RU2187426C2 - Self-adaptive electric drive of robot - Google Patents

Abstract

FIELD: robotics, namely systems for controlling robot drive mechanisms. SUBSTANCE: robot drive includes in addition second position pickup, functional generator, fourth and fifth multiplying units, third signal setter and eight adder. It provides complete invariance of dynamic properties of electric drive for continuous and rapid changes of its dynamic loading characteristics at motion of manipulator according to its all four freedom degrees. EFFECT: enhanced dynamic accuracy of drive control. 3 dwg

Description

 The invention relates to robotics and can be used to create robot drive control systems.

 A device for controlling a robot drive is known, comprising a first multiplication unit and a first adder connected in series, an amplifier and an engine connected in series with the first speed sensor directly and via a gearbox with a first position sensor, the output of which is connected to the first input of the second adder connected to the second input to the input of the device, the second position sensor, the third adder, the fourth adder, the first quadrator and the second multiplication unit, the second input of the cat The second one is connected to the output of the mass sensor and the first input of the third multiplication unit, and the output to the first input of the fifth adder, connected by the second input to the output of the first signal generator, and by the third input to the output of the second quadrator, the input of which is connected to the output of the third adder and the first input of the sixth the adder connected by the output to the first input of the fourth multiplication unit, and the second input to the output of the third multiplication unit, the second input of which is connected to the output of the fourth adder connected by the second input to the output of W cerned setpoint signal, the output of the third setpoint signal is connected to the second input of the third adder, and a second velocity sensor output is connected to a second input of the fourth multiplier. In addition, it contains a fifth multiplication unit, a seventh adder and a relay unit and an eighth adder connected in series, the output of which is connected to the second input of the first adder connected by the output to the amplifier input, the output of the first speed sensor is connected to the input of the relay unit, to the second input of the eighth adder and the first input of the seventh adder, the second input of which is connected to the output of the second adder, and the output to the first input of the first multiplication unit connected by the second input to the output of the fifth adder, the first input the fifth multiplication block is connected to the output of the fourth multiplication block, the second input is connected to the output of the first speed sensor, and the output is connected to the third input of the eighth adder (see AS of the USSR 1484702, MKI B 25 J 13/00, 1989).

 The disadvantage of this device is that it is intended only for a rotary drive of the first degree of mobility of the robot. To drive the extension of the horizontal link (the third degree of mobility), this device will not provide the required accuracy and stability.

 A self-adjusting robot electric drive is also known, comprising a first adder, a first multiplication unit, a second adder, an amplifier and an engine connected to the first speed sensor directly and through a reducer, with a gear driving a rail fixed to the horizontal link of the robot, and an engine the first position sensor mounted on a vertical link and measuring the position of a characteristic point of the horizontal link relative to the vertical, connected in series the relay block and the third adder, the second input of which is connected to the output of the first speed sensor, the input of the relay block and the second input of the first adder, the first signal master, the fourth adder, the fifth adder connected to the second input of the second signal master, the second multiplication unit , the sixth adder and the third block of multiplication, as well as the mass sensor, and the output of the position sensor is connected to the first input of the seventh adder connected by the second input to the input of the drive, and the output to the first at the input of the first adder, the output of the third adder is connected to the second input of the second adder, the second speed sensor and a quadrator are connected in series, the output of which is connected to the second input of the third multiplication unit, the output connected to the third negative input of the third adder, the output of the mass sensor is connected to the second inputs of the first and the second multiplication blocks, the output of the position sensor is connected to the second input of the fourth adder, the output of which is connected to the second input of the sixth adder, and the output of the first adder connected to the third input of the second adder (cm. RF patent 2037173, BI 16, 1995).

The disadvantage of this device is that it is effective only for the executive body of the robot, which has three degrees of mobility. However, with three degrees of mobility, the robot significantly reduces the working area (service area). For example, when working on a conveyor, it is desirable that the robot can move along this conveyor, accompanying a moving product and performing the required technological operations. However, with the introduction of the fourth linear degree of mobility q ₄ , additional perturbing moment effects appear in the drive in question, which significantly worsen its quality indicators. As a result, the task arises of compensating for these harmful momentary effects by introducing additional correction signals.

