Steering device

A steering device, comprising:

• an electric drive device which includes a plurality of systems comprising a first system that includes a first electric motor and a second system that includes a second electric motor, the first electric motor comprising a first driving circuit and a first winding, the second electric motor comprising a second driving circuit and a second winding;
• and
• a controller configured to select any of an assist control for assisting a steering force based on a steering torque input by an operation of a steering wheel, and an automatic steering control for controlling a steering angle of the steering wheel based on a steering instruction value, and to control an output of the electric drive device to be in a range not exceeding a preset output limit value,
• wherein the controller is configured such that when a fault occurs in the first system that includes the first electric motor during the control by the automatic steering control, the controller continues to perform the automatic steering control using the second electric motor of the second system, and when the controller then shifts to the assist control, the controller sets the output limit value of the second electric motor of the second system to a value lower than an output limit value used during normal operation when the first electric motor and the second electric motor are normally operated,
• wherein the controller is configured to retrieve an automatic steering contribution ratio which is a ratio of an output of the second electric motor required for the automatic steering control as a calculation value therein and an assist control contribution ratio which is the ratio of the output of the second electric motor required for the assist control, and the controller is configured to increase the assist control contribution ratio with reducing the automatic steering contribution ratio upon switching from the automatic steering control to the assist control,
• wherein the controller includes a warning generator configured to issue a warning providing notification of a fault when the fault occurs in one of the first electric motor and the second electric motor when executing the automatic steering control, and
• wherein the controller is configured to perform the automatic steering control to guide a vehicle to a low-speed lane when a fault occurs in one or more of the first electric motor and the second electric motor during the control of the automatic steering control.