CN114571453A - Control method and control device for cooperative robot - Google Patents
Control method and control device for cooperative robot Download PDFInfo
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- CN114571453A CN114571453A CN202210201743.XA CN202210201743A CN114571453A CN 114571453 A CN114571453 A CN 114571453A CN 202210201743 A CN202210201743 A CN 202210201743A CN 114571453 A CN114571453 A CN 114571453A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1628—Programme controls characterised by the control loop
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1694—Programme controls characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
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Abstract
The invention provides a control method and a control device of a cooperative robot, wherein the method comprises the following steps: establishing a compensation model of the relationship between the axial deformation of the arm tube of the cooperative robot in the DH model and the joint temperature and environment temperature; after a starting instruction of the cooperative robot is received, acquiring the current environment temperature and the current joint temperature of the cooperative robot in a preset period, and acquiring the axial deformation of an arm pipe of the cooperative robot according to the compensation model, the current environment temperature and the current joint temperature; acquiring a joint compensation angle corresponding to the arm pipe according to the axial deformation amount of the arm pipe; and carrying out angle compensation on the corresponding joint according to the joint compensation angle. The invention can carry out angle compensation on the joint according to joint temperature self-adaption in the working process of the cooperative robot, thereby avoiding the problem of poor repeated positioning precision of the cooperative robot caused by factors such as environmental temperature change and the like, and improving the working efficiency of the cooperative robot without heat engine.
Description
Technical Field
The invention relates to the technical field of automation, in particular to a control method and a control device of a cooperative robot.
Background
The repeated positioning precision (referring to the consistency of multiple positioning results at the same position) of the cooperative robot is greatly influenced by temperature changes, and the temperature changes comprise two aspects: firstly, the environmental temperature changes, and secondly, the joint temperature is increased due to the heating of a motor, the frictional heating between structural members and the like of the robot in the moving process. The change of the temperature can cause the deformation of a mechanical arm (an arm tube) of the cooperative robot, so that the problem of poor repeated positioning precision of the cooperative robot is caused, and the working reliability of the cooperative robot is reduced.
In the related art, in order to avoid the influence of the environmental temperature change on the repeated positioning precision of the cooperative robot, the cooperative robot is generally heated for two or three hours before being used, and then starts to normally work after the joint temperature is stable, and the environmental temperature is required to be ensured not to change as much as possible in the using process. The mode not only wastes time and causes the working efficiency of the cooperative robot to be greatly reduced, but also causes the reliability to be low due to the burstiness and uncontrollable property of the external environment.
Disclosure of Invention
In order to solve the above technical problem, a first aspect of the present invention provides a method for controlling a cooperative robot.
The embodiment of the second aspect of the invention provides a control device of a cooperative robot.
The technical scheme adopted by the invention is as follows:
an embodiment of a first aspect of the present invention provides a method for controlling a cooperative robot, including the following steps: establishing a compensation model of the relation between the axial deformation quantity of the arm tube and the joint temperature and the environment temperature of the cooperative robot in a DH model (a standard method for modeling a connecting rod and a joint of the robot); after a starting instruction of the cooperative robot is received, acquiring the current environment temperature and the current joint temperature of the cooperative robot in a preset period, and acquiring the axial deformation of an arm pipe of the cooperative robot according to the compensation model, the current environment temperature and the current joint temperature; acquiring a joint compensation angle corresponding to the arm tube according to the axial deformation of the arm tube; and carrying out angle compensation on the corresponding joint according to the joint compensation angle.
The control method of the cooperative robot of the present invention further has the following additional technical features:
according to an embodiment of the invention, establishing a compensation model of the relationship between the axial deformation quantity of the arm tube of the cooperative robot in the DH model and the joint temperature and the environment temperature specifically includes: obtaining a compensation coefficient of the relation between the axial deformation and joint temperature and environment temperature; and establishing the compensation model according to the compensation coefficient.
According to one embodiment of the invention, a compensation model of the relationship between the arm tube axial deformation and the joint temperature and the environment temperature of the cooperative robot in the DH model is established according to the following formula:
Δa＝k1*((t2+t3+2*t∞)–(t2(0)+t3(0)+2*tcal))+k2*(t∞-tcal)；
wherein, delta a is the axial deformation of the arm tube, k1 is a first coefficient, k2 is a second coefficient, t2 is the joint temperature of one end of the arm tube, t3 is the joint temperature of the other end of the arm tube, tcalTo calibrate the ambient temperature, t∞And t2(0) is the calibrated joint temperature of one end of the arm tube, and t3(0) is the calibrated joint temperature of the other end of the arm tube.
