CN111590567B - Space manipulator teleoperation planning method based on Omega handle - Google Patents

Abstract

The invention relates to a space manipulator teleoperation planning method based on an Omega handle, which decomposes the motion of a manipulator into a translational motion of a wrist and a rotational motion of the last three joints for controlling, so that the degree of freedom of the manipulator related to the translational motion of the wrist is less than that of the whole manipulator, thereby reducing the probability of occurrence of kinematic singularity. The movement of the mechanical arm is divided into the rotation of the last three joints and the translation of the wrist, the movement of the other joints except the last three joints generates the translation of the wrist, the translation and the rotation are decoupled mutually, the movement control is simple and reliable, the physical significance is clear, and the occupied resources are less. The gesture of the tail end of the space manipulator is mapped into the motion of the last three joints in the joint space, and compared with a traditional gesture mapping method, the gesture motion of the space manipulator does not have a singular problem.

Description

A teleoperation planning method of space manipulator based on Omega handle

technical field

The invention relates to a teleoperation planning method for a space manipulator based on an Omega handle, and belongs to the field of teleoperation motion planning of a space manipulator.

Background technique

On-orbit service is usually performed by a robotic arm equipped on the tracking spacecraft. At the current level of technology, teleoperation of the space manipulator by the operator through the handle is the main way to perform on-orbit service tasks. The Omega handle is a commonly used teleoperation device. It has six degrees of freedom and is used to control the position and attitude of the end effector of the robotic arm.

The motion mapping relationship between the Omega handle and the various degrees of freedom of the robotic arm directly determines the operator's experience and work efficiency. Among them, the position mapping between the Omega handle and the space manipulator is relatively simple, but the attitude mapping between the two is relatively complicated. At present, the commonly used attitude mapping method is to use the angular velocity of the fixed coordinate system at the end of the manipulator relative to the coordinate system of the base of the manipulator as the attitude control output of the Omega handle. The physical meaning of this method is clear, but it has the following disadvantages:

(1) This attitude mapping method is not intuitive enough, and the operation experience is not good;

(2) There are singular problems in the attitude control of the end of the space manipulator in some configurations;

(3) The algorithm is complex, which is not conducive to on-orbit application.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, to provide a teleoperation planning method for a space manipulator based on an Omega handle, and to solve the problem that the attitude mapping between the Omega handle and the space manipulator is not intuitive.

The present invention is achieved through the following technical solutions:

A teleoperation planning method for a space manipulator based on an Omega handle, comprising:

(1) Establish the translational mapping between the Omega handle and the wrist of the robotic arm;

(2) Establish the rotation mapping of the three rotating joints of the Omega handle and the last three joints of the mechanical arm;

(3) According to the rotation output of the Omega handle, generate the rotation speed of the last three joints of the manipulator; According to the translation output of the Omega handle, generate the rotation speed of the first n-3 joints of the manipulator corresponding to the translation speed of the wrist of the manipulator. , where n is the number of degrees of freedom of the manipulator.

(4) The speed of each joint of the space manipulator can be integrated to obtain the position of each joint. After the joint speed or joint position is obtained, the teleoperation planning of the space manipulator can be completed.

Preferably, the method for establishing the translational mapping between the Omega handle and the wrist of the robotic arm in step (1) is:

Denote the output p _trans ∈ R ^{3 × 1} of the three translational degrees of freedom of the Omega handle with respect to the zero position p ₀ as

p _trans =p _t -p ₀

where p _t ∈ R ^3×1 is the current translational output of the Omega handle.

The translation command p _cmd ∈ R ^3×1 of the Omega handle to the manipulator is denoted as

p _cmd = ^robot T _omega p _trans

Among them, ^robot T _omega ∈ R ^3×3 is the transformation matrix from the coordinate system of the Omega handle to the base system of the robot arm.

Preferably, the coordinate system of the robot arm base is arranged in parallel with each coordinate axis of the handle coordinate system, and the directions are the same or opposite.

