scholarly journals ON THE ACCURACY OF POSITIONING OF MOBILE ROBOT'S WALKING PROPULSION DEVICES

2021 ◽  
pp. 69-73
Author(s):  
L. D. Smirnaya ◽  
I. P. Vershinina
Keyword(s):  
Material Point ◽  
Kinematic Scheme ◽  
Positioning Accuracy ◽  
Positioning Errors ◽  
Parallel Chain ◽  
Walking Mechanism

The problems of the influence of the choice of the kinematic scheme of the walking mechanism on the positioning accuracy of its foot with the same small positioning errors are considered. The relationships between the laws of changing the coordinates of the foot of the walking mechanism as a material point and the change in the position of the output elements of the motors of the drives of the orthogonal mover and the mover with a parallel chain of drives are established.

scholarly journals Intelligent Calibration of a Heavy-Duty Mechanical Arm in Coal Mine

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1186
Author(s):  
Yunhong Jia ◽  
Xiaodong Zhang ◽  
Zhenchong Wang ◽  
Wei Wang
Keyword(s):  
Extreme Learning Machine ◽  
Coal Mine ◽  
Absolute Error ◽  
Calibration Method ◽  
Heavy Duty ◽  
Maximum Absolute Error ◽  
Positioning Accuracy ◽  
Positioning Errors ◽  
Roof Bolter ◽  
Learning Machine

Accurate positioning of an airborne heavy-duty mechanical arm in coal mine, such as a roof bolter, is important for the efficiency and safety of coal mining. Its positioning accuracy is affected not only by geometric errors but also by nongeometric errors such as link and joint compliance. In this paper, a novel calibration method based on error limited genetic algorithm (ELGA) and regularized extreme learning machine (RELM) is proposed to improve the positioning accuracy of a roof bolter. To achieve the improvement, the ELGA is firstly implemented to identify the geometric parameters of the roof bolter’s kinematics model. Then, the residual positioning errors caused by nongeometric facts are compensated with the regularized extreme learning machine (RELM) network. Experiments were carried out to validate the proposed calibration method. The experimental results show that the root mean square error (RMSE) and the mean absolute error (MAE) between the actual mast end position and the nominal mast end position are reduced by more than 78.23%. It also shows the maximum absolute error (MAXE) between the actual mast end position and the nominal mast end position is reduced by more than 58.72% in the three directions of Cartesian coordinate system.

Coordination error control for accurate positioning in movable robotic drilling

2015 ◽  
Vol 35 (4) ◽  
pp. 329-340 ◽  
Author(s):  
Biao Mei ◽  
Weidong Zhu ◽  
Huiyue Dong ◽  
Yinglin Ke
Keyword(s):  
Error Control ◽  
Vision System ◽  
Aviation Industry ◽  
Accurate Estimation ◽  
Positioning Accuracy ◽  
Content Type ◽  
Positioning Errors ◽  
Aircraft Manufacturing ◽  
Robotic Drilling ◽  
Drilling System

Purpose – This paper aims to propose a roadmap to control the robot–subassembly (R–S) coordination errors in movable robotic drilling. Fastener hole drilling for multi-station aircraft assembly demands a robotic drilling system with expanded working volume and high positioning accuracy. However, coordination errors often exist between the robot and the subassembly to be drilled because of disturbances. Design/methodology/approach – Mechanical pre-locating and vision-based robot base frame calibration are consecutively implemented to achieve in-process robot relocation after station transfer. Thus, coordination errors induced by robotic platform movements, inconsistent thermal effects, etc. are eliminated. The two-dimensional (2D) vision system is applied to measure the remainder of the R–S coordination errors, which is used to enhance the positioning accuracy of the robot. Accurate estimation of measured positioning errors is of great significance for evaluating the positioning accuracy. For well estimation of the positioning errors with small samples, a bootstrap approach is put forward. Findings – A roadmap for R–S coordination error control using a 2D vision system, composed of in-process relocation, coordination error measurement and drilled position correction, is developed for the movable robotic drilling. Practical implications – The proposed roadmap has been integrated into a drilling system for the assembly of flight control surfaces of a transport aircraft in Aviation Industry Corporation of China. The position accuracy of the drilled fastener holes is well ensured. Originality/value – A complete roadmap for controlling coordination errors and improving positioning accuracy is proposed, which makes the high accuracy and efficiency available in movable robotic drilling for aircraft manufacturing.

