A kind of online error-compensating apparatus of robot based on camera chain and methodTechnical field
The present invention relates to a kind of industrial robot more particularly to a kind of robot inaccuracy online compensations based on camera chainDevice and method.
Background technique
Industrial robot is because it has many advantages, such as biggish working space, high flexibility and lower price, more and more extensivelyIt is applied to industrial processes manufacturing field generally.But since there are biggish machining errors for itself, along with workedOther factors in journey: such as temperature, the influence vibrated, although the repetitive positioning accuracy of robot is higher, its absolute fix essenceIt spends very low.And due to being concatenated open loop structure, the rigidity of mechanical arm is relatively low, in the case where bearing load, errorIt is more obvious.Therefore it can not be applied in fields such as the higher machinings of precision prescribed.Meanwhile industrial robot is offlineProgramming is also increasingly rapidly developed.It has the downtime that can be reduced on production line, so that benefit etc. is excellentPoint, and programmer can be made to can be avoided and worked under dangerous working environment.But for off-line programing, machineThe absolute fix precision of people is exactly its key request.
The most common method for providing industrial robot precision is to improve work by carrying out off-line calibration to robotThe absolute fix precision of industry robot.It is recognized by the rigidity of its rigidity model, error caused by reducing due to load.However thisKind method needs carry out cumbersome calibration in robot working space, and the selection for demarcating dot matrix has very big shadow to precisionIt rings.Position except calibration point, error can not be guaranteed.Moreover, calibration is merely able to demarcate location error,It is unable to demarcate attitude error, have some limitations.
Summary of the invention
There are the machining reasons such as equal error and lower rigidity because of it in the theoretical pose that industrial robot needs to be implementedAnd there are large errors, its error amount can be obtained by being compared by the pose of actual measurement with theoretical pose.For existing skillDefect existing for art, the present invention provide a kind of online error-compensating apparatus of the robot based on camera chain and method, Ke YitiHigh robot absolute fix precision, by pose data that more survey station polyphaser combination shot measuring system real-time measurements obtain withAnd the space that two-dimentional dipmeter is combined with the higher angle-data rotated about the z axis of a precision that robot itself resolvesThe attitude data that inertial coordinate measuring system real-time measurement obtains merges to obtain high-precision robot end's pose data.And itsEnd is measuring known to the theoretical pose under coordinate system (using industrial robot itself resolving pose as the theory in the present inventionPose), obtained error is fed back into robot, robot compensates error amount.Robot in the present invention is onlineError compensating method is using the theoretical value in the case where measuring coordinate system as true value, and the value that externally measured systematic survey is obtained is as realActual value, to guarantee to reach identical precision in its Work Space Range in industrial robot, the attainable precision of institute is higher.Error compensating method of the invention is simple, without carrying out off-line calibration to robot, can reduce calibration bring and calculate, improveEfficiency and precision can be applied in industrial circles such as processing and manufacturings.
