| With the development of modern technology, research of robots is widely concerned. Especially, mobile robots for uneven terrain became a hotspot of research. This subject is supported by Project of National Natural Science Foundation of China, named "Trafficability control with low-power consumption toward wheeled robot in rough terrain". This thesis mainly focuses on the building of control system, the kinematics development and the estimation of status and contact angle estimation.At first, according to the research status and the tendency of mobile robot control system, choose and build a control system which has the character of portable, easy to implement, good compatibility and stability. For this consideration, the subject chose the IPC with the PC/104 bus as the main control unit. CAN bus is chosen as a motor drive control bus. Steering servo control card is chosen for the steering servo controlling. Select IMU to return the pitch, roll and yaw, which are the body angle of the rover. Encoder is fixed on the differential mechanism, which is able to measure the differential angle of the rocker. The control system have to be able to control the mobile robot movement, beside, the information of the rover like posture, contact angle, and the current and angular velocity need to be fed back. The control software has the function of communication connection, manual control and auto-maneuver control.Secondly, because kinematics analysis is the foundation of rover control, and contact angle and slippage estimation are based on it, so, according to the existing mobile robot platform, applies coordinate transformation method, establishes kinematics model, and analyze the relevant characteristics. In the kinematic modeling process, slip and contact angle will be taken into account; for the cast and camber of each wheel of the mobile robot platform are adjustable, the caster and camber are considered in the derivation; in addition, the impact of adjustment of caster and camber to the body movement are analyzed. At last several patterns of movement are derived for the rover. Several maneuver model are derived based on kinematics development.Then, assuming that the terrain function is known, based on the kinematics modeling, simulate the contact:build the terrain model first, then solve the contact angle according to the kinematics modeling. In the condition of terrain is unknown, according to kinematics modeling, iterating function for contact angle estimation could be derived. Based on the principle of rigid body movement, according to the relationship of velocity of components, contact angle estimation is developed. For the IMU and other sensors on the rover feedback values with deviation, to accurate the estimated value of contact angle, UKF is adopted. In addition, for the platform could attach a fifth wheel which is empowered, according to the principle of kinematics, establish kinematics model for the fifth wheel system, build the relationship between the fifth wheel and the reference point, combining the kinematics modeling for the rover, the slippage estimation method is derived.Finally, execute maneuver model of straight, Ackerman, double Ackerman, differential, turn-point and omi-oriential on hard ground and sandlot, the body posture of pitch, roll and yaw are fed back, at the same time, driving current and angular velocity are fed back. Via analyzing these information to compare the advantages and disadvantages of each maneuver model. The experiment also tests the stability and excitability of the control system. Besides, carry out uneven terrain test bed experiment, to testify the contact angle estimation method; carry out uneven sand lot experiment with the fifth wheel, to testify the slippage estimation method. In all these experiment, the body posture and other information are feedback. |
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