Preferably, the method for establishing the rotation mapping between the three rotating joints of the Omega handle and the last three joints of the mechanical arm is:

2.1 The roll, yaw, and pitch degrees of freedom of the Omega handle correspond to the rotational motion of the wrist roll joint, wrist yaw joint, and wrist pitch joint of the robotic arm, respectively;

的输出为

2.2 The three rotational degrees of freedom of the Omega handle are relative to the zero position

The output is

为Omega手柄的当前转动输出；in,

It is the current rotation output of the Omega handle;

2.3 The rotation command of the Omega handle to the robotic arm

Among them, ^robot R _omega ∈ R ^3×3 is the mapping matrix between the rotational degrees of freedom of the Omega handle and the rotational degrees of freedom of the last three joints of the robotic arm.

Preferably, if the roll, pitch, and yaw of the last three joints of the robotic arm are consistent with the layout of the three rotation joints of the Omega handle, then the ^robot _Romega is a unit matrix.

Preferably, according to the rotation output of the Omega handle, the method for generating the rotation speeds of the last three joints of the robotic arm is:

则Let the angular velocity control commands of the Omega handle corresponding to the last three joints of the robotic arm be

but

k_ω1、k_ω2、k_ω3分别为机械臂腕部三个转动自由度相对于Omega手柄在滚动、俯仰、偏航方向上的缩放量；where k _ω ∈ R ^3×3 is the diagonal matrix of scaling factors corresponding to rotational degrees of freedom,

k _ω1 , k _ω2 , k _ω3 are respectively the scaling amounts of the three rotational degrees of freedom of the robotic arm wrist relative to the Omega handle in the roll, pitch, and yaw directions;

为The rotational speed of the last three joints of the robotic arm

for

Preferably, according to the translation of the Omega handle, the method of generating the rotation speeds of the first n-3 joints of the robotic arm corresponding to the translation speed of the wrist of the robotic arm is:

Let the translation speed control command of the robotic arm wrist corresponding to the Omega handle be v _cmd ∈ R ^3×1 , then

v _cmd =k _v p _cmd

k_v1、k_v2、k_v3分别为机械臂腕部平动相对于Omega手柄平动方向的缩放量；where k _v ∈ R ^3×3 is the diagonal matrix of scaling factors corresponding to the translational degrees of freedom,

k _v1 , k _v2 , and k _v3 are the scaling amounts of the manipulator wrist translation relative to the translation direction of the Omega handle;

为Velocity of the first n-3 joints of the robotic arm

for

为J_for的经典伪逆。Among them, J _for ∈R ^(n-3)×6 is the Jacobian matrix corresponding to the wrist of the manipulator,

is the classical pseudo-inverse of J _for .

后，还包括根据机械臂关节速度指令生成机械臂关节位置指令：Preferably, the speed command of the joint of the manipulator is generated

After that, it also includes generating the robot arm joint position command according to the robot arm joint speed command:

The joint speed command of the space manipulator is

Based on the speed command of the robot arm joint, the position command is generated, and the specific method is as follows:

The joint position of the space manipulator at time t _k+1 is

At time t _k+1 , the joint positions of the space manipulator are approximately given by

Among them, q(t _k ) is the joint position of the space manipulator at time t _k .

In summary, after obtaining the joint speed or joint position, the teleoperation planning of the space manipulator can be completed.

Preferably, a pedal is provided to enable the output of Omega handle teleoperation control commands to the robotic arm.

An on-orbit manipulator teleoperation system is provided, including an on-board manipulator, a satellite-ground communication link, a ground measurement and control system, a vision processing and analysis subsystem, a telemetry data processing subsystem, a teleoperation planning control subsystem, and an automatic control command Generation subsystem and three-dimensional vision and prediction display simulation subsystem;