In order to solve the above-mentioned technical problem, the present invention proposes a kind of online error compensation side, the robot based on camera chainMethod, used in the structure of device be: the device includes the industrial robot for being connected with robot control cabinet, more survey station multiphasesMachine combines Digital Photogrammetric System, space inertial coordinate measuring system, Digital Photogrammetric System auxiliary target and host computer, the spaceInertial coordinate measuring system is made of the encoder that two-dimentional dipmeter is carried with industrial robot；More survey station polyphasersCombination shot measuring system includes four survey stations, and four survey stations are arranged according to 2 × 2 rectangular array and horizontal planeSame plane P in, the ranks spacing of rectangular array is 1m, each survey station have a camera, the optical axis of the camera withHorizontal line is in 25 degree of angles, and the optical axis focuses on the point O at the rectangular surfaces center 1.5m where four survey stations of distance, four phasesThe full measurement visual field of machine covering；The range of the full measurement visual field is centered on point O and to be greater than the space 1m × 1m × 1m；InstituteThe end that Digital Photogrammetric System auxiliary target is mounted on the industrial robot is stated, the Digital Photogrammetric System auxiliary target is by fiveThe highlighted reflective marker ball of a 20mm standard forms；Each survey station of more survey station polyphaser combination shot measuring systems capturesTo at least four highlighted reflective marker balls, through each highlighted reflective marker ball centre of sphere mutual alignment relation of determination, based on accurateCalculate position and the posture of industrial robot end；The two dimension dipmeter is for measuring industrial robot end relative to waterThe posture of plane, the two dimension dipmeter are installed on the end of industrial robot, the Z of the industrial robot basis coordinates systemAxis and horizontal plane；The initial makeup location of the two dimension dipmeter is X-axis, the Y-axis of the two-dimentional dipmeterIt is overlapped respectively with X-axis, the Y-axis of the tool coordinates system of the industrial robot end；Using the two-dimentional dipmeter as non-Two coordinates of horizontal plane rotation, using the rotation angle rotated about the z axis that industrial robot encoder itself resolves as levelThe coordinate of face rotation, to obtain the attitude data A of industrial robot end；More survey station polyphaser combination shot measurements systemSystem, the two-dimentional dipmeter and the industrial robot control cabinet are each individually connected to the host computer, the host computerExternally measured data and resolved data will be read, the externally measured data include the attitude data of above-mentioned industrial robot endThe position data B and attitude data for the industrial robot end that A and more survey station polyphaser combination shot measuring systems measureB；The resolved data refers to industrial robot the terminal position data C and attitude data C that industrial robot itself resolves；It is describedHost computer carries out the data fusion based on Kalman filtering to the attitude data A and attitude data B, to obtain externally measuredAttitude data D；Above-mentioned attitude data C, attitude data D, position data B and position data C are handled, finally realize workThe online error compensation of industry robot end position and posture；
Online error compensating method the following steps are included:
Step 1: being demarcated to more survey station polyphaser combination shot measuring systems；
Step 2: industrial robot passes to the industrial robot terminal position data C and attitude data C that itself resolveHost computer；
Step 3: the host computer receives the industrial robot end X-axis and Y-axis phase that the two-dimentional dipmeter measuresFor the inclination data of gravity direction, and industrial robot encoder itself is combined to resolve obtained industrial robot end-of-arm toolingThe rotation angle that coordinate system is rotated around industrial robot basis coordinates system Z axis, is calculated the attitude data of industrial robot endA；
Step 4: utilizing the highlighted of five 20mm standards in the auxiliary target of Digital Photogrammetric System described in four cameras capturesThe position of the highlighted reflective marker ball and attitude data are passed to host computer, to obtain industrial machine by reflective marker ballThe position data B and attitude data B of people end；
Step 5: the attitude data B that step 4 obtains and attitude data A that step 3 obtains merge by host computerTo the attitude data D of industrial robot end, using the position data B that attitude data D and step 4 are obtained as externally measured numberAccording to；
Step 6: the position data C and attitude data C and step of the industrial robot end that host computer obtains step 2The five industrial robot terminal positions obtained and the externally measured data, that is, position data B and attitude data D of posture are carried out respectivelyIt compares, finds out the error amount of the two；Judge whether the error amount meets the requirements, if not satisfied, then by the error value back to workIndustry robot, the industrial robot adjust position and the posture of industrial robot end, return step three according to the error amount；Until meeting error requirements.
Compared with prior art, the beneficial effects of the present invention are:
The present invention has the advantages that the present invention can compensate the error of robot to real-time online, machine is improvedThe position of people end and attitude accuracy, and without accurately being demarcated to it, reduce based on error model off-line calibrationTedious steps and calculating, improve efficiency.
