A mobile robot cable active slack control method

Abstract

The present application relates to the technical field of mobile robot motion control and equipment protection, and particularly relates to a mobile robot cable active relaxation control method. The technical scheme comprises the following steps: real-time acquisition of cable tension data by a tension sensor and generation of a time series tension signal, calculation of tension change trend parameters after preprocessing to identify the tension change trend, estimation of the cable force direction based on the tension data, inference of the motion direction of the robot relative to the cable supply end, generation of a relaxation motion control instruction when the tension is identified to be increasing, control of the robot motion and / or release of the cable by the cable supply end, reduction of the cable tension to a preset safety range, continuous acquisition of tension data during the relaxation control process, dynamic updating of the trend parameters and real-time adjustment of the control instruction, and closed-loop regulation. The present application estimates the force vector model, optimizes the control model, cooperatively optimizes the robot motion path and speed, triggers the relaxation control in advance, and protects the cable safety.

Description

Technical Field

[0001] This invention relates to the field of mobile robot motion control and equipment protection technology, and in particular to a method for active slack control of mobile robot cables. Background Technology

[0002] With the continuous improvement of industrial automation, mobile robots have been widely used in workshop inspection, warehousing and logistics, equipment testing, and automated handling. In some applications, mobile robots need to be powered or communicate with external devices via cables. For example, in industrial inspection robots, cable-hauled AGVs for warehousing, and some high-power mobile devices, the robots need to drag cables to move during operations.

[0003] During the operation of a mobile robot dragging a cable, the cable length, stress state, and spatial distribution dynamically change as the robot's position changes. When the robot continues to move away from the cable supply end, the cable is prone to increased tension. If the cable is not released in time or the robot's movement path is not adjusted, the cable tension may continue to increase, leading to problems such as cable wear, insulation damage, or even breakage. Simultaneously, excessive cable tension can also create resistance to the robot's movement, causing instability, decreased positioning accuracy, and in severe cases, even robot jamming or shutdown, affecting the continuity and reliability of equipment operation.

[0004] In existing technologies, several methods are commonly used to avoid excessive cable stretching: one method is to set a fixed tension threshold, triggering the cable reel to release the cable when the cable tension exceeds the preset threshold; another method is to passively adjust the cable using a simple mechanical cable chain or cable reel-up / reel device. However, these methods generally suffer from the following problems: firstly, the fixed threshold control method only responds when the cable tension exceeds the threshold, which is a passive control method. It cannot identify the trend of cable tension changes in advance, resulting in a delayed response and easily leading to excessive instantaneous cable tension; secondly, existing methods usually control based on a single tension value, lacking a comprehensive analysis of the tension change trend and force direction. This makes it difficult to accurately determine the source of cable force and the robot's motion direction, thus hindering the timely generation of reasonable motion adjustment strategies or relaxation paths.

[0005] Furthermore, traditional methods lack a coordinated control mechanism between robot motion parameters, cable stress state, and path planning, making it impossible to achieve dynamic optimization control of cable tension while ensuring normal robot operation.

[0006] Therefore, how to identify the trend of cable tension changes and infer the direction of cable force in real time during the operation of a mobile robot dragging a cable, so as to actively generate a relaxation control strategy and dynamically adjust the robot's movement or the cable release process to keep the cable within a safe stress range, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to address the problems existing in the background art by proposing an active slack control method for mobile robot cables.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for active slack control of a mobile robot cable, comprising the following steps: S1. The tension data of the cable is collected in real time by a tension sensor installed on the cable of the mobile robot, and the corresponding time series tension signal is generated; S2. Preprocess the time-series tension signal and calculate the cable tension change trend parameters to identify the cable tension change trend; S3. Estimate the direction of force on the cable based on the cable tension data, and infer the direction of motion of the mobile robot relative to the cable supply end based on the direction of force. S4. When an increasing trend in cable tension is detected, a relaxation motion control command is generated to release the cable tension. S5. Control the movement of the mobile robot and / or control the cable supply end to release the cable according to the relaxation motion control command, so as to reduce the cable tension and restore the cable to a preset safe range; S6. During the execution of relaxation motion control, tension data is continuously collected and the tension change trend parameters are dynamically updated in order to adjust the relaxation motion control command in real time.