According to one embodiment of the invention, the first coefficient k1 is obtained by the following steps: controlling the cooperative robot to touch the tool at a first posture at a preset frequency; controlling the environment temperature to be unchanged, wherein the environment temperature is the same as the calibrated environment temperature, and acquiring the actual axial deformation of the arm pipe of the cooperative robot, the actual joint temperature of one end of the arm pipe and the actual joint temperature of the other end of the arm pipe; and acquiring the first coefficient k1 according to the compensation model, the actual axial deformation of the arm tube of the cooperative robot, the actual joint temperature of one end of the arm tube and the actual joint temperature of the other end of the arm tube.
According to one embodiment of the invention, the second coefficient k2 is obtained by the following steps: controlling the cooperative robot to be powered on and keeping a first posture unchanged; controlling the ambient temperature to rise at a first preset rate; acquiring actual axial deformation of the arm tube of the cooperative robot at different environmental temperatures; and acquiring the second coefficient k2 according to the compensation model and the actual axial deformation of the arm tube of the cooperative robot at different environmental temperatures.
According to one embodiment of the invention, the joint compensation angle is obtained using a polygonal model.
According to an embodiment of the present invention, the cooperative robot is a six-axis robot, the joints in the DH model sequentially include first to sixth joints from bottom to top, the arm tube includes a first arm tube and a second arm tube, one end of the first arm tube is a second joint, the other end of the first arm tube is a third joint, one end of the second arm tube is a third joint, and the other end of the second arm tube is a fourth joint, and specifically, the joint compensation angle corresponding to the arm tube is obtained by using the following formula:
Δtheta2＝theta2′-theta2
Δtheta3＝theta3′-theta3
Δtheta4＝theta4′-theta4
wherein a2 is the length of the first arm pipe, a3 is the length of the second arm pipe, theta3 is the included angle between the first arm pipe and the second arm pipe, Δ a2 is the axial deformation amount of the first arm pipe, Δ a3 is the axial deformation amount of the second arm pipe, Δ theta2 is the compensation angle of the second joint, Δ theta3 is the compensation angle of the third joint, and Δ theta4 is the compensation angle of the fourth joint.
According to one embodiment of the invention, the ratio of the arm tube length of the cooperative robot to the corresponding joint length satisfies a first preset condition.
According to an embodiment of the present invention, the first preset condition is: the ratio of the length of the arm tube to the length of the joint of the cooperative robot is greater than or equal to 5.
A second aspect of the present invention provides a control apparatus for a cooperative robot, including: the establishing module is used for establishing a compensation model of the relationship between the axial deformation quantity of the arm tube of the cooperative robot in the DH model and the joint temperature and environment temperature; the detection module is used for acquiring the current environment temperature and the current joint temperature of the cooperative robot in a preset period after receiving a starting instruction of the cooperative robot, and acquiring the axial deformation amount of the arm pipe of the cooperative robot according to the compensation model, the current environment temperature and the current joint temperature; the calculation module is used for acquiring a joint compensation angle corresponding to the arm tube according to the axial deformation of the arm tube; and the control module is used for carrying out angle compensation on the corresponding joint according to the joint compensation angle.
The control device for a cooperative robot according to the present invention further has the following additional features:
according to one embodiment of the invention, the detection module comprises: a first temperature sensor disposed in a module housing of a joint of a cooperative robot, the first temperature sensor for detecting a joint temperature of the cooperative robot; a second temperature sensor disposed in a control cabinet of the cooperative robot, the second temperature sensor being for detecting an ambient temperature.
According to an embodiment of the present invention, the establishing module is specifically configured to: obtaining a compensation coefficient of the relation between the axial deformation quantity and joint temperature and environment temperature; establishing the compensation model according to the compensation coefficient
According to an embodiment of the invention, the establishing module is used for establishing a compensation model of the relationship between the arm tube axial deformation variable and the joint temperature and the environment temperature of the cooperative robot in the DH model according to the following formula:
Δa＝k1*((t2+t3+2*t∞)-(t2(0)+t3(0)+2*tcal))+k2*(t∞-tcal)；
wherein, delta a is the axial deformation of the arm tube, k1 is a first coefficient, k2 is a second coefficient, t2 is the joint temperature of one end of the arm tube, t3 is the joint temperature of the other end of the arm tube, tcalTo calibrate the ambient temperature, t∞And t2(0) is the calibrated joint temperature of one end of the arm tube, and t3(0) is the calibrated joint temperature of the other end of the arm tube.
