Method and device for measuring and controlling loss of contact force of robot, and robot

Abstract

The application relates to the technical field of robots, in particular to a robot contact force loss measurement and control method and device and a robot. The method comprises the following steps: acquiring the pose of an end tool of a target robot in a preset coordinate system and the measurement result of a force acquisition device, the force acquisition device being used for measuring the external force borne by the end tool; performing coordinate system conversion on the measurement result based on the relative position relationship between the force acquisition device and the preset coordinate system, and determining the target external force value of the external force borne by the end tool in the preset coordinate system; determining the contact force detection result of the end tool according to the pose and the target external force value; and when the contact force of the end tool is lost, controlling a mechanical arm connected to the end tool so that the mechanical arm returns to a target operation track. The pose and the force bearing condition of the end tool are used to determine whether the contact force of the end tool is lost, so that the precision of contact force detection can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of robots, and in particular to a robot contact force loss detection and control method and device and robot. BACKGROUND

[0002] The robot includes a moving body and a mechanical arm, and a work tool is installed at the end of the mechanical arm, i.e., an end tool, through which corresponding work is performed. For example, the end tool is used to polish a workpiece, or the end tool is used to clean a hand washing table. In order to achieve a better work effect, constant force control is adopted for the end tool, the moving body is driven to move by the movement of the mechanical arm, and the moving body has positioning and point error, so an environment perception module is introduced to obtain the relative position relationship between the target to be worked and the robot base coordinate system, and then the relative position relationship is provided to an obstacle avoidance path planning module to generate an obstacle avoidance path according to the coverage path planning result.

[0003] However, since the environment perception module has positioning error, the positioning error of the environment perception module is introduced into the subsequent work process of the target to be worked, i.e., there is a deviation between the result obtained by the robot obstacle avoidance path planning module and the result obtained by the coverage path planning module, thereby causing the end tool to be out of contact with the target to be worked during constant force control movement, resulting in contact force loss and causing an abnormal state. SUMMARY

[0004] Therefore, the embodiments of the present application provide a robot contact force loss detection and control method, device and robot to solve the abnormal problem caused by contact force loss.

[0005] According to a first aspect, the embodiments of the present application provide a robot contact force loss detection and control method, comprising:

[0006] Obtaining the pose of the end tool of the target robot in a preset coordinate system and the measurement result of a force collection device, the force collection device being used to measure the external force acting on the end tool;

[0007] Based on the relative position relationship between the force collection device and the preset coordinate system, performing coordinate system conversion on the measurement result to determine the target external force value of the external force acting on the end tool in the preset coordinate system;

[0008] According to the pose and the target external force value, determining the contact force detection result of the end tool;

[0009] When the contact force of the end tool is lost, controlling the mechanical arm connected to the end tool to return to the target work trajectory.

[0010] The robot contact force loss detection and control method provided by the embodiment of the present application can determine whether the contact force of the end tool is lost by using the pose and the force bearing condition of the end tool during the target robot operation process, so that the detection accuracy of the contact condition can be improved; and when the contact force of the end tool is determined to be lost, the mechanical arm connected to the end tool is controlled to return to the target operation trajectory, that is, the mechanical arm does not directly stop when the contact force is lost, but returns to the target operation trajectory, so as to start the operation again and improve the operation efficiency.

[0011] In some embodiments, the determining the contact force detection result of the end tool according to the pose and the target external force value comprises:

[0012] comparing the pose and the target external force value with respective corresponding threshold conditions respectively;

[0013] when the pose and the target external force value do not satisfy the respective corresponding threshold conditions, determining that the contact force of the end tool is not lost.

[0014] The robot contact force loss detection and control method provided by the embodiment of the present application converts the pose and the target external force value to a preset coordinate system, compares the threshold conditions in the same preset coordinate system, and ensures the accuracy of the comparison result.

[0015] In some embodiments, the threshold condition of the pose is less than a position threshold, and the determining the contact force detection result of the end tool according to the size relationship between the pose and the target external force value and the respective corresponding threshold conditions comprises:

[0016] extracting a first value of the pose in a first coordinate axis direction of the preset coordinate system, the first coordinate axis direction being perpendicular to the operation surface of the end tool;

[0017] when the first value is less than the position threshold, determining that the detection result is the contact force loss.

