Abstract
In recent years, a novel skid-steered duct-cleaning mobile platform was developed to remove dust accumulated on the inner surface of an air-ventilation duct with its rolling brushes. During the cleaning process, the irregular brushing pressure acting on the upper arm makes it difficult to control the platform through the duct path. In fact, the repulsive external force due to the brushing pressure is not directly measurable or computable because of the nonlinear deformation of the brush. In addition, dynamic uncertainties in platform motion can occur during reciprocating motion of the upper arm. Therefore, a model-based trajectory-tracking controller is required to control the mobile cleaning platform by considering irregular external forces. The robustness of the developed controller based on the adaptable PD(Proportional-Derivative)-backstepping method has been proposed and evaluated through numerical analysis and experiments. For the turning motion in a narrow space, a skid-steered platform model considering wheel slippage has been also implemented. The result shows that tracking control can be successfully achieved under various conditions of frequencies in brushing-arm motion and torque limitation of the traction motors.
Highlights
Effective air-duct-cleaning techniques have been studied to improve the air quality of ventilation-duct systems broadly used in subway stations and buildings
The performance of the trajectory-tracking controller was examined in an air-ventilation duct by applying random external forces to the platform
The experimental results shows that the PD-backstepping method improves system stability by minimizing trajectory tracking errors during the changes of brushing force, and the motor torques are more adaptable to the external force in case of PD-backstepping method
Summary
Effective air-duct-cleaning techniques have been studied to improve the air quality of ventilation-duct systems broadly used in subway stations and buildings. Automatic control platforms have been developed for duct-cleaning robots and devices to enhance their operability in the dark and limited space inside the duct. Various ventilation-duct-cleaning robots have been developed with intelligent controllers, sensors, skid-steering functions, and brushing-arm mechanisms. The mobile platform requires a stable trajectory-tracking controller with skid-steering to be used in the limited air-duct space. To achieve effective control of the duct-cleaning platform, it is essential to construct a dynamic model of the system including unknown variables such as nonlinear deformation of the filaments of the brush and unknown friction coefficients at each contacting point of the cleaning mechanism. The lateral loads of the mobile platform and the reciprocating motion of the Electronics 2019, 8, 401; doi:10.3390/electronics8040401 www.mdpi.com/journal/electronics
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