According to an embodiment of the present invention, the establishing module specifically adopts the following steps to obtain the first coefficient k 1: controlling the cooperative robot to touch the tool at a first posture at a preset frequency; controlling the environment temperature to be unchanged, wherein the environment temperature is the same as the calibrated environment temperature, and acquiring the actual axial deformation of the arm pipe of the cooperative robot, the actual joint temperature of one end of the arm pipe and the actual joint temperature of the other end of the arm pipe; and acquiring the first coefficient k1 according to the compensation model, the actual axial deformation of the arm tube of the cooperative robot, the actual joint temperature of one end of the arm tube and the actual joint temperature of the other end of the arm tube.
According to an embodiment of the present invention, the establishing module specifically obtains the second coefficient k2 by: controlling the cooperative robot to be powered on and keeping a first posture unchanged; controlling the ambient temperature to rise at a first preset rate; acquiring actual axial deformation of the arm tube of the cooperative robot at different environmental temperatures; and acquiring the second coefficient k2 according to the compensation model and the actual axial deformation of the arm tube of the cooperative robot at different environmental temperatures.
According to one embodiment of the invention, the calculation module obtains the joint compensation angle using a polygon model.
According to an embodiment of the present invention, the cooperative robot is a six-axis robot, the joints in the DH model sequentially include first to sixth joints from bottom to top, the arm tube includes a first arm tube and a second arm tube, one end of the first arm tube is a second joint, the other end of the first arm tube is a third joint, one end of the second arm tube is a third joint, and the other end of the second arm tube is a fourth joint, and the calculation module specifically obtains a joint compensation angle corresponding to the arm tube by using the following formula:
Δtheta2＝theta2′-theta2
Δtheta3＝theta3′-theta3
Δtheta4＝theta4′-theta4
wherein a2 is the length of the first arm pipe, a3 is the length of the second arm pipe, theta3 is the included angle between the first arm pipe and the second arm pipe, Δ a2 is the axial deformation amount of the first arm pipe, Δ a3 is the axial deformation amount of the second arm pipe, Δ theta2 is the compensation angle of the second joint, Δ theta3 is the compensation angle of the third joint, and Δ theta4 is the compensation angle of the fourth joint.
According to one embodiment of the invention, the ratio of the arm tube length of the cooperative robot to the corresponding joint length satisfies a first preset condition.
According to an embodiment of the present invention, the first preset condition is: the ratio of the length of the arm tube to the length of the joint of the cooperative robot is greater than or equal to 5.
The invention has the beneficial effects that:
according to the invention, the axial deformation of the arm tube can be automatically obtained according to the joint temperature in the working process of the cooperative robot, and the angle compensation is carried out on the joint in a self-adaptive manner according to the axial deformation of the arm tube, so that the problem of poor repeated positioning precision of the cooperative robot caused by factors such as environmental temperature change can be avoided, the repeated positioning precision of the cooperative robot is improved, the working reliability of the cooperative robot is further improved, a heat engine is not required, and the working efficiency of the cooperative robot is improved.
Drawings
Fig. 1 is a flowchart of a control method of a cooperative robot according to one embodiment of the present invention;
FIG. 2 is a DH model diagram of a six-axis robot according to one embodiment of the present invention;
FIG. 3 is a simplified model of an arm tube of a cooperative robot in accordance with one embodiment of the present invention;
FIG. 4 is a simplification of the first arm tube L1 and the second arm tube L2 of a six-axis robot according to one embodiment of the present invention;
FIG. 5 is a schematic diagram of the acquisition principle of the compensation angle of a six-axis robot according to one embodiment of the present invention;
fig. 6 is a block schematic diagram of a control device of a cooperative robot according to one embodiment of the present invention.
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.
Fig. 1 is a flowchart of a control method of a cooperative robot according to one embodiment of the present invention. As shown in fig. 1, the method comprises the steps of:
and S1, establishing a compensation model of the relationship between the axial deformation quantity of the arm tube of the cooperative robot in the DH model and the joint temperature and environment temperature.
Specifically, the arm tube is a mechanical arm part of the cooperative robot in the axial direction, and two ends of the arm tube are tightly connected with joints. Taking a six-axis robot as an example, as shown in FIG. 2, the first joint to the sixth joint 1-6 are arranged from bottom to top, (x)i，yi，zi) The robot represents point coordinates of corresponding joints, i is 1-6 and i is a positive integer, the length change of the robot under the influence of temperature is larger than that of a first arm pipe L1 between a second joint and a third joint and a second arm pipe L2 between a third joint and a fourth joint, the first arm pipe L1 and the second arm pipe L2 can be simplified into round pipes, the length change (axial deformation) of the first arm pipe L1 is influenced by the temperature change and the environmental temperature change of the second joint 2 and the third joint 3, and the length (axial deformation) of the second arm pipe L2 is influenced by the joint temperature change and the environmental temperature change of the third joint 3 and the fourth joint 4. The joint temperature of the invention is the temperature of two joints which are closely connected with the knuckle pipe, the environment temperature is the temperature of the environment where the cooperative robot is located, the joint temperature can be measured by arranging a temperature sensor in the module shell of the joint, and the environment temperature can be measured by arranging a temperature sensor in the control cabinet of the cooperative robot.
