Calibration algorithm for wheel encoder for four-wheel mobile robot

A mobile robot, encoder technology, applied in the direction of instruments, measuring devices, etc., can solve problems such as affecting the navigation performance of the robot and reducing the positioning accuracy of the mobile robot

Active Publication Date: 2019-06-21
成都天富若博特科技有限责任公司
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Problems solved by technology

The above two types of systematic errors reduce the positioning accu...

Method used

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  • Calibration algorithm for wheel encoder for four-wheel mobile robot
  • Calibration algorithm for wheel encoder for four-wheel mobile robot
  • Calibration algorithm for wheel encoder for four-wheel mobile robot

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Embodiment Construction

[0054] The present invention will be further described below in conjunction with the accompanying drawings.

[0055] First, the motion model of the four-wheeled mobile robot is established:

[0056] Such as figure 1 As shown, assuming that the robot moves on a plane, the effective radius of each wheel on the left is r L , the radius of each wheel on the right is r R , ω L and ω R are the rotational speeds of the left and right wheels, respectively. Then an approximate relationship between the wheel speed and the robot speed can be obtained:

[0057]

[0058] Among them, J is a function about the relevant parameters of the mobile robot body:

[0059]

[0060] where b is the wheel base.

[0061] From the above series of equations, it can be clearly seen that theoretically, the speed v of the trolley body x and ω can be transformed into the trolley wheel speed ω through the relevant parameter matrix L and ω R . So far, the motion model modeling of the four-wheele...

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Abstract

The invention belongs to the field of mobile robot positioning technologies and discloses a calibration algorithm for a wheel encoder for a four-wheel mobile robot. The algorithm includes the following steps that: the robot moves along a specific trajectory, and the measured values of the wheel encoder are collected; in each time period, an iterative closest point algorithm operates, so that the pose estimated values of the origin of a laser radar sensor coordinate system are obtained, and the measured values and estimated values constitute the data samples of each time period; linear parameter estimation is carried out: a linear parameter pair J21 and J22 is constructed on the basis of the left wheel radius rL, the right wheel radius rR and the wheelbase b of the robot, and linear estimation is performed; and calibration parameter estimation is carried out: calibration parameters are determined as b, lx, ly, and ltheta, wherein l is a relative pose relationship between the sensor coordinate system and a robot body coordinate system, a log likelihood function obtained in calibration problem description is established, and calibration parameters are calculated. With the calibrationalgorithm of the wheel encoder of the invention adopted, the parameters of a sensor and an actuator and the parameters of pose relationships can be accurately obtained in various environments with nomanual intervention required.

Description

technical field [0001] The invention relates to the technical field of mobile robot positioning, in particular to a wheel encoder calibration algorithm for a four-wheel mobile robot. Background technique [0002] Mobile robot positioning and navigation is a hotspot in the field of robotics research. In order to improve the positioning accuracy, mobile robots usually integrate data from multiple sensors for positioning, so as to learn from the strengths of various sensors. Before multi-sensor data fusion, the calibration of each sensor is an essential link. Wheeled mobile robots can be mainly divided into two-wheel drive, four-wheel drive and multi-wheel drive according to the number of wheels that provide power. Compared with two-wheeled mobile robots, in complex ground environments, four-wheeled mobile robots have better passability and stability of the body, and are more suitable for working in rough environments. [0003] The sensors arranged on the mobile robot can be ...

Claims

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Application Information

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IPC IPC(8): G01C25/00
Inventor 何仁杰郭润吴侃之
Owner 成都天富若博特科技有限责任公司
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