Design And Analysis Of Hip Joint And Pelvis Of Humanoid Robot

Robots are widely used in disaster rescue in harsh environments nowadays,Such as fire-fighting activities in the forest and rescue missions in the earthquake.Robots can assist humans in dangerous tasks to reduce the number of death.wheeled robots and pedrail robots are not good at working on the uneven surface because of limited movements.But humanoid robots work better than wheeled robots and pedrail robots in these envirenments,because they have small support region and highly sensitive movement.so,it is very important to improve the humanoid robots research.The design method and the movement way of humanoid robot's hip joint and pelvis influence humanoid robot's stability.So,This paper introduces the design and control method of humanoid robot's hip joint and pelvis and display a new method of gait planning to analyze its influence to gait.the main research contents are as follows:Firstly,I have designed a structure of humanoid's hip joint and pelvis which is driven by servo motor and servo hydraulic cylinder.Refer to human's movement of the hip and pelvis during walking.Based on the motion characteristics of hip joint and pelvis during walking,the degrees of freedom distribution of hip joint and pelvis of humanoid robot are optimized.The servo hydraulic cylinders are selected as the original part of the hip joint moving in the yaw direction,and the linear motion of the servo hydraulic cylinders are transformed into rotary motion through two sets of connecting rod mechanisms,so that the hip joint rotated in the yaw direction.The high torque motors are selected as the original part of the hip joint and pelvis moving in the other direction,and the harmonic reducers are selected as the transmission part,and the motor driving module of each joint is designed.The hip joint and pelvis structure of the humanoid robot has been designed on the premise of ensuring no interference of each joint,standard driving performance and compact structure.Secondly,servo control of the hip joint and the pelvis are carried out on the humanoid robot.According to the model,the PID control simulation and PID parameter optimization are carried out on the servo cylinder.The control bus,terminal module and servo driver of the humanoid robot are selected on the basis of the demand,and the control system of the servo motor is built as well.Finally,The mathematical modeling of humanoid robot is completed.Based on the model,a new gait planning method is proposed.On this basis,the influence of the degrees of freedom of hip joint and pelvis on the gait of humanoid robot is analyzed.In order to study the humanoid robot more conveniently,it is simplified into a six-link model in which each link is represented by a vector calculated by coordinate transformation,therefore the centroid coordinates of each link and the centroid coordinates of the humanoid robot are obtained.Motions of the joints of the humanoid robot are represented by quartic curves,and constraints such as the step size,the step frequency and the ZMP point control range are set as well.Coefficients of the quadratic polynomial curves are solved by the SQP algorithm,therefore related gaits are generated.In doing so,the smooth gait will be calculated commendably.Based on the gait data research,it is found that The freedoms of hip joint and pelvis will affect the walking of humanoid robot in all directions.