Design and manufacturing of a prototype passive-active suspension system for a mobile robot used in greenhouse environments

Abstract

One of the main problems in modern agriculture is the need to increase pro duction to meet a growing population’s demand while dealing with limited resources and a reduced labor force. The use of mobile robots in agriculture has the potential to revolutionize traditional farming, increasing productivity and efficiency. Mobile robots in agriculture are already used to automate tasks like weeding, spraying and harvesting. This thesis presents the design and manufacture of a prototype passive-active suspension system that provides sufficient mobility and stability for a mobile robot used in green-house environments. The engineering design method was followed, starting from the generation of design concepts and culminating in the manufacturing of a final design. Computer-aided manufacturing techniques were employed to produce the components of the mobile robot. A combination of computer numerical control (CNC) and conventional milling and turning machines were utilized for the manufacture. The robot is specifically designed for green house applications and features a passive-active suspension system capable of navigating various types of terrain. To achieve mobility, the robot utilizes a skid-steering mechanism, employing four independently powered in-wheel motors. The robot’s passive suspension incorporates a rocker type suspension that enables the robot to overcome obstacles up to a height of 200 mm while adapting to different terrain conditions. The designed suspension system helps distribute the load evenly across the wheels, improving traction and stability. Furthermore, the robot’s active suspension includes a variable height mechanism that allows adjusting the ground clearance between 343 mm and 541 mm, giving the robot the ability to adapt to different terrain types and obstacles. The variable height system is also capable of modifying the roll angle of the vehicle, this can be used for the compensation of the roll angle when driving on inclined terrain. The maximum roll angle compensation achievable is 12.7 ◦ . In conclusion, the designed systems enhance the mobility of the mobile robot, enabling it to navigate through unstructured environments commonly encountered in the agricultural sector.