting rod 29 are sequentially connected in a rotating mode, and the first section of connecting rod 19 is fixed on the upper platform 17.
Preferably, the Z-direction movement module includes 4Z-direction electric cylinders 22;
the 4 electronic jars 22 of Z direction are fixed under on platform 2, and sharp module fixed platform 25 is located under between platform 2 and the sharp module fixed platform 25, and the motion end of the electronic jar 22 of 4Z directions is connected with sharp module fixed platform 25's bottom surface, and the electronic jar 22 concerted movement of 4Z directions realizes the motion of sharp module fixed platform 25 in vertical direction.
Preferably, the XY-direction movement module comprises two sets of X-direction linear modules and two sets of Y-direction linear modules;
the two sets of X-direction linear modules are placed on the linear module fixing platform 25 in parallel;
each set of X-direction linear module is provided with two X-direction linear module sliders, one set of X-direction linear module sliders on the same side of the two sets of X-direction linear modules is provided, each set of X-direction linear module sliders is fixed with one set of Y-direction linear module, and the four X-direction linear module sliders cooperatively drive the two sets of Y-direction linear modules to realize X-direction movement; every set of Y direction sharp module is equipped with two Y direction sharp module sliders, and upper mounting plate 17 is fixed on four Y direction sharp module sliders, and four Y direction sharp module sliders drive upper mounting plate 17 in coordination and realize the motion of Y direction.
Preferably, the simulation device further comprises two primary weights 21, wherein one primary weight 4 is suspended on each side of the lower platform 2, and the primary weights 4 are used for ensuring that the lower platform 2 is kept horizontal when the simulation is not started.
Preferably, two secondary weights 4 are also included; two secondary counterweights 4 are respectively hung on two sides of the linear module fixing platform 25, and the secondary counterweights 4 are used for ensuring that the linear module fixing platform 25 keeps horizontal when simulation is not started.
The invention also provides a simulation method of the ground variable-centroid zero-gravity simulation device, which comprises the following steps:
s1, determining the combined mass center m of the mass center sensitive element 18, the mechanical arm connecting rod and the upper platform 17
cPosition in coordinate system 0
According to
The displacement of the upper platform 17 in the coordinate system {0} is calculated, and the movement of the Z-direction movement module and the XY-direction movement module is controlled according to the displacement, so as to integrate the mass center m
cTo the center of the spherical
air bearing rotor 24;
coordinate system {0} is coordinate system O0X0Y0Z0Plane X0O0Y0Is arranged on the lower surface of the base 1 and has an origin O0Is located at the center of the lower surface of the base 1 and has an axis X0Parallel to the X direction in the XY direction motion module, and the axis Z0The plumb is upward;
s2, ventilating the spherical air bearing pedestal 3, forming a layer of air film between the spherical air bearing pedestal 3 and the spherical air bearing rotor 24, lifting the spherical air bearing rotor 24 together with the upper platform 17, the centroid sensing element 18 and the mechanical arm connecting rod in the air and freely rotating around the spherical center of the spherical air bearing rotor 24, realizing microgravity simulation, and starting the mechanical arm connecting rod to work;
s3, acquiring the angle of the mechanical arm connecting rod at the moment when the current control cycle is ended:
and
according to
And
obtaining a current combined centroid m
cPosition in coordinate system 0
According to
Calculating the displacement of the X-direction linear module, the Y-direction linear module and the Z-direction motion module in the current control period
And
and controlling the movement thereof, i ═ i +1, repeating S3;
and
respectively showing the included angles between the first section of connecting rod 19 and the second section of connecting rod 20, between the second section of connecting rod 20 and the third section of connecting rod 30, and between the third section of connecting rod 30 and the fourth section of connecting rod 29 in the ith control period; i is 1,2, … ….
