Abstract: This device consists of a car body, which further consists of a first wheel and a second wheel; a first angular compensation mechanism which further consists of a first transmission set for transmitting a first torque generated by the first wheel, a second transmission set for transmitting a second torque generated by the second wheel; a second angular compensation mechanism having a first planetary gear train which is connected to and installed at the first transmission set of the first angular compensation mechanism for receiving the first torque, a second planetary gear train which is connected to and installed at the second transmission set of the first angular compensation mechanism for receiving the second torque; and a direction pointer which is connected to and installed at the second angular compensation mechanism wherein the direction pointer is driven by the first and the second torque to generate a rotation in order to obtain a compensation angular velocity.