On Developing an Open Architecture Four Joints Serial Manipulator

The presented paper describes how, within a course of Mechatronics Engineering, a low cost, four joints serial manipulator has been designed and implemented. The system has been actively developed by two master degree students within a period of about 10 months, and will be used within laboratory activity modules in courses of Applied Mechanics and Manufacturing Automation. The first part of the paper presents the conceptual design of the manipulator, first by stating requirements and specifications, then by describing the design choices that have been done, from the point of views of system architecture, of mechanical systems, and of electronics and control systems. The second part of the paper presents the aspects of dynamic modeling that are involved in optimal joints movement interpolation, and the related algorithms that have been developed. The third part of the paper outlines the choices that have been done about the software environment (languages and development systems) and detailedly describes the software architecture that has been implemented at low level (i.e. programming of microcontroller that provides the motor driver function) and at high level (i.e. programming of the inverse kinematics, motor dynamics, 3-D motion simulator, user interface). The resulting system can operate in two modes: a manual/teaching mode, where the operator can move the manipulator by means of a joystick and pick a list of points to be saved on a file and routinely reached later on, and an automatic mode, where the manipulator autonomously moves through the points defined in a file (either manually written or created during a previous step while in teaching mode). The last part discusses how the described system suits within an advanced mechatronics course, and how an experimental module can be organized by exploiting the open architecture of the manipulator.