Preferably, the combined center of mass m of the center of mass sensor 18, the mechanical arm connecting rod and the upper platform 17 is determined in S1
cPosition in coordinate system 0
The method comprises the following steps:
s11, establishing a coordinate system O
0X
0Y
0Z
0Coordinate system O
1X
1Y
1Z
1Coordinate system O
2X
2Y
2Z
2Coordinate system O
3X
3Y
3Z
3And a coordinate system O
4X
4Y
4Z
4Upper platform 17, center of massThe centroid of the sensor 18 and the first segment of the connecting rod 19 is denoted as m
1The centroid of the second segment of the connecting rod 20 is marked as m
2The centroid of the third link 30 is denoted as m
3The centroid of the fourth segment of the connecting rod 29 is recorded as m
4(ii) a Determining centroid m
1Has homogeneous coordinates in the coordinate system {1} of
Centroid m
2Has homogeneous coordinates in the system {2}, of
Centroid m
3Has homogeneous coordinates in the system {3}, of
Centroid m
4Has homogeneous coordinates in the system {4}, of
Coordinate system O0X0Y0Z0Mid-plane X0O0Y0Is arranged on the lower surface of the base 1 and has an origin O0Is located at the center of the lower surface of the base 1 and has an axis X0Parallel to the direction of movement of the X-axis linear module, axis Z0Plumb-bob up, coordinate system O0X0Y0Z0Abbreviated as coordinate system {0 };
coordinate system O1X1Y1Z1Origin O1Is located at the center of the upper platform 17, axis X1Parallel to the direction of movement of the X-axis linear module, axis Z1Plumb-bob up, coordinate system O1X1Y1Z1Abbreviated as coordinate system {1 };
coordinate system O2X2Y2Z2Is the intersection of the axis of rotation of the second link 20 relative to the first link 19 and the axis of rotation of the third link 30 relative to the second link 20, and axis Z2The rotation direction is defined as the axis Z in line with the rotation axis of the second link 20 relative to the first link 192Forward, coordinate system O2X2Y2Z2Abbreviated as coordinate system {2 };
coordinate system O3X3Y3Z3Is the intersection of the axis of the third link segment 30 and the axis of the second link segment 20, and the axis Z3The rotation axis of the third-stage link 30 relative to the second-stage link 20 is collinear, and the positive rotation direction is defined as the axis Z3Forward direction; axis of third link 30 and axis X3Collinear, axis Z3And the axis Y2Co-directional and co-linear, coordinate system O3X3Y3Z3Abbreviated as coordinate system {3 };
coordinate system O4X4Y4Z4Is the intersection of the axis of the fourth link 29 and the axis of the third link 30, and the axis Z4The rotation axis of the fourth link 29 relative to the third link 30 is collinear, and the positive rotation direction is defined as the axis Z4Positive, axis Z4And axis X3Perpendicularly intersecting, axis Z4And axis Z3Parallel to the axis Z of the fourth link 294Collinear; coordinate system O4X4Y4Z4Abbreviated as coordinate system {4 };
s12, calculating the centroid m
1Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein:
α, β, γ are X of the coordinate system {1} relative to the coordinate system {0}1、Y1、Z1Rotation angle of three axes, [ x ]1,y1,z1]T
Is the position coordinate of the origin of the coordinate system {1} in the coordinate system {0 };
s13, calculating the centroid m
2Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein
Is the angle of rotation, [ x ] of the current second link 20
2,y
2,z
2]
TIs the position coordinate of the origin of the coordinate system {2} in the coordinate system {1 };
s14, calculating the centroid m
3Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein, theta3Is the angle of rotation, b, of the present third link 301Represents a point O2And point O3The distance between them;
s15, calculating the centroid m
4Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein, theta4Is the angle of rotation of the present fourth link 29, b2Represents a point O3And point O4Along the axis Z4A distance of l1Represents a point O3And point O4Along the axis X3The distance of (d);
s16, calculating the centroid m
1、m
2、m
3、m
4Combined centroid m
cPosition in coordinate System {0}
According to the centroid synthesis theorem, there are:
displacement of upper stage 17 under the coordinate system {0}
Comprises the following steps:
wherein h is the height of the center of the spherical air bearing rotor 24 relative to the lower surface of the lower stage 2, and the coordinate of the center of the spherical air bearing rotor 24 in the coordinate system {0} is [0,0, h ]]T。
Preferably, in S1, the controlling the movement of the Z-direction movement module and the XY-direction movement module based on the displacement amount includes:
s17, number of pulses N sent to X-direction linear module driving motor 6pul_xComprises the following steps:
ωmotor_xangle omega for representing rotation required by X-direction linear module driving motor 6motor_xThe number of pulses corresponding to one rotation of the X-direction linear module driving motor 6 is N1,[]Expressing taking an integer;
if omega
motor_xIf the number is positive, the motor rotates forwards; if negative, the motor is reversed, and the X-direction linear module driving motor 6 can drive the upper platform 17 on the X-axis
0Direction movement
