Performance Design And Control Experiment Of A Novel Hexapod Robot With P-P Structure

Hexapod robot is famous for its good performance in stability, payload capability,mobility. It can also been used in the complex, special and unstructured environment,hence it was a very hot research feld. Since70s last century, many kinds of hexapodrobots have been developed by diferent scholars. Most of them apply simple serialmechanism and very few tried to use parallel mechanisms for their legs. In this paper,a novel hexapod robot using parallel-parallel structure is introduced. The most specialpart is that it applies3-limbs parallel mechanism for its leg, which improves the legpayload capability, rigidity and accuracy. Besides, when the robot uses its body towork, all its6legs should be on the ground to support its body, then the body-legs-ground can be treated as a bigger parallel system. Thus it’s called PP structure. Thispaper mainly focus on the mechanism design, performance analysis, control systemand fault tolerance et. al. The experiments are showed too. The major contents arelisted as follow:1. We use theFset theory to design the leg mechanism. First we did the numbersynthesis, which gives the limb number, actuation number, joint number andso on. After that we synthesized the mechanism type, which fnally gives thehexapod robot leg mechanism.2. We discovered an interesting relationship between the computational complexityand the joint rotational axis direction. We proved that only under some certainconditions, the direct kinematic model has explicit solution, while other con-fgurations only give inexplicit solutions. Thus in purpose of realize real-timecontrol, the robot mechanism design should follow those conditions. 3. The kinematical, velocity, and payload model are built, which are the theoreticalfoundation of the robot performance research and gait plan methodology.4. We use the parallel mechanism evaluation indexes in the walking robot, whichcan be used to estimate the velocity and payload performance of the robot. Theperformanceinthesupportingandmovingplaneiscaredmostlywegivedetailedresults in these planes.5. Wedevelopedthecontrolsystemfortherobot, includingbothsoftwareandhard-ware. Based on the system, the control strategy is derived and the gait library isbuilt. The user interface is also thoroughly studied and we give many kinds ofinteraction method between human and robot.6. We created three kinds of control strategy and methodology for robot-tracking-missions. Then the evaluating indices can be brought to evaluate each strategy.Based on these indices, the optimal method and parameters can be selected forthe mission.7. We defned two types of actuation fault, based on which the combination of allkinds of leg fault is studied. Then the criterion to judge the fault tolerance isbrought out, which gives both fault tolerable type and non-fault tolerable leg.8. Apart from the theoretical analysis, the prototype is also built using which wehave done a lot of experiments. First we test the normal gaits of the robot; thenthe payload capability is tested; after that the climbing obstacle experiment isdone; fnally the operational experiment of rotating a valve is done.Our research is very helpful for the mechanism design, control strategy and faulttolerance of the hexapod robot.