WO2018119759A1

WO2018119759A1 - Robot motion control method and related device

Info

Publication number: WO2018119759A1
Application number: PCT/CN2016/112678
Authority: WO
Inventors: 张志明
Original assignee: 深圳配天智能技术研究院有限公司
Priority date: 2016-12-28
Filing date: 2016-12-28
Publication date: 2018-07-05
Also published as: CN108513636A; CN108513636B

Abstract

A robot motion control method and a related device. A path-related third-order Bezier curve is used as a smooth track for a robot to move from a preceding track to a subsequent track, a time-related third-order Bezier curve is used for planning the speed of motion, the planned speed is used for determining location points to which the robot needs to move in each control cycle, and the location points compose the smooth track. The present application is of increased control accuracy and has a broadened scope of application.

Description

Robot motion control method and related device

Technical field

This invention relates to the field of motion control and, more particularly, to robot motion control techniques.

Background technique

The movement of the robot is carried out according to a pre-planned trajectory. The planned motion trajectory can be decomposed into multiple segments. See Figure 1a. A segment of motion trajectory consists of two segments, lc and ln. The robot needs to move from the trajectory lc to the trajectory ln. The trajectory lc can be called the anterior segment trajectory, and ln can be called the posterior segment trajectory. .

The transition of the two-segment trajectory can be a sharp-angled transition. As shown in Fig. 1a, after the robot moves to the end of the trajectory lc (at point O), the velocity drops to zero, and then moves on the trajectory ln at a certain speed. In this kind of transition mode, the initial velocity and the final velocity on the single-segment trajectory (lc or ln) are both 0, which will greatly reduce the working efficiency of the robot, and the frequent acceleration and deceleration motion will also generate the service life of the motor and the reducer. influences.

In order to solve the above problem, a smooth transfer method can be used between the tracks at both ends. That is, a smooth curve is planned between the two trajectories, and when the robot transitions from one trajectory to another in a smooth curve manner, the speed is not zero. At present, methods for planning smooth curves include vector addition and subtraction and arc transfer.

As shown in Fig. 1b, the vector addition and subtraction method is to add the interpolation point of the previous trajectory lc from the inflection point to the intersection point O by the space vector addition, and coincide with the interpolation point of the backward trajectory ln from the inflection point to the intersection point O, and the superimposed interpolation. The points form an arc of space that smoothes the trajectory. However, the smooth trajectory of this kind of superposition is uncertain and will change with the change of the trajectory speed of the two sections before and after, and the accuracy is low.

As shown in Fig. 1c, in the arc transfer method, the turn-out point A of the front track lc and the turn-out point B on the back track ln are determined, and the common cut circle of the two tracks before and after the turn-out point and the turn-in point are determined. The arc AB composed of the turning point and the turning point on the common tangent circle is a smooth transition track. However, the application range of this method is small, and it is definitely applicable only when the two trajectories need to be straight lines. However, the robot's motion track includes linear and circular transitions, arc and arc transitions in addition to linear and linear transitions. In the latter two types of transitions, since the straight line and the arc, the arc and the arc are not necessarily coplanar, it is not always possible to find the common tangent, which makes the method unsuitable.

Therefore, it is necessary to plan a smooth smooth trajectory for the robot and allow the robot to pass the smooth trajectory at a speed other than zero.

Summary of the invention

In view of this, the present invention provides a robot motion control method for controlling a robot to perform motion according to a pre-established smooth trajectory represented by a third-order Bezier curve of a path.

The application provides the following technical solutions:

In one aspect, the present application provides a robot motion control method for controlling a robot to move according to a pre-established smooth trajectory represented by a third-order Bezier curve of a path for each of a plurality of control cycles The position points to which the robot needs to move are determined within a control cycle, wherein each control cycle includes the following steps:

Determining a duration value from a first control period to a current control period; using a pre-built expression of a third-order Bezier curve on time, solving a value of a Bezier parameter corresponding to the duration value; wherein the third order with respect to time The Bezier curve represents a curve relationship between the Bezier parameter and the duration; the value of the Bezier parameter is substituted into the expression of the third-order Bezier curve of the path to obtain a position coordinate value; wherein the path is three The order Bezier curve represents a curve relationship between the Bezier parameter and the position coordinates; the position coordinate value is transmitted to the driving device to cause the driving device to move the robot to the position point indicated by the position coordinate value.

In one possible design, the method of constructing a third-order Bezier curve with respect to time includes:

Determining the temporal feature points T ₀ , T ₁ , T of the third-order Bezier curve with respect to time according to the position feature point of the third-order Bezier curve about the path, the speed of the preset starting point, and the speed of the preset end point. ₂ and T ₃ ; The expression of the third-order Bezier curve with respect to time constructed according to the time feature points T ₀ , T ₁ , T ₂ and T ₃ is: T(u)=T ₀ (1-u) ³ _{+ 3T 1 u (1-u} ) 2 + 3T 2 u 2 (1-u) + T 3 u 3, wherein, u is a Bezier parameter and u∈ [0,1], T (u ) represented along the The length of time required for the smooth trajectory motion represented by the third-order Bezier curve of the path.

