Reduced DOF Type Walking Robot Based on Closed Link Mechanism

摘要

In this chapter, we have proposed a new type of walking machine by use of reduced DOF mechanical design. Our walking machine is designed for environment that has combination of flat terrain and some steps. This mobile environment is often found in environment for human walking, such as office or factory. Therefore, our walking machine is enough practical, though it has a limitation in walling environment. As the result of our simulations and experiment, we can get the following results. Our walking machine can walk on flat terrain by use of 6 DOF. Then, to realize walking over a step, 7 DOF is minimum required number of DOF. In this case, there exists a limitation about the body direction. If more than 2 DOF are applied, it can remove this limitation. As mentioned above, general hexapod walking machine requires 18 DOF totally. Thus, our robot can reduce number of DOF less than or equal to the half number of general type. Our walking machine has several strong points as well as the reduced DOF design. One of them is that the machine can keep high static stability, because more than five legs including the S-legs always keep contact to the ground. Then, the combination of the vertical prismatic joints and closed linkage of the body can realize high mechanical stiffness. Although we can confirm the validity of our waking machine by use of prototype model, we need to solve the following problems to make the machine into practical use. In the bottom of the S-legs, ball caster is applied. In case of prototype model, it does not cause mechanical problem, because size of the model is very small. Some redesign is required for this part, when we build up a practical size of the walking machine. One more problem is about the body shape. The main body of our machine is based on the hexagonal closed link mechanism. Therefore, this link mechanism is not suitable for carrying load, since the shape of the body is always changeable. Some device may be required for such purpose.