scholarly journals Negotiating Uneven Terrain by a Simple Teleoperated Tracked Vehicle with Internally Movable Center of Gravity

2022 ◽  
Vol 12 (1) ◽  
pp. 525
Author(s):  
Yasuhiro Fukuoka ◽  
Kazuyuki Oshino ◽  
Ahmad Najmuddin Ibrahim
Keyword(s):  
Mechanical Design ◽  
Center Of Gravity ◽  
The Body ◽  
Unmanned Ground Vehicle ◽  
Tracked Vehicle ◽  
Ground Vehicle ◽  
High Position ◽  
Uneven Terrain ◽  
Dc Motors ◽  
Mass Position

We propose a mechanical design for a simple teleoperated unmanned ground vehicle (UGV) to negotiate uneven terrain. UGVs are typically classified into legged, legged-wheeled, wheeled, and tanked forms. Legged vehicles can significantly shift their center of gravity (COG) by positioning their multi-articulated legs at appropriate trajectories, stepping over a high obstacle. To realize a COG movable mechanism with a small number of joints, a number of UGVs have been developed that can shift their COG by moving a mass at a high position above the body. However, these tend to pose a risk of overturning, and the mass must be moved quite far to climb a high step. To address these issues, we design a novel COG shift mechanism, in which the COG can be shifted forward and backward inside the body by moving most of its internal devices. Since this movable mass includes DC motors for driving both tracks, we can extend the range of the COG movement. We demonstrate that a conventional tracked vehicle prototype can traverse a step and a gap between two steps, as well as climb stairs and a steep slope, with a human operating the vehicle movement and the movable mass position.

Mobile Robot Decision-Making Based on Offline Simulation for Navigation over Uneven Terrain

2018 ◽  
Vol 30 (4) ◽  
pp. 671-682
Author(s):  
Yuichi Kobayashi ◽  
Masato Kondo ◽  
Yuji Hiramatsu ◽  
Hokuto Fujii ◽  
Tsuyoshi Kamiya ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Path Selection ◽  
Outdoor Environment ◽  
Selection Strategy ◽  
Unmanned Ground Vehicle ◽  
Ground Vehicle ◽  
Uneven Terrain ◽  
Simulated Environment ◽  
Terrain Features ◽  
Selection Of

This paper presents an action decision framework for an autonomous mobile robot or an unmanned ground vehicle (UGV) to navigate an unknown environment. It is difficult for a UGV without global map information to decide which path to travel when it comes to a fork. However, locally observed terrain features can enable the UGV if it can utilize its past experience. The proposed path selection method utilizes correlations between features of the local terrain obtained by its laser range finder and the values of paths obtained through offline simulation using global path planning. During navigation, the UGV estimates the values of each path at a fork based on the correlation between the terrain feature and the value. It was confirmed that the proposed method allows the selection of paths that are more effective compared with a simple path selection strategy with which the UGV selects the closer path to the goal. The proposed method was evaluated in both a simulated environment and a real outdoor environment.

A Quasi-Static Approach to Optimize the Motion of an UGV Depending on the Track Profile

2015 ◽  
Vol 220-221 ◽  
pp. 774-780 ◽  
Author(s):  
Eduardo Corral ◽  
Gennady Aryassov ◽  
Jesús Meneses
Keyword(s):  
Vehicle Control ◽  
The Body ◽  
Unmanned Ground Vehicle ◽  
Vehicle Model ◽  
Complex Profile ◽  
Ground Vehicle ◽  
Normal Forces ◽  
Static Approach ◽  
Optimal Values ◽  
Numerical Program

The aim of this work is to improve the navigation capabilities of an off-road unmanned ground vehicle (UGV) by optimizing the angles between its legs and its body (its configuration angles), as the vehicle travels by a particular track profile. We present a numerical program based on a quasi-static half vehicle model. For a profile entered by the user, the program will be able to calculate how the angles between the legs and the body must vary along the trajectory, so that to maintain the torque on the wheels as constant as possible. Results may be helpful in vehicle control tasks, in particular when passing obstacles efficiently.First of all, some considerations concerning the nomenclature and geometry of the vehicle are presented. Then, the kinematics of the vehicle is exposed starting from the function that defines the profile. We focus on the position and/or trajectories of remarkable points to be employed later. From the kinematics, the quasi-static model is developed and the equations to calculate the forces and torques involved are presented. The algorithm basically calculates the position along the track and the angles between the legs and the body and then, by using the previous equations, finds the optimal values of those angles that satisfy a given condition (as equal to normal forces, torque constancy, minimum torque, etc.)As results, we present the configuration angles that equal to the normal forces on the wheels when the vehicle ascends a ramp, depending on the slope. We also present the optimal configuration angles variation required for the vehicle to pass over a step obstacle. And for a complex profile how the torque changes in function of the angles between the legs.

