| Summary: | 碩士 === 淡江大學 === 電機工程學系碩士班 === 98 === In this thesis, a small size of humanoid robot (HR) is developed such that it can walk on uneven ground with the reduction of falling down. The proposed HR is height of 58 cm, weight of 3.5 kg, and degrees of freedoms (DOFs) of 21, including both hands with 8 DOFs, the waist with one DOF and both feet with 12 DOFs. A posture sensor formed by the combination of a tri-axial accelerometer and two single-axis gyros is installed in the center of gravity of an HR to measure its postures in the pitch and roll directions as it is on (un)even ground. Based on the measured posture, a decentralized balance control is on-line applied to prevent an HR tilt down.
The use of tri-axis accelerometer can measure the acceleration of X, Y and Z axes. After the suitable calculation, the posture of an HR (i.e., the pitch and roll angles with respect to gravitational direction) is obtained. However, accelerometers are vulnerable to external interference caused by system noise. Therefore, two single-axis gyros are added to avoid the inaccurate measurement of the posture of an HR. Because the dynamic balance needs the quick access of sensor data for different sensors to prevent the unnecessary loss of time. Due to the advantages of parallel processing of FPGA, it is employed to receive the sensor data and to send the command for the balance. In addition, the use of SoPC (System on a Programmable Chip) for the processing of the data can reduce the computation time of decentralized balance control. For example, the communication port with high-speed baud rate can speed up the signal transmission for enhancing the effect of dynamic balance.
In general, one period of the walking for an HR possesses single support phase (SSP) and double support phase (DSP). The strategies of dynamic balance for these two phases are different. It must separately discuss. In the beginning, the responses of pitch and roll axes of an HR with a stable walking on an even ground. After appropriate analysis of the corresponding posture, a reference posture for the decentralized balance control of an HR on uneven ground is obtained. Finally, the experiments of an HR on (un)even ground with (or without) balance control are arranged to confirm the effectiveness of the proposed methodology.
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