مدل سازي ديناميك فضايي و كنترل حركت يك ربات كم عملگر متحرك با پايه كروي

چكيده انگليسي :

Spatial Dynamic Modeling and Control of an Underactuated Single Spherical Wheeled Mobile Robot Amin Lotfiani a lotfiani@me iut ac ir 2012 04 22 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Dr Mehdi Keshmiri mehdik@cc iut ac ir Dr Mohamad Danesh danesh@cc iut ac ir AbstractMulti wheel statically stable mobile robots tall enough to interact meaningfully with people must have lowcenters of gravity wide bases of support and low accelerations to avoid tipping over These conditions present anumber of performance limitations Ballbot is a single spherical wheeled mobile robot which can move fast indifferent directions This kind of robot has the same height width and weight of a person and a high center ofgravity Unlike balancing 2 wheel platforms which must turn before driving in some directions the single wheelrobot can move directly in any direction Ballbot is an underactuated system with two nonholonomic velocityconstraints In order to deal with the real situations in this thesis a spatial model of ballbot will be presented Then trajectory planning and robust control of the robot will be applied on the achieved model First a 3Ddynamic model of the ballbot is derived by using Lagrange method for nonholonomic systems Using the nullspace of constraint coefficients matrix Lagrange multipliers are omitted from the equations Then to deal withinput coupling a change of variables will be used Since ballbot is an underactuated system finding a normalform of equations could be helpful in the control point of view Therefore its equations of motion are examinedto find whether there is a simple normal form or not However it can be seen that there is no normal form forthese motion equations Next an offline trajectory planning is proposed to move the robot between two staticconfigurations This strategy is also used to move among several configurations while the sphere velocity is nonzero at midpoints The most important challenge in trajectory planning and control of the ballbot is to make thecylindrical body upright while moving the sphere on the ground Thus the offline trajectory is proposed forunactuated joints cylinder angles with limited amplitudes and unknown parameters Using optimizationtechniques in evaluating the unknown parameters the least error at final desired configuration is derived Inorder to track the planned trajectory in the presence of uncertainties and disturbances two different controllers computed torque and sliding mode controllers are applied to the system An online trajectory planning is alsosuggested using fuzzy logic to track the desired time dependent sphere trajectories on the ground The inputs ofthe fuzzy blocks are tracking errors of the sphere angles while the outputs are desired cylinder angles which areto be tracked by feedback controllers The tracking of cylinder angles leads to track desired trajectories of therobot on the ground This method is applied to the system to track different paths like a straight line and roundpaths Computed torque method and sliding mode controllers are used beside fuzzy trajectory planning to helptracking of the desired trajectory To consider uncertainties and disturbances some simulations are performed the result of which show that sliding mode controller demonstrate much better performance compared withcomputed torque controller On the other hand when such unfavorable conditions do not exist the computedtorque method is the candidate showing less tracking error than the sliding controller KeywordsBallbot Spatial Dynamic Modeling Nonholonomic Systems Trajectory Planning SlidingMode Controller Computed Torque Controller Fuzzy

لطفياني، امين

مدل سازي ديناميك فضايي و كنترل حركت يك ربات كم عملگر متحرك با پايه كروي

بالبت , مدل سازي سه بعدي , سيستم هاي مقيد , طراحي مسير , منطق فازي