In a possible design, the time of the third-order Bezier curve with respect to time is determined according to the position feature point of the third-order Bezier curve about the path, the speed of the preset starting point, and the speed of the preset end point. Feature points T ₀ , T ₁ , T ₂ and T ₃ , including:

Determining the time feature point T ₀ is 0; substituting the position feature point P ₀ , the position feature point P ₁ and the velocity υ _s into the expression

Solving the time feature point T ₁ , wherein the velocity υ _s is a preset speed of the robot at the starting point of the smooth track; and the position feature point P ₂ , the position feature point P _{3 ,} and the velocity υ _{f are} substituted into the expression

Solving a difference T _3-2 between the time feature point T ₃ and the time feature point T ₂ , wherein the speed υ _f is a speed of the preset robot at the end point of the smooth track; according to the difference T _{3 -2,} determining T ₂ and T _3.

In one possible design, the determining T ₂ and T ₃ according to the difference T _3-2 includes:

A preset time feature point T _{3 is obtained} , and the time feature point T _{3 is} subtracted from the difference value T _3-2 to obtain a time feature point T ₂ .

Substituting the position feature point P ₁ , the position feature point P ₂ , the velocity υ _s , the velocity υ _{f ,} and the time feature point T ₁ into the expression

Solving the time feature point T ₂ ;

The time feature point T _{2 is} added to the time difference point T _3-2 to obtain a time feature point T ₃ .

In one possible design, the third-order Bezier curve about the path is used as a smooth trajectory of the robot moving from the front trajectory to the back trajectory, and the steps of constructing the third-order Bezier curve about the path include:

Determining a position feature point of the third-order Bezier curve according to the front trajectory and the back trajectory, and constructing a third-order Bezier curve about the path according to the position feature point; wherein the position feature point includes a start point and a termination a point, the front trajectory has an inflection point, the rear trajectory has a turning point, and the starting point coincides with the inflection point, the end point coincides with the turning point, the starting point The tangent vector direction is the same as the tangent vector direction of the inflection point, and the tangent vector direction of the end point is the same as the tangent vector direction of the inflection point.

In another aspect, the present application provides a robot motion control device having a function of implementing robot motion control behavior in the above method. The function can be implemented by hardware or The corresponding software implementation is performed by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a possible design, the robot motion control device comprises a communication interface, a processor and a memory, the communication interface being connected to the driving device, wherein the memory stores program codes and data installed in the robot motion control device. The processor is configured to invoke program code and data in the memory to determine a location point to which the robot needs to move during each control cycle of the plurality of control cycles, and specifically perform the following steps:

Determining the duration value from the first control period to the current control period;

Solving a value of a Bezier parameter corresponding to the duration value using a pre-built expression of a third-order Bezier curve with respect to time; wherein the third-order Bezier curve with respect to time represents a curve relationship between the Bezier parameter and the duration ;

Substituting the value of the Bezier parameter into the expression of the third-order Bezier curve about the path, obtaining a position coordinate value; wherein the third-order Bezier curve about the path represents a curve between the Bezier parameter and the position coordinate relationship;

The position coordinate value is transmitted to the drive device through the communication interface to cause the drive device to move the robot to a position point indicated by the position coordinate value.

In still another aspect, an embodiment of the present invention provides a robot including the above-described robot motion control device, and a driving device that drives the robot to move to a position point indicated by the position coordinate value.

Compared with the prior art, the present application uses the third-order Bezier curve about the path as a smooth trajectory of the robot from the front trajectory to the back trajectory, and uses the third-order Bezier curve about time to plan the motion speed, and the planning speed is used. In determining the position point to which the robot needs to move during each control period, each position point constitutes the above-mentioned smooth trajectory, and the control precision of the present application is high and the application range is wide.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, obviously, the following The drawings in the description are only some of the embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

Figure 1a is a schematic diagram of a robot's motion trajectory;

FIG. 1b is a schematic diagram of path planning by vector addition and subtraction in the prior art; FIG.

1c is a schematic diagram of path planning by a circular arc transfer method in the prior art;

2 is a schematic diagram of a third-order Bezier curve for a path provided by the present application;

FIG. 3 is a schematic diagram of the movement of the control robot along the third-order Bezier curve provided by the present application; FIG.

4 is a flow chart of a robot motion control method provided by the present application;

FIG. 5 is a schematic structural diagram of a robot motion control apparatus provided by the present application; FIG.

6 is another schematic structural diagram of a robot motion control apparatus provided by the present application;

FIG. 7 is a schematic diagram showing the hardware structure of the robot motion control apparatus provided by the present application.

detailed description

The technical terms, abbreviations or abbreviations that may be used in the present invention are as follows:

TCP point: tool coordinate center point;

Linear motion: The robot TCP point moves along a linear path in Cartesian space;

Circular motion: The robot TCP point moves along a circular arc in Cartesian space;

CP: continuous motion, trajectory motion in Cartesian space, including linear motion and circular motion;

PTP: point-to-point motion, trajectory motion in joint space;

The Bezier curve is a curve composed of line segments and nodes. Orders can be used to represent Bezier curves of different shapes.