 The task to which the claimed technical solution is directed is to ensure complete invariance of the dynamic properties of the electric drive to continuous and rapid changes in its dynamic moment load characteristics when the manipulator moves along all four degrees of mobility and, thereby, increase the dynamic control accuracy.

The technical result that can be obtained by implementing the claimed technical solution is expressed in the formation of an additional control signal supplied to the input of the drive, which provides an additional moment effect compensating for the harmful moment effect from the fourth degree of mobility (see coordinate q ₄ ) on quality performance indicators of the drive in question.

 The problem is solved in that in a self-adjusting electric drive of the robot, containing a first adder, a first multiplication unit, a second adder, an amplifier and an engine connected in series with the first speed sensor directly and through a gearbox with a gear driving the rack fixed motionless on a horizontal link the robot, and the engine of the first position sensor mounted on a vertical link and measuring the position of a characteristic point of the horizontal link relative to the vertical, therefore, the connected relay unit and the third adder, the second input of which is connected to the output of the first speed sensor, the input of the relay unit and the second input of the first adder, the first signal master, the fourth adder, the fifth adder connected to the second input of the second signal master, the second block multiplication, the sixth adder and the third unit of multiplication, as well as a mass sensor, and the output of the position sensor is connected to the first input of the seventh adder connected to the input of the drive by the second input ode, and the output to the first input of the first adder, the output of the third adder is connected to the second input of the second adder, the second speed sensor and the quadrator are connected in series, the output of which is connected to the second input of the third multiplication unit, the output connected to the third input of the third adder, the output of the mass sensor connected to the second inputs of the first and second multiplication units, the output of the position sensor is connected to the second input of the fourth adder, the output of which is connected to the second input of the sixth adder, and the output of the first the matrix is connected to the third input of the second adder, an additional second position sensor, a functional converter, a fourth multiplication unit, the second input of which is connected to the output of the acceleration sensor and a fifth multiplication unit, the output of which is connected to the fourth input of the third adder, and also the third a signal adjuster and an eighth adder, the second input of which is connected to the output of the mass sensor, and the output to the second input of the fifth multiplication block.

 A comparative analysis of the essential features of the proposed technical solution with the essential features of analogues and prototype indicates its compliance with the criterion of "novelty."

 Moreover, the distinctive features of the claims provide high accuracy and stability of the robot drive in conditions of a significant change in load parameters.

 Figure 1 presents a diagram of the proposed self-tuning electric robot. Figure 2 presents the kinematic diagram of the Executive body of the robot, and figure 3 shows a top view in projection on the horizontal plane xy.

 The self-adjusting electric drive of the robot contains a first adder 1, a first multiplication unit 2, a second adder 3, an amplifier 4 and an engine 5 connected in series with the first speed sensor 6 directly and through a reducer 7 with a gear 8 driving the rail (in FIG. shown), fixed motionless on the horizontal link of the robot (figure 2), and the engine of the first position sensor 9 mounted on a vertical link and measuring the position of a characteristic point of the horizontal link relative to the vertical, subsequently the reliably connected relay unit 10 and the third adder 11, the second input of which is connected to the output of the first speed sensor 6, the input of the relay unit 10 and the second input of the first adder 1, are connected in series to the first signal setter 12, the fourth adder 13, and the fifth adder 14 to the second input which is connected to the second signal adjuster 15, the second multiplication unit 16, the sixth adder 17 and the third multiplication unit 18, as well as the mass sensor 19, the output of the position sensor 9 being connected to the first input of the seventh adder 20 connected to the second input by the electric drive, and the output to the first input of the first adder 1, the output of the third adder 11 is connected to the second input of the second adder 3, the second speed sensor 21 and the square 22 are connected in series, the output of which is connected to the second input of the third multiplication unit 18, the output connected to the third the negative input of the third adder 11, the output of the mass sensor 19 is connected to the second inputs of the first 2 and second 16 multiplication units, the output of the position sensor 9 is connected to the second input of the fourth 13 adder, the output of which is connected to the second input of the sixth adder 17, and the output of the first adder 2 is connected to the third input of the second adder 3, the second position sensor 23, the functional converter 24, the fourth multiplication unit 25, the second input of which is connected to the output of the acceleration sensor 26 and the fifth multiplication unit 27, are connected in series the output of which is connected to the fourth input of the third adder 11, as well as the third signal setter 28 and the eighth adder 29, the second input of which is connected to the output of the mass sensor 19, and the output to the second input yatogo multiplying unit 27.