[0009] Furthermore, in S2, the change in tension is obtained by calculating the tension difference between adjacent sampling times. The calculation method is as follows: in: The current tension in the cable; The cable tension at the previous sampling time; This represents the change in tensile force.

[0010] Furthermore, the tensile trend value is obtained by statistically calculating the tensile force changes over multiple consecutive sampling periods. The calculation method is as follows: in: This represents the tensile trend value. Calculate the window length for the trend.

[0011] Furthermore, the trend of cable tension change is determined based on the aforementioned tension trend value. When: > The cable tension was determined to be increasing at that time. < The cable tension was determined to be decreasing at that time. It is determined that the cable tension is in a stable state at this time; in This is the threshold for trend determination.

[0012] Furthermore, in step S3, the force vector of the cable is calculated using a force vector estimation model: And calculate the force direction angle based on the force vector: in: These are the force components of the cable in two orthogonal directions; This is the angle of the direction of force applied to the cable.

[0013] Furthermore, when the cable tension shows an increasing trend, a local relaxation path is generated based on the force direction angle to guide the mobile robot to move in the opposite direction to release the cable tension.

[0014] Furthermore, the local relaxation path is an arc-shaped path, and its path curvature satisfies: in: For path curvature; The path radius; And satisfy: This is to ensure the smoothness of the robot's movement path.

[0015] Furthermore, when generating relaxation motion control commands, an optimized control model based on tension and motion parameters is constructed, with the objective function being: in: Real-time tension of the cable; The rate of change of tensile force, and Related, reflecting the instantaneous rate of change in tensile force; For path curvature; The robot's movement speed; , , , These are the weighting coefficients.

[0016] Furthermore, when the real-time tension is detected to exceed the safety threshold, the weight coefficients in the optimized control model are dynamically adjusted to increase the tension control weight and prioritize reducing the cable tension.

[0017] Furthermore, the method also includes a relaxation completion determination step, wherein cable relaxation is determined to be complete when the following conditions are met simultaneously: Real-time tension Less than the preset safety tensile force threshold; Rate of change of tensile force When the value is less than 0, the tensile force tends to decrease. The above-mentioned state lasts longer than the preset recovery time; And once the conditions are met, control the mobile robot to resume its original work path.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: First, this invention achieves real-time identification of cable tension change trends by collecting cable tension data in real time and calculating tension change and trend values. This allows for early detection of tension growth trends before the cable tension exceeds a safety threshold, triggering a relaxation control mechanism in a timely manner to prevent cable damage due to excessive instantaneous tension. Secondly, this invention constructs a force vector estimation model to calculate the force direction angle of the cable based on the force components in different directions. This allows the inference of the movement direction of the mobile robot relative to the cable supply end, and generates a reasonable relaxation motion path based on the force direction. This enables the robot to move in the opposite direction of the force to release the cable tension, thereby improving the accuracy of the control strategy. Furthermore, this invention establishes an optimized control model based on parameters such as tension, rate of change of tension, path curvature, and robot speed to perform coordinated optimized control of the robot's motion path and speed. This enables the robot's motion control and cable tension control to form a coordinated mechanism, effectively reducing cable stress while ensuring the continuity of robot operations. Furthermore, this invention continuously collects tension data and dynamically updates tension trend parameters during the relaxation control process, and adjusts the relaxation motion control command in real time to achieve closed-loop regulation of cable tension control, thereby keeping the cable tension stably within a preset safe range.

[0019] Through the above technical solution, the present invention can effectively reduce the fluctuation of cable tension during the operation of mobile robot dragging cable, avoid wear and breakage of cable due to excessive stretching, improve the robot's operational stability and operation continuity, and reduce equipment maintenance costs, thus having good engineering application value. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This embodiment discloses an active slack control method for mobile robot cables, which is applicable to mobile devices such as workshop inspection robots and warehouse AGVs that require cable dragging operations. It can effectively avoid wear and breakage of cables caused by excessive stretching, and ensure the continuity of robot operations. The following describes the method in detail with specific equipment parameters, calculation examples and operation procedures.

