CN101237964A - Robotic arm comprising a plurality of articulated elements and means for determining the shape of the arm - Google Patents

Abstract

A robotic arm comprises a plurality of articulated elements (12), and control means (6) for controlling the position of various of the elements (12a,12b,12c) such that the arm may adopt serpentine shape for tip following movement. Means (2) for measuring directly the relative positions of at least some of the elements are provided in order to calculate deviation from the theoretical shape, and apply corrections to the arm control means.

Description

The device that comprises the mechanical arm of a plurality of hinged members and be used for determining the mechanical arm shape

Technical field

The present invention relates to a kind of mechanical arm, particularly relate to mechanical arm with " pinnacle is driven " function.

Background technology

The robot field, the mechanical arm with the driven function in pinnacle is the direction of development; That is to say that mechanical arm vertically advances in similar snakelike mode.This mechanical arm can carry live load and instrument, and can be used for having the equipment of limited passage, and for example the inner body of jet engine is checked.

The pinnacle slave unit usually medical field with endoscope form and at industrial circle in a way with the form extensive use of boroscope.Yet these devices depend on external environment condition and control workbench or sensing device and carry out given task at a suitable position.Endoscope is guided by intrinsic hole usually, though can carry out certain control in endoscope tip, in fact the major part of endoscope is passive in essence, and wherein only guiding is provided by hole or the pipe in the mobile body therein of device.

The pinnacle that is used for mechanical arm from the major advantage of braking technique we simultaneously the patent application No.WO0216995 of pending trial be described.This application is described and is protected a kind of mechanical arm, and this arm is made up of a plurality of vertical segments, and each segment comprises a plurality of passive Connection Elements.The end of each segment by changing the length of lead, can make brachiocylloosis like this by lead " guiding ".In typical mechanical arm, can have many segments, for example 4 to 20, each segment analogy can comprise 10 to 20 Connection Elements.The tension force of the control line by adjusting each segment, arm can move and take multiple spatial shape and structure.For example can realize by twining each root control line on the axle that in engine, uses.Engine is for example controlled by computerized control system.

Arm is fixed on the base and to target and advances, and continuous change of profile the tip with " following " simultaneously.

Use this mechanical arm, the joint of Connection Element is under the impaction state, promptly provides tension force on each control line, " tightening " each joint.Make arm have the space certainty like this, better the locus of control arm.Like this, just can control one group of Connection Element in the segment, rather than each element of independent control, utilize the rigidity Design of this Connection Element to come transfer charge, make the change of any motion and/or load variations or moment in the Connection Element of segment, transmit.We copending application WO02/100608 also relates to a kind of mechanical arm, wherein bonding or lock the parts in two joints between the intersegmental adjacent Connection Element of formation chain by inserting one deck rubber or artificial rubber, rubber layer forms fixing contact surface between link member, provide elastic shear force to produce " rigidity " that connects simultaneously.

Can depart from or change the driven mechanical arm in very little pinnacle along predefined paths in the space and itself and predefined paths in order to provide a kind of, be necessary to understand a large amount of assemblies or the relative exact position and the structure of element of arm.In the segment that does not have friction of " ideal ", work as applied external force, when not existing as load, gravity, friction etc., each segment will keep along the circular arc of its length direction constant radius.In addition, will provide accurate measurement with pilot length to lead around the measurement of the angular displacement of tube or capstan winch.

Yet in fact, external factor is all influential to each hinge, and it can change profile, makes that arm no longer is the positive circular arc of a circle.And lead may slide on tube during the arm load variations.This makes control arm difficult more along a predefined paths, will change the load of arm, the distribution of weight/friction because change the attitude of arm, therefore changes the shape of arm itself, causes the predefined paths that departs to small part.Though can accept in some cases has some to depart from predefined paths, other departs from situation is receptible scarcely.

Summary of the invention

Purpose of the present invention is just in order to alleviate these problems.

According to the present invention, a kind of mechanical arm is provided, it comprises at least one segment, and described segment has a plurality of hinged members; One control device is controlled the position of mechanical arm by the control element that acts on a segment or each segment; With a measurement mechanism, described measurement mechanism is associated with control device, is used in the gage beam at least one Connection Element and the relative position of another Connection Element at least in one or each segment, in order to determine the true form of arm.