[0018] The robot contact force loss detection and control method provided by the embodiment of the present application, the first coordinate axis direction is the direction perpendicular to the operation surface of the end tool, and the end tool is in contact with the operation surface during the operation process of the end tool. The pose component in the first coordinate axis direction is used for detecting the contact force loss, so that the accuracy of the detection result can be ensured.

[0019] In some embodiments, the threshold condition of the target external force value is greater than an external force threshold, and the determining the contact force detection result of the end tool according to the size relationship between the pose and the target external force value and the respective corresponding threshold conditions comprises:

[0020] extract a second value of the target external force in a second coordinate axis direction of the preset coordinate system and / or a third value of the target external force in a third coordinate axis direction of the preset coordinate system;

[0021] When the second value is greater than a first external force threshold and / or the third value is greater than a second external force threshold, it is determined that the detection result is contact force loss.

[0022] The robot contact force loss measurement and control method provided in the embodiments of the application can accurately determine whether contact force loss occurs, because the values in the second coordinate axis direction and the third coordinate axis direction are small in the normal operation process.

[0023] In some embodiments, when the contact force of the end tool is lost, the mechanical arm connected to the end tool is controlled to return to the target trajectory, including:

[0024] When the contact force of the end tool is lost, the constant force control module of the target robot is controlled to output a fixed control amount, so that the end tool slows down to stop;

[0025] The mechanical arm is controlled to move to eliminate the displacement amount introduced by the control amount, so that the mechanical arm returns to the target trajectory.

[0026] The robot contact force loss measurement and control method provided in the embodiments of the application can gradually slow down the speed to zero when the displacement amount is constant, because the control amount output by the constant force control module is a displacement amount. At the same time, the mechanical arm is controlled to move to pull the mechanical arm back to the target trajectory, so as to facilitate the next operation control.

[0027] In some embodiments, the pose of the end tool of the target robot in the preset coordinate system is obtained, including:

[0028] The angles of the joints in the mechanical arm and the transformation matrix of the coordinate system of the end tool relative to the preset coordinate system are obtained.

[0029] Based on the angles of the joints and the transformation matrix, the pose of the end tool in the preset coordinate system is determined.

[0030] The robot contact force loss measurement and control method provided in the embodiments of the application can improve the accuracy of the determined pose of the end tool, because the links of the mechanical arm are linked, and the angles of the joints used to connect the links are processed when the pose is calculated.

[0031] In some embodiments, the measurement result of the force acquisition device is obtained, including:

[0032] acquire a measurement value of the force acquisition device;

[0033] perform gravity compensation on the measurement value of the force acquisition device, and determine the measurement result.

[0034] The robot contact force loss measurement and control method provided by the embodiments of the present application can ensure the accuracy of the measurement result because the gravity of the end tool has an influence on the measurement value of the force acquisition device, and the measurement value is compensated for gravity after being obtained.

[0035] According to a second aspect, the embodiments of the present application further provide a robot contact force loss measurement and control device, comprising:

[0036] an acquisition module, configured to acquire a pose of an end tool of a target robot in a preset coordinate system and a measurement result of a force acquisition device, the force acquisition device being configured to measure an external force suffered by the end tool;

[0037] a conversion module, configured to perform coordinate system conversion on the measurement result based on a relative position relationship between the force acquisition device and the preset coordinate system, and determine a target external force value of the external force suffered by the end tool in the preset coordinate system;

[0038] a determination module, configured to determine a contact force detection result of the end tool according to the pose and the target external force value;

[0039] a control module, configured to control a mechanical arm connected to the end tool to return to a target operation track when the contact force of the end tool is lost.

[0040] According to a third aspect, the embodiments of the present application provide a robot, comprising a force acquisition device, a memory and a processor, which are in communication connection with each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the robot contact force loss measurement and control method in the first aspect or any one of the embodiments of the first aspect.

[0041] According to a fourth aspect, the embodiments of the present application provide a computer readable storage medium, which stores computer instructions, and the computer instructions are used to make the computer execute the robot contact force loss measurement and control method in the first aspect or any one of the embodiments of the first aspect.