Arm tube of cooperative robotSimplified as a circular tube, FIG. 3 is a simplified model of the arm tube of a cooperative robot, t1、t2The joint temperatures, t, at the two ends of the arm tube∞And L is the vertical distance from a certain position in the arm pipe to the left end face.
The joint temperature and the environment temperature do not change violently, and only steady state changes are considered for simplicity. According to the theory of heat transfer, the temperature distribution of the arm tube can be described by a second order differential equation:
wherein lambda is the coefficient of thermal conductivity,
is the change in heat per unit volume of the arm tube, phidFor the surface heat dissipation of the dl infinitesimal segment, then:
φd＝(2πrouter dl)h(t-t∞)
in the formula, routerThe radius of the outer surface of the arm tube is h, and the heat dissipation coefficient of the surface of the arm tube is h.
The cross-sectional area at l is AeComprises the following steps:
wherein r isinnerIs the radius of the inner surface of the arm tube. While
Thereby, it is possible to obtain:
the boundary condition of the formula is
Wherein t is c1eml+c2e-ml+t∞，
t is the arm tube temperature, c1、c2Is a constant term.
It can be found that:
the arm tube length ε is integrated: d epsilon ═ K (t (l) -tcal)dl；
The following can be obtained:
wherein K is a thermal expansion coefficient
Namely:
wherein, tcalFor calibrating the ambient temperature, a setpoint is set, for example, 22 ℃ depending on the actual situation.
The parameters h, r are knownouter、rinnerWhen K, L and lambda are substituted into the formula, the arm-tube axial deformation of the collaborative robot in the DH model is as follows:
Δa＝k1*((t2+t3+2*t∞)-(t2(0)+t3(0)+2*tcal))+k2*(t∞-tcal)，
wherein, delta a is the axial deformation of the arm tube, k1 is the first coefficient, k2 is the second coefficient, t2 is the joint temperature of one end of the arm tube, t3 is the joint temperature of the other end of the arm tube, tcalTo calibrate the ambient temperature, t∞And (3) indicating the ambient temperature, wherein t2(0) is the calibrated joint temperature at one end of the arm tube, and t3(0) is the calibrated joint temperature at the other end of the arm tube. Thus, according to one embodiment of the invention, arms of a collaborative robot in a DH model are builtThe compensation model of the relation between the axial deformation quantity of the pipe and the joint temperature and the environment temperature specifically comprises the following steps: obtaining a compensation coefficient of the relation between the axial deformation and joint temperature and environment temperature; and establishing a compensation model according to the compensation coefficient.
In a specific embodiment of the invention, a compensation model of the relationship between the arm tube axial deformation and the joint temperature and the environment temperature of the collaborative robot in the DH model can be established according to the following formula:
Δa＝k1*((t2+t3+2*t∞)-(t2(0)+t3(0)+2*tcal))+k2*(t∞-tcal)；
wherein, delta a is the axial deformation of the arm tube, k1 is the first coefficient, k2 is the second coefficient, t2 is the joint temperature of one end of the arm tube, t3 is the joint temperature of the other end of the arm tube, tcalTo calibrate the ambient temperature, t∞As the ambient temperature, t2(0) is the nominal joint temperature at one end of the arm tube, and t3(0) is the nominal joint temperature at the other end of the arm tube.
It is understood that k1 and k2 are not the same for different arm tubes, and can be obtained in advance through related experiments, specifically referring to the following description, so as to obtain a compensation model of the arm tube.
According to an embodiment of the present invention, the following steps may be taken to obtain the first coefficient k 1: controlling the cooperative robot to touch the tool at a first posture at a preset frequency; controlling the ambient temperature t∞Constant and ambient temperature t∞And a calibrated ambient temperature tcalSimilarly, acquiring an actual axial deformation quantity delta a of the arm tube of the cooperative robot, an actual joint temperature t2 at one end of the arm tube and an actual joint temperature t3 at the other end of the arm tube; and acquiring a first coefficient k1 according to the compensation model, the actual axial deformation delta a of the arm tube of the cooperative robot, the actual joint temperature t2 at one end of the arm tube and the actual joint temperature t3 at the other end of the arm tube.