Thereby measurement mechanism provides the information relevant with actual arm shape, makes the control of arm can be conditioned the compensator arm profile because the difference that produces with predetermined profile that extraneous factor causes.For example, arm can comprise the arithmetic unit that is associated with control device and measurement mechanism, is used for calculating arm exact shape and predetermined appearance difference, and it offers control device with correction value.

Preferably, measurement mechanism is measured every pair of adjacent elements, perhaps every pair of interelement relative position of at least one or each segment end.So just can obtain the exact image of arm exact shape, the compensating motion of any requirement can be calculated.

For example, can record relative position by the position of the external symbol on observation and the gage beam.In another example, measurement mechanism is used to the angular relationship of the transverse plane between measuring cell or the Connection Element.

In order to describe the spatial relationship between two bodies comprehensively, need six independently descriptors.The simplest form is designated as X, Y, Z (translation), α, beta, gamma (direction).Translation and direction are commonly used to determine " attitude ".And in according to a more accurate arm of the present invention, the relative position that measurement mechanism can measuring cell.

For example, measurement mechanism can comprise and produces one group by the device of a described element energy carried bundle with by other element energy carried array sensing device, and it is suitable for the detected energy bundle.Preferably, described power array has the size range greater than energy beam, makes a described element cause energy beam relative to the moving of array with respect to another element mobile, therefore can demonstrate relative another the position of in the element one.

A plurality of energy beams and array are used for calculating the locus of an element with respect to another element to being set on the diverse location on the element.Although three groups are enough to provide six information in theory, find in one plane to use four such groups better.Each all provides two measurement data described energy beam and array group.These eight measurement data use algorithm can derive six independently descriptors then, finish appearance information thus.Energy beam can be any suitable energy beam, electromagnetic energy typically particularly, for example, the light that produces by light emitting diode.This sensing device can be for detecting the elongation array of pixel, and it extends along the expectation path that energy beam moves.

The character of energy beam and structure can be controlled by the light that passes the slit projection.By the distance of control light generating device and slit, the shape of energy beam and character can be controlled in clearly in the margin amount.When considering the potential direction of motion of array, when producing, energy beam all has penumbra on both sides.Penumbra preferably can cover at least six pixelated array, makes the finishing of light to be detected, and can clearly demonstrate the position and the direction of energy beam motion with regard to the receiver cell array.Like this, energy source can produce the light with unique intensity or the screen of energy.

Perhaps, this measurement mechanism also can directly be measured the distance of adjacent elements between diverse location.If measure at least three positions, the relative position of the transverse plane of described element can be determined.For example, measurement mechanism can comprise three linear potential instrument, and they are fixed between the peripheral or contiguous periphery of element.Potentiometer occupies very little space and can be taken a sample fast.

This measurement mechanism is applicable to only can be at various mechanical arms and the pinnacle slave unit of interelement with the less free degree (being less than complete six-freedom degree) relative motion.So only need less measurement just can determine the element spatial attitude of another element relatively fully.For example, if ignore or effectively elimination distortion displacement and shearing, just seldom there are or do not have distortion or shearing motion so between the element.

The method that the transverse plane of another kind of measuring cell tilts is a mount accelerometers on element.Preferably use three accelerometers, an axis that is used for described element rotation.

By on each segment at least one or preferably all on the elements measurement mechanism being set, can carry out continuous monitoring to the relative position of each the relative arm data in the element.The weight on top is minimum, can pass to the computer that links to each other with the control device that is used for arm by the signal of each measurement mechanism transmission, thereby can regulate the deviation of the tension force compensating element of lead or element group and predefined paths, profile, structure thus.Like this can be better in the following characteristic of path upper suspension arm, also can accurately regulate the tension force on the control line of some or whole segment, considered load, position this moment or the influence of the variation of the operating pressure that produces by the workbench of arm end.