[0042] It should be noted that the corresponding beneficial effects of the robot contact force loss measurement and control device, the robot and the computer storage medium provided by the embodiments of the present application are described in the beneficial effects of the robot contact force loss measurement and control method, and will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0044] Figure 1 is a flow chart of a robot contact force loss measurement and control method according to an embodiment of the present application;

[0045] Figure 2 is a flow chart of a robot contact force loss measurement and control method according to an embodiment of the present application;

[0046] Figure 3 is a flow chart of a robot contact force loss measurement and control method according to an embodiment of the present application;

[0047] Figure 4 is a structural block diagram of a robot contact force device according to an embodiment of the present application;

[0048] Figure 5 is a hardware structure schematic diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the protection scope of the present application.

[0050] The robot provided by the embodiments of the present application includes a moving body, a mechanical arm and an end tool installed at the end of the mechanical arm. The specific type of the end tool is related to the working scene of the robot, for example, a cleaning tool, a welding tool, etc., which is not limited here, and is set according to actual needs.

[0051] The mechanical arm comprises a connecting rod and a joint, and the movement of the connecting rod is driven by the rotation of the joint; since the mechanical arm is installed on the moving body, the movement of the moving body will drive the movement of the mechanical arm, and at this time, the contact force loss between the end tool and the target to be operated may occur. Specifically, in the non-operation condition, the operation track of the mechanical arm does not contact the target to be operated; and in the operation condition, the mechanical arm is controlled by the constant force control module in the robot, so that the end tool contacts the target to be operated. At this time, since the movement of the moving body is path planned by the sensing result of the environment sensing module in the robot, and the environment sensing module may have sensing errors, the planned path has errors, and thus the contact force between the end tool and the target to be operated is lost.

[0052] Based on this, the embodiment of the application provides a robot contact force loss detection and control method, which is used for detecting whether the contact force of the end tool is lost in real time during the operation of the robot, and performing motion control on the mechanical arm of the robot in the case of loss, so that the mechanical arm returns to the desired motion track.

[0053] According to the embodiment of the application, a robot contact force loss detection and control method is provided, and it should be noted that the steps shown in the flowchart of the drawings can be executed in a computer system such as a group of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0054] In this embodiment, a robot contact force loss detection and control method is provided, which can be used in the above-mentioned robots such as cleaning robots, operation robots, etc. Figure 1 The flowchart of the robot contact force loss detection and control method according to the embodiment of the application is shown in FIG. 1, which comprises the following steps: Figure 1 As shown in the figure, the flowchart comprises the following steps:

[0055] S11, acquiring the pose of the end tool of the target robot in a preset coordinate system and the measurement result of the force acquisition device.

[0056] The force acquisition device is used for measuring the external force acting on the end tool.

[0057] The preset coordinate system includes, but is not limited to, a robot base coordinate system, or a world coordinate system, etc. Different selection of the preset coordinate system will affect the judgment threshold in the subsequent contact force detection process. Taking the world coordinate system as an example, the pose of the end tool in the preset coordinate system is obtained by first detecting the joint angles of each joint of the robot arm, determining the pose of the end tool in the end tool coordinate system by using the joint angles, then obtaining the pose in the robot base coordinate system by using the relative position relationship between the end tool coordinate system and the robot base coordinate system, and finally obtaining the pose of the end tool in the preset coordinate system by combining the relative position relationship between the robot base coordinate system and the world coordinate system.

[0058] The force collecting device is used to measure the external force suffered by the end tool, which is the reaction force of the action force exerted by the end tool on the target to be worked. The end tool required in the robot working process is installed at the lower end of the force collecting device, and the force collecting device is used to measure the external force suffered by the end tool.

[0059] S12, based on the relative position relationship between the force collecting device and the preset coordinate system, the measurement result is converted into the coordinate system to determine the target external force value of the external force suffered by the end tool in the preset coordinate system.

[0060] In order to accurately compare, it is necessary to convert the measurement result of the force collecting device into the preset coordinate system. The measurement result of the force collecting device is obtained in the force collecting device coordinate system. Since the position between the force collecting device and the end tool is fixed, the measurement result in the force collecting coordinate system can be converted into the end tool coordinate system, and finally the external force suffered by the end tool is converted into the preset coordinate system by using the position relationship between the end tool coordinate system and the preset coordinate system, to obtain the target external force value in the preset coordinate system.

