Rope retraction and release control system and method for tension correction of rope-tethered wheeled mobile robot

Abstract

The present invention provides a rope retraction and release control method for synchronous tension correction of a rope-tethered wheeled mobile robot. The rope retraction and release are synchronized with the vehicle body movement, and the rope tension is used as a correction of the rope retraction and release speed, so as to achieve comprehensive optimization of the wheel drive motor torque and rope tension. The present invention has a small amount of calculation, is simple to implement, has good rope tension and retraction and release control performance, can reduce the operating power consumption of the rope-tethered robot, reduce rope wear, increase the service life of the rope, and improve the detection capability of the robot.

Description

Technical Field

[0001] The invention belongs to the field of mobile robot motion control, and in particular relates to a rope retracting and releasing control method for synchronous tension correction of a rope-tethered wheeled mobile robot motion. Background Art

[0002] Many areas on the planet's surface that are worth exploring are often located in extreme terrains such as steep slopes and gullies. Most existing robots can only operate and work on relatively flat rocky terrain with slopes less than 30 degrees, and are not suitable for exploring the aforementioned extreme terrain areas. Steep slopes will weaken the traction of the patrol vehicle and greatly reduce the passability of the terrain; the traditional rocker bogie structure will significantly increase the slippage on steep slopes and cannot enter certain areas at all; gullies are also very dangerous for patrol vehicles; on rugged terrain, ordinary patrol mobile robots may fall.

[0003] In order to overcome the limitations brought by the above-mentioned extreme terrain areas, the current patrol vehicles designed for steep slopes, gullies and other terrains are tethered mobile robots. Through a rope with one end fixed to a fixed mother robot or anchor point to provide tension or support, the tethered mobile robot can reach steep slopes, gullies and other areas that ordinary wheeled robots cannot pass through for fixed-point detection, making it possible to detect these extreme terrain areas.

[0004] For tethered robots, tether management is very important. Rope management is defined as the process of reducing its inherent problems and obtaining useful information about the environment by managing the rope. The first problem to be solved by rope management is the rope entanglement problem. If a tethered robot wants to return to its starting point, it must solve the rope entanglement problem. There are generally two ways to solve the rope entanglement problem: one is to perform precise motion planning on the robot to avoid the occurrence of rope entanglement; the other is to locate the location where the entanglement occurs and then return along the homotopic route.

[0005] In the above two solutions to the problem of rope entanglement, it is necessary to ensure that the rope has a certain tension, thereby ensuring that the rope is always in a taut state.

[0006] An intuitive method of controlling the tension of a rope is to change the length of the rope. When the actual tension is greater than the desired tension, the rope is released; otherwise, the rope is tightened. This method often results in excessive tension and a large deviation from the desired force, which causes the robot to consume a lot of power and be unstable. Another method is to control from the perspective of motion control. These control methods are based on kinematic and dynamic models and require information such as the direction of motion and the angle between the rope and the direction of motion. The system is complex and these quantities are difficult to measure. The influence of the winch is not considered, so the method is difficult to implement and the control effect is difficult to predict due to many influencing factors. Summary of the invention

[0007] In order to solve the technical problems mentioned in the above background technology, the present invention proposes a rope tension and retraction control method for a rope-tethered wheeled mobile robot, so that the rope retraction speed is consistent with the vehicle body movement speed, and the rope tension deviation is used as compensation for the rope retraction speed.

[0008] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0009] A rope control system based on tension correction for a rope-tethered wheeled mobile robot comprises a navigation positioning perception and planning module, a rope winch driver, a rope tension sensor, and a rope tension calculation model. The navigation positioning perception and planning module measures and outputs environmental information and the robot body movement speed v, and the speed v is combined with a transformation coefficient to obtain an ideal value of the rotation speed of the rope retracting winch; a target tension value is further calculated based on the environmental information, and the tension sensor measures an actual rope tension value. Based on the target tension value, the actual tension value and the ideal value, the final expected rope retracting winch rotation speed is obtained and input into the rope winch driver.

