Terrestrial mobile robots face diverse topographies while in field missions. Rough terrains cause the platform to oscillate, which is undesirable for some tasks. Robotic platforms with active tracked flippers can use such mechanisms to reach and maintain a leveled configuration while halted or moving. Thus, this work presents a posture controller that regulates the robot's orientation and contact plane clearance using flippers while the robot moves over unknown, uneven ground. The method takes as input the flippers' joint position, torque, and the robot chassis orientation, outputting as the command signal the flippers' joint velocities. Based on Stewart platforms, a differential kinematics model relates desired platform's motion to flippers' frame velocities. Later, a flippers-ground interaction model transforms their frames' computed velocities to flippers' joint speed commands. The controller is based on dual-quaternion algebra for generating the error signal. The efficacy of the proposed controller is evaluated experimentally in an industrial robotic platform moving as it moves along an open field track. The method successfully regulates the robot's posture while navigating over non-modeled rough terrain.

The traditional programming method for industrial robots is teaching by demonstration with a joystick or teaching pendant. However, high precision welding, machining, painting or thermal spraying, and other tasks require pre-computed trajectories, since an operator would not be able to accurately guide the manipulator and achieve suitable results. Giving the CAD model of a 3-D freeform surface, and the operating parameters of the task, this paper describes the methodology and steps involved in off-line programming for automatic trajectory generation. The computed waypoints comprise position, orientation, manipulator's end-effector velocities, and accelerations. This work describes the software platform employed for simulation, surface sampling, the use of radial basis function (RBF) for surface modelling, and intersection of surfaces (marching method) to generate paths. The case study for the developed method is the EMMA project∗, a robotic system for in situ high velocity oxy-fuel coating (HVOF) of hydraulic turbine blades. The results highlight the efficacy of the method and the impact of the solution for similar problems.

Describes the development and implementation of a dynamic positioning system for remotely operated underwater vehicles (ROVs) which is based on a mechanical passive arm (PA) for position measurement. The system, named DPSROV, is suited for tasks which require precise positioning within a limited range around a working site. The DPSROV was configured aiming at easy installation in most commercially available ROVs. The effectiveness of the DPSROV was tested on real ROVs. Two different control strategies were adopted: a conventional linear controller and a robust variable structure model-reference adaptive control. Experimental results are presented to illustrate the DPSROV performance.