[0061] S13, according to the pose and the target external force value, the contact force detection result of the end tool is determined.

[0062] For the robot arm, in the two cases of normal working and contact force loss, the pose of the end tool and the target external force value will be obviously different. For example, in the normal working condition, the end tool needs to contact the target to be worked, at this time, the pose of the end tool is in the preset range of the target to be worked; if the contact force loss occurs, the pose of the end tool will exceed the preset range. In the normal working condition, the end tool contacts the target to be worked at a certain angle and mainly applies a vertical action force to the target to be worked, so the contact force of the end tool in other directions is relatively small. Based on this, the pose and the target external force value are compared, so that whether the contact force of the end tool is lost can be determined.

[0063] S14, when the contact force of the end tool is lost, control the robotic arm connected to the end tool so that the robotic arm returns to the target working trajectory.

[0064] When it is determined that the end effector has lost contact force, the movement of each joint in the robotic arm is controlled to move the end effector's robotic arm, causing the robotic arm to return to the target working trajectory. The target working trajectory is the preset working trajectory of the robotic arm when the constant force control module is not activated. At this time, the end effector is not in contact with the target. After the constant force control module is activated, the end effector makes contact with the target to perform the work.

[0065] The robot contact force loss measurement and control method provided in this embodiment determines whether the contact force of the end tool is lost by using the robot's pose and the force on the end tool during the target robot's operation, which can improve the detection accuracy of the contact situation; and when it is determined that the contact force of the end tool is lost, the robotic arm connected to the end tool is controlled to return to the target operation trajectory. That is, when the contact force is lost, the robot does not stop directly, but controls the robotic arm to return to the target operation trajectory so that the operation can be restarted, which improves the operation efficiency.

[0066] This embodiment provides a method for measuring and controlling the loss of contact force in a robot, which can be used in the aforementioned robots, such as cleaning robots and operational robots. Figure 2 This is a flowchart of a robot contact force loss measurement and control method according to an embodiment of the present invention, as shown below. Figure 2 As shown, the process includes the following steps:

[0067] S21, acquire the pose of the end effector of the target robot in the preset coordinate system and the measurement results of the force acquisition device.

[0068] The force acquisition device is used to measure the external force applied to the end effector.

[0069] Please see details Figure 1 S11 of the illustrated embodiment will not be described again here.

[0070] S22, based on the relative positional relationship between the force acquisition device and the preset coordinate system, performs coordinate system transformation on the measurement results to determine the target external force value of the end tool under the preset coordinate system.

[0071] Please see details Figure 1 S12 of the illustrated embodiment will not be described again here.

[0072] S23, determine the contact force detection result of the end effector based on the pose and the target external force value.

[0073] Specifically, S23 above includes:

[0074] S231, compare the pose and the target external force value with the respective threshold condition.

[0075] The respective threshold condition is a threshold condition of contact force loss. As described above, the setting of the threshold condition is related to the selection of the preset coordinate system. Different preset coordinate systems have different respective threshold conditions. For example, if the application scenario of the robot is cleaning a washbasin, and the world coordinate system is selected as the preset coordinate system, and the origin of the preset coordinate system is on the ground, then the threshold condition of the pose is less than the height of the washbasin.

[0076] S232, when the pose and the target external force value do not satisfy the respective threshold condition, it is determined that the contact force of the end tool is not lost.

[0077] To confirm that the contact force is not lost, the pose and the target external force value must not satisfy the respective threshold condition. If only one does not satisfy, it cannot be determined that the contact force of the end tool is not lost.

[0078] In some embodiments, the threshold condition of the pose is less than a position threshold value. Based on this, the above S23 includes:

[0079] (1) extracting a first value of the pose in the first coordinate axis direction of the preset coordinate system, the first coordinate axis direction being perpendicular to the working surface of the end tool.

[0080] (2) when the first value is less than the position threshold value, it is determined that the detection result is contact force loss.