Control device comprises control line, and each control line is on a main shaft or capstan winch of deciding diameter or change diameter adjacent with the near-end of arm.The position of the end of each segment is by on the motor drives wire-wound on each main shaft or lay out and control.In this layout, the tension force that line is reeled can change, and like this, the encoder on the motor no longer can be measured the length of lead accurately.Therefore, measurement mechanism can comprise the linear movement measuring device, with the length that accurately measures each line with by the position of the element of line traffic control.

The linear movement measuring device for example can comprise one and measure roller, and lead is angled around it passes, and perhaps preferably on each root lead both sides a pair of pinch roller is set, and detects the angular displacement of at least one roller with a sensor.The contact pressure of pinch roller should enough cause measuring accordingly the angular displacement of roller greatly with the displacement of guaranteeing line.The direct measurement of the actual displacement of lead can be used to correct the position of spindle drive motor encoder and determines.

Yet the tension force of supposing lead is a constant, perhaps is the function of lead displacement at least, and tension force just can calculate like this.Because lead is flexible, the tension force of lead will influence the length of lead.Therefore a kind of more accurate lead displacement measuring device comprises two pairs of pinch rollers.Obtain displacement and the tension force that two angle displacement measurement values can be used to calculate lead from described roller, so just can determine the length of line more accurately.

In another example, the linear movement measuring device comprises optics or magnetic sensor.For example, each control line can be near optical pickocff be provided with a plurality of marks along the conductor spacing, and mark moving and then being detected by optical pickocff to mobile can being easy to of described control line like this.Mark can merely be positioned at the outer surface of described line, perhaps in the bundle conductor one can be different with other colors, this contrast is very significantly allowing to detect the bundle conductor passage, and then measures the displacement of line own.

The magnetic transducing device comprises one or more hall effect sensor, and magnetic devices is provided with a plurality of marks at certain intervals along pilot in the scope at proximity sense.These magnetic marks comprise that the interval with rule is embedded in a plurality of magnet in the pilot.Perhaps, magnetic mark can obtain by the main line in the line of magnetization assembly, perhaps main line and other forms of magnetic stripe is replaced to obtain, and hall effect sensor can be used for determining the cumulative displacement of the relative sensor of control line like this.

As mentioned above, for the accurately displacement of measurement lead, displacement and the elongation that must measure control line with this optics and magnetic devices, but for measuring lead, a displacement is just enough.

The device that one of advantage of optics, magnetic and accelerator sensing device comes to this does not apply any physical force or influences on line.

Measure the another kind of method of control line displacement, can provide other slotted line, itself and control line are separated along the arm direction.The displacement of these lines can be recorded as described above.Advantage is not load on the line, and the tension force of line can not change.Yet need bigger space and more complicated structure like this, this is more suitable in large-scale mechanical arm.

Description of drawings

Be more readily understood in order to make to invent, method by way of example, with accompanying drawing as a reference, wherein:

Fig. 1 is the schematic diagram according to mechanical arm of the present invention;

Fig. 2 is the cross section of Fig. 1 along II-II, shows the layout of control line;

Fig. 3 cuts open the stereogram that shows according to the part of a specific embodiment of mechanical arm of the present invention;

Fig. 4 is the exploded view of the mechanical arm part of Fig. 3;

Fig. 5 is the profile of Fig. 4 along V-V;

Fig. 6 is the stereogram of the terminal segment part of the mechanical arm of invention;

Fig. 7 is the perspective view according to mechanical arm of the present invention;

Fig. 8 is the schematic diagram of arm segment according to an embodiment of the invention;

Fig. 9 is the force diagram of mechanical arm;

Figure 10 is the stereogram of mechanical arm according to another embodiment of the present invention;

Figure 11 be according to further embodiment of this invention mechanical arm stereogram;

Figure 12 is the partial enlarged drawing of arm shown in Figure 11;

Figure 13,14 and 15 is for being used for the diagrammatic sketch according to the different measuring device on the arm of the present invention;

Figure 16 is the diagrammatic sketch of the measurement mechanism of arm shown in Figure 10;

Figure 17 shows that a series of curve map of the data that from measurement mechanism shown in Figure 16, obtain.