Specifically, the ambient temperature t is known from the compensation model∞The actual joint temperature t2 at one end of the arm tube and the actual joint temperature t3 at the other end of the arm tube can be directly measured by using related temperature sensors, t2(0) is the calibrated joint temperature at one end of the arm tube, and t3(0) is the calibrated joint at the other end of the arm tubeThe temperature and the calibrated environment temperature tcal can be directly called as preset values, so that the first coefficient k1 and the second coefficient k2 can be obtained only by detecting the actual axial deformation delta a of the arm tube of the cooperative robot at different temperatures by using related experiments.
Taking the six-axis robot shown in fig. 2 as an example, mapping the first arm tube L1 between the second joint and the third joint and the second arm tube L2 between the third joint and the fourth joint to the coordinate system can be simplified as shown in fig. 4, and as can be seen from fig. 4, the deformation amounts Δ x and Δ z of L1 and L2 in the x-axis direction and the z-axis direction are:
Δz＝Δa3*cos(180-θ2-θ3)-Δa2*cosθ2；
Δx＝Δa2*sinθ2+Δa3*sin(180-θ2-θ3)；
where Δ a2 is the actual amount of deformation of the first arm tube L1, and Δ a3 is the actual amount of deformation of the second arm tube L2. Therefore, as long as Δ z and Δ x are measured, Δ a2 and Δ a3 can be acquired. Therefore, the change values delta z and delta x of the arm tube length in the y-axis direction and the z-axis direction are obtained, and the actual deformation quantity of the arm tube can be obtained by utilizing a related mathematical algorithm.
For this reason, in an embodiment of the present invention, the cooperative robot may be controlled to make a table in a fixed posture, that is, the mechanical arm is kept touching a tool in a fixed posture (first posture), two distance detection probes may be disposed on the tool, and the two distance detection probes may detect the change values Δ z and Δ x of the arm tube length in the z-axis and x-axis directions when the cooperative robot touches the tool. After the mechanical arm touches the tool at each time, an action can be executed, and then the first gesture is returned to continue touching the tool, so that the temperature is different when the tool is touched at each time, but the gestures are the same. The change values Δ z and Δ x of the arm tube in the z-axis and x-axis directions at different temperatures (joint temperature and ambient temperature) in the posture can be measured through the probe.
Controlling the ambient temperature t∞Constant and calibrated ambient temperature tcalSimilarly, the compensation model is simplified to:
Δa＝k1*((t2+t3)-(t2(0)+t3(0)))；
the robot moves to enable the joint temperature to rise and the touch posture to be unchanged, the delta a can be obtained by measuring the values of delta a2 and delta a3, and the coefficient k1 value can be obtained according to the preset calibrated joint temperature t2(0) at one end of the arm pipe, the calibrated joint temperature t3(0) at the other end of the arm pipe, and the detected joint temperature t2 at one end of the arm pipe and the detected joint temperature t3 at the other end of the arm pipe.
Controlling the cooperative robot to be electrified and keeping the first posture unchanged, electrifying for a period of time to keep the temperature of each joint constant, then changing the ambient temperature, enabling the ambient temperature to linearly rise at a relatively low rate, and acquiring joint temperature data and change values delta z and delta x of the arm tube in the directions of the z axis and the x axis at intervals of time, wherein the joint temperature rise and the ambient temperature rise are basically kept the same because the cooperative robot does not move, and then the compensation model is simplified as follows:
Δa＝k2*(t∞-tcal)；
the value of k2 can be obtained by obtaining Δ a from the measured values of Δ z and Δ x.
And S2, after receiving a starting instruction of the cooperative robot, acquiring the current environment temperature and the current joint temperature of the cooperative robot in a preset period, and acquiring the axial deformation of the arm tube of the cooperative robot according to the compensation model, the current environment temperature and the current joint temperature.
Specifically, in the motion process of the cooperative robot, the temperature variation of each joint is not fast, the temperature information can be acquired at a preset period (at a certain interval), the axial deformation of the arm tube of the cooperative robot is acquired according to the compensation model after the temperature information is acquired, the joint angle is compensated, and the process is repeated.
And S3, acquiring the joint compensation angle corresponding to the arm tube according to the axial deformation of the arm tube.
According to an embodiment of the present invention, the joint compensation angle may be obtained using a polygonal model.
Further, according to an embodiment of the present invention, in the example of the cooperative robot shown in fig. 2, the first joint to the sixth joint 1-6 are provided in the DH model from bottom to top, the arm tube includes a first arm tube L1 and a second arm tube L2, one end of the first arm tube L1 is the second joint 2, the other end of the first arm tube is the third joint 3, one end of the second arm tube L2 is the third joint 3, and the other end of the second arm tube L2 is the fourth joint 4.