[0081] The first coordinate axis direction is perpendicular to the working surface of the end tool. If the working scenario is cleaning a washbasin, the working surface of the end tool is the surface of the washbasin, and the first coordinate axis direction (i.e. the Z-axis direction) is perpendicular to the direction of the washbasin. Wherein, the preset coordinate system is the world coordinate system and the origin is on the ground, based on which the position threshold value is the height of the washbasin surface. During normal operation of the end tool, the first value of the pose in the first coordinate axis direction is greater than or equal to the height of the washbasin surface. If it is found through comparison that the first value is less than the height of the washbasin surface, it can be determined that the end tool has fallen into the washbasin surface at this time, and the end tool has contact force loss with the washbasin surface.

[0082] The first coordinate axis direction is the direction perpendicular to the working surface of the end tool. During the operation of the end tool, the end tool is in contact with the working surface. Using the pose component in the first coordinate axis direction for contact force loss detection can ensure the accuracy of the detection result.

[0083] In some embodiments, the threshold condition of the target external force value is greater than an external force threshold value. Based on this, the above S23 includes:

[0084] (1) extracting a second value of the target external force value in the direction of the second coordinate axis of the preset coordinate system and / or a third value of the target external force value in the direction of the third coordinate axis of the preset coordinate system.

[0085] (2) when the second value is greater than the first external force threshold and / or the third value is greater than the second external force threshold, determining that the detection result is contact force loss.

[0086] Continuing to use the above example, the second coordinate axis direction is the Y-axis direction, and the third coordinate axis direction is the X-axis direction. As described above, in the normal working process of the end tool, the external force components in the X-axis direction and the Y-axis direction are small, and based on this, any one or both of the two directions is compared with the corresponding external force threshold. If it is greater than the corresponding external force threshold, it is determined that the contact force is lost. For example, if the second value in the X-axis direction is greater than the first external force threshold, it is determined that the contact force is lost; if the third value in the Y-axis direction is greater than the second external force threshold, it is determined that the contact force is lost; if in the X-axis direction and the Y-axis direction, it is greater than the corresponding external force threshold, it is determined that the contact force is lost.

[0087] Since the values in the second coordinate axis direction and the third coordinate axis direction are small in the normal working process, comparing the values in the two coordinate axis directions with the threshold can accurately determine whether the contact force loss occurs.

[0088] S24, when the contact force of the end tool is lost, the mechanical arm connected to the end tool is controlled to return to the target working trajectory.

[0089] Specifically, the above S24 includes:

[0090] S241, when the contact force of the end tool is lost, the constant force control module of the target robot is controlled to output a fixed control amount, so that the end tool is decelerated to stop.

[0091] The control amount output by the constant force control module is constant, and since the control amount is a displacement amount, i.e., the angle value of joint motion, the relationship between displacement and speed can be used to control the end tool to decelerate and stop.

[0092] S242, the mechanical arm is controlled to move to eliminate the displacement amount introduced by the control amount so that the mechanical arm returns to the target trajectory.

[0093] Although the end tool can be decelerated to stop at this time, the fixed control amount will still introduce a corresponding displacement amount, which will be added to the interpolation module of the robot for motion control of the mechanical arm. Specifically, the displacement amount introduced by the constant force control module is eliminated by performing speed planning in the joint space and controlling the robot motion, so that the mechanical arm of the robot returns to the target trajectory.

[0094] In some embodiments, if it is determined that the target robot arm has contact force loss, the alarm module is triggered to send a warning signal.

[0095] The robot contact force loss measurement and control method provided in the embodiment converts the pose and the target external force value to a preset coordinate system, compares the threshold conditions in the same preset coordinate system, and ensures the accuracy of the comparison result. Since the control amount output by the constant force control module is a displacement amount, the speed can gradually slow down to zero when the displacement amount is constant. At the same time, the motion control is performed on the robot arm to pull it back to the target trajectory for the next operation control.

[0096] A robot contact force loss measurement and control method is provided in the embodiment, which can be used in the above-mentioned robots, such as cleaning robots, work robots, etc. Figure 3 The flowchart of the robot contact force loss measurement and control method according to the embodiment of the application is shown in FIG. 1, which includes the following steps: Figure 3

[0097] S31, obtaining the pose of the end tool of the target robot in a preset coordinate system and the measurement result of the force collection device.

[0098] The force collection device is used to measure the external force on the end tool.

[0099] Specifically, the above S31 includes:

[0100] S311, obtaining the angle of each joint in the robot arm and the transformation matrix of the coordinate system of the end tool relative to the preset coordinate system.

