This is the Robotic sliding fox Tamiya 71116 beginners robot this is how the robot works and what it does. 
Internal motor spins a cylindrical plate with a weight (a screw) placed on one side creating an up down rapid vibrating movement. This vibration is then conveyed to 3 rods that smoothly propel the model forward in a sliding type movement. Model features easy assembly using snap on parts and screws and is powered by a Type 130 motor. Direction can be easily altered by changing the direction of the rods. Speed can be adjusted by changing the angle of the rods. Body shape designed to maintain a curved form to move around obstacles. Eyes act as rollers to also help fox to smoothly work around obstacles. Games and races can be easily made by building an obstacle course using cardboard. Best performance on smooth flat surfaces. This is the robot I am thinking about building there are 2 more that I am thinking about building also but I will right about them in my next blog. I think it would be easier to build this robot because it is cheaper and cost less money