Gait generation of a biped robot and construction of measurement system
Date Issued
2010
Date
2010
Author(s)
Lu, Jau-Ching
Abstract
This thesis discusses the design and realization of stable walking pattern for a humanoid biped robot, and the development of 9-axis IMU (inertial measurement unit) system which is able to derive linear and angular accelerations of COG (Center Of Mass) of the robot.
In the kinematics of robot, we defined the parameter to describe to relationship each links on the robot, and derived the relationship between rotational direction of each motor and the ground coordinate. Next, we deal with the transformation equations between the Joint Space and the Working Space. In the dynamics of robot, we introduce the concept of ZMP (Zero-Moment Point), and analysis the condition for a stable walking of humanoid robot. We simplified the robot to an inverted pendulum model, and derived the COG trajectory base on reasonable assumptions. We also derived the transformation equations between the COG trajectory and the ZMP trajectory.We separated a full walking into several stages, including squat down stage and stand up stage. According to characteristics of each stage, different dynamic model is applied to derive the COG and feet trajectories. Next, the angular positions of motors are derived through inverse kinematics. Furthermore, the ZMP trajectory was derived by the motor trajectory through forward kinematics, and was proved to satisfy the condition of stable walking.We first simulated the motor trajectory by Matlab, and approve it is reasonable in kinematics. Then we simulated the motor trajectory by Adams to approved it generate a stable walking of robot in dynamics. After simulations, the trajectory was applied to real robot and to walk in real environment.
To obtain the information of robot, we develop the 9-axis IMU (Inertial Measurement Unit) system. Three 2-axis accelerometers and one 3-axis rate gyro are installed to measure 3-axis linear accelerations and 3-axis angular accelerations of COG. The 9-axis IMU system releases the limitation that the tradition IMU is required to install on COG, and the 9-axis IMU system obtain better quality of signal than the tradition IMU. Besides, a 2-axis inclinometer is applied to compensate the effect of gravity.
Subjects
biped robot
trajectory generation
ZMP
IMU
Type
thesis
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