S18, number of pulses N sent to Y-direction linear module driving motor 16pul_yComprises the following steps:
in the formula (2)]The number of pulses corresponding to one rotation of the Y-direction linear module driving motor 16 is N2Angle omega of rotation required by the Y-direction linear module driving motor 16motor_y;
If omega
motor_yIs a positive numberIf so, the motor rotates forwards; if negative, the motor is reversed and the motor drives the upper table 17 in the Y axis
0Direction movement
S19, moving the module in Z direction according to the instruction to drive the upper platform 17 to move on the axis Z
0Direction movement
Preferably, in S17, the first step,
wherein, the X-direction linear module adopts an X-direction driving motor transmission gear 11, an X-direction linear module transmission gear 10 and an X-direction linear module lead screw to realize the transmission of the X-direction linear module slide block,
the radius of the drive gear 11 of the X-direction drive motor is shown,
is the radius of the X-direction linear module transmission gear 10,
the lead of the lead screw of the X-direction linear module is shown;
the Y-direction linear module adopts a Y-direction linear module lead screw 14 to realize the transmission of a Y-direction linear module slide block,
the lead of the Y-direction linear module lead screw 14 is shown.
The invention has the beneficial effects that the invention provides a set of device capable of simultaneously completing the mass center adjusting task of the space mass center changing device during the ground zero gravity simulation experiment of the space mass center changing device and a corresponding leveling method. The ground zero-gravity simulation device capable of finishing the center-of-mass leveling mainly has the following advantages that:
(1) the ground zero-gravity simulation device provided by the invention can realize ground zero-gravity simulation test of the space metamorphic center device, for example, the device can be used for the ground zero-gravity simulation test of a space robot with a movable mechanism and a center-of-mass sensitive device, and the traditional simulation system can not adapt to the ground simulation experiment of the space metamorphic center device.
(2) Compared with the traditional mass center adjusting device, the mass center adjusting device can adjust the mass center of the outer space device to the spherical center of the air floating ball of the ground zero-gravity simulator without changing the structure and the mass characteristics of the outer space metamorphic center device.
(3) The simulation device can perform ground simulation experiments on any space metamorphic core device, does not need a traditional method for adjusting the mass center, needs to design how to place two sets of orthogonal sliding rails on the sliding block for each set of space metamorphic core device independently, and can use one set of device to complete the experiments on various space metamorphic core devices.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
The ground variable-centroid zero-gravity simulation device comprises a base 1, a lower platform 2, a spherical air bearing pedestal 3, a spherical air bearing rotor 24, a middle platform 5, a Z-direction movement module, a linear module fixing platform 25, an XY-direction movement module, an upper platform 17, a centroid sensing element 18, a mechanical arm connecting rod and a controller;
the spherical air bearing pedestal 3 is fixed on the base 1, the spherical air bearing rotor 24 is arranged on the spherical air bearing pedestal 3, the middle platform 5 is positioned above the spherical air bearing rotor 24, and air floatation can be formed between the middle platform 5 and the spherical air bearing rotor 24;
the lower platform 2 is positioned below the middle platform 5, the lower platform 2 is fixedly connected with the middle platform 5 through a support rod 23, the Z-direction movement module is arranged on the lower platform 2, the linear module fixing platform 25 is arranged on the Z-direction movement module, and the Z-direction movement module is used for driving the linear module fixing platform 25 to move in the vertical direction;
the XY direction movement module is arranged on the linear module fixing platform 25, the upper platform 17 is arranged on the XY direction movement module, and the XY direction movement module is used for driving the upper platform 17 to move on a horizontal plane;
the centroid sensing element 18 and the mechanical arm connecting rod are arranged on the upper platform 17 and are an integral piece;
the signal output end of the centroid sensing element 18 is connected with the signal input end of the controller, and the X, Y direction motion control signal output end of the controller is connected with the X, Y direction motion control signal input end of the XY direction motion module;
the Z-direction motion control signal output end of the controller is connected with the Z-direction motion control signal input end of the Z-direction motion module; the air injection control signal output end of the controller is connected with the air injection control signal input end of the spherical air bearing rotor 24.
