Analysis, investigation and design of flexible universal pneumatic industrial manipulators involving Cartesian and joint control in the basis of economic feasibility and appropriate technology

摘要

Pneumatic cylinders and systems have dominated the majority of industrial plants as two-position actuators due to that they are light-weight, clean, non-flammable; available in a wide range of sizes, have high cycle rates, can be installed with ease and have payload-to-weight ratios much higher than their other actuator counterparts. These advantages encouraged researchers to develop the performance of pneumatic cylinders and encompass mid-position control to broaden their applications for robotic manipulation. This thesis introduces a novel design, construction, control and analysis of a pneumatically driven reconfigurable modular manipulator system (PRMMS). The focus lies on a hypothesis of encompassing a hybrid electro-pneumatic manipulator while providing a low cost, lightweight, modular and reconfigurable system that can be of great assistant to small-to-medium enterprises (SMEs). The proposed system is mainly pneumatic actuated, for gross movements, with an electrical wrist that should compensate for errors and provide fine motions at the manipulator end effector. This thesis is only involved with the pneumatic actuated modules as part of this hybrid electro-pneumatic proposed system. A general review on modular systems did not encompass pneumatic actuated modular systems. Therefore, an exploration of the validity of pneumatic actuation in these modular systems and a proposed fuzzy logic PD + I controller was set for a passive damped pneumatic system capable of controlling and tracking the movement of a pneumatic cylinder to repeated accuracy of less than ±0.1mm with small displacement capabilities of the same order.Furthermore, a general simulation based methodology for robotic systems is studied. This methodology is based on an iterative process of system modifications leading to improved successful designs of robotic systems. Performance tuning criteria for the system was made possible through experimentations and modifications of the controller and the examination of different valves and cylinder combinations, all within the simulator. In addition, a combined Cartesian-joint control algorithm using low cost microcontrollers was established. Each joint module is controlled via an integrated local microcontroller while a global task controller computes and sets the path motions and control requirements to the modules through communication processes.Further benefiting from the properties of pneumatic cylinders, a proposed compliance control algorithm is applied to achieve safe interactions with humans at the work place by disabling modules which exceed a predefined amount of compliance. This issue of disabled modules opened an investigation for fault tolerance in redundant manipulators for assuring the completion of a task in structured and unstructured environments.