scholarly journals Positioning Accuracy Analysis of the Parallel Mechanism Near Singular Positions

2015 ◽  
Vol 20 (1) ◽  
pp. 5-18 ◽  
Author(s):  
J. Bałchanowski
Keyword(s):  
Numerical Modelling ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Accuracy Analysis ◽  
Parallel Mechanisms ◽  
Contact Interactions ◽  
Positioning Accuracy ◽  
Singular Configurations ◽  
Positioning Errors ◽  
Three Degrees Of Freedom

Abstract This paper presents a method of numerical modelling of parallel mechanisms with clearances in their kinematic pairs taken into account. The pairs with clearances are modelled as shape connections based on constraints in the form of contact interactions. Using the created models simulations were run to determine the positioning errors of the links in a parallel mechanism with three degrees of freedom (MR2120). In particular, the accuracy of positioning the links close to the mechanism singular configurations was studied.

scholarly journals Performance of BDS B1 frequency standard point positioning during the main phase of different classes of geomagnetic storms in China and its surrounding area

2021 ◽  
Author(s):  
Junchen Xue ◽  
Sreeja Vadakke Veettil ◽  
Marcio Aquino ◽  
Xiaogong Hu ◽  
Lin Quan ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Frequency Standard ◽  
Satellite System ◽  
Navigation Systems ◽  
Surrounding Area ◽  
Positioning Accuracy ◽  
Positioning Errors ◽  
Radio Signals ◽  
Point Positioning ◽  
Similar Class

Abstract. Geomagnetic storms are one of the space weather events. The radio signals transmitted by modern navigation systems suffer from the effects of storms which can degrade the performance of the whole system. In this study, the performance of BeiDou Navigation Satellite System (BDS) B1 frequency standard point positioning in China and its surrounding area during different classes of storms is investigated for the first time. The analysis of the results revealed that BDS B1 frequency standard point positioning accuracy was deteriorated during the storms. The probability of the extrema in the statistics of positioning errors during strong storms is the largest, followed by moderate and weak storms. The positioning accuracy for storms of a similar class is found not to be at the same level. The root mean square error (RMSE) in position for the different classes of storms could be at least tens of centimeters in the East, North and Up directions.

scholarly journals Simulation of Crane Trolley Motion Control to Reduce Load Sway

2021 ◽  
Vol 2096 (1) ◽  
pp. 012004
Author(s):  
A A Reutov
Keyword(s):  
Control Parameters ◽  
Optimal Parameters ◽  
Wind Force ◽  
Positioning Accuracy ◽  
Swing Angle ◽  
Positioning Errors ◽  
Acceptable Range ◽  
Satisfactory Performance ◽  
Optimal Values ◽  
Universal Mechanism

Abstract the work aims to develop a method for controlling a crane trolley, providing a decrease in the swinging of the load on the rope at a given positioning accuracy and minimum time for moving the load. Computer simulation of the trolley controlled movement with a load on a rope was carried out within the "Universal Mechanism" software. The 2D computer model includes a trolley with a pulley, a rope with a hook, and a load. T-force represents the wind force effect. The control system (CS) contains three blocks that ensure the movement of the trolley with limited speed and acceleration, the positioning accuracy of the trolley, limiting the deviation and acceleration of a load. List of requirements for the crane CS comprises six issues. The simulation results illustrate the satisfactory performance of the proposed method. The swing angle and trolley positioning accuracy can be controlled within the acceptable range and the external wind disturbance on the load can be successfully suppressed. The optimal parameters of the proportional-differential corrective control, which ensure the minimum travel time of the trolley with limited oscillation of the load, have been determined. The optimal values of the control parameters depend on the inertial characteristics of the load. The maximum permissible values of speed, acceleration, and positioning errors of the trolley limit from above the optimal values of the control parameters.