The manipulator on the satellite performs space operation tasks, collects the motion state of the manipulator and the hand-eye camera image and sends it to the ground measurement and control system through the satellite-ground communication link; the ground measurement and control system demodulates the image and sends the image to the vision processing and analysis subsystem. The motion state of the robotic arm is sent to the telemetry data processing subsystem; the vision processing and analysis subsystem sends the processed images to the three-dimensional vision and prediction display simulation subsystem and the teleoperation planning control subsystem for display respectively; the telemetry data processing subsystem The motion state data of the manipulator is removed and sent to the teleoperation planning and control subsystem. The teleoperation planning and control subsystem generates the manipulator control instructions based on the space manipulator teleoperation planning method of the Omega handle, and sends them to the 3D vision and prediction display. The simulation subsystem updates the simulation scene; the teleoperation planning control subsystem displays the hand-eye camera image of the manipulator, receives the operation input of the operator's Omega handle and pedal, and generates the speed and position commands of the manipulator based on the motion state data of the manipulator; Under the circumstance, the automatic control command generation subsystem performs protocol conversion based on the speed and position commands of the manipulator and sends it to the 3D vision and prediction display simulation subsystem. Conduct a safety test and perform a virtual display of the robotic arm executing the command to determine whether there is a collision. If there is no collision, it will be sent to the on-board robotic arm through the satellite-to-ground communication link for execution.

Compared with the prior art, the present invention has the following advantages:

(1) In the method disclosed in the present invention, the attitude of the Omega handle is mapped to the motion of the last three joints of the space manipulator in the joint space. Compared with the traditional attitude mapping method, there is no singular problem in the attitude motion of the space manipulator.

(2) The method disclosed in the present invention divides the motion of the manipulator into two parts, the translation of the wrist and the rotation of the last three joints, so that the degree of freedom of the manipulator involved in the translation of the wrist is less than the degree of freedom of the whole arm, Thereby reducing the probability of kinematic singularity.

(3) The present invention divides the motion of the mechanical arm into the rotation of the last three joints and the translation of the wrist, and the motion of the remaining joints produces the translation of the wrist, decoupling the translation and the rotation from each other, the motion control is simple and reliable, and the physical It has clear meaning and takes up less resources.

(4) The time complexity of the method disclosed in the present invention is relatively small, and the operation of the space manipulator is controlled after the command is generated on the ground, and the hardware configuration requirements of the ground operating system are relatively low.

Description of drawings

Fig. 1 is the structure and coordinate system schematic diagram of Omega handle;

FIG. 2 is a schematic diagram of the mechanical arm structure and the base coordinate system in the embodiment;

Figure 3 shows the composition and signal flow diagram of the teleoperation test system.

Detailed ways

Based on the built teleoperation ground test system, the robotic arm teleoperation planning method disclosed in the present invention is used. The robotic arm adopts a series structure, and a hand-eye binocular camera is installed at the end. Considering the safety, in the remote operation test, the enabling device-pedal was introduced. It can control whether the operation command generated by the Omega handle is sent to the robot arm for execution: when the operator steps on the pedal, the operation command can be sent to the robot arm for execution; when the operator releases the pedal, the stop command is sent to the robot arm, The robotic arm stops. After confirming that the status of each device is correct, start the test: Based on the images returned by the hand-eye binocular camera, the operator operates the Omega handle to control the robotic arm to move toward the target star, and when the target star docking ring is in the grip at the end of the robotic arm, close it. Grab it with your hand to complete the capture of the target star's docking ring.

The present invention is a space manipulator teleoperation planning method based on an Omega handle, comprising the following steps:

(1) Establish the translational mapping between the Omega handle and the robotic arm;

(2) Establish the rotation mapping between the Omega handle and the robotic arm;

(3) According to the output of the Omega handle, the joint speed command for operating and controlling the robotic arm is generated;

(4) The speed of each joint of the space manipulator can be integrated to obtain the position of each joint. After the joint speed or joint position is obtained, the teleoperation planning of the space manipulator can be completed.

The concrete method of described step (1) is:

Establish the translational mapping between the Omega handle and the robotic arm, specifically:

The translation of the wrist of the robotic arm is controlled by the three translation degrees of freedom of the Omega handle. With reference to Figure 2, here, the wrist of the manipulator is defined as the root of the penultimate joint from the end of the manipulator, and the specific position of the root is based on the position obtained by the DH modeling method. The position mapping relationship between the Omega handle and the robotic arm is defined as: the three translational degrees of freedom of the Omega handle correspond one-to-one with the translational degrees of freedom of the wrist of the robotic arm.

