Till Örebro universitet

Working conditions in the dry cleaning and sanitation of confined interior spaces are often extreme, and workers need overall protection with tight clothing, helmets, face mask, earmuffs, and respirators. The environment is dirty, noisy with bad visibility and heavy with a high static work load. Dry cleaning is mainly practised in silos for grain, foodstuff and flour, etc. The inside of the silo is a hazardous environment due to many factors such as an unsafe oxygen level, engulfment, biological, mechanical, electrical, and atmospheric hazards. The requirements of the EU norms related to hygiene and food quality indicate that silos should be cleaned frequently and cleaning is obligatory after a silo is totally emptied. Therefore, there is an increased societal need for silo cleaning and a natural necessity to replace humans by robot manipulators in executing this risky and dangerous job.

This thesis presents a new concept of a flexible crawling mechanism for an industrial food cleaning robot, which is evaluated from the viewpoint of the capability to work inside a large food silo, scanning the desired surface, and performing the cleaning task. The main research questions investigated in this thesis are about: how to select the most important characteristics in designing a robot to fulfil the surface cleaning operation of a large confined space; how the crawling movement affects the dynamic behaviour of the robot mechanism; how the cleaning process affects the dynamic behaviour of the robot mechanism; how to develop the control of the robot to realize the locomotion and the cleaning process.

The structure of the robot and the cleaning technology are well defined after an overview of the existing technologies and solutions for cleaning large confined spaces. The robot design is based on a suspension and crawling system, using minimal actuators, where the force of gravity is well used to simplify the control system and to stabilise the robot. Further, the static and dynamic analysis of the mechanical system is studied. In addition, the control architecture of the system is performed, where the required sensors and control algorithm are given. A scale model testing has also been used to verify the locomotion of the concept, while simple controllers and algorithms are used to manage the motions of the prototype.

The requirements of the working and safety norms demonstrate significant need of increased efficiency and improved working conditions in cleaning confined spaces. This paper presents an overview of the existing technologies and solutions for cleaning large confined spaces. A special attention is directed for cleaning interior surface of confined spaces used mainly for storing bulk materials or liquids, such as silos. The cleaning technologies for confined space depend on several aspects as the build-up material, the surface material, the ambient conditions. Four cleaning techniques are presented in this paper. The mechanisms and robots related to the studied problem are surveyed and evaluated from the viewpoint of their capability to clean interior surfaces. The dominating majority of the existing cleaning equipment is constructed to serve cleaning the entire volume of the respective confined space (silo), but not for cleaning the interior surface.

All mechanical systems are subjected to dynamic forces when they are in functioning. Thus a dynamical analysis has to be studied to determine the system behaviour. The vibration is of interest to study, due to its destructive or constructive effect. In the present era computational techniques are quite common and are very reliable as far as the modal analysis is concerned. In this work, the robot of silo cleaning is analysed for its vibration behaviour using finite element method (FEM).The robot was modelled and meshed in ANSYS. Modal analysis was conducted to calculate few initial natural frequencies. After carrying out the modal analysis, harmonic and transient analysis were done to see the response of the robot under dynamic loading. It was observed that robot is safe in its entire range of operation.

Underwater robots are being developed for various applications ranging from inspection to maintenance and cleaning of submerged surfaces and constructions. These platforms should be able to travel on these surfaces. Furthermore, these platforms should adapt and reconfigure for underwater environment conditions and should be autonomous. Regarding the adhesion to the surface, they should produce a proper attaching force using a light-weight technics. Taking these facts into consideration, this paper presents a survey of different technologies used for underwater cleaning and the available underwater robotics solutions for the locomotion and the adhesion to surfaces.

This paper presents the mechanical design and the control system architecture of anunderwater robot, developed for bio-fouling cleaning surfaces. The robotic system presented herehas been designed to improve the productivity, reduce the environmental impacts, and excludethe hazards for the operators. The control system has a layered structure which is distributed intotwo blocks: cleaning robot, and on-board base station connected with power and control cablesand a water hose, to facilitate different modes of operations and to increase the system reliability.A low level control has been implemented on the robotic platform. The onboard station designedto be in different layers of the control system: manual, semiautonomous and autonomous modes.A scaled prototype has been implemented and tested to prove the concept, and to make certainthat the mechanical design and the chosen control system are perfectly suited to the mainfunctions of the robotic system.

Both the principle of operation and the motion-control system of a suspended robot for surface cleaning in silos are presented in this paper. The mechanical design is a reasonable compromise between basically contradictory factors in the design: the small entrance and the large surface of the confined space, and the suspension and the stabilization of the robot. The design consists of three main parts: a support unit, the cleaning robot and a cleaning mechanism. The latter two parts enter the silo in a folded form and, thereafter, the robot’s arms are spread in order to achieve stability during the cleaning process. The vertical movement of the robot is achieved via sequential crawling motions.

The control system is divided into two separate subsystems, the robot’s control subsystem and a support-unit control subsystem, in order to facilitate different operational modes. The robot has three principle motion-control tasks: positioning the robot inside the silo, holding a vertical position during the cleaning process and a crawling movement.

A scaled prototype of the robot has been implemented and tested to prove the concept, in order to make certain that the mechanical design suits the main functions of the robotic system, to realize the robot’s design in an industrial version and to test it in a realistic environment.

A suspended robot for surface cleaning in silos is presented in this paper. Thesuggested concept is a reasonable compromise between the basic contradictingfactors in the design: small entrance and large surface of the confined space,suspension and stabilization of the robot. A dynamic study for the suspendedrobot is presented in this paper. A dynamic simulation in MSC ADAMS iscarried out to confirm the results from the theoretic study.

A concept of a suspended robot for surface cleaning in silos is presented in this paper. The main requirements and limitations resulting from the specific operational conditions are discussed. Due to the large dimension of the silo as a confined space, specific kinematics of the robot manipulator is proposed. The major problems in its design are highlighted and an approach to resolve them is proposed. The suggested concept is a reasonable compromise between the basic contradicting factors in the design: small entrance and large surface of the confined space, suspension and stabilization of the robot