[0101] The angle of each joint is obtained by the encoder of each joint, and the angle obtained at this time is in the local coordinate system of each connecting rod. The transformation matrix of the coordinate system of the end tool relative to the preset coordinate system is related to the selection of the preset coordinate system. If the preset coordinate system is the robot base coordinate system, the transformation matrix of the end tool coordinate system relative to the robot coordinate system can be obtained by using the forward kinematics model of the target robot. If the preset coordinate system is the world coordinate system, the transformation matrix can be determined based on the forward kinematics model and the pose of the target robot in the world coordinate system.

[0102] S312, determining the pose of the end tool in the preset coordinate system based on the angle of each joint and the transformation matrix.

[0103] The pose of the end tool in the end tool coordinate system is calculated based on the angle of each joint, and the pose of the end tool in the preset coordinate system is obtained by multiplying the pose in the end tool coordinate system by the transformation matrix. ​

[0104] S313, acquire the measured values ​​from the force acquisition device.

[0105] S314 performs gravity compensation on the measured values ​​of the force acquisition device to determine the measurement results.

[0106] During robot operation, an end effector is typically used, which is mounted at the lower end of a force acquisition device. Under different postures, gravity affects the values ​​collected by the end effector, preventing a complete reflection of the end effector force, as the weight of the tool also plays a role. Therefore, gravity compensation is necessary to accurately reflect the end effector force.

[0107] Specifically, the force acquisition device is an end effector six-dimensional force sensor. Using the end effector six-dimensional force sensor and load parameter calibration algorithm, gravity compensation parameters such as the sensor zero point, end effector mass, and end effector center of gravity coordinates are obtained. Substituting the end effector six-dimensional force sensor readings, the angles of each robot joint, and the gravity compensation parameters into the forward kinematics model and the end effector gravity compensation model, the projection of the external force acting on the end effector in the end effector six-dimensional force sensor coordinate system is obtained, thus yielding the aforementioned measurement results.

[0108] S32, based on the relative positional relationship between the force acquisition device and the preset coordinate system, performs coordinate system transformation on the measurement results to determine the target external force value of the end tool under the preset coordinate system.

[0109] Please see details Figure 1 S12 of the illustrated embodiment will not be described again here.

[0110] S33, based on the pose and the target external force value, determine the contact force detection result of the end tool.

[0111] Please see details Figure 2 S23 of the illustrated embodiment will not be described again here.

[0112] S34, when the contact force of the end tool is lost, control the robotic arm connected to the end tool so that the robotic arm returns to the target working trajectory.

[0113] Please see details Figure 2 S24 of the illustrated embodiment will not be described again here.

[0114] The robot contact force loss measurement and control method provided in this embodiment improves the accuracy of the determined end-effector pose by combining the angles of the joints connecting the links when performing pose calculations, since the links of the robotic arm are linked together.

[0115] A robotic contact force loss detection and control apparatus is also provided in the present embodiments, which is used to implement the above embodiments and preferred embodiments, and will not be described again. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware is also possible and contemplated.

[0116] The present embodiments provide a robotic contact force loss detection and control apparatus, as shown in Figure 4 comprises:

[0117] The acquisition module 41 is configured to acquire a pose of an end tool of a target robot in a preset coordinate system and a measurement result of a force acquisition device, the force acquisition device being configured to measure an external force acting on the end tool.

[0118] The conversion module 42 is configured to perform coordinate system conversion on the measurement result based on a relative position relationship between the force acquisition device and the preset coordinate system, to determine a target external force value of the external force acting on the end tool in the preset coordinate system.

[0119] The determination module 43 is configured to determine a contact force detection result of the end tool according to the pose and the target external force value.

[0120] The control module 44 is configured to control a robot arm connected to the end tool to return to a target work trajectory when the contact force of the end tool is lost.

[0121] In some embodiments, the determination module 43 comprises:

[0122] The comparison unit is configured to compare the pose and the target external force value with respective threshold conditions.

[0123] The first determination unit is configured to determine that the contact force of the end tool is not lost when the pose and the target external force value do not satisfy the respective threshold conditions.

