Universal Path-Following of Wheeled Mobile Robots: A Closed-Form Bounded Velocity Solution

This paper presents a nonlinear, universal, path-following controller for Wheeled Mobile Robots (WMRs). This approach, unlike previous algorithms, solves the path-following problem for all common categories of holonomic and nonholonomic WMRs, such as omnidirectional, unicycle, car-like, and all steerable wheels. This generality is the consequence of a two-stage solution that tackles separately the platform path-following and wheels’ kinematic constraints. In the first stage, for a mobile platform divested of the wheels’ constraints, we develop a general paradigm of a path-following controller that plans asymptotic paths from the WMR to the desired path and, accordingly, we derive a realization of the presented paradigm. The second stage accounts for the kinematic constraints imposed by the wheels. In this stage, we demonstrate that the designed controller simplifies the otherwise impenetrable wheels’ kinematic and nonholonomic constraints into explicit proportional functions between the velocity of the platform and that of the wheels. This result enables us to derive a closed-form trajectory generation scheme for the asymptotic path that constantly keeps the wheels’ steering and driving velocities within their corresponding, pre-specified bounds. Extensive experimental results on several types of WMRs, along with simulation results for the other types, are provided to demonstrate the performance and the efficacy of the method.

A Review of Mobile Robot Navigation System for Volcano Monitoring Application

Volcano is a geological environment including magma, eruption, volcanic edifice and its basements. For continuous monitoring after eruption, a mobile robot could be proposed as an alternative to prevent hazardous effect to volcanologist who perform up close monitoring. In this paper, the robots were divided into 3 types according to their different structures: legged, track-legged and wheeled mobile robots. Meanwhile, the navigation system were implemented in 4 steps suitable for volcano condition: environment mapping, trajectory design, motion control and obstacle avoidance. These navigation system also tested in different locations: indoor, outdoor and real volcano with different testing method for these robots. The testing result was discussed in robot kinematics parameter such as trajectory, velocity, slope angle, rollover and sideslip angels.

A Review of Mobile Robot Navigation System for Volcano Monitoring Application

Volcano is a geological environment including magma, eruption, volcanic edifice and its basements. For continuous monitoring after eruption, a mobile robot could be proposed as an alternative to prevent hazardous effect to volcanologist who perform up close monitoring. In this paper, the robots were divided into 3 types according to their different structures: legged, track-legged and wheeled mobile robots. Meanwhile, the navigation system were implemented in 4 steps suitable for volcano condition: environment mapping, trajectory design, motion control and obstacle avoidance. These navigation system also tested in different locations: indoor, outdoor and real volcano with different testing method for these robots. The testing result was discussed in robot kinematics parameter such as trajectory, velocity, slope angle, rollover and sideslip angels.

Model-Based Control of a Mobile Platform With Independently Controlled In-Wheel Hydraulic Motors

Wheeled mobile platforms are important subsystems of heavy-duty working machines, but precise motion control of vehicles with multiple actuated wheels can be challenging, as linear controllers relying solely on velocity feedback could lead to excessive slippage of the wheels in face of varying terrain conditions. When aiming for more advanced control tasks as opposed to path-following, torque control of individual wheels could become necessary in order to distribute the traction effort in a desired fashion between each wheel. Studies on dynamic-model-based control of wheeled mobile robots concentrate on eletrically driven platforms that exhibit more linear behaviour than hydraulic drives, and dynamics of hydraulic motors are rarely addressed in the control design. In this paper, a model-based control design is pursued for a four-wheel vehicle actuated by in-wheel hydraulic motors, all independently controllable by high-bandwidth valves. Experiments on a heavy-duty mobile platform, equipped with wheel odometry, pressure transducers and satellite positioning, are conducted to study the feasibility of the proposed controller.