The formula for the n-order Bezier curve is:

Where b _i,n (t) is the Bernstein basis function,

P ₀ -P _n can be called a feature point or a control point of a Bezier curve, and a feature point can be used to define a Bezier curve, and a polygon composed of feature points is called a feature polygon. t=0 corresponds to the starting point P _{0 of the} Beizer curve, and t=1 corresponds to the end point P _{n of the} Beizer curve.

According to the general formula of the above n-order Bezier curve, the formula of the third-order Bezier curve can be known, that is, the third-order Bezier curve is obtained by substituting n=3 into the formula:

B(t)=P ₀ (1-t) ³ +3P ₁ t(1-t) ² +3P ₂ t ² (1-t)+P ₃ t ³ ,t∈[0,1].

A third-order Bezier curve P ₀ P ₃ as shown in FIG. 2, wherein four points of P ₀ , P ₁ , P _{2 ,} and P ₃ can define the Bezier curve. The curve starts at P ₀ to P ₁ , from P ₁ to P ₂ , and from P ₂ to P ₃ . It should be noted that generally the third-order Bezier curve does not pass P ₁ , P ₂ , and these two points only provide directions.

Deriving the Bezier curve, you can get the tangent vector of the Bezier curve at the beginning and end points.

then:

When t=0, B'(0)=n(P ₁ -P ₀ ), B′(0) is the tangent vector of the n-order Bezier curve at the starting point;

When t = 1, B '(1 ) = n (P n -P n-1), B' (1) is the n-order Bezier curves tangent vector at the end point.

Among them, the tangent vector is the tangential direction. It can be seen from the above tangent vector that the tangent direction of the n-th order Bezier curve at the starting point and the ending point is consistent with the first side and the last side of the feature polygon. Taking the third-order Bezier curve shown in Fig. 2 as an example, B'(0)=3(P ₁ -P ₀ ), B'(1)=3(P ₃ -P ₂ ), and the first side of FIG. 2 It is P ₁ P ₀ and the last edge is P ₃ P ₂ .

This application uses a Bezier curve as a smooth trajectory for the two-segment trajectory. The robot transitions from the front trajectory through the Bezier curve to the rear trajectory, and the speed of the transition motion is not zero.

In the present application, the third-order Bezier curve is used as a smooth trajectory. Of course, the smooth trajectory can also use other order Bezier curves. Taking the third-order Bezier curve as an example, the construction method of the third-order Bezier curve is introduced. It should be noted that the third-order Bezier curve here can be called the third-order Bezier curve about the path, so as to be the third-order Bezier curve with respect to time below. distinguish.

The position feature points of the third-order Bezier curve are determined according to the front and rear trajectories, and the third-order Bezier curve is constructed as a smooth trajectory according to the determined position feature points. Among them, the location feature points include a starting point and a ending point.

It can be understood that, as shown in FIG. 2, during the motion, the robot will deviate from the original trajectory at the end of the front trajectory lc and the beginning of the trajectory ln. Therefore, there is an inflection point A at the end of the front end trajectory lc. At the beginning of the trailing trajectory ln, there is a turn-in point B.

When constructing the third-order Bezier curve about the path, it is necessary to ensure that the starting point of the Bezier curve coincides with the turning point of the previous trajectory, the ending point of the Bezier curve coincides with the turning point of the back trajectory, and the Bezier curve is cut at the starting point. The vector direction is the same as the front trajectory in the direction of the tangent vector of the inflection point. The direction of the tangent vector of the Bezier curve at the end point is the same as the direction of the tangent vector of the trailing path at the point of entry.

The third-order Bezier curve about the path constructed above can be used as a smooth trajectory for the anterior segment trajectory and the posterior segment trajectory.

The present application provides a robot motion control method for controlling a robot to move according to the smooth trajectory represented by the third-order Bezier curve described above with respect to a path. The control method is used to determine a position to which the robot needs to move in each of a plurality of control periods (which may also be referred to as an interpolation period), as shown in FIG. 3, on a smooth trajectory represented by a third-order Bezier curve Each small dot indicates the position at which the robot moves to each control cycle.

As shown in FIG. 4, the following steps S41 to S41 are executed every control cycle.

Step S41: determining a duration value from the first control period to the current control period.

The duration value is the length of time from the first control period to the current control period. For example, if the control period is 1 millisecond and the current control period is the 81st control period, the duration from the first control period to the current control period is 0.08. s.

Step S42: Using the expression of the third-order Bezier curve with respect to time, the value of the Bezier parameter corresponding to the duration value is solved.

Wherein, the expression of the third-order Bezier curve about time is pre-built, and the third-order Bezier curve about time represents the relationship between the Bezier parameter and the duration.

The expression for the third-order Bezier curve constructed on time is:

T(u)=T ₀ (1-u) ³ +3T ₁ u(1-u) ² +3T ₂ u ² (1-u)+T ₃ u ³ .

Where T(u) represents the length of time required for the smooth trajectory motion represented by the third-order Bezier curve of the path, and T ₀ , T ₁ , T ₂ and T ₃ are the third-order Bezier curves of the time The time feature point, in the above-mentioned expression that has been constructed, the time feature points T ₀ , T ₁ , T _{2 ,} and T ₃ are known values. For how to determine the values of the four time feature points, see below. Narration.