[0010] Preferably, the environmental information includes the angle between the caster arm and the ground and the inclination of the ground when the mobile robot moves. Based on the angle and inclination, combined with the ground friction coefficient and the mass of the robot, the target tension value can be obtained; the angle and inclination are obtained by the inertial sensor built into the navigation, positioning, perception and planning module, and the distance sensor installed perpendicular to the central axis of the caster arm of the tethered wheeled mobile robot.

[0011] The present invention also discloses a control method for a rope control system based on tension correction for a rope-tethered wheeled mobile robot, comprising the following steps: Step 1, measuring or planning the robot body movement speed v through a navigation positioning perception and planning module, and calculating the conversion coefficient K between the rotation speed of the rope retracting winch and the body movement speed. r Multiply them to get the ideal value of the rotation speed of the rope retracting winch; Step 2, according to the environmental information measured by the perception system in the navigation positioning perception and planning module, input it into the rope tension calculation model to calculate the target tension value F of the rope * Step 3: Use the rope tension as a correction for the rope retraction and release speed, that is, measure the actual tension F based on the rope tension sensor, compare the difference between the target tension F* and the actual rope tension F, and use the difference to compensate for the rope tension proportional control parameter K PF Multiply them to obtain the compensation value of the rotation speed of the rope retracting winch; step 4, add the compensation value of the rotation speed of the rope retracting winch to the ideal value obtained in step 1 to obtain the expected value and input it into the rope winch driver to realize the control of the rope retracting speed.

[0012] Preferably, in step 1, the conversion coefficient K between the rotation speed of the rope retracting winch and the vehicle body movement speed is r Determined by the robot structure, K r =1 / r, r is the radius of the winch including the rope, which is calculated based on the number of rope windings.

[0013] Preferably, in step 2, the target tension value F obtained by the rope tension calculation model is * , that is, the target rope tension value of the rope retraction and release control method for the synchronous tension correction of the rope-tethered wheeled mobile robot is:

[0014]

[0015] Among them, θ c is the angle between the caster arm and the ground; θ s is the ground inclination angle; μ is the friction coefficient between the wheel and the ground, m is the mass of the robot, θ c With θ s It can be obtained through simple calculation using the built-in inertial sensor and the distance sensor installed perpendicular to the body surface of the tethered wheeled mobile robot; μ can be estimated based on the smoothness of the road surface.

[0016] Preferably, in step 4, the rope retracting and releasing speed is controlled by changing the rotation speed of the rope winch, and the control law is:

[0017] ω u =K PF (F * -F)+K r v

[0018] In the formula, ω u is the angular velocity of the winch; F* is the target tension of the rope; F is the actual tension of the rope; K PF is the proportional control parameter of rope tension compensation; K r is the conversion coefficient between the winch rotation speed and the vehicle body movement speed; v is the vehicle body movement speed.

[0019] The beneficial effects brought by adopting the above technical solution are:

[0020] The present invention combines the rope retracting and releasing speed with the vehicle body movement speed, and the rope tension deviation is used as compensation for the retracting and releasing speed of the rope retracting and releasing winch. The method has a small amount of calculation, is simple to implement, and has good rope tension and retracting and releasing control performance. It can reduce the operating power consumption of the tethered robot, increase the detection distance of the robot, and enhance the stability of the system; at the same time, it reduces the wear of the rope and increases the service life of the rope. In this way, the rope can be effectively tightened to ensure that the rope tension is within a reasonable range, thereby effectively avoiding the problems of rope entanglement and difficult rope positioning in the motion control of the tethered wheeled mobile robot. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The block diagram of the control system for synchronous correction of the movement of the tethered wheeled mobile robot and the retraction and release of the rope;

[0022] Figure 2 This is the rope tension analysis diagram of the tethered wheeled mobile robot. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, a rope retraction and extension control method for synchronous tension correction of a tethered wheeled mobile robot is provided, wherein the tethered wheeled mobile robot includes modules related to rope retraction and extension control, such as a navigation positioning perception and planning module, a rope winch driver, and a rope tension sensor.