скорости изменения соответствующих обобщенных координат

ε - ошибка привода (величина рассогласования);
m₂, m₃, m_г - соответственно массы второго, третьего звеньев исполнительного органа и захваченного груза;
l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ = const - расстояние от оси вращения горизонтального звена до его центра масс при q₃=0;
l₃ = const - расстояние от центра масс горизонтального звена до средней точки охвата;

скорость вращения ротора двигателя;
U*, U - соответственно усиливаемый сигнал и сигнал управления двигателем 5.The following notation is introduced in the drawings:
q _in - signal of the desired position;
q _i - the corresponding generalized coordinates of the executive body of the robot

rate of change of the corresponding generalized coordinates

ε is the drive error (mismatch value);
m ₂ , m ₃ , m _g - respectively, the mass of the second, third links of the executive body and the captured cargo;
l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ = const is the distance from the axis of rotation of the horizontal link to its center of mass at q ₃ = 0;
l ₃ = const is the distance from the center of mass of the horizontal link to the midpoint of coverage;

rotor speed of the engine;
U *, U - respectively, the amplified signal and the engine control signal 5.

The device operates as follows. The error signal ε after correction in units 1, 2, 3, amplifying, is supplied to the motor 5, causing its shaft into a rotary motion with a direction and velocity (acceleration) depending on the magnitude of the incoming U signal friction moments and external torque impact _M. The electric drive when working with various loads, as well as due to the mutual influence of the degrees of mobility of the executive body, has variable torque characteristics that can vary widely. This reduces the quality indicators of the electric drive and even leads to a loss of stability of its operation. As a result, a problem arises related to ensuring the invariance of the dynamic properties of the electric drive to continuous and rapid changes in its momentary load characteristics, which ensures the stability of a given quality of the control system.

The drive in question controls the generalized coordinate q ₃ . The design of the robot (figure 2) is the most typical for domestic and foreign industrial robots.

This design allows vertical rectilinear movement of the load (coordinate q ₂ ), rotation in the horizontal plane (coordinate q ₁ ) and horizontal rectilinear movements (coordinates q ₃ and q ₄ ).

и груза m_г. В связи с этим для качественного управления координатой q₃ необходимо точно компенсировать отрицательное влияние изменения этих координат, а также переменной массы груза m_г на динамические свойства рассматриваемого привода (координата q₃).The moment characteristics of the drive controlling the coordinate q ₃ substantially depend on the change in coordinates

and cargo m _g . In this regard, for quality control of the q ₃ coordinate, it is necessary to precisely compensate for the negative effect of changes in these coordinates, as well as the variable mass of the load m _g on the dynamic properties of the drive in question (q ₃ coordinate).

 Suppose that the horizontal link is moved by an electric drive by means of a gear-rack transmission. Moreover, the rail is installed along the horizontal link, and the gear 8 is on the output shaft of the gearbox 7 of the electric drive and has a radius r.