Substituting the duration value determined in step S41 as T(u) into the above-mentioned expression constructed, the value of the Bezier parameter u corresponding to the duration value can be obtained, and the Bezier parameter can be simply referred to as a parameter. It should be noted that there are three Bezier parameters u solved. Since u ∈ [0, 1], the value in the range of [0, 1] is determined as the value of the Bezier parameter u.

Step S43: Substituting the value of the Bezier parameter into the expression of the third-order Bezier curve of the path to obtain the position coordinate value.

Wherein, the third-order Bezier curve about the path represents the relationship between the Bezier parameter and the position coordinate, and the expression is:

P(u)=P ₀ (1-u) ³ +3P ₁ u(1-u) ² +3P ₂ u ² (1-u)+P ₃ u ³ .

Wherein, P (u) represents a position coordinate on the third-order Bezier curve in the _{_{path, P 0, P 1, P}} 2 and P ₃ of the third-order Bezier curve on the positions of feature points of the path, has been constructed in the above-described expression Among them, P ₀ , P ₁ , P ₂ and P ₃ are all known values.

It should be noted that the third-order Bezier curve about the path is related to the third-order Bezier curve about time, and the Bezier parameter u in the two expressions is the same value. Therefore, P(u) can be solved by substituting the value of the Bezier parameter u solved in accordance with the third-order Bezier curve with respect to time into the above-described expression of the third-order Bezier curve of the path in step S42.

Step S44: Sending the position coordinate value to the driving device to cause the driving device to move the robot to the position point indicated by the position coordinate value.

Among them, a driving device (such as a drive controller) is provided in the robot to control the movement of the robot or the like. Sending the position coordinate value P(u) solved in step S43 to the driving device, the driving device generates a corresponding movement command according to the position coordinate value, and transmits the movement command to the moving component such as the robot arm to control the movement of the robot to the position coordinate value. The location point indicated. As shown in FIG. 3, if the current control period is the first control period, the control robot moves to the first small circle, and if the current control period is the second control period, the control robot moves to the second small dot. At the same time, the robot moves to the end of the smooth trajectory.

In the above robot motion control method, the third-order Bezier curve about the path is used as a smooth trajectory of the robot from the front trajectory to the rear trajectory, and the motion velocity is planned using the third-order Bezier curve with respect to time, and the planned speed is used for determination. The position point to which the robot needs to move during each control cycle, and each position point constitutes the above smooth track.

In the present application, the robot can transfer from the previous trajectory to the rear trajectory at a speed other than 0. The transit trajectory is a third-order Bezier curve about the path, and the construction of the curve does not need to rely on the robot on the two trajectories. The speed, therefore, can avoid the problem of low accuracy of smooth track constructed by vector addition and subtraction. Moreover, the curve is not a common cut circle for determining the trajectory of the front segment and the trajectory of the latter segment, and the problem of less applicability can be solved. The application can be applied to the trajectory transfer scenarios of various shapes, and the application range is wide.

After constructing a smooth trajectory, it is necessary to control the robot to move according to the smooth trajectory. The control process includes a speed planning process that determines how fast the robot passes the smooth trajectory.

It can be understood that the speed is related to the time and the path. The speed of the plan needs to be converted into a position point on the path. When the control robot moves to the position point within a certain time, the robot can be reflected according to the planned speed. motion. Therefore, in the robot motion control method shown in FIG. 4 above, the position point to which the motion is required is determined for each control period, and the robot moves at a certain speed from the viewpoint of the entire motion process.

The current speed planning scheme has S-type speed planning and T-type speed planning. The path length and the starting speed are known in the two speed planning schemes, and the speed is planned for the target speed or the target time. In the two speed planning schemes, it is necessary to ensure that the equal difference parameter corresponds to the length of the equal path, and therefore, it can only be applied to a straight line or an arc.

However, the present application uses the Bezier curve as a smooth trajectory, and the Bezier curve is a parametric curve. The path length cannot be accurately calculated and can only be calculated by numerical integration. Since the path points are sparsely dense, the equal parameters do not necessarily correspond to the equal path. Length, therefore, the existing speed planning scheme does not accurately plan the speed of the Bezier curve.

In this regard, the present application is directed to a third-order Bezier curve for a path, and determines a corresponding speed planning scheme, that is, adding a time dimension based on the coordinate dimension of the Bezier curve. By controlling the time feature points in the time dimension, the robot is controlled to meet the preset start and end speeds, so that the interpolation period of the speed plan corresponds to the parameters of the Bezier curve, and each point of the Bezier curve is the transit time. To control the speed change, so as to achieve the purpose of continuous speed.

Wherein, the Bezier curve of increasing the time dimension may be an expression of the above-mentioned third-order Bezier curve with respect to time, namely:

T(u)=T ₀ (1-u) ³ +3T ₁ u(1-u) ² +3T ₂ u ² (1-u)+T ₃ u ³ .

It can be understood that the Bezier parameter u is a variable in the expression, but the values of the time control points T ₀ , T ₁ , T ₂ and T ₃ need to be determined. After determining the four time feature points, the third-order Bezier curve about time can be constructed by substituting the above expression.