[0124] In some embodiments, the threshold condition of the pose is less than a position threshold, and the determination module 43 comprises:

[0125] The first extraction unit is configured to extract a first value of the pose in a first coordinate axis direction of the preset coordinate system, the first coordinate axis direction being perpendicular to a work surface of the end tool.

[0126] The second determination unit is configured to determine that the detection result is contact force loss when the first value is less than the position threshold.

[0127] In some embodiments, the threshold condition of the target external force value is greater than an external force threshold, and the determining module 43 comprises:

[0128] a second extracting unit configured to extract a second value of the target external force value in a second coordinate axis direction of the preset coordinate system and / or a third value of the target external force value in a third coordinate axis direction of the preset coordinate system;

[0129] a third determining unit configured to determine that the detection result is contact force loss when the second value is greater than a first external force threshold and / or the third value is greater than a second external force threshold.

[0130] In some embodiments, the control module 44 comprises:

[0131] a first control unit configured to control a constant force control module of the target robot to output a fixed control amount when the contact force of the end tool is lost, so as to slow down the end tool to stop;

[0132] a second control unit configured to control the movement of the robot arm to eliminate the displacement amount introduced by the control amount so that the robot arm returns to the target trajectory.

[0133] In some embodiments, the obtaining module 41 comprises:

[0134] a first obtaining unit configured to obtain the angles of each joint in the robot arm and a transformation matrix of the coordinate system of the end tool relative to the preset coordinate system;

[0135] a fourth determining unit configured to determine the pose of the end tool in the preset coordinate system based on the angles of each joint and the transformation matrix.

[0136] In some embodiments, the obtaining module 41 comprises:

[0137] a second obtaining unit configured to obtain the measurement value of the force acquisition device;

[0138] a fifth determining unit configured to perform gravity compensation on the measurement value of the force acquisition device to determine the measurement result.

[0139] The robot contact force loss measurement and control device in the embodiment is in the form of a functional unit. The unit herein refers to an ASIC circuit, a processor and a memory executing one or more software or fixed programs, and / or other devices that can provide the above functions.

[0140] Further function descriptions of the above modules are the same as those of the above corresponding embodiments, which will not be described here.

[0141] The embodiment of the application further provides a robot having the above Figure 4The robot contact force loss monitoring device is shown.

[0142] Please refer to Figure 5 , Figure 5 is a structural schematic diagram of a robot provided by an optional embodiment of the application. As shown in Figure 5 , the robot can include a force acquisition device, at least one processor 51, such as a CPU (Central Processing Unit), at least one communication interface 53, a memory 54, and at least one communication bus 52. The communication bus 52 is used to realize the connection and communication between the components. The communication interface 53 can include a display, a keyboard, and the optional communication interface 53 can also include a standard wired interface and a wireless interface. The memory 54 can be a high-speed RAM memory (Random Access Memory) or a non-volatile memory, such as at least one disk memory. The memory 54 can also be at least one storage device located away from the aforementioned processor 51. The processor 51 can be combined with Figure 4 the device described above, the memory 54 stores an application program, and the processor 51 calls the program code stored in the memory 54 for executing any of the above method steps.

[0143] The communication bus 52 can be a PCI (peripheral component interconnect) bus or an EISA (extended industry standard architecture) bus, etc. The communication bus 52 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 only one thick line is used in the figure, but it does not mean that there is only one bus or only one type of bus.

[0144] The memory 54 can include a volatile memory, such as a RAM (random-access memory); the memory can also include a non-volatile memory, such as a flash memory, a hard disk (HDD) or a solid-state disk (SSD); and the memory 54 can also include a combination of the above types of memories.

[0145] The processor 51 can be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and an NP.

[0146] The processor 51 can further include a hardware chip. The hardware chip can be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0147] Optionally, the memory 54 is further configured to store program instructions. The processor 51 can invoke the program instructions to implement the method for measuring and controlling the loss of contact force of a robot as shown in any embodiment of the present application.

[0148] The embodiments of the present application further provide a non-transitory computer storage medium storing computer executable instructions. The computer executable instructions can implement the method for measuring and controlling the loss of contact force of a robot in any method embodiment described above. The storage medium can be a disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), a solid-state drive (SSD), or the like. The storage medium can further include a combination of the above-mentioned storage mediums.