The first arm tube L1 and the second arm tube L2 can be simplified as shown in fig. 5, a2 and a3 are respectively the lengths of the first arm tube L1 and the second arm tube L2, theta3 is the included angle between the second arm tube and the first arm tube, and can be directly obtained according to the posture (pose) of the cooperative robot, and an auxiliary line r (the connection line between the second joint 2 and the fourth joint 4) is made, and obtained according to the cosine theorem:
by the same token, the included angle theta2 between L1 and r and the included angle theta4 between L2 and r are respectively as follows:
after the first arm tube L1 and the second arm tube L2 are deformed, the lengths of three sides of the triangle shown in fig. 5 are a2+ Δ a2, a3+ Δ a3, and r respectively; the three angles of the triangle shown in fig. 5 are:
alternatively, theta4 ' is 180-theta2 ' -theta3 '.
The angle variation of the triangle shown in fig. 5 is:
Δtheta2＝theta2′-theta2
Δtheta3＝theta3′-theta3
Δtheta4＝theta4′-theta4
alternatively, Δ theta4 is equal to Δ theta2 and Δ theta 3.
Thus, the compensation angle Δ theta2 for the second joint, the compensation angle Δ theta3 for the third joint, and the compensation angle Δ theta4 for the fourth joint may be obtained.
It can be understood that, as described above for the acquisition principle of the compensation angle of the six-axis robot shown in fig. 5, for cooperative robots of other models, the joint angle compensation is not limited to the triangular form, and can be simplified into the solution calculation of geometric models such as other polygons, and the like, and can be acquired according to the specific situation and the related mathematical principle.
And S4, performing angle compensation on the corresponding joint according to the joint compensation angle.
Specifically, a compensation model is obtained in advance through the method; secondly, determining a correlation coefficient involved in the compensation model; thirdly, calculating the axial deformation of the arm tube caused by temperature change by acquiring the joint temperature and the ambient temperature, and calculating the joint compensation angle through the axial deformation of the arm tube; and finally, the joint compensation angle is sent to a related control module in a pulse number mode, so that the related control module directly performs angle compensation on the corresponding joint according to the joint compensation angle.
In an embodiment of the present invention, a ratio of an arm tube length of the cooperative robot to a corresponding joint length satisfies a first preset condition, where the first preset condition may be: the ratio of the arm tube length to the joint length of the cooperative robot is greater than or equal to 5.
Specifically, when the length of the arm tube is significantly greater than the length of the joint, for example, the ratio of the length of the arm tube to the length of the joint is greater than or equal to 5, the influence of the temperature on the axial deformation of the arm rod is much greater than that of the joint, and the change in the length of the arm tube is simply considered.
According to the control method of the cooperative robot, the axial deformation quantity of the arm pipe can be automatically obtained according to the joint temperature in the working process of the cooperative robot, and the angle compensation is carried out on the joint in a self-adaptive mode according to the axial deformation quantity of the arm pipe, so that the problem that the repeated positioning precision of the cooperative robot is poor due to factors such as environmental temperature change can be solved, the repeated positioning precision of the cooperative robot is improved, the working reliability of the cooperative robot is improved, a heat engine is not needed, and the working efficiency of the cooperative robot is improved.
Corresponding to the control method of the cooperative robot, the invention also provides a control device of the cooperative robot. Since the embodiment of the apparatus of the present invention corresponds to the above embodiment of the method, the above embodiment of the method for controlling a cooperative robot is also applicable to the apparatus for controlling a cooperative robot provided in this embodiment, and details that are not disclosed in the embodiment of the corresponding apparatus may refer to the above embodiment of the method, and are not described again in the present invention.
Fig. 6 is a block schematic diagram of a control apparatus of a cooperative robot according to an embodiment of the present invention, as shown in fig. 6, the apparatus including: a building block 10, a detection block 20, a calculation block 30 and a control block 40.
The establishing module 10 is used for establishing a compensation model of the relationship between the axial deformation quantity of the arm tube of the cooperative robot in the DH model and the joint temperature and environment temperature; after receiving a starting instruction of the cooperative robot, the detection module 20 obtains the current environment temperature and the current joint temperature of the cooperative robot in a preset period, and obtains the axial deformation amount of the arm tube of the cooperative robot according to the compensation model, the current environment temperature and the current joint temperature; the calculation module 30 is used for acquiring a joint compensation angle corresponding to the arm tube according to the axial deformation amount of the arm tube; the control module 40 is used for performing angle compensation on the corresponding joint according to the joint compensation angle.
