The first is efficiency. The wheat wheel moves in all directions at the expense of partial speed for lateral movement. Even if the ordinary wheel moves, it needs the A wheel and the B wheel to cancel each other's lateral speed.
The second is the structural problem. Wheat wheels move in all directions by attaching unpowered rollers, which means that each wheel needs an independent power system, and the bearings at both ends of the rollers need sufficient strength to support the load. Bearings are precision parts, and rollers need to be considered separately. The complexity of the structure is not a little more than that of ordinary wheels.
The third is the defects of the wheat wheel itself. The omni-directional movement of the wheat wheel is realized when the roller of each wheat wheel touches the ground alone, that is to say, if it is on the rugged ground, the speed cannot be decomposed and it cannot move laterally, so the pavement requirements of the wheat wheel itself are relatively high.
Brief introduction of McNamham wheel
McNamun wheel is a patent of Swedish McNamun company, and it is an omnidirectional wheel. Ordinary tires are bidirectional, either forward or backward, and steering is realized by changing the direction of the tires. McNamham wheel is arranged around the main axle at a certain angle, and the rotating force of the main wheel is converted to other directions through different driving combinations, so as to realize omni-directional movement.
McNamun wheel can move forward, backward, translate left and right, rotate diagonally, etc. It is more flexible than ordinary steering system, but because of its complex structure, it can't bear too much load, and it will wear more easily than ordinary tires in use.