Electric power steering system
US5904223A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 27, 1996 |
| Grant date | May 18, 1999 |
| Priority date | — |
| Expiry date | Nov 27, 2016 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB62D6/006
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
In an electric power steering system, a road surface reaction applied to a steering mechanism is estimated from a voltage and an electric current applied to an electric actuator, and a steering torque. Because the road surface reaction provides a useful data for assessing the condition of the road surface, it is possible to optimally control various control systems which depends on the condition of the road surface. In particular, a frictional coefficient between a road surface and a tire of the vehicle can be estimated according to a steering angle and the road surface reaction, for instance by comparing the estimated road surface reaction with a reference road surface reaction which is computed from a set of standard conditions. Thus, the road surface reaction and the road frictional coefficient can be obtained during a normal steering action by using functions which are normally provided in the electric power steering system. By knowing the current road surface condition, an optimum steering assist action can be executed according to each particular road surface condition, and can substantially reduce the effort required by the vehicle operator to steer the vehicle under all con…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.