Study On The Mobile Robot's Trajectory Based On Inertial Sensors

The mobile robot’s trajectory research is a relatively new subject, which is basedon the positioning and navigation, and on the premise of data from various sensors. Thebasis theoretical of mobile robot’s trajectory realization is differential flatness. Based onits kinematics and dynamics model, revolving around three basic subsystems, includingthe control subsystem, sensor subsystem and drive subsystem, in unknown environmenthow to get and accomplish mobile robot’s moving trajectory are researched.Firstly，history of domestic, foreign research and development trends of mobilerobots are introduced. Additionally, the research’s background, content and significanceare presented.The mobile robot’s control subsystem, sensor subsystem and drive subsystem areintroduced in this paper. Accelerometers, gyroscopes, and ultrasonic sensors arespecially analyzed, including their principles, characteristics and classification, and theirerror factor are studied. To control subsystem, the relationship of layers is introduced.For computer-controlled drive subsystem, analog PID algorithm is introduced, and itscontrol procedures accomplish successfully.Then, the combination of differential flatness theory and the B-spline curve arebrought forward to generate robot’s trajectory. Wheeled mobile robot is a typicalnonholonomic system, which also is a typical nonlinear system. Through the applicationof differential flatness theory, the nonlinear problem can be transformed into a flatsystem to analyse. B-spline curves can be used to construct a straight line segment, cuspand tangent, and other special cases. To curves in two dimensions which can not beaccurately represented by the function expression, taking the continuity, piecewisepolynomial parametric and modeling flexible type of B-spline into account, so using theB-spline curve to fit the robot trajectory is feasible. Through the B-spline curve fitting,getting robot trajectory curve’s fitting function expression, then combining with thedifferential flatness theory, the flat control volume is acquired, on this point it meansmotor drive’s output torque.Lastly, how to get a mobile robot’s point which it pass, on the point the principle of the inertial navigation is introduced. When a mobile robot is moving, use ultrasonicsensors to get its absolute positioning, use accelerometers and gyros to sample mobilerobot’s acceleration and angular velocity signal, after calculation the position andorientation of the mobile robot can be determined. Accordingly, numbers of suchpositions and orientations constitute mobile robot’s trajectory. On the other hand,combining of differential flat and B-spline curve fitting to get flat output, in this wayany mobile robot’s trajectory can be restored．...