The specific embodiment

With reference to Fig. 1, mechanical arm 10 comprises a plurality of elements of the form that is in the Connection Element 12 that connects with articulation joint 14.Arm is installed on the base 16 at approach end.Extend in many control line 18 slave controllers 6 and pass base 16 and pass hole 38 in each Connection Element 12 periphery.Control line 18 is divided into three groups to be opened along the circle spacing as shown in Figure 2, and each group terminates at specific Connection Element 12a by being bonded on the Connection Element along arm, and 12b is on the 12c.Meet the place at one group of line end, these Connection Elements are control connection elements, and have determined the end of segment 20.Moving of this group control line 18 by controller control controlled specific control connection element 12a, 12b, and the position of 12c, and then control the position of corresponding segment 20.

As mentioned above, measurement mechanism 2 is for example from the control connection element assembling position data of each segment.Arithmetic unit 4 is used for handling these position datas and is used for the actual measurement location of arm and theory or precalculated position are made comparisons.Any difference makes that needing to calculate required compensation moves, and these differences are transmitted to controller 6, convert control element 12a then to, 12b, and 12c moves.

With reference to Fig. 3 and Fig. 4, each Connection Element 12 comprises pair of outer wheel disc 22, and each joint comprises a pair of inner disc 24.Inner disc 24 is processed to have the outer surface 26 of arcuate convex, and each all has the inner surface 28 that is complementary with arcuate convex outer disc.The surface 26,28 of these correspondences links together by TR thin rubber layer or elastomeric layer 30, and TR thin rubber layer or elastomeric layer can be bonded on each surface.Each all has centre bore interior wheel disc and outer wheel disc 22,24, and this centre bore has formed the conduit 32 that passes through along the arm center, is used to the control device that holds power supply, bus or be used to be installed in the workbench of arm end.

With reference to Fig. 5, each outer disc 22 and each inner disc 24 all comprise the pin hole 34,36 at a plurality of intervals separately.Therefore when the assembly of an outer disc 22 and an inner disc 24 along with the pin that is arranged in hole 34,36 during mutual placed adjacent, arm component just can keep together under the tension force effect of control line.Each outer disc comprises that a plurality of conduits 38 hold control line 18.

At the end of each segment, three 18a in the control line, 18b, the 18c termination, and be fixed in the groove 40 of expansion, described groove is arranged in one (as shown in Figure 6) of the outer disc 22 of the Connection Element that limits end of the chain end.Several such segments join end to end and are formed with the arm of certain-length, and other several groups of group control lines arrive another segment by conduit 38.Control line 18 remains under the compressive load that the Connection Element assembly is kept together Connection Element towards the tensioning of base direction.

With reference to Fig. 7, lead 18 passes base and each is all by on capstan winch 42 separately.Rotatablely moving of each capstan winch 42 utilizes the computer control system (not shown) to come the position of control arm.

Fig. 8 shows control principle.The motion of control line has determined the position at the transverse slat 44 of the Connection Element of a segment far-end." passive " Connection Element 45 between near-end Connection Element 46 and far-end Connection Element 44 makes arm form accurate profile on segment.In desirable segment, should be one section accurate arc of circle.Yet in fact gravity and load make described arm stray circle arc, as shown in Figure 9.

Figure 10 has shown a kind of device that is used for measuring the relative position of adjacent Connection Element, to determine this effect.Assembly shown in Figure 10 comprises installing plate 48, and it places between every pair the inner disc 24, and every pair of inner disc 24 is being supported light emitting diode 50 at its contiguous peripheral place.In this assembly, outer disc 54,56 shapes are arranged in its periphery and have gap 57.Be guided through the outer slit 52 of placing setting of one of every pair of outer disc 54 from the light of light emitting diode 50.Another outer disc 56 of this centering comprises the array 58 that is positioned at the optical sensor of periphery inner surface as the wheel, aligns with slit 52.It is tangent that array 58 is arranged to outer disc 56, like this, when another relatively moves relatively when a Connection Element, passes the light of slit 52 from light emitting diode and strafed array 58.If arrange four such devices at interval circumferentially around the Connection Element assembly, just can determine the attitude of adjacent outer discs and the accurate profile of arm.