Denote the output p _trans ∈ R ^{3 × 1} of the three translational degrees of freedom of the Omega handle with respect to the zero position p ₀ as

p _trans =p _t -p ₀

Among them, p _t ∈ R ^3×1 is the current translation output of the Omega handle, unit: mm, it is the position of the handle wrist in the handle coordinate system given by the handle encoder, and the handle wrist is defined as the parallel part of the Omega handle and the The joint of the handle rolling joint. p ₀ ∈R ^3×1 is the translational output of the Omega handle at a certain zero position, unit: mm, such as (0,0,0) ^T of the handle coordinate system.

The translation command p _cmd ∈ R ^3×1 of the Omega handle to the manipulator is denoted as

p _cmd = ^robot T _omega p _trans

如果机械臂与手柄的平动方向X、Y、Z轴均一致，则

Among them, ^robot T _omega ∈ R ^3×3 is the transformation matrix from the Omega handle coordinate system to the manipulator base system. In this embodiment, the coordinate axes of the manipulator coordinate system and the handle coordinate system are arranged in parallel, with the same or opposite directions. In one embodiment, since the X and Y directions of the coordinate system of the robot arm base are opposite to those of the Omega handle coordinate system, and the Z direction is consistent, then:

If the X, Y, and Z axes of the manipulator arm and the handle are consistent, then

The concrete method of described step (2) is:

Establish the rotation mapping between the Omega handle and the robotic arm, specifically:

The last three joints of the robotic arm, that is, the rotation of the wrist, are controlled by the three rotational degrees of freedom of the three joints of the Omega handle. The attitude mapping relationship between the Omega handle and the robotic arm is defined as: the rolling degree of freedom of the Omega handle corresponds to the rolling rotation of the end of the robotic arm, and the yaw and pitch degrees of freedom of the Omega handle correspond to the yaw and the wrist of the robotic arm, respectively. Rotational motion of the pitch joint.

(分别对应滚动、俯仰、偏航)，记为The output of the three rotation joints of the Omega handle relative to a certain zero position

(corresponding to roll, pitch and yaw respectively), denoted as

为Omega手柄的当前转动输出，单位：deg；

为Omega手柄在某零位时的转动输出，单位：deg，例如(0,0,0)^T。in,

It is the current rotation output of the Omega handle, unit: deg;

It is the rotation output of the Omega handle at a certain zero position, unit: deg, such as (0,0,0) ^T .

记为The rotation command of the Omega handle to the robotic arm

marked as

Among them, ^robot R _omega ∈ R ^3×3 is the mapping matrix between the rotational degrees of freedom of the Omega handle and the rotational degrees of freedom of the last three joints of the robotic arm. In one embodiment, the layout of the last three joints of the robotic arm is pitch, yaw, and roll in sequence, that is, the order of roll, pitch, and yaw performed by the three joints. The layout of the three rotating joints of the Omega handle is roll, pitch, and yaw, and the pitch direction of the robotic arm is opposite to that of the Omega handle, and the roll and yaw directions are the same, so

The concrete method of described step (3) is:

According to the output of the Omega handle, the joint speed command to operate and control the robotic arm is generated, specifically:

The control of the robotic arm by the Omega handle adopts the speed method, that is, the deviation of the Omega handle relative to a certain zero position configuration is used as the speed control input of the robotic arm. The first three components are the translation speed of the wrist, and the last three components are the rotation of the wrist. speed. That is, the greater the offset of a certain degree of freedom of the Omega handle relative to the zero position, the greater the corresponding control speed. When the target configuration differs greatly from the current configuration, the operator can apply a larger speed control input, otherwise reduce the speed control input until the robot arm reaches the target configuration.

Let the translation speed control command of the robotic arm wrist corresponding to the Omega handle be v _cmd ∈ R ^3×1 , then

v _cmd =k _v p _cmd

k_v1、k_v2、k_v3分别为机械臂腕部平动相对于Omega手柄X、Y、Z方向的缩放量。where k _v ∈ R ^3×3 is the diagonal matrix of scaling factors corresponding to the translational degrees of freedom,

k _v1 , k _v2 , and k _v3 are the scaling amounts of the manipulator wrist translation relative to the X, Y, and Z directions of the Omega handle, respectively.