Mechatronics Implementation of Inverse Dynamics-Based Controller for an Off-Road UGV

2015 ◽  
Author(s):  
Mostafa Salama ◽  
Vladimir V. Vantsevich
Keyword(s):  
Power Distribution ◽  
Control Algorithm ◽  
Inverse Dynamics ◽  
Dc Motor ◽  
Unmanned Ground Vehicle ◽  
Power Losses ◽  
Wheel Load ◽  
Ground Vehicle ◽  
Dc Motors ◽  
And Control

This paper presents a project developed at the University of Alabama at Birmingham (UAB) aimed to design, implement, and test an off-road Unmanned Ground Vehicle (UGV) with individually controlled four drive wheels that operate in stochastic terrain conditions. An all-wheel drive off-road UGV equipped with individual electric dc motors for each wheel offers tremendous potential to control the torque delivered to each individual wheel in order to maximize UGV slip efficiency by minimizing slip power losses. As previous studies showed, this can be achieved by maintaining all drive wheels slippages the same. Utilizing this approach, an analytical method to control angular velocities of all wheels was developed to provide the same slippages of the four wheels. This model-based method was implemented in an inverse dynamics-based control algorithm of the UGV to overcome stochastic terrain conditions and minimize wheel slip power losses and maintain a given velocity profile. In this paper, mechanical and electrical components and control algorithm of the UGV are described in order to achieve the objective. Optical encoders built-in each dc motor are used to measure the actual angular velocity of each wheel. A fifth wheel rotary encoder sensor is attached to the chassis to measure the distance travel and estimate the longitudinal velocity of the UGV. In addition, the UGV is equipped with four electric current sensors to measure the current draw from each dc motor at various load conditions. Four motor drivers are used to control the dc motors using National Instruments single-board RIO controller. Moreover, power system diagrams and controller pinout connections are presented in detail and thus explain how all these components are integrated in a mechatronic system. The inverse dynamics control algorithm is implemented in real-time to control each dc motors individually. The integrated mechatronics system is distinguished by its robustness to stochastic external disturbances as shown in the previous papers. It also shows a promising adaptability to disturbances in wheel load torques and changes in stochastic terrain properties. The proposed approach, modeling and hardware implementation opens up a new way to the optimization and control of both unmanned ground vehicle dynamics and vehicle energy efficiency by optimizing and controlling individual power distribution to the drive wheels.

Development of path tracking control of a tracked vehicle for an unmanned ground vehicle

2020 ◽  
Vol 8 (4) ◽  
pp. 136
Author(s):  
Muhammad Akhimullah Subari ◽  
Khisbullah Hudha ◽  
Zulkiffli Abd Kadir ◽  
Syed Mohd Fairuz Bin Syed Mohd Dardin ◽  
Noor Hafizah Amer
Keyword(s):  
Tracking Control ◽  
Path Tracking ◽  
Unmanned Ground Vehicle ◽  
Tracked Vehicle ◽  
Ground Vehicle

scholarly journals Obstacle Detection for Unmanned Ground Vehicle on Uneven Terrain

2016 ◽  
Vol 65 (2) ◽  
pp. 342-348 ◽  
Author(s):  
Tok Son Choe ◽  
Sang Hyun Joo ◽  
Yong Woon Park ◽  
Jin Bae Park
Keyword(s):  
Obstacle Detection ◽  
Unmanned Ground Vehicle ◽  
Ground Vehicle ◽  
Uneven Terrain

scholarly journals Design of a Mechanism with Embedded Suspension to Reconfigure the Agri_q Locomotion Layout

Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 15
Author(s):  
Carmen Visconte ◽  
Paride Cavallone ◽  
Luca Carbonari ◽  
Andrea Botta ◽  
Giuseppe Quaglia
Keyword(s):  
Precision Agriculture ◽  
Ground Contact ◽  
Unmanned Ground Vehicle ◽  
Kinematic Synthesis ◽  
Ground Vehicle ◽  
Uneven Terrain ◽  
Contact Points ◽  
Curved Trajectories ◽  
Wide Contact ◽  
Driving Torque

The Agri_q is an electric unmanned ground vehicle specifically designed for precision agriculture applications. Since it is expected to traverse on unstructured terrain, especially uneven terrain, or to climb obstacles or slopes, an eight-wheeled locomotion layout, with each pair of wheels supported by a bogie, has been chosen. The wide contact surface between the vehicle and the ground ensures a convenient weight distribution; furthermore, the bogie acts like a filter with respect to ground irregularities, reducing the transmissibility of the oscillations. Nevertheless, this locomotion layout entails a substantial lateral slithering along curved trajectories, which results in an increase of the needed driving torque. Therefore, reducing the number of ground contact points to compare the torque adsorption in different configurations, namely four, six, or eight wheels, could be of interest. This paper presents a reconfiguration mechanism able to modify the Agri_q locomotion layout by lifting one of the two wheels carried by the bogie and to activate, at the same time, a suspension device. The kinematic synthesis of the mechanism and the dynamic characteristics of the Agri_q suspended front module are presented.

