Control system for vehicle

1 . A control system for a vehicle provided with a differential mechanism that applies a torque difference to left and right wheels and two electric motors coupled to the differential mechanism, the control system comprising:

two control units being connected to each other via high-speed communication means and each controlling one of the two electric motors;

a first rotation speed sensor that detects a first rotation speed of a first electric motor of the two electric motors and outputs the first rotation speed to the two control units;

a second rotation speed sensor that detects a second rotation speed of a second electric motor of the two electric motors and outputs the second rotation speed to the two control units; and

a superordinate control unit that calculates demanded torques of the two electric motors based on vehicle information of the vehicle, wherein

at least a first control unit of the two control units calculates two assigned torques to achieve the demanded torques calculated in the superordinate control unit based on a detection signal of the first rotation speed sensor and a detection signal of the second rotation speed sensor,

the first control unit calculates the two assigned torques based on the two detection signals, controls the first electric motor using a first assigned torque of the two assigned torques, and transmits the first assigned torque and a second assigned torque of the two assigned torques to a second control unit of the two control units via the high-speed communication means, and

the second control unit calculates the two assigned torques based on the two detection signals and carries out fail monitoring by comparing the first assigned torque calculated therein and the first assigned torque received from the first control unit and carries out fail monitoring by comparing the second assigned torque calculated therein and the second assigned torque received from the first control unit.

2 . The control system according to claim 1 , wherein

the first control unit is a main control unit, and the second control unit is a sub control unit that controls the second electric motor, using

the second assigned torque transmitted from the main control unit.

3 . The control system according to claim 1 , wherein

the second control unit controls the second electric motor using the second assigned torque calculated therein, and

the control units transmit and receive the two calculated assigned torques calculated in the respective control units to and from each other via the high-speed communication means and carry out fail monitoring.

4 . The control system according to claim 3 , wherein

each of the control units carries out synchronous control by comparing the calculated assigned torque with the assigned torque received via the high-speed communication means, and

each of the control units determines, in the synchronous control, whether or not the two compared assigned torques match, transmits and receives signal information representing a result of the determining, and controls the electric motors by referring to the signal information.

5 . The control system according to claim 4 , wherein

each of the control units calculates the two assigned torques at a predetermined calculation cycle and stores at least values of the assigned torque of one of the electric motors that the control unit controls of predetermined calculation cycles,

in the synchronous control,

each of the control units compares the assigned torques of the electric motor that the control units controls, and

transmits, if the compared assigned torques match, the signal information representing the matching,

determines, if the compared assigned torques do not match, whether or not past assigned torques stored therein includes a value matching the received assigned torque,

transmits, if a value matching the received assigned torque is present, the signal information representing the number of cycles tracing back from present time point, and

transmits, if a value matching the received assigned torque is not present, the signal information representing that the matching value is not present.

6 . The control system according to claim 1 , wherein

at least the first control unit carries out axle torque control that includes feedback control using the two detection signals and achieves axle torques corresponding to the demanded torques calculated in the superordinate control unit.

7 . The control system according to claim 1 , wherein

at least the first control unit carries out wheel velocity control that calculates target wheel velocities of the left and right wheels of the vehicle based on the demanded toques calculated in the superordinate control unit and achieves the target wheel velocities of the left and right wheels, using the two detection signals.