[0025] The rope retraction and release control method of the rope-tethered wheeled mobile robot with synchronous tension correction takes into account that the vehicle body movement and the rope retraction and release speed should be consistent during the actual movement process, that is, the rope retraction and release speed is consistent with the vehicle body movement speed. The rope tension deviation is used as the compensation for the movement speed of the rope retraction and release winch, that is, the rope retraction and release winch rotation speed control law is:

[0026] ω u =K PF (F * -F)+K r v

[0027] Among them, ω u is the angular velocity of the winch; F* is the target tension of the rope; F is the actual tension of the rope; K PF is the proportional control parameter of rope tension compensation; K r is the conversion coefficient between the winch and the vehicle body speed; v is the vehicle body speed.

[0028] A rope retraction and release control method for synchronous tension correction of a rope-tethered wheeled mobile robot comprises the following control steps:

[0029] Step 1: Measure or plan the robot body movement speed v through the navigation positioning perception and planning module, and use it as the conversion coefficient K between the rope retracting winch rotation speed and the body movement speed r Multiply them together to get the ideal value of the rotation speed of the rope retracting winch.

[0030] The conversion coefficient K between the rotation speed of the rope retracting winch and the vehicle body movement speed r Determined by the robot structure. K r=1 / r, r is the radius of the winch including the rope. For greater accuracy, it can be further calculated based on the number of rope windings.

[0031] Step 2: According to the environmental information measured by the perception system in the navigation positioning perception and planning module, it is input into the rope tension calculation model to calculate the target tension value F of the rope. * .

[0032] Among them, the rope tension model takes into account the robot's movement on a slope. The force on the rope when the robot moves on a slope is as follows: Figure 2 As shown in the figure, when the robot moves to the left, the wheel motor should make the wheel rotate counterclockwise, and the rope winch rotates to recycle the rope. At this time, the rotation direction of the rope winch is related to the winding direction of the rope on the winch. However, since the robot is in a balanced state when it moves at a constant speed, the angle θ between the caster arm and the ground is c Approximately equal to the angle θ between the rope and the ground t , the equilibrium equation is as follows:

[0033] ∑F x = -Fcosθ t +f s cosθ s +Nsinθ s =0

[0034] ∑F y =Fsinθ t -f s sinθ s +Ncosθ s -mg=0

[0035] f s =μN

[0036] Calculate the rope tension F * for

[0037]

[0038] Among them, θ c is the angle between the caster arm and the ground; θ s is the ground inclination angle; μ is the friction coefficient between the wheel and the ground. c With θ s It can be obtained through simple calculation using the built-in inertial sensor and the distance sensor installed perpendicular to the middle axis of the caster arm of the tethered wheeled mobile robot; μ can be estimated based on the smoothness of the road surface.

[0039] Step 3: Compare the difference between the target tension F* and the actual rope tension F, and compare it with the proportional control parameter K of the rope tension compensation PFMultiply them to get the compensation value of the rotation speed of the rope retracting winch.

[0040] Step 4: Add the rope taking-up and releasing winch rotation speed compensation value to the ideal value of the rope taking-up and releasing winch rotation speed to obtain the desired rope taking-up and releasing winch rotation speed.

[0041] In the embodiment of the present invention, the rope control of the tethered two-wheeled mobile robot adopts a correction control method that is synchronized with the robot's movement speed, thereby obtaining good rope tension following performance, while reducing rope wear and increasing the service life of the rope; the operating power consumption of the tethered robot can be reduced, the detection distance of the robot can be increased, and the stability of the system can be enhanced. This method can be applied to the rope management technology of a tethered mobile robot that provides support through a rope with one end fixed to the mother robot / anchor position. It can effectively tighten the rope and ensure that the rope tension is within a reasonable range, thereby effectively avoiding problems such as rope entanglement and difficulty in rope positioning. This type of robot can be used in fields such as planetary surface exploration and disaster relief, and therefore has broad application prospects.

