as desired around the vertical axial line the mode of operation of the illustrated embodiment is described in the following a rider places his feet upon the corresponding steps 46 and holds the two ends of the grip bar 23 the drive wheels 20 are actuated so that the vehicle 100 stands still in an upright orientation according to the principle of the inverted pendulum vehicle when the rider desires to travel ahead he leans forward causing the gravitational center of the rider to be shifted forward conversely when the rider desires to travel backward he leans back causing the gravitational center of the rider to be shifted backward likewise when the rider desires to make a turn he leans laterally in the desired direction and this causes the vehicle to turn in the desired direction the control system for this vehicle 100 is described in the following referring to fig3 the control system comprises a control device 60 which essentially consists of a microcomputer the control device 60 receives information on the roll angle of the body frame 14 from the roll angle sensor 62 and the pitch angle of the body frame 14 from the pitch angle sensor 64 and controls the drive wheels 10 according to the principle of the inverted pendulum so as to cause the vehicle to move about while maintaining an upright orientation in a stable manner alternatively or additionally the control device 60 may further receive output signals from the left foot load sensor 44 l and the right foot load sensor 44 r so that the shifting of the gravitational center of the rider may be detected and individually controls the electric motors 24 and 58.