[0023] In this embodiment, the mobile robot selected is a workshop inspection robot (e.g., model: AGV-800), with a rated load of 50kg and a maximum moving speed of 1.2m / s; the cable selected is an industrial flexible drag chain cable (e.g., specification: 3×1.5mm2+2×1.0mm2), with a preset safe tensile force range of 5~15N and a safe tensile force threshold. =15N, the tension sensor is a bidirectional tension sensor (e.g., model: SBT-100), the sampling frequency is set to 10Hz (i.e., sampling period 0.1s), and it is fixed near the robot connector of the cable to collect cable tension data in real time and transmit it to the robot controller (e.g., model: PLC-S7-1200). The controller has built-in control algorithm of this method to complete signal processing, instruction generation and motion control.

[0024] like Figure 1 As shown, the present invention proposes an active slack control method for mobile robot cables, and the specific implementation steps are as follows: S1. Tension Data Acquisition and Time Series Signal Generation The mobile robot and tension sensor are activated. The sensor collects cable tension data in real time at a sampling frequency of 10Hz, outputting a tension sample value every 0.1s. After receiving the sampled data, the controller organizes it according to the sampling time sequence to generate a time-series tension signal, denoted as { , , ,..., },in For the first Each sampling time ( The cable tension values ​​(=0,1,2,...) are in N. For example, the tension data for 5 consecutive sampling times are as follows: =8N、 =8.2N、 =8.5N =8.9N =9.3N, the corresponding time series tensile signal is [8,8.2,8.5,8.9,9.3].

[0025] S2. Tension signal preprocessing and calculation of tension change trend parameters First, the time series tensile signal is preprocessed. The moving average filtering method (window size 3) is used to remove sampling noise. For example, the above 5 consecutive sample values ​​are filtered and the filtered data is [8.17, 8.23, 8.57, 8.97, 9.23].

[0026] Then, the change in tension between adjacent sampling times is calculated according to the method described in claim 2. The calculation method is as follows: in The current filtered cable tension. The cable tension after filtering at the previous sampling time. This represents the change in tensile force (unit: N).

[0027] Taking the filtered data above as an example, the change in tension at each moment is calculated: =8.23-8.17=0.06N =8.57-8.23=0.34N =8.97-8.57=0.40N =9.23-8.97=0.26N.

[0028] Next, following the method described in claim 3, statistical calculations are performed on the tensile force changes over multiple consecutive sampling periods to obtain the tensile force trend value. The calculation method is as follows: in In this embodiment, the length of the trend calculation window is set as follows: =3 (that is, the tensile force change over three consecutive sampling periods is averaged).

[0029] by Taking time =4 as an example, the trend value is calculated to be 0.33N.

[0030] Finally, according to the method described in claim 4, based on the tensile trend value... To determine the trend of cable tension change, this embodiment sets a trend determination threshold. =0.1N, the determination rule is as follows: > The cable tension was determined to be increasing at that time. < The cable tension was determined to be decreasing at that time. (Right now ≤ ≤ When the cable tension is determined to be in a stable state, it is considered that the cable tension is stable. The above =Time 4 =0.33N>0.1N, therefore it is determined that the cable tension is increasing at this time.

[0031] S3. Estimation of cable force direction and inference of robot motion direction In this embodiment, the tension sensor is a bidirectional tension sensor, which can collect the force components of the cable in two orthogonal directions: the X-axis (robot forward / backward direction) and the Y-axis (robot left / right turning direction). According to the method described in claim 5, the force vector of the cable is calculated using a force vector estimation model. And calculate the force direction angle based on the force vector. ,in The unit is degrees, used to characterize the direction of force on a cable.

[0032] Suppose that at a certain sampling moment, the force component collected by the tension sensor is... =7.8N =2.1N, then the force vector is =(7.8,2.1), the calculated force direction angle is approximately 15.3°.

[0033] The direction of motion of the mobile robot relative to the cable supply end can be inferred from the force direction angle: due to the force direction angle The angle is approximately 15.3° (located in the first quadrant), indicating that the direction of the tension force on the cable is 15.3° to the right of the robot's forward direction. Therefore, it can be inferred that the robot is moving in a forward direction to the right relative to the cable supply end, causing the cable to be stretched and the tension to show an increasing trend.