The following describes how to determine the value of the four time feature points.

Wherein, according to the position feature points (P ₀ , P ₁ , P ₂ and P ₃ ) of the third-order Bezier curve of the path, the speed of the preset starting point and the speed of the preset end point, the time-dependent is determined. The temporal feature points T ₀ , T ₁ , T ₂ and T _{3 of the} third-order Bezier curve.

Specifically, the time feature point T ₀ can be determined to be zero.

Substituting position feature point P ₀ , position feature point P ₁ and velocity υ _s into an expression

Feature computation time point T _1, wherein the velocity υ _s is set in advance in the robot starting a smooth trajectory velocity, i.e., the starting point position of the feature point P _0.

Substituting the position feature point P ₂ , the position feature point P _{3 ,} and the velocity υ _f into the expression

Solving a difference T _3-2 between the time feature point T ₃ and the time feature point T ₂ , wherein the speed υ _f is a preset speed of the robot at the end point of the smooth trajectory, and the end point is the position feature point P ₃ .

Based on the difference T _3-2 , T ₂ and T _{3 are} determined.

It should be noted that T ₀ and T ₁ can be accurately calculated based on the position feature points and the preset start and end speeds. As for T ₂ and T ₃ , the difference T _3-2 between T ₃ and T ₂ can be calculated. Therefore, only the difference between T ₃ and T ₂ is required to satisfy T _3-2 , that is, both are satisfied. Any difference between T ₃ and T ₂ of T _3-2 is acceptable. The following two determination methods can be provided in the present application, and it should be noted that the following two types are not limited.

In a specific example, the value of the time feature point T ₃ may be set in advance, the value indicating the total duration of the smoothed trajectory, and the time feature point T _{3 is} subtracted from the difference T _3-2 to obtain the time feature. Point T ₂ .

In another specific example, the position of the feature point may be P _1, the position of the feature point P _2, the speed υ _s, and the velocity υ _f characteristic time point T ₁ is substituted into the expression

The time feature point T _{2 is} solved; the time feature point T _{2 is} added to the difference value T _3-2 to obtain a time feature point T ₃ .

Where the expression

and

The way to get it is:

Expressions for the third-order Bezier curve on the path, respectively, P(u)=P ₀ (1-u) ³ +3P ₁ u(1-u) ² +3P ₂ u ² (1-u)+P ₃ u ³ Deriving at the starting point P ₀ and the ending point P ₃ , obtaining P′(0)=-3P ₀ +3P ₁ and P′(1)=-3P ₂ +3P ₃ ;

The expression T(u)=T ₀ (1-u) ³ +3T ₁ u(1-u) ² +3T ₂ u ² (1-u)+T ₃ u ³ respectively for the third-order Bezier curve with respect to time Deriving at the starting point P ₀ and the ending point P ₃ , obtaining T'(0)=-3T ₀ +3T ₁ and T'(1)=-3T ₂ +3T ₃ .

Where u=0 corresponds to the starting point P ₀ , and u=1 corresponds to the ending point P ₃ .

According to P'(0)=-3P ₀ +3P ₁ and T'(0)=-3T ₀ +3T ₁ , the following expression about the velocity at the starting point can be obtained:

According to P'(1)=-3P ₂ +3P ₃ and T'(1)=-3T ₂ +3T ₃ , the following expression about the velocity at the end point can be obtained:

Wherein T ₃ -T ₂ can be represented as T _3-2 .

Let T ₀ be 0, and the expression can be derived from the above two expressions.

and

In addition, if

The above expression can be written as:

Further, you can

Written as

In the above derivation process, the first derivative formula of the Bezier curve is used to derive the influence of the time feature point on the velocity of the beginning and the end, and then the time on each feature point is derived from the velocity of the beginning and the end and the spatial relationship of the feature point.

See Figure 5, which shows the structure of the robot motion control device provided by the present application.

The robot motion control device is applied to the robot, and specifically may be a controller or a processor of the robot, configured to control the robot to perform motion according to a pre-established smooth trajectory represented by a third-order Bezier curve of the path, and the control device is controlled in each Determine the position to which the robot needs to move during the cycle.

As shown in FIG. 5, the control device specifically includes:

The duration value determining unit 51 is configured to determine a duration value from the first control period to the current control period;

a parameter value determining unit 52, configured to solve a value of a Bezier parameter corresponding to the duration value by using a pre-built expression of a third-order Bezier curve about time; wherein the third-order Bezier curve about time represents Bezier a curve relationship between parameters and duration;

a coordinate value determining unit 53 for substituting the value of the Bezier parameter into the expression of the third-order Bezier curve about the path to obtain a position coordinate value; wherein the third-order Bezier curve about the path represents Bezier a curve relationship between parameters and position coordinates;

Moving to the coordinate value unit 54 for transmitting the position coordinate value to the driving device to cause the driving device to move the robot to a position point indicated by the position coordinate value.

Referring to Figure 6, there is shown another configuration of the robotic motion control device provided by the present application. The control device may further include a time curve construction unit 55 and a path curve construction unit 56 based on the control device illustrated in FIG. 5 described above. It should be noted that the components 51 to 54 in FIG. 6 can be referred to the above description, and are not described herein.

a time curve construction unit 55 for constructing a third-order Bezier curve with respect to time;

The path curve construction unit 56 is configured to construct a third-order Bezier curve about the path, and the third-order Bezier curve about the path is used as a smooth trajectory of the robot moving from the front trajectory to the back trajectory.