According to one embodiment of the present invention, the detection module 20 may include: the first temperature sensor is arranged in a module shell of the joint of the cooperative robot and is used for detecting the joint temperature of the cooperative robot; and the second temperature sensor is arranged in a control cabinet of the cooperative robot and is used for detecting the ambient temperature.
According to an embodiment of the present invention, the establishing module 10 specifically establishes a compensation model of the relationship between the arm-tube axial deformation and the joint temperature and the environment temperature of the cooperative robot in the DH model according to the following formula:
Δa＝k1*((t2+t3+2*t∞)-(t2(0)+t3(0)+2*tcal))+k2*(t∞-tcal)；
wherein, delta a is the axial deformation of the arm tube, k1 is the first coefficient, k2 is the second coefficient, t2 is the joint temperature of one end of the arm tube, t3 is the joint temperature of the other end of the arm tube, tcalTo calibrate the ambient temperature, t∞As the ambient temperature, t2(0) is the nominal joint temperature at one end of the arm tube, and t3(0) is the nominal joint temperature at the other end of the arm tube.
According to an embodiment of the present invention, the establishing module 10 specifically obtains the first coefficient k1 by: controlling the cooperative robot to touch the tool at a first posture at a preset frequency; controlling the environmental temperature to be unchanged, wherein the environmental temperature is the same as the calibrated environmental temperature, and acquiring the actual axial deformation of the arm pipe of the cooperative robot, the actual joint temperature of one end of the arm pipe and the actual joint temperature of the other end of the arm pipe; and acquiring a first coefficient k1 according to the compensation model, the actual axial deformation of the arm tube of the cooperative robot, the actual joint temperature of one end of the arm tube and the actual joint temperature of the other end of the arm tube.
According to an embodiment of the present invention, the establishing module 10 specifically obtains the second coefficient k2 by: controlling the cooperative robot to be powered on and keeping the first posture unchanged; controlling the ambient temperature to rise at a first preset rate; acquiring actual axial deformation of an arm pipe of the cooperative robot at different environmental temperatures; and acquiring a second coefficient k2 according to the compensation model and the actual axial deformation of the arm tube of the cooperative robot at different environmental temperatures.
According to an embodiment of the present invention, the cooperative robot is a six-axis robot, the joints in the DH model sequentially include first to sixth joints from bottom to top, the arm tube includes a first arm tube and a second arm tube, one end of the first arm tube is a second joint, the other end of the first arm tube is a third joint, one end of the second arm tube is a third joint, and the other end of the second arm tube is a fourth joint, and the calculating module 30 specifically obtains the joint compensation angle corresponding to the arm tube by using the following formula:
Δtheta2＝theta2′-theta2
Δtheta3＝theta3′-theta3
Δtheta4＝theta4′-theta4
wherein a2 is the length of the first arm tube, a3 is the length of the second arm tube, theta3 is the included angle between the first arm tube and the second arm tube, Δ a2 is the axial deformation amount of the first arm tube, Δ a3 is the axial deformation amount of the second arm tube, Δ theta2 is the compensation angle of the second joint, Δ theta3 is the compensation angle of the third joint, and Δ theta4 is the compensation angle of the fourth joint.
In an embodiment of the present invention, a ratio of the length of the arm tube of the cooperative robot to the length of the corresponding joint satisfies a first preset condition, where the first preset condition may be: the ratio of the arm tube length to the joint length of the cooperative robot is greater than or equal to 5. In summary, according to the control device of the cooperative robot in the embodiment of the present invention, the axial deformation amount of the arm tube can be automatically obtained according to the joint temperature in the working process of the cooperative robot, and the angle compensation is performed on the joint in a self-adaptive manner according to the axial deformation amount of the arm tube, so that the problem of poor repeated positioning accuracy of the cooperative robot due to factors such as environmental temperature changes can be avoided, the repeated positioning accuracy of the cooperative robot is improved, the working reliability of the cooperative robot is improved, a heat engine is not required, and the working efficiency of the cooperative robot is improved.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. A method of controlling a cooperative robot, comprising the steps of:
establishing a compensation model of the relationship between the axial deformation quantity of the arm tube of the cooperative robot in the DH model and the joint temperature and environment temperature;
after a starting instruction of the cooperative robot is received, acquiring the current environment temperature and the current joint temperature of the cooperative robot in a preset period, and acquiring the axial deformation of an arm pipe of the cooperative robot according to the compensation model, the current environment temperature and the current joint temperature;
acquiring a joint compensation angle corresponding to the arm tube according to the axial deformation of the arm tube;
and carrying out angle compensation on the corresponding joint according to the joint compensation angle.