[0042] The present invention has many specific application paths. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements made without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A rope control system for tension correction of a rope-tethered wheeled mobile robot, characterized in that: It includes a navigation positioning perception and planning module, a rope winch driver, a rope tension sensor, and a rope tension calculation model. The navigation positioning perception and planning module measures and outputs environmental information and the robot body movement speed v. The speed v is combined with the transformation coefficient to obtain the ideal value of the rope retracting winch rotation speed; The target tension value is further calculated based on the environmental information, the tension sensor measures the actual tension value of the rope, and the final expected rope retracting and releasing winch rotation speed is obtained based on the target tension value, the actual tension value and the ideal value and input into the rope winch driver.

2. The cable control system for tension correction of a tethered wheeled mobile robot according to claim 1, characterized in that: The environmental information includes the angle between the caster arm and the ground and the ground inclination when the mobile robot moves. Based on the angle and inclination, the target tension value can be obtained in combination with the ground friction coefficient and the mass of the robot; the angle and inclination are obtained by the inertial sensor built into the navigation, positioning, perception and planning module, and the distance sensor installed perpendicular to the central axis of the caster arm of the tethered wheeled mobile robot.

3. A control method for a cable control system for tension correction of a cable-tethered wheeled mobile robot, characterized in that: The following steps are involved: Step 1: Measure or plan the robot body movement speed v through the navigation positioning perception and planning module, and use it as the conversion coefficient K between the rope retracting winch rotation speed and the body movement speed r Multiply them together to get the ideal value of the rotation speed of the rope retracting winch; Step 2: According to the environmental information measured by the perception system in the navigation positioning perception and planning module, it is input into the rope tension calculation model to calculate the target tension value F of the rope. * ; Step 3: Use the rope tension as a correction for the rope retraction and release speed, that is, measure the actual tension F based on the rope tension sensor, compare the difference between the target tension F* and the actual rope tension F, and use the difference to compensate for the rope tension proportional control parameter K. PF Multiply them to get the compensation value of the rotation speed of the rope retracting winch; Step 4, adding the compensation value of the rotation speed of the rope retracting winch to the ideal value obtained in step 1 to obtain the expected value and input it into the rope winch driver to achieve control of the rope retracting speed.

4. The control method of the cable control system for tension correction of a tethered wheeled mobile robot according to claim 3, characterized in that: In step 1, the conversion coefficient K between the rotation speed of the rope retracting winch and the vehicle body movement speed is r Determined by the robot structure, K r =1 / r, r is the radius of the winch including the rope, which is calculated based on the number of rope windings.

5. The control method of the cable control system for tension correction of a tethered wheeled mobile robot according to claim 3 or 4, characterized in that: In step 2, the target tension value F is obtained by the rope tension calculation model. * , that is, the target rope tension value of the rope retraction and release control method for the synchronous tension correction of the rope-tethered wheeled mobile robot is: Among them, θ c is the angle between the caster arm and the ground; θ s is the ground inclination angle; μ is the friction coefficient between the wheel and the ground, m is the mass of the robot, θ c With θ s It can be obtained through simple calculation using the built-in inertial sensor and the distance sensor installed perpendicular to the body surface of the tethered wheeled mobile robot; μ can be estimated based on the smoothness of the road surface.

6. The control method of the cable control system for tension correction of a tethered wheeled mobile robot according to claim 5, characterized in that: In step 4, the rope retraction and release speed is controlled by changing the rotation speed of the rope winch, and its control law is: ω u =K PF (F * -F)+K r v In the formula, ω u is the angular velocity of the winch; F* is the target tension of the rope; F is the actual tension of the rope; K PF is the proportional control parameter of rope tension compensation; K r is the conversion coefficient between the winch rotation speed and the vehicle body movement speed; v is the vehicle body movement speed.

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