scholarly journals Improved RSSI Positioning Algorithm for Coal Mine Underground Locomotive

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Bin Ge ◽  
Kai Wang ◽  
Jianghong Han ◽  
Bao Zhao
Keyword(s):  
Coal Mine ◽  
Gaussian Model ◽  
Correction Method ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Positioning Errors ◽  
Weighted Model ◽  
The Difference ◽  
Positioning Algorithm ◽  
Received Signal Strength Indication

Aiming at the large positioning errors of traditional coal mine underground locomotive, an improved received signal strength indication (RSSI) positioning algorithm for coal mine underground locomotive was proposed. The RSSI value fluctuates heavily due to the poor environment of coal mine underground. The nodes with larger RSSI value corrected by Gaussian-weighted model were selected as beacon nodes. In order to reduce the positioning error further, the estimated positions of the locomotives were corrected by the weighted distance correction method. The difference between actual position and estimated position of beacon node was regarded as the positioning error and was given a corresponding weight. The results of simulation show that the positioning accuracy of Gaussian-weighted model is better than statistical average model and Gaussian model and it has a high positioning accuracy after correcting positioning error correction. In the 10 m of communication range, positioning error can be maintained at 0.5 m.

Horizontal GPS Positioning Accuracy During the 1999 Solar Eclipse

2001 ◽  
Vol 54 (2) ◽  
pp. 293-296 ◽  
Author(s):  
Renato Filjar
Keyword(s):  
Statistical Analysis ◽  
Solar Eclipse ◽  
Space Weather ◽  
Significant Activity ◽  
Positioning Accuracy ◽  
Positioning Systems ◽  
Gps Positioning ◽  
Positioning Errors ◽  
Satellite Positioning ◽  
The Impact

Although GPS positioning errors are now well described, there are still some uncertainties regarding the impact of some rare space weather phenomena on GPS positioning accuracy. Solar eclipses have been considered as one source of such rare events, so the 1999 solar eclipse gave the opportunity to collect horizontal GPS positioning data for further analysis. The results of statistical analysis show no deterioration of horizontal GPS positioning accuracy. Space weather, ionospheric and geomagnetic conditions were also carefully analysed and showed no significant activity. In conclusion, the experiment confirmed negligible impact of the 1999 solar eclipse on horizontal GPS positioning accuracy, and opens discussion concerning application of satellite positioning systems in space and ionospheric weather monitoring.

scholarly journals Research on the Integrated Navigation Technology of SINS with Couple Odometers for Land Vehicles

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 546
Author(s):  
Jiaxin Gao ◽  
Kui Li ◽  
Jiyang Chen
Keyword(s):  
Navigation System ◽  
Dead Reckoning ◽  
Integrated System ◽  
Integrated Navigation ◽  
Fiber Optic Gyroscope ◽  
Velocity Difference ◽  
Positioning Accuracy ◽  
Integrated Navigation System ◽  
Positioning Errors ◽  
Over Time