2. The method for controlling the cooperative robot according to claim 1, wherein establishing a compensation model of the relationship between the axial deformation quantity of the arm tube of the cooperative robot in the DH model and the joint temperature and the environment temperature specifically comprises:
obtaining a compensation coefficient of the relation between the axial deformation quantity and joint temperature and environment temperature;
and establishing the compensation model according to the compensation coefficient.
3. The cooperative robot control method according to claim 2, wherein a compensation model of the relationship between the arm-tube axial deformation amount and the joint temperature and the environment temperature of the cooperative robot in the DH model is established according to the following formula:
Δa＝k1*((t2+t3+2*t∞)–(t2(0)+t3(0)+2*tcal))+k2*(t∞-tcal)；
wherein, delta a is the axial deformation of the arm tube, k1 is a first coefficient, k2 is a second coefficient, t2 is the joint temperature of one end of the arm tube, t3 is the joint temperature of the other end of the arm tube, tcalTo calibrate the ambient temperature, t∞And t2(0) is the calibrated joint temperature of one end of the arm tube, and t3(0) is the calibrated joint temperature of the other end of the arm tube.
4. The cooperative robot control method according to claim 3, wherein the first coefficient k1 is obtained by:
controlling the cooperative robot to touch the tool at a first posture at a preset frequency;
controlling the environment temperature to be unchanged, wherein the environment temperature is the same as the calibrated environment temperature, and acquiring the actual axial deformation of the arm pipe of the cooperative robot, the actual joint temperature of one end of the arm pipe and the actual joint temperature of the other end of the arm pipe;
and acquiring the first coefficient k1 according to the compensation model, the actual axial deformation of the arm tube of the cooperative robot, the actual joint temperature of one end of the arm tube and the actual joint temperature of the other end of the arm tube.
5. The cooperative robot control method according to claim 3, wherein the second coefficient k2 is obtained by:
controlling the cooperative robot to be powered on and keeping a first posture unchanged;
controlling the ambient temperature to rise at a first preset rate;
acquiring actual axial deformation of the arm tube of the cooperative robot at different environmental temperatures;
and acquiring the second coefficient k2 according to the compensation model and the actual axial deformation of the arm tube of the cooperative robot at different environmental temperatures.
6. The cooperative robot control method according to claim 1, wherein the joint compensation angle is obtained using a polygon model.
7. The method of claim 6, wherein the cooperative robot is a six-axis robot, the joints include first to sixth joints in the DH model from bottom to top, the arm tube includes a first arm tube and a second arm tube, one end of the first arm tube is a second joint, the other end of the first arm tube is a third joint, one end of the second arm tube is a third joint, and the other end of the second arm tube is a fourth joint, and the joint compensation angle corresponding to the arm tube is obtained by using the following formula:
Δtheta2＝theta2′-theta2
Δtheta3＝theta3′-theta3
Δtheta4＝theta4′-theta4
wherein a2 is the length of the first arm tube, a3 is the length of the second arm tube, theta3 is the included angle between the first arm tube and the second arm tube, Δ a2 is the axial deformation amount of the first arm tube, Δ a3 is the axial deformation amount of the second arm tube, Δ theta2 is the compensation angle of the second joint, Δ theta3 is the compensation angle of the third joint, and Δ theta4 is the compensation angle of the fourth joint.
8. The cooperative robot control method according to any one of claims 1 to 7, wherein a ratio of an arm tube length of the cooperative robot to a corresponding joint length satisfies a first preset condition.
9. A control device for a cooperative robot, comprising:
the establishing module is used for establishing a compensation model of the relationship between the axial deformation quantity of the arm tube of the cooperative robot in the DH model and the joint temperature and environment temperature;
the detection module is used for acquiring the current environment temperature and the current joint temperature of the cooperative robot in a preset period after receiving a starting instruction of the cooperative robot, and acquiring the axial deformation amount of the arm pipe of the cooperative robot according to the compensation model, the current environment temperature and the current joint temperature;
the calculation module is used for acquiring a joint compensation angle corresponding to the arm tube according to the axial deformation of the arm tube;
and the control module is used for carrying out angle compensation on the corresponding joint according to the joint compensation angle.
10. The control device of a cooperative robot according to claim 9, wherein the detection module comprises:
a first temperature sensor disposed in a module housing of a joint of a cooperative robot, the first temperature sensor for detecting a joint temperature of the cooperative robot;
a second temperature sensor disposed in a control cabinet of the cooperative robot, the second temperature sensor being for detecting an ambient temperature.
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