Сила F в процессе движения робота создает на выходном валу редуктора 7 момент, равный
M_в=F•r. (1)
С учетом соотношения (1), а также уравнения электрической

и механической

цепей электродвигателя постоянного тока с постоянными магнитами или независимого возбуждения рассматриваемый привод, управляющий координатой q₃, можно описать следующим дифференциальным уравнением

где R - активное сопротивление якорной цепи двигателя; J - момент инерции якоря двигателя и вращающихся частей редуктора, приведенный к валу двигателя; К_м - коэффициент крутящего момента; K_w - коэффициент противоЭДС; К_в - коэффициент вязкого трения; i_p - передаточное отношение редуктора; М_стр - момент сухого трения; К_у - коэффициент усиления усилителя 4; i - ток якоря двигателя 5;

ускорение вращения вала двигателя третьей степени подвижности.It is easy to show that during the movement of the robot, a force acts on its horizontal link

The force F during the movement of the robot creates a moment on the output shaft of the gearbox 7 equal to
M _in = F • r. (1)
Taking into account relation (1), as well as the equation of electric

and mechanical

chains of a DC motor with permanent magnets or independent excitation, the drive in question, which controls the coordinate q ₃ , can be described by the following differential equation

where R is the active resistance of the engine armature circuit; J is the moment of inertia of the motor armature and the rotating parts of the gearbox, reduced to the motor shaft; K _m - coefficient of torque; K _w - counter-emf coefficient; K _in - coefficient of viscous friction; i _p - gear ratio; M _p is the moment of dry friction; To _y - the gain of the amplifier 4; i is the armature current of the motor 5;

acceleration of rotation of the motor shaft of the third degree of mobility.

и m_г. В результате для реализации поставленной выше задачи необходимо сформировать такое корректирующее устройство, которое стабилизировало бы параметры привода таким образом, чтобы он описывался дифференциальным уравнением с постоянными желаемыми параметрами.From (2) it can be seen that the parameters of this equation, and therefore, the parameters and dynamic properties of the drive controlling the coordinate q ₃ , are essentially variable, depending on

and m _g . As a result, in order to accomplish the above task, it is necessary to form such a corrective device that would stabilize the drive parameters so that it is described by a differential equation with constant desired parameters.

Первый и второй положительные входы сумматоров 13 и 14 имеют единичные коэффициенты усиления. На выходах первого 12 и второго 15 задатчиков сигнала соответственно формируются сигналы l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ = const и l₃=const. В результате на выходе сумматора 13 формируется сигнал l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ +q₃, а на выходе сумматора 14 - сигнал l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ +l₃+q₃, так как датчик 9 измеряет положение точки горизонтального звена, отстоящей от центра масс этого звена на расстояние l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ .
Первый положительный вход сумматора 17 имеет коэффициент усиления r/i_p, а его второй положительный вход - коэффициент усиления r m₃/i_p. В результате на выходе сумматора 17 формируется сигнал r[m₃(l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ +q₃)+m_r(l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ +q₃+l₃)]/i_p, а на выходе блока умножения 18 - сигнал

так как датчик 21 установлен в первой степени подвижности робота (фиг.2) и измеряет координату

Датчик положения 23 измеряет угол поворота q₁, а датчик 26 ускорение в четвертой степени подвижности

Функциональный преобразователь 24 реализует функцию sinq₁. В результате на выходе блока 25 умножения формируется сигнал

Задатчик сигнала 28 формирует сигнал m₃=const. Первый и второй положительные входы сумматора 29 имеют единичные коэффициенты усиления. В результате на четвертый положительный вход сумматора 11, имеющий коэффициент усиления, равный r/i_p, поступает сигнал

Первый положительный и третий отрицательный входы третьего сумматора 11 имеют единичные коэффициенты усиления, а второй положительный вход - коэффициент усиления

В результате на выходе этого сумматора формируется сигнал

Выходной сигнал релейного элемента 10 с нулевой нейтральной точкой имеет вид

где |M_т| - величина момента сухого трения при движении.Suppose that the first positive input of adder 1 is single and its second negative input has a gain K _w / K _y . Therefore, at the output of the adder 1, a signal is generated

