Biomimetic Motion Plan And Control Of Modular Self-reconfigurable Robot

Modular robot is a complex robot systemcomposed of a large number of basic modules with motor and sensory function, which can transform into varieties of configurations to complete multiple tasks. Through the change of connected relation between modules, it can transform into varieties oftopological configurationto adapt to the environment and task requirements of various situation. Compared with the traditional robot, modular robot has features of modularity, self-reconfiguration and self-repair, etc.Meanwhile the modular robot system composed ofpluralities of modules has the characteristics of redundancy and flexibility,therefore, the modular robot has strong movement ability adapting to different road condition through movement configuration and locomotion mode change. However, hyper-redundancy, motion configuration diversity and multi-mode movement also make motion control of the modular robot much more complex. It is the research priorities of this paper to find a way of controlling multi-mode movement of the movement configuration of modular robot and making the corresponding gait adjustment to external feedback. Furthermore, this method should make the modular robot be able to exercise in unstructured environments.As the basic unit of the robot, structure characteristic of modules has great influence on motion mode of overall configuration. This paper takes the UBot module of cube structure as study object. It can be divided into active module and passive module, respectively, with the active and passive hook-claw type bindiny mechanism, the active module and passive module can achieve connection/disconnection automatically. Modules could identify direction and connection state, though orientation recognition unit on bindiny mechanism, which has the regular module structure and flexiblebindiny mechanismcharacteristics of array-type robots. Each module has two mutually perpendicular rotational freedom, the rotation direction (-90°,90°), so it can achieve the function of coordinated movement of chain type modular robots. In order to make the robot system capable of environment perception, designing the sensing module for UBot system, which is equipped with a camera, infrared sensor, linear Holzer sensor and accelerometer sensors, etc. Meanwhile, it has the same bindiny mechanism with the passive module of UBot, and could be connected with the active module to join onto movement configuration in real-time sensing of the external environment.Referencing the biological motion controlnervous system, it establishes motion control system of Bionic network, which consists of various kinds of neurons and the central pattern generator (CPG) composed by neurons. According to the characteristics of the UBot module, it also establishes a dual output CPG phase motion control network, to simulate neural control system of animal’s spinal cord and build up robot’s motion control system of Bionic network by introducing the intermediate neurons, efferent neurons, and Perception neurons, etc.Based on the establishedmotion control system of Bionic network, motion planning strategies are established for configurations with limbs and configurations with no limbs, respectively. Through simulating the nerve center of lower organisms’ movement control method sending the lower self-excited behavior directly to each joint, motion planning has been done for several typical configurations with no limbs. For CPG phase modulation control network, different CPG node connection can lead different phase timing output, using this characteristic, we have planned the uniform CPG node connection method for snake configuration to achieve mantis movement, wriggling, rolling, turning and multi-segmented worm-like locomotion without changing the quantity of the CPG nodes. We have also successfully achievedforward motion and turning motion plan of cross configuration, rolling motion plan of loop configuration through this bionic network. Using CPG phase modulation control network to simulate spinal cord nervous system of higher animal and making use of Efferent neurons to each joints, motion strategy has been proposed for configurations with limbs. For the configuration with limbs which has hip, knee and ankle joints on each limb, efferent neuron’s model has been designed for each joint. The unified planning for trot and walk motion of bionic quadrupedconfiguration is implemented.From topology changed and topology unchanged aspects, motion planning coordinating changing methods with configuration deformation have been studied. For the topology changed deformation, single-chain configuration’s topology changing method and motion plan has been researched, and deformation conditions from open-chain structure to closed-chain structure have been obtained. Through adjusting CPG nodes’ connection of bionic network, the motion planning method which can adjust open-chain squirming and closed-chain rolling has been established. Through the simulation of loop and snake configuration’s deformation and motion, the method has been proved. For the topology unchanged, but motion function changed deformation, the configuration with limbs has been studied. Bionic motion network’s node parameter coordinatedchanging strategy has been formulated for the deformation from the configuration with limbs to its derivative squirming configuration. Adaptive coordinated motion simulation between bionic quadruped configuration and its two derivativeH configurations has been conducted to prove the method.In order to realize the motion function of the robot in unstructured environment, simulate the three-level structure of regulatory function of biological neural system, it establishes a set of motion controller with the sensing function of environmental feedback, composed of information acquisition unit, underlying local information reflecting planner, and High-level information processing system, which makes the robot autonomously accomplish reconstruction of special situation and finish the motion of obstacle crossing, obstacle avoidance, self-reconfiguration, up and down the slope, so as to adapt to the external environment.Experiment system of movement and environmental feedback is constructed, and coordinated motionexperiments of multiple modes of snake-like configuration, cross configuration, loop configuration and bionic quadruped configuration are carried out, to test and verify overall control ability of the control system of Bionic network in different motion mode. The transformation experiment from rolling mode of loop configuration to peristalsismode of snake-like configuration are conducted, to test and verify coordination and adaptation ability of bionic motion control system for the topological configuration transformation. Motion experiment of autonomic robot response to environment in the environment with obstacle of slope, road bump, block and arch, etc, are finished to test and verify environmental perception and adaptation ability of the modular robot.