In the simulation process, the controller controls the XY-direction motion module, the Z-direction motion module and the spherical air bearing rotor 24 to inject air according to the change of the center of mass detected by the center-of-mass sensing element 18, so that the center of mass of the integrated piece moves to the center of the spherical air bearing rotor 24, and the center of mass adjustment is realized.
The base 1 of the embodiment is placed on a horizontal plane, and the base 1 upwards supports a spherical air bearing pedestal 3; the spherical air bearing pedestal 3 supports a spherical air bearing rotor 24, and the spherical air bearing rotor 24 can form a layer of air film between the middle platform 5 and the spherical air bearing rotor 24 through air injection, so that the middle platform 5 is air-floated; the middle platform 5 is connected to the lower platform 2 through 4 support rods 23; meanwhile, the lower platform 2 upwards supports the Z-direction movement module; the Z-direction movement module is arranged perpendicular to the lower platform 2, the linear module fixing platform 25 is supported upwards, and the movement of the linear module fixing platform 25 in the vertical direction can be realized by controlling the movement of the Z-direction movement module;
the linear module fixing platform 25 supports the XY-direction movement modules, and the two sets of X-direction linear modules are placed on two sides of the linear module fixing platform 25 in parallel; the X-direction linear module consists of an X-direction linear module driving motor 6, an X-direction driving motor fixing plate 7, an X-direction transmission belt 8, an X-direction linear module track 9, an X-direction linear module transmission gear 10, an X-direction driving motor transmission gear 11, an X-direction linear module sliding block and an X-direction linear module lead screw, wherein one X-direction linear module driving motor 6 is connected with two X-direction driving motor transmission gears 11, the two X-direction driving motor transmission gears 11 are fixed by using the two X-direction driving motor fixing plates 7, the two X-direction driving motor transmission gears 11 are connected with the two X-direction linear module transmission gears 10 through the two X-direction transmission belts 8 in opposite directions, the two X-direction linear module transmission gears 10 are fixed to two sets of X-direction linear module tracks 9, the two X-direction linear module sliding blocks are connected to one X-direction linear module lead screw and are integrally placed on one set of X-direction linear module track 9 The module rails 9 form an X-direction linear module, and the other set of modules have the same principle. The X-direction linear module driving motor 6 is controlled to move to drive the transmission gears 11 of the 2X-direction driving motors to move, the X-direction transmission belts 8 are respectively transmitted to X-direction linear module lead screws on the two sets of linear modules, and the X-direction linear module slide blocks are driven to move through the movement of the X-direction linear module lead screws, so that the movement in the X direction is realized; on the two sets of X-direction linear modules, two X-direction linear module sliding blocks positioned on the left side of the two sets of X-direction linear module rails 9 support a Y-direction fixed rail 12, and two X-direction linear module sliding blocks positioned on the right side of the two sets of X-direction linear module rails 9 support a Y-direction fixed rail 12;
the XY direction movement module upwards supports an upper platform 17 and drives the upper platform 17 to realize X, Y direction movement; a mass center sensing element 18 is arranged on the upper platform 17, whether the mass center changes or not can be judged through measurement information, and a mechanical arm connecting rod is arranged at the same time; the mechanical arm connecting rod can move at any angle in space; the upper platform 17 and the mechanical arm connecting rod form a space mass center variable device. According to the change of the mass center, the direction adjustment X, Y, Z movement module drives the upper platform 17, the mechanical arm connecting rod and the mass center sensing element 18 to move, and the mass center is adjusted to the center of the spherical air bearing rotor 24.
The Z-direction movement module in this embodiment includes 4Z-direction electric cylinders 22;
the 4 electronic jars 22 of Z direction are fixed under on platform 2, and sharp module fixed platform 25 is located under between platform 2 and the sharp module fixed platform 25, and the motion end of the electronic jar 22 of 4Z directions is connected with sharp module fixed platform 25's bottom surface, and the electronic jar 22 concerted movement of 4Z directions realizes the motion of sharp module fixed platform 25 in vertical direction.