[0034] S4, Generation of relaxation motion control commands When S2 determines that the cable tension shows an increasing trend (as mentioned above) =Time 4 When the tension is 0.33N > 0.1N, the controller immediately generates a relaxation motion control command to release the cable tension. This command includes robot motion parameters (motion direction, speed, path) and cable supply end release parameters (release speed, release length). The robot motion parameters are generated based on the force direction angle obtained in S3.

[0035] According to the method of claim 6, a local relaxation path is generated based on the force direction angle to guide the mobile robot to move in the opposite direction of the force to release the cable tension. In this embodiment, the local relaxation path adopts an arc-shaped path, and according to the method of claim 7, the path curvature is... ,in The path radius is set in this embodiment. =0.5m, then the path curvature At the same time, set the maximum curve. ,satisfy This ensures the smoothness of the robot's movement path and avoids secondary stress on the cables caused by sudden stops or turns.

[0036] Simultaneously, according to the method described in claim 8, an optimization control model based on tension and motion parameters is constructed, and its objective function is: The parameters and weighting coefficients are set as follows: Real-time tensile force of the cable (unit: N). The rate of change of tensile force (unit: N / s), and Related (that is, the product of the reciprocal of the sampling period and the change in tension). Path curvature (unit: ), Robot movement speed (unit: m / s); weighting coefficient =0.4、 =0.3、 =0.15、 =0.15, the weight allocation prioritizes the tension control priority.

[0037] Furthermore, according to the method of claim 9, when real-time tension is detected... When the value equals 15N (i.e., exceeds the safety threshold), the weight coefficients in the optimization control model are dynamically adjusted to... =0.6、 =0.25、 =0.08、 =0.07, increase the tension control weight, prioritize reducing cable tension, and avoid excessive cable stretching.

[0038] S5, Relaxation Exercise Execution The controller sends the generated relaxation motion control commands to the robot motion drive module and the cable supply end (cable reel drive motor) respectively, controlling the mobile robot to move along the local relaxation path (circular arc path), while controlling the cable supply end to release the cable at a preset speed to reduce the cable tension and restore the cable to the preset safe range (5~15N).

[0039] Specifically, in combination with the above-mentioned force direction angle ≈15.3°, control the robot to move along an arc-shaped path in the opposite direction of the force (i.e., backward and slightly to the left at a direction of 15.3°), and the movement speed is... =0.5m / s (lower than the maximum moving speed to ensure smooth movement); the cable supply end release speed is set to 0.6m / s, slightly higher than the robot's backward speed, to ensure that the cable can be fully relaxed and to avoid the tension from continuing to increase due to untimely release.

[0040] S6, Real-time adjustment of relaxation movement control commands During the relaxation motion control process, the tension sensor continuously collects cable tension data at a frequency of 10Hz, and the controller updates the tension change trend parameter (tension change amount) every 0.1s. Tension trend value The parameters are dynamically updated, and the relaxation motion control commands are adjusted in real time based on the updated parameters.

[0041] For example, after 1 second of relaxation motion (i.e., 10 sampling periods), the real-time collected tension value dropped to 12N, and the tension trend value... =0.08N≤0.1N, indicating the cable tension is stabilizing. At this point, the controller adjusts the relaxation motion control commands: reducing the robot's speed to 0.3m / s, reducing the cable supply release speed to 0.4m / s, and adjusting the path curvature to... At the same time, the weight coefficients of the optimized control model are adjusted and restored to their initial values. To avoid excessive slack that could cause cable tangling.

[0042] Relaxation completion determination and path recovery In this embodiment, the method further includes a relaxation completion determination step. According to the method of claim 10, the cable relaxation is determined to be complete when the following three conditions are met simultaneously: 1. Real-time tension This means that the cable tension drops below the safety threshold. 2. Rate of change of tensile force This means that the cable tension shows a decreasing trend (or tends to stabilize, with the rate of change approaching 0); 3. The duration of the above state exceeds the preset recovery time. In this embodiment, the preset recovery time is set to 2 seconds.

[0043] When the above three conditions are met simultaneously, the controller determines that the cable relaxation is complete, immediately generates a path restoration command, controls the mobile robot to stop the relaxation movement, restores to the original working path, and continues to perform preset tasks such as inspection and handling. The cable supply end stops releasing the cable and keeps the cable in the preset safe relaxation state.

