Self-propelled personal transportation device

An apparatus for transportation, comprising:

• a surface to receive a plurality of forces at a plurality of locations on the surface;
• a plurality of force sensors, attached to the surface, to provide information related to the plurality of forces on the surface;
• a plurality of wheels beneath the surface, wherein each of the plurality of wheels are coupled with a motor;
• and
• a controller configured to:
• enter an initialization state in which the apparatus is in a stationary state;
• determine, based on the information provided by the plurality of force sensors, a first plurality of forces at the plurality of locations;
• determine, based on the first plurality of forces, a reference distribution of forces associated with the plurality of locations in the initialization state;
• enter a motion state;
• determine, based on the information provided by the plurality of force sensors, a second plurality of forces at the plurality of locations;
• determine, based on the second plurality of forces, an updated distribution of forces associated with the plurality of locations in the motion state;
• determine a relationship between the reference distribution of forces and the updated distribution of forces;
• determine a target speed of the apparatus based on the relationship;
• and
• provide one or more first signals to the motors to cause the apparatus to move at the target speed, wherein
• the apparatus further comprises a rolling angle measurement device configured to measure a rolling angle of the surface with respect to a horizontal surface;
• wherein the controller is further configured to determine a differential rotational speed between at least two of the plurality of wheels based on the rolling angle, wherein the rolling angle is determined as the difference between the rolling angle measured by the rolling angle measurement device and the reference rolling angle determined at the initialization state.