Design and experimental characterization of an omnidirectional unmanned ground vehicle for unstructured terrain

Robotica ◽  
2014 ◽  
Vol 33 (9) ◽  
pp. 1984-2000
Author(s):  
Chenghui Nie ◽  
Marin Assaliyski ◽  
Matthew Spenko
Keyword(s):  
Energy Consumption ◽  
Real World ◽  
Experimental Validation ◽  
Mechanical Design ◽  
Unmanned Ground Vehicle ◽  
Experimental Characterization ◽  
Ground Vehicle ◽  
Confined Spaces ◽  
Outdoor Environments

SUMMARYThis paper describes the design and experimental validation of an omnidirectional unmanned ground vehicle built for operation on real-world, unstructured terrains. The omnidirectional capabilities of this robot give it advantages over skid-steered or Ackermann-steered vehicles in tight and confined spaces. The robot's conventional wheels allow for operation in natural, outdoor environments as compared to omnidirectional robots that use specialized wheels with small, slender rollers and parts that can easily become obstructed with debris and dirt. Additionally, the robot's active split offset caster design allows the robot to kinematically follow continuous but non-differentiable paths and heading angles regardless of its current kinematic configuration. The active split offset caster design also results in less scrubbing torque and therefore less energy consumption during steering as compared to actively steered caster designs. The focus of this paper is the robot's mechanical design as it relates to kinematic isotropy and experimental validation of the design.

Unmanned Ground Vehicle Energy Efficiency Validation in Territory Surveillance Mission

2016 ◽  
Vol 251 ◽  
pp. 164-170
Author(s):  
Eero Väljaots ◽  
Raivo Sell ◽  
Marius Rimasauskas
Keyword(s):  
Energy Efficiency ◽  
Mechanical Design ◽  
Major Influence ◽  
Vehicle Design ◽  
Test Case ◽  
Environment Interaction ◽  
Unmanned Ground Vehicle ◽  
Design Validation ◽  
Ground Vehicle ◽  
And Control

This paper describes test case of an energy efficiency validation method. Test case is selected as surveillance mission which is simple and common case for universal unmanned ground vehicle where environment dynamics has major influence. The prototype UGV platform is equipped with combined measurement system providing data about dynamic parameters of platform physical movement as well as real-time energy consumption. Platform energy efficiency is evaluated on several stages, enabling to evaluate both mechanical design and control system algorithms. In addition, environment interaction with the vehicle is measured also for analyzing the vehicle limitations and scope of use. Real-condition missions are used for vehicle design validation purposes.

scholarly journals Methodology for the navigation optimization of a terrain-adaptive unmanned ground vehicle

2018 ◽  
Vol 15 (1) ◽  
pp. 172988141775272 ◽  
Author(s):  
Eduardo Corral Abad ◽  
Jesús Meneses Alonso ◽  
María Jesús Gómez García ◽  
Juan Carlos García-Prada
Keyword(s):  
Dynamic Model ◽  
Equation System ◽  
The Body ◽  
Unmanned Ground Vehicle ◽  
Profile Function ◽  
Ground Vehicle ◽  
Unstructured Environments ◽  
Navigation Algorithm ◽  
Static Approach ◽  
Dynamic Variables

The goal of this article is to design a navigation algorithm to improve the capabilities of an all-terrain unmanned ground vehicle by optimizing its configuration (the angles between its legs and its body) for a given track profile function. The track profile function can be defined either by numerical equations or by points. The angles between the body and the legs can be varied in order to improve the adaptation to the ground profiles. A new dynamic model of an all-terrain vehicle for unstructured environments has been presented. The model is based on a half-vehicle and a quasi-static approach and relates the dynamic variables of interest for navigation with the topology of the mechanism. The algorithm has been created using a simple equation system. This is an advantage over other algorithms with more complex equations which need more time to be calculated. Additionally, it is possible to optimize to any ground-track-profile of any terrain. In order to prove the soundness of the algorithm developed, some results of different applications have been presented.

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