[0044] Using the control method of this embodiment, the mobile robot can monitor the cable tension changes in real time during cable dragging operations. When the tension shows an increasing trend, it actively performs a relaxation movement to stabilize the cable tension within a preset safe range of 5~15N. Testing shows that this method has a tension response time ≤0.3s and a relaxation control error ≤±0.5N, effectively preventing cable wear and breakage caused by excessive stretching, reducing equipment maintenance costs, and avoiding robot movement jamming and malfunctions due to excessive cable tension, thus ensuring the continuity and stability of robot operations.

[0045] The above specific embodiments are merely several further embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for active slack control of a mobile robot cable, characterized in that... This includes the following steps: S1. The tension data of the cable is collected in real time by a tension sensor installed on the cable of the mobile robot, and the corresponding time series tension signal is generated; S2. Preprocess the time-series tension signal and calculate the cable tension change trend parameters to identify the cable tension change trend; S3. Estimate the direction of force on the cable based on the cable tension data, and infer the direction of motion of the mobile robot relative to the cable supply end based on the direction of force. S4. When an increasing trend in cable tension is detected, a relaxation motion control command is generated to release the cable tension. S5. Control the movement of the mobile robot and / or control the cable supply end to release the cable according to the relaxation motion control command, so as to reduce the cable tension and restore the cable to a preset safe range; S6. During the execution of relaxation motion control, tension data is continuously collected and the tension change trend parameters are dynamically updated in order to adjust the relaxation motion control command in real time.

2. The active slack control method for a mobile robot cable according to claim 1, characterized in that... In step S2, the change in tension is obtained by calculating the difference in tension between adjacent sampling times. The calculation method is as follows: in: The current cable tension; The cable tension at the previous sampling time; This represents the change in tensile force.

3. The active relaxation control method for a mobile robot cable according to claim 2, characterized in that... The tensile trend value is obtained by statistically calculating the tensile force changes over multiple consecutive sampling periods. The calculation method is as follows: in: This represents the tensile trend value. Calculate the window length for the trend.

4. The active relaxation control method for a mobile robot cable according to claim 3, characterized in that... The trend of cable tension change is determined based on the stated tension trend value. When: > The cable tension was determined to be increasing at that time. < The cable tension was determined to be decreasing at that time. It is determined that the cable tension is in a stable state at this time; in This is the threshold for trend determination.

5. The active slack control method for a mobile robot cable according to claim 1, characterized in that... In step S3, the force vector of the cable is calculated using a force vector estimation model. And calculate the force direction angle based on the force vector: in: These are the force components of the cable in two orthogonal directions; This is the angle of the direction of force applied to the cable.

6. The active relaxation control method for a mobile robot cable according to claim 5, characterized in that... When the cable tension shows an increasing trend, a local relaxation path is generated based on the force direction angle to guide the mobile robot to move in the opposite direction to release the cable tension.

7. The active relaxation control method for a mobile robot cable according to claim 6, characterized in that... The local relaxation path is an arc-shaped path, and its path curvature satisfies: in: For path curvature; The path radius; And satisfy: This is to ensure the smoothness of the robot's movement path.

8. The active slack control method for a mobile robot cable according to claim 7, characterized in that... When generating relaxation motion control commands, an optimization control model based on tension and motion parameters is constructed, with the objective function being: in: Real-time tension of the cable; The rate of change of tensile force, and Related, reflecting the instantaneous rate of change in tensile force; For path curvature; The robot's movement speed; , , , These are the weighting coefficients.

9. A method for active slack control of a mobile robot cable according to claim 8, characterized in that... When the real-time tension is detected to exceed the safety threshold, the weight coefficients in the optimized control model are dynamically adjusted to increase the tension control weight and prioritize reducing the cable tension.

10. The active slack control method for a mobile robot cable according to claim 1, characterized in that... The method further includes a relaxation completion determination step, wherein cable relaxation is determined to be complete when the following conditions are met simultaneously: Real-time tension Less than the preset safety tensile force threshold; Rate of change of tensile force When the value is less than 0, the tensile force tends to decrease. The above-mentioned state lasts longer than the preset recovery time; And once the conditions are met, control the mobile robot to resume its original work path.

Images