则Let the angular velocity control command corresponding to the Omega handle be

but

k_ω1、k_ω2、k_ω3分别为机械臂腕部三个转动自由度相对于Omega手柄在滚动、俯仰、偏航方向上的缩放量。where k _ω ∈ R ^3×3 is the diagonal matrix of scaling factors corresponding to rotational degrees of freedom,

k _ω1 , k _ω2 , and k _ω3 are the scaling amounts of the three rotational degrees of freedom of the robotic arm wrist relative to the Omega handle in the roll, pitch, and yaw directions, respectively.

为Velocity of the last three joints of the robotic arm

for

为Let the degree of freedom of the manipulator be n, then the other joints except the last three joints, that is, the speed of the first n-3 joints of the manipulator

for

为J_for的经典伪逆。Among them, J _for ∈R ^(n-3)×6 is the Jacobian matrix corresponding to the wrist of the manipulator,

is the classical pseudo-inverse of J _for .

The concrete method of described step (4) is:

The speed of each joint of the space manipulator can be integrated to obtain the position of each joint. After obtaining the joint speed or joint position, the teleoperation planning of the space manipulator can be completed, specifically:

为Space Manipulator Joint Speed Command

for

The joint speed command of the space manipulator is

Based on the speed command of the robot arm joint, the position command is generated, and the specific method is as follows:

The joint position of the space manipulator at time t _k+1 is

At time t _k+1 , the joint positions of the space manipulator are approximately given by

Among them, q(t _k ) is the joint position of the space manipulator at time t _k .

After obtaining the joint speed or joint position, the teleoperation planning of the space manipulator can be completed.

1 and 3, the present invention is used in an on-orbit manipulator teleoperation system, including an on-board manipulator, a satellite-ground communication link, a ground measurement and control system, a vision processing and analysis subsystem, a telemetry data processing subsystem, and a teleoperation system. Control subsystem, automatic control command generation subsystem, three-dimensional vision and prediction display simulation subsystem.

The manipulator on the satellite performs space operation tasks, collects the motion state of the manipulator and the hand-eye camera image and sends it to the ground measurement and control system through the satellite-ground communication link; the ground measurement and control system demodulates the image and sends the image to the vision processing and analysis subsystem. The motion state of the robotic arm is sent to the telemetry data processing subsystem; the vision processing and analysis subsystem sends the processed images to the three-dimensional vision and prediction display simulation subsystem and the teleoperation planning control subsystem for display respectively; the telemetry data processing subsystem The motion state data of the manipulator is removed and sent to the teleoperation planning and control subsystem. The teleoperation planning and control subsystem generates the manipulator control instructions based on the space manipulator teleoperation planning method of the Omega handle, and sends them to the 3D vision and prediction display. The simulation subsystem updates the simulation scene; the teleoperation planning control subsystem displays the hand-eye camera image of the manipulator, receives the operation input of the operator's Omega handle and pedal, and generates the speed and position commands of the manipulator based on the motion state data of the manipulator; Under the circumstance, the automatic control command generation subsystem performs protocol conversion based on the speed and position commands of the manipulator and sends it to the 3D vision and prediction display simulation subsystem. Conduct a safety test and perform a virtual display of the robotic arm executing the command to determine whether there is a collision. If there is no collision, it will be sent to the on-board robotic arm through the satellite-to-ground communication link for execution.

The test system involved in the method embodiment of the present invention includes an Omega handle, a pedal, and a six-degree-of-freedom robotic arm with a fixed base, and a binocular hand-eye camera is installed at the end of the robotic arm to provide visual feedback information for the teleoperation of the robotic arm.

The above is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited to this. Substitutions should be covered within the protection scope of the present invention.