In the embodiment, the XY direction movement module comprises two sets of X direction linear modules and two sets of Y direction linear modules;
the two sets of X-direction linear modules are placed on the linear module fixing platform 25 in parallel;
each set of X-direction linear module is provided with two X-direction linear module sliders, one set of X-direction linear module sliders on the same side of the two sets of X-direction linear modules is provided, each set of X-direction linear module sliders is fixed with one set of Y-direction linear module, and the four X-direction linear module sliders cooperatively drive the two sets of Y-direction linear modules to realize X-direction movement; every set of Y direction sharp module is equipped with two Y direction sharp module sliders, and upper mounting plate 17 is fixed on four Y direction sharp module sliders, and four Y direction sharp module sliders drive upper mounting plate 17 in coordination and realize the motion of Y direction.
Specifically, as shown in fig. 1, the linear module fixing platform 25 supports two sets of linear modules capable of moving in the X direction, and the two sets of linear modules in the X direction are placed on two sides of the linear module fixing platform 25 in parallel; the X-direction linear module consists of an X-direction linear module driving motor 6, an X-direction driving motor fixing plate 7, an X-direction transmission belt 8, an X-direction linear module track 9, an X-direction linear module transmission gear 10, an X-direction driving motor transmission gear 11, an X-direction linear module sliding block and an X-direction linear module lead screw, wherein one X-direction linear module driving motor 6 is connected with two X-direction driving motor transmission gears 11, the two X-direction driving motor transmission gears 11 are fixed by using the two X-direction driving motor fixing plates 7, the two X-direction driving motor transmission gears 11 are connected with the two X-direction linear module transmission gears 10 through the two X-direction transmission belts 8 in opposite directions, the two X-direction linear module transmission gears 10 are fixed to two sets of X-direction linear module tracks 9, the two X-direction linear module sliding blocks are connected to one X-direction linear module lead screw and are integrally placed on one set of X-direction linear module track 9 The module rails 9 form an X-direction linear module, and the other set of modules have the same principle. The X-direction linear module driving motor 6 is controlled to move to drive the transmission gears 11 of the 2X-direction driving motors to move, the X-direction transmission belts 8 are respectively transmitted to X-direction linear module lead screws on the two sets of linear modules, and the X-direction linear module slide blocks are driven to move through the movement of the X-direction linear module lead screws, so that the movement in the X direction is realized; on the two sets of X-direction linear modules, two X-direction linear module sliding blocks positioned on the left side of the two sets of X-direction linear module rails 9 support a Y-direction fixed rail 12, and two X-direction linear module sliding blocks positioned on the right side of the two sets of X-direction linear module rails 9 support a Y-direction fixed rail 12; the left Y-direction fixed rail 12 supports a Y-direction linear module; the Y-direction linear module consists of a Y-direction linear module track 13, a Y-direction linear module lead screw 14, Y-direction linear module sliding blocks 15 and a Y-direction linear module driving motor 16, wherein the two Y-direction linear module sliding blocks 15 are also connected to one Y-direction linear module lead screw 14 in series and placed on the Y-direction linear module track 13, the Y-direction linear module driving motor 16 is connected to one end of the Y-direction linear module lead screw 14, the Y-direction linear module lead screw 14 is driven to move by controlling the Y-direction linear module driving motor 16, the two Y-direction linear module sliding blocks 15 are further driven to move, and therefore the Y-direction movement is achieved; the right Y-direction fixed track 12 supports a Y-direction linear guide set; the Y-direction linear guide set consists of Y-direction linear module slide blocks 15 and Y-direction linear module guide rods, wherein the two Y-direction linear module slide blocks 15 are connected to the Y-direction linear module guide rods in series, and the two Y-direction linear module slide blocks 15 can be driven by external force to slide on the Y-direction linear module guide rods; the 4Y-direction linear module sliding blocks 15 positioned on the left side and the right side in the Y direction jointly support an upper platform 17 upwards, and when the 2 left Y-direction linear module sliding blocks 15 move, the 2 right Y-direction linear module sliding blocks 15 are driven to move together, so that the movement in the Y direction is realized;
the simulation platform further comprises two primary balance weights 21, one primary balance weight 4 is hung on each of two sides of the lower platform 2, and the primary balance weights 4 are used for ensuring that the lower platform 2 keeps horizontal when the simulation is not started.
