Mobile manipulators provide more advantages and flexibility in a wide range of applications than standard manipulators by introducing mobility. However, adding mobile platforms to standard manipulators, especially nonholonomic mobile platforms, introduces new challenges to the system modeling and control. Most existing methods for mobile manipulators do not consider the performance difference between the mobile platform and the manipulator and therefore cannot handle the uncertain and unexpected events happened in both the mobile platform and the manipulator. This paper introduces a planning and control method in a perceptive reference frame for a nonholonomic mobile manipulator to efficiently handle uncertain and unexpected events. The experimental results on a nonholonomic mobile manipulator demonstrate the effectiveness and advantages of the designed method.

Robot calibration is widely used in the manufacture industry to enhance and achieve a higher level of accuracy on industrial robot manipulators. Currently, there are many reliable calibration systems able to perform the calibration task. Those systems, however, are far from being a user friendly calibration tool; they are time consuming, very expensive, and usually requires a lot of human interaction. Therefore, we proposed a new calibration system able to overcome those problems with promising results. However, to take the system to the next level, and create an automated calibration process, we need to create a control system capable of guiding the robot's tool center point to a multi-position alignment. Throughout this paper the control approach needed to achieve automation of the entire system is presented and discussed. Simulations and experimental results demonstrated the feasibility of the overall calibration system including hardware, software and control algorithms.

This paper describes our updated system for industrial robot joint offset calibration. The system consists of an IRB1600 industrial robot, a laser tool attached to the robot's end-effector, a portable position-sensitive device (PPD), and a PC based controller. By aiming the laser spot to the center of position-sensitive-detector (PSD) on the PPD with different robot configurations, the developed system ideally implements our proposed calibration method called the virtual line-based single-point constraint approach. However, unlike our previous approach, the calibration method is extended to identify the offset parameters with an uncalibrated laser tool. The position errors of the PPD and the sensitivities of error in the PSD plane to the variation of joint angles are analyzed. Two different robot configuration patterns are compared by implementing the calibration method. Both simulation and real experimental results are consistent with the mathematical analysis. Experimental results with small (10−3−10−2) mean and standard deviation of parameters error verify the effectiveness of both the sensitivity analysis and the developed system.