Referring to Figure 16, illustrate in greater detail described device.The light source of light emitting diode 50 is installed diffuser 51 back of adjacent slots 52.Slit 52 enlarges along the direction of leaving light source 50.Curve 53 has represented to be located at position on the plane of sensor array 58 that any one side has penumbra 65 to the relation of the beam intensity that obtains.As shown in figure 17, this is arranged so that penumbra 55 covers at least 2 and 1/2 pixel 59 of array 58.Column Figure 61 of pixel value can be used for producing " the best fits " line 63, can infer the border of penumbra 55 like this.Therefore the median of penumbra can be determined more accurate than the width of pixel 59.Therefore can concentrate from beam array and draw two segment informations.

Figure 11 shows the another kind of method of determining the adjacent outer discs relative position.Potentiometer is set between Connection Element in this example.A potentiometer body 69 is extended between the outer disc 62,64 of adjacent Connection Element, and between a pair of wheel disc 60,62 of each Connection Element, preloading spring 70 keeps pad 70 to be resisted against on the smooth reaction plan 68.Pad 70 is installed on the spherical bearing 73 that is positioned at potentiometer axle 69 ends, and pad can be rotated.The relatively moving of Connection Element causes producing in the potentiometer measurable linearity and moves.Therefore, each potentiometric reading is exactly the distance of the adjacent Connection Element of mounting points.

As seen, along relative angle position (just arriving the distance on next Connection Element plane and the orientation on this plane) that three such potentiometers of circumferentially-spaced of Connection Element can provide enough information to determine adjacent Connection Element transverse plane.Like this, the shape of actual arm can be determined in such device, does not reverse with tangential motion in this device between the Connection Element or reverses with tangential motion very little.

This device has an advantage, is exactly that potentiometer can be sealed, makes that control line can be lubricated and be not wound.The space that potentiometer needs is also very little, and sampled faster such as optical pickocff shown in Figure 10.

The method of another kind of gage beam true form is that slotted line is equally passed the Connection Element periphery with control line, measures the length of these lines then.Such slotted line extends from base, can need measured Connection Element in position of termination, perhaps can return base then in the wraparound of Connection Element place.Described measurement lead is as shown in figure 13 on reel 74.Line 76 passes a pair of pinch roller 78.One of them the length of measuring lead that is measured as of angular displacement of pinch roller provides accurate data.Like this, can accurately measure to the distance of Connection Element, use three such slotted lines 76 if center on around the circle spacing of Connection Element, the angle of Connection Element transverse plane also can be determined.

Another method of determining slotted line 76 length is by optical markings 80 is set on slotted line, and optical pickocff 82 is placed the position of contiguous slotted line 76, as shown in figure 14.Yet another method of measuring slotted line 76 length is that portion embeds magnet 84 within it.Hall effect sensor 86 be installed in slotted line near, the displacement that is used for measuring lead.

Control line is on capstan winch, and each capstan winch has a motor and an encoder that is used to control usually.Yet, be appreciated that the angular displacement of capstan winch can not represent accurately that usually wire-wound goes out or move into the amount of capstan winch.This is because the elasticity of lead and friction when reel etc. contacts.Therefore, above-mentioned traverse survey technology also can be used to measure the displacement of the line adjacent with each capstan winch.Provide the more accurate measurement of each control line length like this, and then can accurately determine the profile of arm again.Therefore might adjust control with the information that these traverse survey technology draw to capstan winch.

Claims (20)

1, a kind of mechanical arm comprises: at least one segment with a plurality of hinged members; Control the control device of described arm position by acting on control element on a described segment or each segment; And, measurement mechanism, itself and control device link, and another relative positions at least is set at least one element be used for measuring in a segment described in the described arm or each segment and the described arm, are used for the true form of definite described arm.

2, mechanical arm as claimed in claim 1 is characterized in that, comprises arithmetic unit, and it connects mutually with control device and measurement mechanism, be used to calculate the difference between described arm exact shape and predetermined profile, and corresponding described difference is come the device of Correction and Control device.

3, mechanical arm as claimed in claim 1 or 2 is characterized in that, measurement mechanism is used to measure the relative positions on the end of every pair of adjacent elements or a described segment or each segment.

As claim 1,2 or 3 described mechanical arms, it is characterized in that 4, measurement mechanism is used to the mutual angular relationship between the transverse plane of measuring cell.