Claims (1)

1. A teleoperation planning method of a space manipulator based on an Omega handle is characterized by comprising the following steps:

(1) establishing translation mapping between an Omega handle and a mechanical arm wrist;

(2) establishing a rotation mapping between three rotation joints of the Omega handle and the last three joints of the mechanical arm;

(3) generating the rotating speeds of the last three joints of the mechanical arm according to the Omega handle rotating output; according to the Omega handle translation output, the rotation speeds of n-3 joints in front of the mechanical arm corresponding to the translation speed of the mechanical arm wrist are generated, wherein n is the number of the degrees of freedom of the mechanical arm;

(4) integrating the speed of each joint of the space manipulator to obtain the position of each joint, namely finishing teleoperation planning of the space manipulator;

the method for establishing the translation mapping between the Omega handle and the mechanical arm wrist in the step (1) comprises the following steps:

three translational degrees of freedom of an Omega handle relative to a zero position p₀Output p of_trans∈R^3×1Is marked as

p_trans＝p_t-p₀

Wherein p is_t∈R^3×1Is the current translational output of the Omega handle;

translation instruction p of Omega handle to mechanical arm_cmd∈R^3×1Is marked as

p_cmd＝^robotT_omegap_trans

Wherein,^robotT_omega∈R^3×3a conversion matrix from an Omega handle coordinate system to a mechanical arm base system;

the specific method for establishing the rotation mapping of the three rotation joints of the Omega handle and the last three joints of the mechanical arm in the step (2) is as follows:

2.1 enabling the rolling, yawing and pitching freedom degrees of the Omega handle to respectively correspond to the rotation motions of a wrist rolling joint, a wrist yawing joint and a wrist pitching joint of the mechanical arm;

2.2 three rotational degrees of freedom of Omega handle with respect to zero position

Is output as

Wherein,

is the current rotational output of the Omega handle;

2.3Omega handle rotation command to arm

Is marked as

Wherein,^robotR_omega∈R^3×3a mapping matrix between the rotational freedom degree of the Omega handle and the rotational freedom degrees of the last three joints of the mechanical arm is formed;

a pedal is arranged for enabling the Omega handle to remotely operate and control the output of the command to the mechanical arm;

the coordinate system of the mechanical arm base and the coordinate system of the handle are arranged in parallel and in the same or opposite directions;

if the rolling, pitching and yawing freedom degrees of the last three joints of the mechanical arm are consistent with the layout of the three rotating joints of the Omega handle, the mechanical arm is provided with a plurality of joints^robotR_omegaIs an identity matrix;

the method for generating the rotating speeds of the last three joints of the mechanical arm according to the Omega handle rotating output in the step (3) comprises the following steps:

the angular speed control commands of the Omega handle corresponding to the last three joints of the mechanical arm are as follows

Then

Wherein k is_ω∈R^3×3For the scale factor diagonal matrix corresponding to the rotational degree of freedom,

k_ω1、k_ω2、k_ω3the three rotational degrees of freedom of the wrist of the mechanical arm are respectively corresponding to the scaling quantities of the Omega handle in the rolling, pitching and yawing directions;

rotational speed of last three joints of mechanical arm

Is composed of

The method for generating the rotation speeds of the front n-3 joints of the mechanical arm corresponding to the translation speed of the mechanical arm wrist according to the translation of the Omega handle in the step (3) comprises the following steps:

let the control command of the translation speed of the wrist of the mechanical arm corresponding to the Omega handle be v_cmd∈R^3×1Then, then

v_cmd＝k_vp_cmd

Wherein k is_v∈R^3×3For the scale factor diagonal matrix corresponding to the translational degree of freedom,

k_v1、k_v2、k_v3respectively the zooming amount of the mechanical arm wrist translation relative to the Omega handle translation direction;

speed of front n-3 joints of mechanical arm

Is composed of

Wherein, J_for∈R^(n-3)×6Is a jacobian matrix corresponding to the wrist of the robot arm,

is J_forThe classical pseudo-inverse of (1);

generating a mechanical arm joint velocity command

And then, generating a mechanical arm joint position instruction according to the mechanical arm joint speed instruction:

the space manipulator joint speed instruction is

Based on the mechanical arm joint speed instruction, a position instruction is generated, and the specific method comprises the following steps:

space manipulator at time t_k+1The joint position of

At time t_k+1The space manipulator joint position is approximately given by

Wherein q (t)_k) For space the arm at time t_kThe joint position of (a).

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