The embodiment also comprises two secondary counterweights 4; two secondary counterweights 4 are respectively hung on two sides of the linear module fixing platform 25, and the secondary counterweights 4 are used for ensuring that the linear module fixing platform 25 keeps horizontal when simulation is not started.
In a preferred embodiment, the mechanical arm link of the present embodiment includes a first-segment link 19, a second-segment link 20, a third-segment link 30, and a fourth-segment link 29;
the mechanical arm connecting rod comprises a first section of connecting rod 19, a second section of connecting rod 20, a third section of connecting rod 30 and a fourth section of connecting rod 29;
the first section of connecting rod 19, the second section of connecting rod 20, the third section of connecting rod 30 and the fourth section of connecting rod 29 are sequentially connected in a rotating mode, and the first section of connecting rod 19 is fixed on the upper platform 17.
Coordinate system description and related dimension definition formed by four sections of connecting rods:
coordinate system O0X0Y0Z0Mid-plane X0O0Y0Is arranged on the lower surface of the base 1 and has an origin O0Is located at the center of the lower surface of the base 1 and has an axis X0Parallel to the direction of movement of the X-axis linear module, axis Z0Plumb-bob up, coordinate system O0X0Y0Z0Abbreviated as coordinate system {0 };
coordinate system O1X1Y1Z1Origin O1Is located at the center of the upper platform 17, axis X1Parallel to the direction of movement of the X-axis linear module, axis Z1Plumb-bob up, coordinate system O1X1Y1Z1Abbreviated as coordinate system {1 };
coordinate system O2X2Y2Z2Is the intersection of the axis of rotation of the second link 20 relative to the first link 19 and the axis of rotation of the third link 30 relative to the second link 20, and axis Z2The rotation direction is defined as the axis Z in line with the rotation axis of the second link 20 relative to the first link 192Forward, coordinate system O2X2Y2Z2Abbreviated as coordinate system {2 };
coordinate system O3X3Y3Z3Is the intersection of the axis of the third section of the connecting rod 30 and the axis of the second section of the connecting rod 2, and the axis Z3Is common with the rotation axis of the third section of connecting rod 30 relative to the second section of connecting rod 20Line, the positive direction of rotation being defined as axis Z3Forward direction; axis of third link 30 and axis X3Collinear, axis Z3And the axis Y2Co-directional and co-linear, coordinate system O3X3Y3Z3Abbreviated as coordinate system {3 };
coordinate system O4X4Y4Z4Is the intersection of the axis of the fourth link 29 and the axis of the third link 30, and the axis Z4The rotation axis of the fourth link 29 relative to the third link 30 is collinear, and the positive rotation direction is defined as the axis Z4Positive, axis Z4And axis X3Perpendicularly intersecting, axis Z4And axis Z3Parallel to the axis Z of the fourth link 294Collinear; coordinate system O4X4Y4Z4Abbreviated as coordinate system {4 };
the center of mass of the upper platform 17, the center of mass sensing element 18 and the first section of connecting rod 19 is recorded as m1The centroid of the second segment of the connecting rod 20 is marked as m2The centroid of the third link 30 is denoted as m3The centroid of the fourth segment of the connecting rod 29 is recorded as m4;
The simulation method of the ground variable-centroid zero-gravity simulation device of the embodiment comprises the following steps:
step one, determining the combined mass center m of the mass center sensitive element 18, the mechanical arm connecting rod and the upper platform 17
cPosition in coordinate system 0
According to
The displacement of the upper platform 17 in the coordinate system {0} is calculated, and the movement of the Z-direction movement module and the XY-direction movement module is controlled according to the displacement, so as to integrate the mass center m
cTo the center of the spherical
air bearing rotor 24;
coordinate system {0} is coordinate system O0X0Y0Z0Plane X0O0Y0Is arranged on the lower surface of the base 1 and has an origin O0Is located at the center of the lower surface of the base 1 and has an axis X0Parallel to the X direction in the XY direction motion module, and the axis Z0The plumb is upward;
ventilating the spherical air bearing pedestal 3, forming a layer of air film between the spherical air bearing pedestal 3 and the spherical air bearing rotor 24, lifting the spherical air bearing rotor 24 together with the upper platform 17, the centroid sensing element 18 and the mechanical arm connecting rod in the air and freely rotating around the spherical center of the spherical air bearing rotor 24, realizing microgravity simulation, and starting the mechanical arm connecting rod to work;
step three, acquiring the angle of the mechanical arm connecting rod at the moment when the current control cycle is finished:
and
according to
And
obtaining a current combined centroid m
cPosition in coordinate system 0
According to
Calculating the displacement of the X-direction linear module, the Y-direction linear module and the Z-direction motion module in the current control period
And
and controlling the movement thereof, i ═ i +1, repeating S3;
and
respectively showing the included angles between the first section of connecting rod 19 and the second section of connecting rod 20, between the second section of connecting rod 20 and the third section of connecting rod 30, and between the third section of connecting rod 30 and the fourth section of connecting rod 29 in the ith control period; i is 1,2, … ….