Wherein, in the aspect of constructing the third-order Bezier curve about the path, the path curve construction unit is specifically configured to:

Determining a position feature point of the third-order Bezier curve according to the front trajectory and the back trajectory, and constructing a third-order Bezier curve about the path according to the position feature point; wherein the position feature point includes a start point and a termination a point, the front trajectory has an inflection point, the rear trajectory has a turning point, and the starting point coincides with the inflection point, the end point coincides with the turning point, the starting point The tangent vector direction is the same as the tangent vector direction of the inflection point, and the end point is cut The vector direction is the same as the tangent vector direction of the turn-in point.

Wherein, in terms of constructing a third-order Bezier curve with respect to time, the time curve construction unit is specifically used for:

Determining the temporal feature points T ₀ , T ₁ , T ₂ and T ₃ of the third-order Bezier curve with respect to time according to the position feature points P ₀ , P ₁ , P ₂ and P ₃ of the third-order Bezier curve of the path;

According to the time feature points T ₀ , T ₁ , T ₂ and T ₃ , the expression of the third-order Bezier curve with respect to time is:

T(u)=T ₀ (1-u) ³ +3T ₁ u(1-u) ² +3T ₂ u ² (1-u)+T ₃ u ³ , where u is the Bezier parameter and u∈[0 , 1], T(u) represents the length of time required for smooth trajectory motion along the third-order Bezier curve of the path.

Wherein, the temporal feature points T ₀ , T ₁ , T ₂ of the third-order Bezier curve with respect to time are determined according to position feature points P ₀ , P ₁ , P ₂ and P ₃ of the third-order Bezier curve with respect to the path. In the aspect of T ₃ , the time curve construction unit is specifically configured to:

Determining that the time feature point T ₀ is 0;

Solving a time feature point T ₁ , wherein the speed υ _s is a speed of a preset robot at a starting point of the smooth track;

Solving a difference T _3-2 between the time feature point T ₃ and the time feature point T ₂ , wherein the speed υ _f is a preset speed of the robot at the end point of the smooth track;

Based on the difference T _3-2 , T ₂ and T _{3 are} determined.

In an example, in the aspect of determining T ₂ and T ₃ according to the difference T _3-2 , the time curve construction unit is specifically configured to:

In another example, in the aspect of determining T ₂ and T ₃ according to the difference T _3-2 , the time curve construction unit is specifically configured to:

Feature computation time point T _2;

FIG. 7 is a schematic diagram showing the hardware structure of the robot motion control apparatus provided by the present application. As shown in FIG. 7, the robot motion control apparatus may include a processor 1, a communication interface 2, a memory 3, and a communication bus 4, wherein the processor 1, the communication interface 2, and the memory 3 complete communication with each other via the communication bus 4.

The memory 3 is configured to store program codes and data installed in the robot motion control device. The memory 3 may be a high speed RAM memory or a non-volatile memory such as a magnetic disk memory. The program code includes operational instructions of the processor.

The processor 1 may be a central processing unit CPU, or an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

The processor 1 is configured to call program code and data in the memory 3 to determine a position point to which the robot needs to move in each control cycle of the plurality of control cycles, thereby controlling the robot according to the pre-built related path The smooth trajectory represented by the third-order Bezier curve moves. The processor 1 calls the program code and the data in the memory 3 to determine a location point to which the robot needs to move during each control period of the plurality of control cycles, and specifically includes the following steps:

Sending the position coordinate value to the driving device through the communication interface 2, so that the driving device is installed The robot is moved to a position point indicated by the position coordinate value. The communication interface 2 is for connection to a drive device to transmit position coordinates to the drive device. The communication interface 2 can be an interface of a communication module, such as an interface of a GSM module, an interface of a PCI module, or the like.

The application also provides a robot, including a robot motion control device and a driving device, wherein:

The robot motion control device is configured to determine a position point to which the robot needs to move in each control cycle; wherein each control cycle performs the following steps: determining a duration value determined from the first control cycle to the current control cycle; a pre-built expression of a third-order Bezier curve about time, solving a value of a Bezier parameter corresponding to the duration value; wherein the third-order Bezier curve about time represents a curve relationship between a Bezier parameter and a duration; Substituting the value of the Bezier parameter into the expression of the third-order Bezier curve about the path, obtaining a position coordinate value; wherein the third-order Bezier curve about the path represents a curve between the Bezier parameter and the position coordinate a relationship; transmitting the position coordinate value to the driving device;

The driving device is configured to drive the robot to move to a position point indicated by the position coordinate value.

Among them, the robot can be specifically a mechanical arm.

The steps of a method or algorithm described in connection with the present disclosure may be implemented in a hardware, or may be implemented by a processor executing software instructions. The software instructions may be comprised of corresponding software modules that may be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable hard disk, CD-ROM, or any other form of storage well known in the art. In the medium. An exemplary storage medium is coupled to the processor to enable the processor to read information from, and write information to, the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC.

