Three-wheeled Mobile Platform Research Articles

A mechatronic system for automated topping and suckering of tobacco plants

In agricultural crops, such as tobacco, the budding part of the plant is removed (topping) and the growth of axillary shoots (called suckers) is controlled with chemicals in order to produce good quality heavy-bodied darker tobacco leaves. Nowadays, topping and suckering are largely performed by hand and as a result the application process is time consuming. In this study, the design and implementation of a novel mechatronic system is presented, whereby the topping and suckering treatments can be performed automatically. The mechatronic system and its auxiliary equipment were mounted on a three-wheeled mobile platform. The novel system includes a topper unit, a high-precision sprayer, and a bifurcated metal guide designed to keep the plants in an upright position. An infrared beam sensor is mounted below the circular saw blade to locate the plant stalk and trigger a pulse so that the high-precision sprayer applies the proper amount of suckercide to the tobacco stalk. The high-precision sprayer travels parallel to and over the tobacco plant rows with a speed that matches the ground speed of the wheeled mobile platform. This is achieved by the use of a built-in drive wheel encoder. The mechatronic system was tested in both laboratory and field conditions. In the tests carried out, the travel speed of the three-wheeled platform was kept between 0.1 and 0.5 m/s. The topping and suckering of five tobacco plants lasted approximately 20 s. Traditional application has a disadvantage over the mechatronic system in that each worker is independent of the others and the speed of the whole process is essentially determined by the slower worker. In future work, the mechatronic system can be integrated into a small autonomous wheeled platform, a drone, or can be mounted on the horizontal boom of a suitably modified trailer sprayer.

Mobile platform with omnidirectional wheels modeling

The subject of the article is the process of a mobile platform with omnidirectional wheels moving. The purpose is computer modeling, which describes the possible directions of a mobile platform with omnidirectional wheels’ movement. The task: to perform computer modeling of the holonomic movement of the three-wheel platform in the Matlab Simulink. The methods used are: system analysis, numerical methods, mathematical and computer modeling methods. The following results are obtained. Possible options for the mobile platform moving in limited space conditions are suggested, in the obstacles presence. Computer simulations describing the holonomic movement of a mobile platform with omni-directional wheels and in the Matlab Simulink environment were performed. Conclusions. The proposed model allows to investigate the holonomic movement of a three-wheeled mobile platform with omnidirectional wheels. Analysis of the obtained results shows the instability of the change in linear velocities along the x and y axes. The nature of the change in the angular velocity and the angle of rotation of the platform is directly proportional to the distance between the center of the platform and the center of the wheel, and the linear velocity depends on the mass of the platform. The obtained results can be used for further studies of the controlling the holonomic movement process of a mobile platform with omni-directional wheels in limited space conditions, in the obstacles presence, and modeling the processes associated with its movement.

Dual closed-loop sliding mode control for a decoupled three-link wheeled mobile manipulator

This paper presents a dual closed-loop sliding mode control strategy for a wheeled mobile manipulator with three-wheeled mobile platform (WMP) and three-link manipulator. The Euler-Lagrange method combined partially with the Newtonian method is applied to obtain full dynamic model and decoupled model is constructed in order to provide simple dynamic model for controller's structure to be simplified. Instead of the conventional velocity command trajectory based kinematic backstepping control method, a dual closed-loop control system is designed. A virtual velocity command based on sliding mode surface is generated in outer loop and the gap between a generated virtual command velocity and real velocity is compensated by an inner loop sliding mode controller. Outer loop helps to faster posture trajectory generation for locomotion of the WMP. Next, a finite-time sliding mode controller with an assumed feedforward dynamic gain method is designed for joint trajectory tracking for three-link manipulator by adding finite-time control terms in the designed controllers to obtain faster settling time and stronger robustness. The designed controllers were implemented into microprocessor connected to DC and dynamixel motor systems equipped in mobile platform and manipulator, respectively. Comparative simulation and experiment with a conventional sliding mode control show the effectiveness of the proposed dual closed-loop finite time sliding mode control scheme.

Influence of external disturbances to dynamic balance of the semi-anthropomimetic robot

The idea of building an artificial man extends through the entire history of mankind. In this paper we present a semi-anthropomimetic robot, as a structure that consists of an upper human-like body mounted on a cart (mobile platform). Semi-anthropomimetic robot uses the three-wheeled mobile platform (two driving wheels and one passive wheel). Upper body configuration is represented as an anthropomimetic structure with antagonistically coupled drives. The aim of this paper is analysis of the robot behaviour under disturbances. Two types of disturbances are examined: disturbances following from the cart motion, and external disturbances. External disturbances (external impulse and long term external force) emulate interaction of the robot with its environment. Numerous simulations were performed, in order to analyze the balance of the robot. Accordingly, appropriate dimensions of the mobile platform are estimated, relying on the ZMP concept. [Projekat Ministarstva nauke Republike Srbije, br. TR-35003 i br. III-44008] <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href="http://dx.doi.org/10.2298/SJEE1603435E">10.2298/SJEE1603435E</a><u></b></font>

HILS for the Design of Three-Wheeled Mobile Platform Motion Surveillance System with a Use of Energy Performance Index

Current tendency in mechatronic design requires the use of comprehensive development of an environment, which gives the possibility to prototype, design, simulate and integrate with dedicated hardware. The paper discusses the Hardware-In-the-Loop Simulations (HILS) mechatronic technique [, used during the design of the surveillance system based on energy performance index [. The presented test configuration (physical controller emulated virtual research object) allows authors to verify responses (in the LabVIEW [) of the mobile platform model, to the optimal control commands (torques), generated by the Real Time controller. Defined energy performance index, supported by the correction velocities, controls the emulated platform while moving along three different trajectories. The demonstrated test results are compared with desired values obtained during numerical computation process of kinematic and dynamic equations of the presented model. The authors investigation of the HILS affected final optimisation of the motion surveillance system design. Real time requirements enforced authors to decrease sampling time of control command (signal generation frequency) and establish high performance execution strategy for on-line algorithm (algorithm execution performed both in Real Time processor and in the FPGA - Field Programmable Gate Array) [. The performed simulations confirmed that the HILS is a powerful technique, which improves system design making that more efficient and low cost consuming.

Balance Analysis of the Mobile Anthropomimetic Robot Under Disturbances – ZMP Approach

Throughout the history of technological progress, attempts have been made to build a machine that looks and behaves like humans. This paper presents a semi-anthropomimetic robot. The robot structure consists of a human-like upper body mounted on a mobile platform (mobile base, cart). The robot uses the three-wheeled mobile platform with two driving wheels and one passive (caster) wheel. The configuration and model of the upper body are represented as an anthropomimetic, compliant robot with antagonistically coupled drives. Robust control is evaluated in order to ensure stability of the robot position. The aim of this work is not the synthesis of control, but rather the examination of the limits of the adopted robot control strategy and the robot behaviour under disturbances (analysis of tip-over stability). The paper analyses both disturbances from the cart motion and external disturbances due to interaction with the environment (external impulse and long term external force). In order to analyse the balance of the robot and to avoid tipping over, different situations are tested and the appropriate dimensions of the cart are estimated (relying on the ZMP calculation).