In the first step of the embodiment, the combined center of mass m of the center of mass sensing element 18, the mechanical arm connecting rod and the upper platform 17 is determined
cPosition in coordinate system 0
The method comprises the following steps:
step one, initializing the position of an upper platform 17, and configuring the center of mass of the upper platform 17 and parts above the upper platform 17 at the center of a spherical
air bearing rotor 24; the known centroid m
1Has coordinates in the system {1} of
Centroid m
2Has coordinates in the system {2} of
Centroid m
3Has coordinates in the system {3} of
Centroid m
4Has coordinates in the system {4} of
In order to facilitate the following coordinate transformation, the above four coordinates are rewritten into the following homogeneous coordinate form:
step one and two, calculating the mass center m
1Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein:
α, β, γ are X of the coordinate system {1} relative to the coordinate system {0}1、Y1、Z1Rotation angle of three axes, [ x ]1,y1,z1]TIs the position coordinate of the origin of the coordinate system {1} in the coordinate system {0 };
step one and three, calculating the mass center m
2Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein
Is the angle of rotation, [ x ] of the current second link 20
2,y
2,z
2]
TIs the position coordinate of the origin of the coordinate system {2} in the coordinate system {1 };
step four, calculating the mass center m
3Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein, theta3Is the angle of rotation, b, of the present third link 301Represents a point O2And point O3The distance between them;
step one or five, calculating the mass center m
4Coordinates of the position of (2) in the coordinate system {0}
Comprises the following steps:
in the formula:
wherein, theta4Is the angle of rotation, b, of the current arm link 4(29)2Represents a point O3And point O4Along the axis Z4A distance of l1Represents a point O3And point O4Along the axis X3The distance of (d);
step one six, calculating the mass center m
1、m
2、m
3、m
4Combined centroid m
cPosition in coordinate System {0}
According to the centroid synthesis theorem, there are:
displacement of upper stage 17 under the coordinate system {0}
Comprises the following steps:
wherein h is the height of the center of the spherical air bearing rotor 24 relative to the lower surface of the lower stage 2, and the coordinate of the center of the spherical air bearing rotor 24 in the coordinate system {0} is [0,0, h ]]T。
And calculating the displacement according to the steps from one to six. The linear module in the X direction, the linear module in the Y direction and the electric cylinder in the Z direction are controlled to move, so that the upper platform 17 and the parts above the upper platform are integrally displaced, and the upper platform is driven to moveSynthetic center of mass mcMoves to the center of the spherical air bearing rotor 24 to achieve center of mass adjustment. In this embodiment, controlling the movement of the Z-direction movement module and the XY-direction movement module according to the displacement includes:
step one seven, recording the radius of a transmission gear 11 of a driving motor in the X direction as
The radius of the X-direction linear module transmission gear 10 is
The lead of the X-direction linear module lead screw is
The angle omega of the rotation required by the X-direction linear module driving motor 6
motor_xComprises the following steps:
assuming that the driving motor 6 of the X-direction linear module is a servo motor, and the servo motor works in a position mode, the number of pulses corresponding to one rotation of the motor is N1I.e. the motor rotates 1/N each time a pulse is sent to the motor1And (6) looping. Therefore, the number of pulses N sent to the X-direction linear module driving motor 6pul_xComprises the following steps:
wherein [ ] represents an integer.