Detailed description of the invention
Fig. 1 is that the present invention is based on the structural block diagrams of the online error-compensating apparatus of the robot of camera chain；
Fig. 2 (a) is the camera installation site master of each survey station of more survey station polyphaser combination shot measuring systems in the present inventionView；
Fig. 2 (b) is the camera installation site side view of each survey station of Fig. 2 (a)；
Fig. 3 (a) is more survey station polyphaser combination shot measuring system auxiliary target target main views；
Fig. 3 (b) is the side view of auxiliary target target shown in Fig. 3 (a)；
Fig. 3 (c) is the top view of auxiliary target target shown in Fig. 3 (a)；
Fig. 4 is that the present invention is based on the functional block diagrams of the online error-compensating apparatus of the robot of camera chain；
Fig. 5 is that the present invention is based on the online error compensation system control flow charts of the robot of camera chain；
In figure: 1- industrial robot, 2- robot control cabinet, 3- two dimension dipmeter, the more survey station polyphaser combinations of 4-Digital Photogrammetric System, 5- Digital Photogrammetric System assist target, 6- host computer.
Specific embodiment
Technical solution of the present invention is described in further detail in the following with reference to the drawings and specific embodiments, it is described specificEmbodiment is only explained the present invention, is not intended to limit the invention.
Inventive concept of the invention is as shown in figure 4, mainly assist target for two-dimentional dipmeter, Digital Photogrammetric SystemBe individually fixed in robotic actuator end, at the same two-dimentional dipmeter, more survey station polyphaser combination shot measuring systems withAnd industrial robot control cabinet is connect with host computer respectively.The initial makeup location of two-dimentional dipmeter is two-dimentional inclination angle measurementX-axis, the Y-axis of instrument are overlapped with X-axis, the Y-axis of the robot basis coordinates system of definition respectively.It is equipped on host computer and is compiled by VC6.0The host computer procedure for the realization error compensation write.Multiple and different position data involved in the technical solution of the present invention realization processAnd attitude data, in order to clear, concise, the difference in the description of technical solution respectively with suffix letter is distinguished, such as,Position data A, position data B, attitude data A, attitude data B, attitude data C and attitude data D.
The present invention is based on the online error-compensating apparatus of the robot of camera chain, as shown in Figure 1, including being connected with robotThe industrial robot 1 of control cabinet 2, industrial robot employed in the present embodiment is KUKA KR5arc industrial robot, and shouldRobot mounting location be so that its basis coordinates system Z axis straight up, which further includes that more survey station polyphaser combination shots are surveyedAmount system 4, space inertial coordinate measuring system, Digital Photogrammetric System auxiliary target 5 and host computer 6, the space inertial coordinateThe function of measuring system is completed jointly by the encoder that two-dimentional dipmeter 3 is carried with industrial robot.
More survey station polyphaser combination shot measuring systems 4 include four survey stations, as shown in Fig. 2, four survey stationsIt is arranged in the same plane P with horizontal plane according to 2 × 2 rectangular array, the ranks spacing of rectangular array is 1m, oftenA survey station have a camera (being indicated respectively with 41,42,43,44 appended drawing references in Fig. 1 and Fig. 2), the optical axis of the camera andHorizontal line is in 25 degree of angles, and the optical axis focuses on the point O at the rectangular surfaces center 1.5m where four survey stations of distance, four phasesThe full measurement visual field of machine covering；The range of the full measurement visual field is centered on point O and to be greater than the space 1m × 1m × 1m.
As shown in Figure 1, the Digital Photogrammetric System auxiliary target 5 is mounted on the end of the industrial robot 1, it is described to take the photographShadow measuring system auxiliary target 5 is made of the highlighted reflective marker ball of five 20mm standards, and Fig. 3 (a), Fig. 3 (b) and Fig. 3 (c) showThe position and connection relationship of five highlighted reflective marker balls are gone out.
Each survey station of more survey station polyphaser combination shot measuring systems 4 can capture at least four highlight it is reflectiveBall is marked, by each highlighted reflective marker ball centre of sphere mutual alignment relation of determination, for accurately calculating industrial robot endPosition and posture；It is communicated by Ethernet with host computer 6, so that host computer 6 obtains pose data in real time.