Those skilled in the art will appreciate that in one or more examples described above, the functions described herein can be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored in a readable medium or transmitted as one or more instructions or code on a readable medium.

The specific embodiments described above carry out the objects, technical solutions and beneficial effects of the present invention. In the following detailed description, it should be understood that the foregoing is only the embodiment of the present invention, and is not intended to limit the scope of the present invention, any of which is based on the technical solution of the present invention. Modifications, equivalent substitutions, improvements, etc., are intended to be included within the scope of the invention.

Claims

A robot motion control method for controlling a robot to move according to a pre-built smooth trajectory represented by a third-order Bezier curve of a path for each control cycle in a plurality of control cycles Determine the location point to which the robot needs to move, and each of the control cycles includes the following steps:

Determining the duration value from the first control period to the current control period;

Solving a value of a Bezier parameter corresponding to the duration value using a pre-built expression of a third-order Bezier curve with respect to time; wherein the third-order Bezier curve with respect to time represents a curve relationship between the Bezier parameter and the duration ;

Substituting the value of the Bezier parameter into the expression of the third-order Bezier curve about the path, obtaining a position coordinate value; wherein the third-order Bezier curve about the path represents a curve between the Bezier parameter and the position coordinate relationship;

The position coordinate value is transmitted to the driving device to cause the driving device to move the robot to a position point indicated by the position coordinate value.
The robot motion control method according to claim 1, wherein the method of constructing the third-order Bezier curve with respect to time comprises:

Determining the temporal feature points T 0 , T 1 , T of the third-order Bezier curve with respect to time according to the position feature point of the third-order Bezier curve about the path, the speed of the preset starting point, and the speed of the preset end point. 2 and T 3 ;

According to the time feature points T 0 , T 1 , T 2 and T 3 , the expression of the third-order Bezier curve with respect to time is:

T(u)=T 0 (1-u) 3 +3T 1 u(1-u) 2 +3T 2 u 2 (1-u)+T 3 u 3 , where u is the Bezier parameter and u∈[0 , 1], T(u) represents the length of time required for smooth trajectory motion along the third-order Bezier curve of the path.
The robot motion control method according to claim 2, wherein the determining is based on a position feature point of a third-order Bezier curve about a path, a speed of a preset starting point, and a speed of a preset end point. The temporal feature points T 0 , T 1 , T 2 and T 3 of the third-order Bezier curve of time include:

Determining that the time feature point T 0 is 0;

Substituting position feature point P 0 , position feature point P 1 and velocity υ s into an expression
Solving a time feature point T 1 , wherein the speed υ s is a speed of a preset robot at a starting point of the smooth track;

The position of the feature point P 2, P 3 and the positions of feature points into Expression velocity υ f
Solving a difference T 3-2 between the time feature point T 3 and the time feature point T 2 , wherein the speed υ f is a preset speed of the robot at the end point of the smooth track;

Based on the difference T 3-2 , T 2 and T 3 are determined.
The robot motion control method according to claim 3, wherein the determining T 2 and T 3 according to the difference T 3-2 comprises:

A preset time feature point T 3 is obtained , and the time feature point T 3 is subtracted from the difference value T 3-2 to obtain a time feature point T 2 .
The robot motion control method according to claim 3, wherein the determining T 2 and T 3 according to the difference T 3-2 comprises:

Substituting the position feature point P 1 , the position feature point P 2 , the velocity υ s , the velocity υ f , and the time feature point T 1 into the expression
Solving the time feature point T 2 ;

The time feature point T 2 is added to the time difference point T 3-2 to obtain a time feature point T 3 .
The robot motion control method according to claim 1, wherein the third-order Bezier curve about the path is used as a smooth trajectory of the robot moving from the front trajectory to the rear trajectory, and the third-order Bezier curve of the path is constructed. Methods include:

Determining a position feature point of the third-order Bezier curve according to the front trajectory and the back trajectory, and constructing a third-order Bezier curve about the path according to the position feature point;

Wherein the location feature point includes a start point and a termination point, and the front track has an exit a point, the back track has a turn-in point, and the start point coincides with the turn-out point, the end point coincides with the turn-in point, the cut vector direction of the start point and the turn-out The tangent vector direction of the point is the same, and the tangent vector direction of the end point is the same as the tangent vector direction of the inflection point.
A robot motion control apparatus for controlling a robot to move according to a pre-established smooth trajectory represented by a third-order Bezier curve of a path, the control apparatus for each control cycle in a plurality of control cycles Determining a location point to which the robot needs to move; the control device includes:

a duration value determining unit for determining a duration value from the first control period to the current control period;

a parameter value determining unit for solving a value of a Bezier parameter corresponding to the duration value using a pre-built expression of a third-order Bezier curve with respect to time; wherein the third-order Bezier curve with respect to time represents a Bezier parameter a curve relationship with the duration;

a coordinate value determining unit, configured to substitute a value of the Bezier parameter into the expression of the third-order Bezier curve about the path to obtain a position coordinate value; wherein the third-order Bezier curve about the path represents a Bezier parameter a curve relationship with position coordinates;