If omega
motor_xIf the number is positive, the motor rotates forwards; if the number is negative, the motor rotates reversely. Sending N to the motor
pul_xA number of pulses, the motor then drives the upper platform 17 on the axis X
0Direction movement
Step (ii) ofOne eight, recording the lead of the linear module lead screw in the Y direction as ry1The angle ω of rotation required for the Y-direction linear module driving motor 16motor_yComprises the following steps:
assuming that the driving motor 16 of the Y-direction linear module is a servo motor, and the servo motor works in a position mode, the number of pulses corresponding to one rotation of the motor is N2I.e. the motor rotates 1/N each time a pulse is sent to the motor2And (6) looping. Therefore, the number of pulses N sent to the Y-direction linear module driving motor 16pul_yComprises the following steps:
wherein [ ] represents an integer.
If omega
motor_yIf the number is positive, the motor rotates forwards; if the number is negative, the motor rotates reversely. Sending N to the motor
pul_yA number of pulses, the motor then drives the upper table 17 in the axis Y
0Direction movement
Step one, as the upper platform 17 is driven to move by the electric cylinders in the Z direction, most of the electric cylinders support inputting instructions through RS232 or RS485 or CAN interfaces, and then the instructions are input
The push rod of the electric cylinder moves according to the command, thereby driving the upper platform 17 to move on the axis Z
0Direction movement
Through steps one-to-nine, the combined center of mass of the upper platform 17 and the parts above it is moved to the center of the spherical air bearing rotor 24.
In the third step of the present embodiment, a simulation experiment is performed, and the equipment for a metamorphic core represented by a robot arm link starts to operate. Assuming the moment when the current control cycle is finished, the three angles of the mechanical arm connecting rod are respectively changed into three angles
And
and calculating the displacements of the X-direction linear module, the Y-direction linear module and the Z-direction electric cylinder in the current control period and controlling the displacements.
(1) Calculating the centroid m at the end of the current control period
1Coordinates of the position of (a) in the system {0}
Comprises the following steps:
(2) calculating the centroid m at the end of the current control period
2Coordinates of the position of (a) in the system {0}
Comprises the following steps:
(3) calculating the centroid m at the end of the current control period
3Coordinates of the position of (a) in the system {0}
Comprises the following steps:
(4) calculating the centroid m at the end of the current control period
4Position ofCoordinates placed in the system {0}
Comprises the following steps:
(5) when the current control period is over, the centroid m is calculated
1、m
2、m
3、m
4Combined centroid m
cPosition in coordinate System {0}
Note the book
According to the centroid synthesis theorem, there are:
(6) the displacement of the upper stage 17 in the coordinate system {0} is obtained
Comprises the following steps:
(7) in the current control period, the motion of the X-direction linear module, the Y-direction linear module and the Z-direction electric cylinder is controlled to ensure that the combined mass center mcMoves to the center of the spherical air bearing rotor 24 to achieve center of mass adjustment. The specific process is as follows:
calculating the number of pulses N input by the X-direction linear modulepul_xThe method comprises the following steps:
send N to the linear module
pul_xA pulse signal to make it move
② calculating the pulse number N of the control input of the Y-direction linear modulepul_yComprises the following steps:
send N to the linear module
pul_yA pulse signal to make it move
Thirdly, directly inputting the position instruction to the Z-direction electric cylinder through the communication interface
Make it move
Before the end of the current control period, the centroid mcIs relocated to the center of the spherical air bearing rotor 24.
The ith step: according to the moment when the ith control cycle is finished, the three angles of the mechanical arm
And
and repeating the calculation process of the step 3. Calculating the displacement of the X-direction linear module, the Y-direction linear module and the Z-direction electric cylinder in the ith control period
And
and controlTo control its movement.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that features described in different dependent claims and herein may be combined in ways different from those described in the original claims. It is also to be understood that features described in connection with individual embodiments may be used in other described embodiments.