The industrial robot 1 that the present embodiment uses, the relationship between coordinate system are determined by six parameters of X, Y, Z, A, B, CIt is fixed.And between its terminal position and the tool coordinates system for being defined in robot end and robot basis coordinates system of posture expressionRelationship.Wherein X, Y, Z are coordinate system translation parameters, and A, B, C are coordinate system rotation parameter.X, Y, Z represent the position of Two coordinate systemSet translation relation.A, B, C represent the posture rotation relationship of Two coordinate system.KUKA KR5arc industrial robot is pivotedCarry out the sequence of posture conversion successively are as follows: 1. rotation angle about the z axis is A；2. the rotation angle around Y-axis is B；3. around X-axisRotation angle is C.Because as experiment measurement it is found that used by industrial robot resolve angle A precision it is higher.
The two dimension dipmeter 3 is for measuring the posture of industrial robot end with respect to the horizontal plane, the two dimensionDipmeter 3 is installed on the end of industrial robot 1, and the Z axis and horizontal plane of the basis coordinates system of the industrial robot 1 hang downDirectly；The initial makeup location of the two dimension dipmeter be the X-axis of the two-dimentional dipmeter, Y-axis respectively with the workX-axis, the Y-axis of the tool coordinates system of industry robot end are overlapped；It is rotated using the two-dimentional dipmeter 3 as non-horizontal surfaceTwo coordinates, the coordinate that the rotation angle rotated about the z axis resolved using industrial robot encoder itself is rotated as horizontal plane,In conjunction with the angle-data that industrial robot itself resolves, so as to the attitude data A of precise measurement industrial robot end.
More survey station polyphaser combination shot measuring systems 4, the two-dimentional dipmeter 3 and the industrial robotControl cabinet 2 is each individually connected to the host computer 6, and the host computer 6 will read externally measured data and resolved data, described outerPortion's measurement data include above-mentioned industrial robot end attitude data A and more survey station polyphaser combination shot measuring systemsThe position data B and attitude data B of the industrial robot end measured；The resolved data refers to that industrial robot itself resolvesIndustrial robot terminal position data C and attitude data C；The host computer 6 to the attitude data A and attitude data B intoData fusion of the row based on Kalman filtering, improves attitude measurement accuracy, to obtain accurate externally measured attitude dataD；Above-mentioned attitude data C, attitude data D, position data B and position data C are handled, it is final to realize industrial robot endThe online error compensation of end position and posture.
As shown in figure 5, the present embodiment realizes that the method for online error compensation is as follows:
Step 1: being demarcated to more survey station polyphaser combination shot measuring systems 4；
Step 2: industrial robot 1 transmits the industrial robot terminal position data C and attitude data C that itself resolveTo host computer 6；
Step 3: the host computer 6 receives the industrial robot end X-axis and Y-axis that the two-dimentional dipmeter 3 measuresRelative to the inclination data of gravity direction, and industrial robot encoder itself is combined to resolve obtained industrial robot end workThe rotation angle that tool coordinate system is rotated around industrial robot basis coordinates system Z axis, is calculated the posture number of industrial robot endAccording to A；
Step 4: utilizing the height of five 20mm standards in the auxiliary target 5 of Digital Photogrammetric System described in four cameras capturesThe position of the highlighted reflective marker ball and attitude data are passed to host computer 6, to obtain industrial machine by bright reflective marker ballThe position data B and attitude data B of device people end；
Step 5: host computer 6 merges the attitude data B that step 4 obtains and attitude data A that step 3 obtainsThe attitude data D of industrial robot end is obtained, using the position data B that attitude data D and step 4 obtain as externally measuredData；
Step 6: the position data C and attitude data C and step of the industrial robot end that host computer 6 obtains step 2It is rapid five obtain industrial robot terminal positions and posture externally measured data, that is, position data B and attitude data D respectively intoRow compares, and finds out the error amount of the two；Judge whether the error amount meets the requirements, if not satisfied, then giving the error value backIndustrial robot 1, the industrial robot 1 adjust position and the posture of industrial robot end according to the error amount, return to stepRapid three；Until meeting error requirements.
Although above in conjunction with attached drawing, invention has been described, and the invention is not limited to above-mentioned specific implementationsMode, the above mentioned embodiment is only schematical, rather than restrictive, and those skilled in the art are at thisUnder the enlightenment of invention, without deviating from the spirit of the invention, many variations can also be made, these belong to of the inventionWithin protection.