Research on the Stationarity of Hexapod Robot Posture Adjustment

Abstract

This paper proposes a smooth adjustment method for the instability problem that occurs during the start and stop of a multi-footed robot during attitude change. First, kinematics analysis is used to establish the mapping relationship between the joint angles of the robot support legs and the body posture. The leg joint angle is a known quantity that can be measured accurately and in real time. Therefore, when the position of the foot end of the support leg is unchanged, a unique set of joint angles can be obtained with the change of body posture at a certain moment. Based on the designed mapping model, the smooth adjustment of the posture can be achieved by the smooth adjustment of the support legs. Second, a constraint index that satisfies the requirements of the robot’s steady adjustment of the robot is given. The S-curve acceleration/deceleration method is used to plan the body’s attitude angle transformation curve, and then the mapping control relationship is used to obtain the control trajectory requirements of the joint to achieve smooth adjustment. In addition, this paper also gives a simple choice and motion control method for the redundancy problem caused by the number of support legs of a multi-footed robot when the attitude is changed. The simulation and prototype experiments verify and analyze the proposed method. The results of comparative experiments show that the posture adjustment method proposed in this paper has continuous acceleration without breakpoints, the speed changes gently during the start and stop phases of the attitude transformation, and there is no sudden change in the entire process, which improves the consistency of the actual values of the attitude planning curve with the target values. The physical prototype experiment shows that the maximum deviation between the actual value of the attitude angular velocity and the target value changes from 62.5% to 5.5%, and the degree of fit increases by 57.0%. Therefore, this study solves the problem of the instability of the fuselage when the robot changes its attitude, and it provides an important reference for the multi-footed robot to improve the terrain adaptability.

Stability analysis of hexapod robot with triangular gait in low gravity environment

“…The structure of the hexapod bionic robot belongs to the parallel mechanism, and the leg structure belongs to the series mechanism. Its motion law is relatively complex, and planning is relatively tricky [1]. Based on the stability consideration, the robot studied in this paper adopts the classical triangular gait, as shown in…”

“…One of the solutions to this problem is to change the wheel structure of the traditional rover into a foot structure. In the comment environment, the foot structure usually has higher stability and more vital terrain adaptability than the wheel structure [1]. Theoretically, legged robots perform better than wheeled robots in dealing with complex terrain conditions, so they have received extensive attention.…”

Stability-Guaranteed and High Terrain Adaptability Static Gait for Quadruped Robots

“…They also may be broken sometimes. Therefore, the attitude–position adjustment strategy without the environmental perception system should be addressed [ 50 ].…”

Expected position and attitude adjustment control method of coal mine roadway support robot

“…Active impedance control and multiobjective layer optimal control methods for legged quadruped robots were proposed to realize the execution of highly dynamic motion tasks and the control of robot position‐attitude adjustment in complex environments, respectively (N. Hu et al, 2018; Semini et al, 2015). For the instability problem in the process of position‐attitude control and change of a legged hexapod robot, a correction‐based position‐attitude adjustment control method and a smooth adjustment method based on the relationship between joint angle and body mapping were proposed to reduce the error of attitude adjustment and realize smooth adjustment (L. Zhang, Wang, et al, 2020; L. Zhang, Zhu, et al, 2020).…”