Moving to a coordinate value unit for transmitting the position coordinate value to the driving device to cause the driving device to move the robot to a position point indicated by the position coordinate value.
The robot motion control device according to claim 7, further comprising:

a time curve construction unit for constructing the third-order Bezier curve about time;

Wherein, in terms of constructing a third-order Bezier curve with respect to time, the time curve construction unit is specifically used for:

Determining the temporal feature points T 0 , T 1 , T of the third-order Bezier curve with respect to time according to the position feature point of the third-order Bezier curve about the path, the speed of the preset starting point, and the speed of the preset end point. 2 and T 3 ;

According to the time feature points T 0 , T 1 , T 2 and T 3 , the expression of the third-order Bezier curve with respect to time is:

T(u)=T 0 (1-u) 3 +3T 1 u(1-u) 2 +3T 2 u 2 (1-u)+T 3 u 3 , where u is the Bezier parameter and u∈[0 , 1], T(u) represents the length of time required for smooth trajectory motion along the third-order Bezier curve of the path.
The robot motion control apparatus according to claim 7, wherein said determining is based on a position feature point of a third-order Bezier curve with respect to a path, a speed of a preset starting point, and a speed of a preset end point. Aspects of the temporal feature points T 0 , T 1 , T 2 and T 3 of the third-order Bezier curve of time, the time curve construction unit being specifically used for:

Determining that the time feature point T 0 is 0;

Substituting position feature point P 0 , position feature point P 1 and velocity υ s into an expression
Solving a time feature point T 1 , wherein the speed υ s is a speed of a preset robot at a starting point of the smooth track;

Substituting the position feature point P 2 , the position feature point P 3 , and the velocity υ f into the expression
Solving a difference T 3-2 between the time feature point T 3 and the time feature point T 2 , wherein the speed υ f is a preset speed of the robot at the end point of the smooth track;

Based on the difference T 3-2 , T 2 and T 3 are determined.
The robot motion control device according to claim 9, wherein in the determining the T 2 and the T 3 according to the difference T 3-2 , the time curve constructing unit is specifically configured to:

A preset time feature point T 3 is obtained , and the time feature point T 3 is subtracted from the difference value T 3-2 to obtain a time feature point T 2 .
The robot motion control device according to claim 9, wherein in the determining the T 2 and the T 3 according to the difference T 3-2 , the time curve constructing unit is specifically configured to:

Substituting the position feature point P 1 , the position feature point P 2 , the velocity υ s , the velocity υ f , and the time feature point T 1 into the expression
Solving the time feature point T 2 ;

The time feature point T 2 is added to the time difference point T 3-2 to obtain a time feature point T 3 .
The robot motion control device according to claim 7, further comprising:

a path curve construction unit for constructing the third-order Bezier curve about the path, the The third-order Bezier curve of the path is used as a smooth trajectory of the robot moving from the front trajectory to the back trajectory;

Wherein, in the aspect of constructing the third-order Bezier curve about the path, the path curve construction unit is specifically configured to:

Determining a position feature point of the third-order Bezier curve according to the front trajectory and the back trajectory, and constructing a third-order Bezier curve about the path according to the position feature point; wherein the position feature point includes a start point and a termination a point, the front trajectory has an inflection point, the rear trajectory has a turning point, and the starting point coincides with the inflection point, the end point coincides with the turning point, the starting point The tangent vector direction is the same as the tangent vector direction of the inflection point, and the tangent vector direction of the end point is the same as the tangent vector direction of the inflection point.
A robot motion control device, comprising: a communication interface, a processor and a memory, wherein the communication interface is connected to a driving device, wherein the memory stores program codes and data installed in the robot motion control device. The processor is configured to invoke program code and data in the memory to determine a location point to which the robot needs to move during each control cycle of the plurality of control cycles, and specifically includes the following steps:

Determining the duration value from the first control period to the current control period;

Solving a value of a Bezier parameter corresponding to the duration value using a pre-built expression of a third-order Bezier curve with respect to time; wherein the third-order Bezier curve with respect to time represents a curve relationship between the Bezier parameter and the duration ;

Substituting the value of the Bezier parameter into a pre-built expression of a third-order Bezier curve about the path to obtain a position coordinate value; wherein the third-order Bezier curve about the path represents between the Bezier parameter and the position coordinate Curve relationship

The position coordinate value is transmitted to the drive device through the communication interface to cause the drive device to move the robot to a position point indicated by the position coordinate value.
A robot comprising: a robot motion control device and a driving device, wherein:

The robot motion control device is configured to determine a position point to which the robot needs to move during each of the plurality of control cycles; wherein each control cycle performs the following steps: determining the first control cycle to the current control cycle a duration value; using a pre-built expression of a third-order Bezier curve for time, solving a value of a Bezier parameter corresponding to the duration value; wherein The third-order Bezier curve represents the curve relationship between the Bezier parameter and the duration; the value of the Bezier parameter is substituted into the pre-built expression of the third-order Bezier curve about the path to obtain the position coordinate value; The third-order Bezier curve about the path represents a curve relationship between the Bezier parameter and the position coordinates; the position coordinate value is sent to the driving device;

The driving device is configured to drive the robot to move to a position point indicated by the position coordinate value.