Autonomous and accurate acquisition of the position and azimuth of the vehicle is critical to the combat effectiveness of land-fighting vehicles. The integrated navigation system, consisting of a strap-down inertial navigation system (SINS) and odometer (OD), is commonly applied in vehicles. In the SINS/OD integrated system, the odometer is installed around the vehicle’s wheel, while SINS is usually installed on the base of the vehicle. The distance along SINS and OD would cause a velocity difference when the vehicle maneuvers, which may lead to a significant influence on the integration positioning accuracy. Furthermore, SINS navigation errors, especially azimuth error, would diverge over time due to gyro drifts and accelerometer biases. The azimuth error would cause the divergence of dead-reckoning positioning errors with the distance that the vehicle drives. To solve these problems, an integrated positioning and orientation method based on the configuration of SINS and couple odometers was proposed in this paper. The proposed method designed a high precision integrated navigation algorithm, which compensated the lever arm effect to eliminate the velocity difference between SINS and odometers. At the same time, by using the measured information of couple odometers, azimuth reference was calculated and used as an external measurement to suppress SINS azimuth error’s divergence over time, thus could further improve the navigation precision of the integrated system, especially the orientation accuracy. The performance of the proposed method was verified by simulations. The results demonstrated that SINS/2ODs integrated system could achieve a positioning accuracy of 0.01% D (total mileage) and orientation accuracy of ±30″ by using SINS with 0.01°/h Fiber-Optic Gyroscope (FOGs) and 50 µg accelerometers.

scholarly journals Positioning Accuracy Determination of the Servo Axes for Grinding Wavy-Tilt-Dam Seals Using a Four-Axis Grinder

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 388
Author(s):  
Guang Feng ◽  
Xiaobao Ma
Keyword(s):  
Nuclear Reactor ◽  
Geometric Model ◽  
Implementation Strategies ◽  
Manufacturing Cost ◽  
Positioning Accuracy ◽  
Positioning Errors ◽  
Homogeneous Transformation Matrix ◽  
Manufacturing Techniques ◽  
Multi Body ◽  
Accuracy Determination

The wavy-tilt-dam (WTD) seal is considered to be one of the ideal sealing patterns used in nuclear reactor coolant pumps (RCPs). Grinding such seals with a four-axis grinder had been proposed and six grinding implementation strategies were described in our previous studies. However, another important issue is to determine the positioning accuracy of each servo axis so that the high-precision moving components can be selected properly. In the present paper, the positioning accuracy analysis is carried out to seek a balance between the manufacturing cost and the accuracy requirements. First, a geometric model is established for investigating the error sensitivity of each axis and setting reasonable accuracy allocation of the four axes. Subsequently, the combined influence of all four axes is assessed based on multi-body system (MBS) theory and homogeneous transformation matrix (HTM). According to the results calculated, positioning errors of the X-axis, Z-axis, B-axis, and C-axis within ±10 μm, ±0.1 μm, ±1 arcsec and ±60 arcsec are acceptable, respectively. Meanwhile, the form error calculated of the ground wavy face is no more than 109.74 nm. It is indicated that the accuracy level of the moving components is achievable by modern manufacturing techniques. The present paper is expected to serve as a theoretical basis for the design and development of the four-axis grinder.

scholarly journals Improvement of Robot Accuracy with an Optical Tracking System

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6341
Author(s):  
Ying Liu ◽  
Yuwen Li ◽  
Zhenghao Zhuang ◽  
Tao Song
Keyword(s):  
Tracking System ◽  
Least Square ◽  
Optical Tracking ◽  
Kinematic Parameters ◽  
Optical Tracking System ◽  
Positioning Accuracy ◽  
Positioning Errors ◽  
Robot Accuracy ◽  
Simulation Based ◽  
Robot Positioning

Robot positioning accuracy plays an important role in industrial automation applications. In this paper, a method is proposed for the improvement of robot accuracy with an optical tracking system that integrates a least-square numerical algorithm for the identification of kinematic parameters. In the process of establishing the system kinematics model, the positioning errors of the tool and the robot base, and the errors of the Denavit-Hartenberg parameters are all considered. In addition, the linear dependence among the parameters is analyzed. Numerical simulation based on a 6-axis UR robot is performed to validate the effectiveness of the proposed method. Then, the method is implemented on the actual robot, and the experimental results show that the robots can reach desired poses with an accuracy of ±0.35 mm for position and ±0.07° for orientation. Benefitting from the optical tracking system, the proposed procedure can be easily automated to improve the robot accuracy for applications requiring high positioning accuracy such as riveting, drill, and precise assembly.

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