The periodic inspection for oil pipelines is required due to the deterioration over time. A multitude of factors brings such a deterioration, from corrosion, leaks, to cracks, which may lead to blowbacks and cause the damages for operators and the environments. With the progress of robotics technology, various types of mobile robots and mechanisms are designed to cope with this issue. Rather than the assignment of human workers in hazardous environments, the deployment of such kinds of inspection robots can take on this duty more time-efficiently and safely, preventing the human workers from the high-risk of the inspection task in the oil pipelines. This paper presents a novel design of a mobile robot for oil pipeline inspection, which is cooperated with the China National Petroleum Corporation (CNPC). With the improvement of the previous inspection robot used in CNPC’s standard oil pipelines, the newly designed robot is composed of six groups of symmetrical supporting wheels, and a more powerful motors as well as a more advanced control system. This new design endows the oil pipeline inspection robot with better performance on six aspects: traction, obstacle-adaptivity, operation endurance, gradeability, visual perception, and stability. The field testing results at multiple oil transfer stations across several months demonstrate the reliability of this mobile robot under various severe situations in China and validate its performance in the studied aspects.

This brief investigates optimal reset law design of reset control systems with fixed reset time instants. First, closed-loop reset control systems are changed to discrete-time linear control systems with reset values as control inputs. Then the optimal reset law design problems are transferred to linear quadratic regulation problems and the optimal reset laws are then obtained by solving algebraic Riccati equations. As an application, the proposed technique is applied to track-seeking control of a kind of hard disk drive systems. Simulations show that the transient response is improved significantly. Especially, the proposed long-span seeking reset control is almost bang-bang, but the design process is much simpler.

Controlling an underactuated robot is always an important research and engineering issue, especially when the robot is suffering from multiple sources of uncertainties, such as unmodeled dynamics, external disturbance, and parameter uncertainties. To cope with these uncertainties in such uncertain nonlinear systems which is not fully-actuated, this paper proposes a control method that can actively estimate these uncertainties via the extended state observer (ESO), under the scheme of output-feedback control, the lumped uncertainties can be online estimated and actively compensated. Every joint of the underactuated robotic system can robustly reach the pre-given state in finite-time even though there are only fewer joints than the actual number of joints that can be controlled directly. The experimental results demonstrate the control process and validate that the proposed method is feasible for the studied underactuated robotic system.

To facilitate the stabilization of nonlinear underactuated robotic systems under perturbation, a novel nonsingular fast terminal sliding mode control method is proposed. Based on the system transformation into an integrator chain, the combination of twisting-like algorithm and a nonsingular fast terminal sliding mode control technique is employed to achieve the stabilization of the studied systems, which can drive the robot states (joint positions and velocities) to the desired region and then maintain the system at the equilibrium point in finite time. The robustness of the proposed method is validated by the Lyapunov direct method. Finally, numerical simulation results further demonstrate that the proposed method has better performance on the convergent speed of the system state (robot joint positions and velocities) than state-of-the-art methods, especially for the underactuated joints.

Controlling an underactuated robot is an attractive research issue as some of the robot joints cannot be controlled directly. Besides, facing the unknown time-varying disturbance, the nature of the plant makes the stability of such uncertain nonlinear system more challenging. This work presents a robust finite-time control scheme that combines Hölder condition based extended state observer and sliding mode control approach to cope with the mentioned issues. The unknown time-varying disturbance and other uncertainties can be well recognized and actively compensated under the proposed scheme. Besides, this control scheme is easy to be implemented due to the small amount of information required. Simulation results demonstrate the performance of the proposed scheme and validate its better robustness and convergent speed compared with other schemes.