5, as claim 1,2,3 or 4 described mechanical arms, it is characterized in that measurement mechanism is used to measure the relative attitude of described element.

As the described mechanical arm of the arbitrary claim in front, it is characterized in that 6, measurement mechanism comprises that one is used for the generating means of produce power bundle, it is by an element supporting and an energy sensing device array, and it is by another element supporting and be used for the detected energy bundle.

7, mechanical arm as claimed in claim 6 is characterized in that, energy beam is an electromagnetic energy, is preferably light, and described sensing device comprises the extension array of sensor, and these sensors extend along the predetermined mobile route of described bundle.

As claim 6 or 7 described mechanical arms, it is characterized in that 8, measurement mechanism comprises the interval attitude of a plurality of described generating means, sensing device.

As claim 1,2,3 or 4 described mechanical arms, it is characterized in that 9, measurement mechanism comprises the device that is used for measuring in the distance between adjacent elements on a plurality of interval locations.

10, mechanical arm as claimed in claim 9 is characterized in that, measurement mechanism comprise a plurality of be installed in place outward or the described element at contiguous peripheral place between linear potentiometer.

11, as the described mechanical arm of the arbitrary claim in front, it is characterized in that control device comprises at least one group of control line, itself and control corresponding element link, and each control line has actuating device, is used for changing the length of described line.

12, mechanical arm as claimed in claim 11 is characterized in that, measurement mechanism comprises that setting is in order to be used for directly measuring the linear movement measuring device of each control line length.

13, as the described mechanical arm of the arbitrary claim in front, it is characterized in that, measurement mechanism comprises the linear movement measuring device, and described linear movement measuring device is used to measure the displacement of one group of slotted line, and measured described one or each element in described slotted line and its position links.

14, as claim 12 or 13 described mechanical arms, it is characterized in that the linear movement measuring device comprises: a pair of pinch roller, an arbitrary end that is set at each lead of described pinch roller centering; And a sensor, the angular displacement that is used for detecting in the described roller at least one is set.

As claim 12 or 13 described mechanical arms, it is characterized in that 15, the linear movement measuring device comprises that a device is used to detect the device of at least one mark of described line.

16, mechanical arm as claimed in claim 13 is characterized in that, the linear movement measuring device comprises optics or magnetic sensor.

17, a kind of method of the arm of operating machine, described arm comprises at least one segment, and described segment has a plurality of hinged members, and described method comprises:

Control the position of control element in described or each segment with control device;

Measure on the above chain of described arm or each segment at least one element with respect to another relative positions at least with measurement mechanism;

Calculating is by the relative position of measurement mechanism measurement and the difference between the precalculated position;

The Correction and Control device compensates described difference.

18, a kind of mechanical arm equipment, it comprises: a plurality of vertical segments, it is arranged continuously along described arm, each segment can move with respect to other segments, determine a serpentine path or shape, wherein, each segment comprises a plurality of Connection Elements, each Connection Element can relative motion at least two dimensions with respect to adjacent Connection Element, and further comprise and be used for detecting described arm profile because the device that influences the relative theory profile variation of extraneous factor, and means for correcting, its with the control device that is used for described arm link be used for computing to small part correction pass to control device to compensate described arm profile because the variation that extraneous factor causes.

19, a kind of equipment that is used for determining relative position between two elements, each of described two elements can move relative to another, and wherein said equipment comprises the device that is used for the produce power bundle, and it is supported by first element; One energy sensing device array, it is used to detect described energy beam by the supporting of second element, it is characterized in that, the dimension scope that described array has is greater than the dimension scope of described energy beam, make the motion of relative second element of the element of winning cause the motion of energy beam, the degree that has shown described relative motion thus perhaps makes energy beam represent relative another the position of in the described element one with respect to the position of array.

20, the mechanical arm that has one or more segment, wherein each segment is by line traffic control, it is characterized in that, the tensioning of each line and/or the capstan that moves with clockwork spring influence, the control of moving of each line is determined by sensing device like this, and the linearity that described sensing device is used for directly and is independent of detecting each lead in capstan motion ground moves.

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