The Research On The Deformable Soft Robot With Multi-locomotion Modes

With infinite degrees of freedom and continuous deformation capacity, the mollusks can arbitrarily change their shapes and sizes so that they have a strong ability to adapt to the natural environment. Developed the bionic robot with similar biological ability is the target for the researchers from all over the world. As a continuation of the bio-robot research, the bionic soft robots have an excellent flexibility and compatibility to the complex environment, through the combination of active deformation and passive deformation. This type of robots has broad application prospects in the military, scientific research, medical and other fields.The bionic soft robot has the problem that the movement pattern is very single, the movement efficiency and the environmental adaptability can not effectively take into account. In order to solve this problem, this thesis takes the soft robot which has three locomotion modes as the research object. Surrounding the implementation mechanisms for accomplishing the multi-locomotion modes, this dissertation carried out the reasearch of multi-locomotion modes bionic implementation principle, the study of how to implementate the bionic soft robot overall structure, the reasearch of the dynamic characteristics of the plannar bending actuator embedded SMA wire and the study of the motion characteristics of the bionic soft robot, etc. The main research contents and contributions of this paper are listed as follows:(1) By analysis of the movement characteristics of the nature mollusks, a bionic soft robot which has rolling motion, peristaltic movements and omega-type motion is designed based on the existing research work and combination of the characteristics of the shape memory alloy. On a flat road, the bionic soft robot uses the rolling movement to improve the movement speed and movement efficiency through the flexible deformation; the body is expanded to use the peristaltic movement to improve the ablitiy of through the narrow space; when the soft robot encountered the obstacles, the body deformation using the Omega-type forward way to improve the ability of through the obstacles. By the detailed study of the three kinds of movement modes, the motion mechanism which achieves three loconmotion modes is obtained and then completed the design of the overall structures of the soft robots according to the front analysis. The soft robot is designed based on the modular concept and it consists of movement unit and separation unit. Each movement unit is comprised by a deflection unit and a peristaltic unit, the design of the deflection unit、the peristaltic movement unit and the head and tail connection structure is detailed designed.(2) The kinematics simulation of the two typical movement patterns of the soft robot, the rolling locomotion and peristaltic movement, are analysed using powerful many-body dynamics emulation software ADAMS. Based on the pseudo-rigid model, the simulation model of the rolling motion of the soft robot in ADAMS is bulilt, by adjusting the control sequence of the spring force to achieve the optimal the rolling speed and obtained the displacement and velocity curve of the rolling movement of the soft robot in X axis and Y axis direction, the control strategy of the rolling motion is given. The simulation model of the peristaltic movement of the soft robot in ADAMS is established by using the micro-sawtooth structure to simulate the bionic seta structure and rough ground, obtained the displacement and velocity curve of the peristaltic movement of the soft robot in X axis direction and analyze the movement characteristics. The movement state transitions and the rolling motion of the softrobot are studied through the experiment method on the basis of the robot structure design and kinematics simulation. The prototype of the soft robot is made by using the existing experimental materials and equipment, the motion unit of the soft robot is bonded by AB glue to simplify the structure of the soft robot, the control system of the bionic soft robot is designed which can simultaneously control the motion of24SMA bent actuator. Verified the feasibility that the bonding method to connect the head and tail of the soft robot can convert from the annular state to the linear motion, and the characteristics of the rolling motion are studied by the experiment method (the soft robot can scroll160mm in6s).(3) Based on the three-dimensional space force system, the mechanical equilibrium of the SMA linear actuator and the dynamic equilibrium equation of the elastic substrate is established, and the SMA constitutive equations and the thermodynamic equilibrium equation is introduced to give the detailed dynamic model of the plannar bending actuator embedded SMA wires, so the deflection process of the plannar bending acuator can be effectively predicted.(4) The quasi-static thermal/mechanical characteristics and the dynamic thermal/mechanical characteristics are detailed study by the experimental, and the research emphasis focused on the characteristics of the change of the phase transition temperature of the SMA wires in different stress conditions and gives the stress-strain characteristics on different train rate. Due to the SMA have characteristics of the large output power and deformation, higher power-weight ratio, low-voltage drive and long life, the plannar bending actuator embedded SMA wires which has stable and reliable performance is designed, and the driving characteristics is detailed study through simulation and experimental to verify the correctness of the mechanical equations. And frome the experimental result, we found that the output angle and output moment of the actuator has a linear relationship, and useing the big pulse current heating method can effectively improve the efficiency of the actuator.