A novel voice-coil actuated mini crawler for in-pipe application employing active force control with iterative learning algorithm

This study proposes the design and development of an in-pipe mini crawler (or robot) capable of performing its various tasks with the ability to reject undesired disturbances resulting from friction and viscosity, as it was modeled, simulated, and experimented using an iterative learning algorithm (ILA)-based active force control (AFC) strategy. The crawler motion was executed based on a rapid and successive push-pull action plus friction that causes the crawler to move in an earthworm-like manner using a linear voice-coil actuator (VCA). A novel self-adjusted mechanism was designed to ensure that the crawler remained concentric in the pipe as it slides along the inner surface of the pipe. A novel control strategy was also proposed consisting of the AFC-based controller cascaded with a proportional-integral-derivative (PID) controller to control the crawler movement and expel off the applied perturbations. An intelligent PD-type ILA was employed to automatically tune the AFC while online. For the validation part, a prototype was designed, developed, and later experimented with using the proposed technique for a given set of conditions. The system integration employed a hardware-in-the-loop (HIL) test configuration utilizing LabVIEW. Experimental results are in good agreement with the simulation counterpart, thereby indicating the practicality and feasibility of the control system in performing accurate and robust trajectory tracking. This shall serve as a good basis for designing more challenging tasks related to miniature crawling mechanism in-pipe applications

Mechatronic development of an in-pipe microrobot with intelligent active force control

In this research, the development of an in-pipe microrobot system with intelligent active force control (AFC) capability was investigated and presented, including both simulation and experimental studies. Three actuated microrobot mechanisms driven by pneumatic, piezoelectric and voice-coil actuators were modelled and simulated in a constrained environment inside a pipe. The mechanisms were then embedded into the proposed AFC-based control strategy. The worm-like movement of these microrobots with the respective actuators were effectively modelled using the impact drive mechanism (IDM). A classic proportional-integralderivative (PID) controller was first designed and applied to the microrobot system to follow a desired trajectory in the presence of disturbances, which may be created due to the frictional force or fluid viscosity inside a pipe. Later, an AFC-based controller was utilized to enhance the system dynamic performance by robustly rejecting the disturbances. To estimate the inertial mass of the AFC loop, artificial intelligence (AI) techniques, namely the variants of fuzzy logic (FL) and iterative learning algorithms (ILA) were explicitly employed. The dynamic response of the fully developed model of the in-pipe microrobot systems (with three different actuators) subject to various input excitations and disturbances was rigorously explored and numerically experimented. This involved the parametric study and sensitivity analysis to observe and to analyse the effects of a number of influential parameters that were deemed to have positive impact on the system performance. The simulation work was validated through an experimental investigation performed on a rig prototype that employed the voice-coil actuated mechanism to drive the selected AFC-based microrobot scheme, considering the given operating and loading conditions. Full mechatronic approach was adopted in the design of the rig by integrating the related sensors, actuator, mechanical parts and digital controller in a hardware-in-the-loop simulation (HILS) configuration. Parametric study was carried out to complement the simulation counterpart by taking into account the different settings and working environments. From the experimental results, the developed inpipe microrobot system was proven to be effective and robust in its trajectory tracking, in spite of the existence of various excitation inputs and external disturbances. This implied that the produced experimental responses were in good agreement with those acquired via simulation. The outcomes of the study shall provide a strong foundation for furthering the design of specific in-pipe microrobot applications, such as visual inspection of the inner surface of pipes, fault-diagnostics, obstacle removal and other related tasks

Modelling and control of a piezo actuated micro robot with active force control capability for in-pipe application

In this paper, a piezo actuated micro robot with active force control (AFC) capability is modelled and simulated for an in-pipe application. A mathematical model that describes the dynamic characteristics of the micro robot is first presented. The dynamic response of the robot system subjected to different input excitations is then investigated by initially considering a conventional proportional-integral-derivative (PID) controller to perform a trajectory tacking task. Subsequently, a robust AFC-based controller is serially added to the PID controller, the primary aim of which is to reject the unwanted disturbances due to frictional forces in the pipe. The control system is tuned so that an accurate trajectory tracking control is achieved. The performance of the control system under different loading and operating conditions is evaluated through a rigorous simulation study. A sliding mode controller (SMC) was also included to provide another means of comparing the system performances apart from the pure PID control scheme. The obtained results clearly demonstrate the robust trajectory tracking performance of the proposed AFC-based micro robot system in spite of the negative effects of the external disturbances

Application of micro-electro-mechanical systems (MEMS) as sensors: A review

This paper presents a review of the current applications of Micro-Electro-Mechanical Systems (MEMS) in the robotics and industrial applications. MEMS are widely used as actuators or sensors in numerous respects of our daily life as well as automation lines and industrial applications. Intersection of founding new polymers and composites such as silicon and micro manufacturing technologies performing micro-machining and micro-assembly brings about re-markable growth of application and efficacy of MEMS devices. MEMS indicated huge improvement in size reduction, higher reliability, multi-functionality, cus-tomized design, and power usage. Demonstration of various devices and technologies utilized in robotics and industrial applications are illustrated in this article along with the use and the role of silicon in the development of the sensors. Some future trends and its perspectives are also discussed