[0149] Although the embodiments of the present application are described in conjunction with the accompanying drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes are intended to fall within the scope of the appended claims.

Claims

1. A method for measuring and controlling the loss of contact force in a robot, characterized in that, The method comprises the following steps: acquiring a pose of an end tool of a target robot in a preset coordinate system and a measurement result of a force acquisition device, the force acquisition device being configured to measure an external force acting on the end tool; performing coordinate system conversion on the measurement result based on a relative positional relationship between the force acquisition device and the preset coordinate system, to determine a target external force value of the external force acting on the end tool in the preset coordinate system; determining a contact force detection result of the end tool according to the pose and the target external force value; when the contact force of the end tool is lost, controlling a robot arm connected to the end tool to return to a target work trajectory; wherein, when the contact force of the end tool is lost, the robot arm connected to the end tool is controlled to return to the target trajectory, comprising: when the contact force of the end tool is lost, controlling a constant force control module of the target robot to output a fixed control amount, so that the end tool slows down to stop, the control amount being used to represent a displacement amount; performing velocity planning in a joint space of the target robot and controlling the movement of the robot arm to eliminate the displacement amount introduced by the control amount, so that the robot arm returns to the target trajectory.

2. The method of claim 1, wherein, The determination of the contact force detection result of the end tool according to the pose and the target external force value comprises: comparing the pose and the target external force value with respective threshold conditions respectively; when the pose and the target external force value do not satisfy the respective threshold conditions, it is determined that the contact force of the end tool is not lost.

3. The method of claim 2, wherein, The threshold condition of the pose is less than a position threshold, and the determination of the contact force detection result of the end tool according to the size relationship between the pose and the target external force value and the respective thresholds comprises: extracting a first value of the pose in a first coordinate axis direction of the preset coordinate system, the first coordinate axis direction being perpendicular to a work surface of the end tool; when the first value is less than the position threshold, it is determined that the detection result is contact force loss.

4. The method of claim 2, wherein, The threshold condition of the target external force value is greater than an external force threshold, and the determination of the contact force detection result of the end tool according to the size relationship between the pose and the target external force value and the respective thresholds comprises: extracting a second value of the target external force value in a second coordinate axis direction of the preset coordinate system and / or a third value of the target external force value in a third coordinate axis direction of the preset coordinate system; when the second value is greater than a first external force threshold and / or the third value is greater than a second external force threshold, it is determined that the detection result is contact force loss.

5. The method of claim 1, wherein, The acquisition of the pose of the end tool of the target robot in the preset coordinate system comprises: acquiring angles of joints in the robot arm and a transformation matrix of a coordinate system of the end tool relative to the preset coordinate system; determining the pose of the end tool in the preset coordinate system based on the angles of the joints and the transformation matrix.

6. The method of claim 1, wherein, The acquisition of the measurement result of the force acquisition device comprises: acquiring a measurement value of the force acquisition device; The measurement value of the force acquisition device is gravity compensated to determine the measurement result.

7. A robot contact force loss detection device, comprising: The method comprises the steps of: obtaining a pose of an end tool of a target robot in a preset coordinate system and a measurement result of a force acquisition device, the force acquisition device being configured to measure an external force acting on the end tool; performing coordinate system conversion on the measurement result based on a relative position relationship between the force acquisition device and the preset coordinate system to determine a target external force value of the external force acting on the end tool in the preset coordinate system; determining a contact force detection result of the end tool according to the pose and the target external force value; controlling a robot arm connected to the end tool to return to a target work trajectory when the contact force of the end tool is lost. The control of the robot arm connected to the end tool to return to the target trajectory when the contact force of the end tool is lost comprises: controlling a constant force control module of the target robot to output a fixed control amount when the contact force of the end tool is lost, so that the end tool slows down to stop, the control amount being used to represent a displacement amount; performing velocity planning in a joint space of the target robot and controlling the movement of the robot arm to eliminate the displacement amount introduced by the control amount so that the robot arm returns to the target trajectory.

8. A robot, characterized in that The method comprises the steps of: a force acquisition device, a memory and a processor, which are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the robot contact force loss measurement and control method according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions for causing a computer to execute the robot contact force loss measurement and control method according to any one of claims 1-6.

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