The first and second positive inputs of the adders 13 and 14 have unity gain. At the outputs of the first 12 and second 15 signal conditioners, signals l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ = const and l ₃ = const. As a result, at the output of the adder 13, a signal l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ + q ₃ , and at the output of adder 14, the signal l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ + l ₃ + q ₃ , since the sensor 9 measures the position of the point of the horizontal link, which is spaced l from the center of mass of this link $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ .
The first positive input of the adder 17 has a gain of r / i _p , and its second positive input has a gain of rm ₃ / i _p . As a result, at the output of the adder 17, a signal r [m ₃ (l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ + q ₃ ) + m _r (l $\genfrac{}{}{0ex}{}{\text{*}}{\text{3}}$ + q ₃ + l ₃ )] / i _p , and the output of the multiplication block 18 is a signal

since the sensor 21 is installed in the first degree of mobility of the robot (figure 2) and measures the coordinate

The position sensor 23 measures the angle of rotation q ₁ and the sensor 26 acceleration in the fourth degree of mobility

Functional Converter 24 implements the function sinq ₁ . As a result, a signal is generated at the output of the multiplication block 25

The signal collector 28 generates a signal m ₃ = const. The first and second positive inputs of the adder 29 have unity gain. As a result, the fourth positive input of the adder 11, having a gain equal to r / i _p , receives a signal

The first positive and third negative inputs of the third adder 11 have unity gain, and the second positive input is the gain

As a result, a signal is generated at the output of this adder

The output signal of the relay element 10 with a neutral zero point has the form

where | M _t | - the magnitude of the dry friction moment in motion.

а третий положительный вход - коэффициент усиления (I+m₃r²/i_p ²)/I_н.The first positive input of adder 3 has a gain of r ² / (i _p ² I _n ), its second positive input has a gain

and the third positive input is the gain (I + m ₃ r ² / i _p ² ) / I _n .

Несложно показать, что поскольку

при движении привода достаточно точно соответствует М_стр, то, подставив полученное значение U* в соотношение (2), получим уравнение

которое имеет постоянные желаемые параметры. То есть предложенный самонастраивающийся привод, управляющий координатой q₃, будет обладать постоянными желаемыми динамическими свойствами и качественными показателями.As a result, a signal is generated at the output of adder 3

It is easy to show that since

when the drive moves, it corresponds quite accurately to M _p , then, substituting the obtained value U * in relation (2), we obtain the equation

which has constant desired parameters. That is, the proposed self-adjusting drive, controlling the coordinate q ₃ , will have constant desired dynamic properties and quality indicators.

 Thus, due to the additional introduction of a position sensor 23, a functional converter 24, multiplication units 25 and 27, an acceleration sensor 26, a signal setter 28, an adder 29 and new connections, it was possible to ensure the complete invariance of the drive in question to the effects of mutual influence between the degrees of mobility and the friction moments. This allows you to get a consistently high quality control in any operating modes of the drive in question.

Claims (1)

 A self-adjusting electric drive of the robot, containing a first adder, a first multiplication unit, a second adder, an amplifier and an engine connected to the first speed sensor directly and through a gearbox with a gear driving a rack fixed motionlessly on the horizontal link of the robot, and an engine of the first position sensor mounted on a vertical link and measuring the position of a characteristic point of the horizontal link relative to the vertical, relay blocks connected in series to and the third adder, the second input of which is connected to the output of the first speed sensor, the input of the relay unit and the second input of the first adder, the first signal pickup, the fourth adder, the fifth adder connected to the second input of the second signal pickup, the second multiplication unit, the sixth the adder and the third multiplication unit, as well as the mass sensor, the input of the device is connected to the first input of the seventh adder connected by the output to the first input of the first adder, the output of the third adder is connected to the second during the second adder, the second speed sensor and the quadrator are connected in series, the output of the third multiplication unit is connected to the third input of the third adder, the output of the mass sensor is connected to the second inputs of the first and second multiplication units, the output of the first position sensor is connected to the second input of the fourth adder, the output of which is connected to the second input of the sixth adder, and the output of the first adder is connected to the third input of the second adder, characterized in that additionally connected in series a second position sensor, a functional converter that implements the sin function, a fourth multiplication unit, the second input of which is connected to the output of the acceleration sensor, and a fifth multiplication unit, the output of which is connected to the fourth input of the third adder, as well as a third signal adjuster and an eighth adder connected in series, the second the input of which is connected to the output of the mass sensor, and the output to the second input of the fifth multiplication block.

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