It is easy to realize that most robots do not move to the desired endpoint (Tool Center Point (TCP)) using high-resolution noncontact instrumentation because of manufacturing and assembly errors, transmission system errors, and mechanical wear. This paper presents a robot calibration solution by changing the endpoint trajectories while maintaining the robot’s control system and device usages. Two independent systems to measure the endpoint positions, the robot encoder and a noncontact measuring system with a high-resolution camera, are used to determine the endpoint errors. A new trajectory based on the measured errors will be built to replace the original trajectory. The results show that the proposed method can significantly reduce errors; moreover, this is a low-cost solution and easy to apply in practice and calibration can be done cyclically. The only requirement for this method is a noncontact measuring device with high-resolution and located independently with the robot in calibration.

In recent years, the term "climate change" has been increasingly receiving a lot of attention from scholars and policy makers, adversely affecting the lives of people (mostly of the poor) around the world in the present, and threatening the environment quality in the future. With many concerns about environmental degradation, countries tend to transform economic growth models causing negative impacts on the environment, especially for those in the stage of industrialization and modernization. This study was aimed at investigating the trade-offs between economic development and climate change among poor nations – the most affected by and most likely causing to climate change. By using a dynamic common correlated effects approach for unbalanced panel data which deals with cross-sectional dependency and time-series persistence, the paper showed that GDP is strongly correlated to CO2 emissions both in the short and long run, and one of the reasons is the use of CO2-generating energy sources.JEL classification: C23, O44, Q54

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This paper introduces a methodology for controlling parallel robots in case they are used as a kind of specialized fixture to expand the technological capabilities of machines. The parallel robot is mounted on the workbench to extend the number of degrees of freedom. However, there are always measurable kinematic errors of the workbench which will be eliminated by the robot’s motion. The actual working motion of the robot is then still performed by its active joints. Therefore, the displacement of each movable joint is now decided by two sources, one is due to the error compensation motion of the workbench, the other is the required work movement. According to the superposition principle, these two motions are combined into a single displacement characteristic curve to control the robot. The base exchange technique to determine the error compensation motion of the workbench, the technique of solving the inverse kinematics problem by the generalized reduced gradient (GRG) method, and the principle of joint motion combination are then introduced in detail in the paper. Finally, an example with the hexapod is presented. The obtained results, which use the robot itself to generate error-compensated movements of the workbench by means of the base exchange technique, will open up the possibility of intervening in hybrid machine systems to ensure the desired forming accuracy without no hardware intervention required.

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