Andrew J Shepherd

US Patent:

6622069, Sep 16, 2003

Filed:

May 7, 2002

Appl. No.:

10/150292

Inventors:

Marc R. Davis - Dublin CA
Andrew J. Shepherd - Danville CA
Michael Bachman - San Ramon CA

Assignee:

Curtis Instruments, Inc. - Livermore CA

International Classification:

B60L 1100

US Classification:

701 22, 180 655, 180308, 475 5, 318139

Abstract:

Methods and apparatus for adjusting at least one of the motors in an electrically driven vehicle having a first motor for controlling a first wheel and a second motor for controlling a second wheel are disclosed. The method is performed in response to input from a user control that enables an operator of the vehicle to steer the vehicle. It is determined from one or more conditions whether the operator of the vehicle is attempting to drive the vehicle straight on approximately level ground. When it is determined from the one or more conditions that the operator of the vehicle is attempting to drive the vehicle approximately straight on approximately level ground, it is then determined whether to adjust one of the motors based upon the input from the operator of the vehicle to the user control. When it is determined that adjustment is appropriate, the appropriate motor is adjusted.

US Patent:

7898203, Mar 1, 2011

Filed:

Jul 11, 2008

Appl. No.:

12/172139

Inventors:

Marc R. Davis - Dublin CA, US
Andrew J. Shepherd - Danville CA, US
Stephen Post - Walnut Creek CA, US

Assignee:

Curtis Instruments, Inc. - Livermore CA

International Classification:

G01R 31/34

US Classification:

318490, 318473, 318558, 318139

Abstract:

Electric motor controllers that dynamically adjust a motor resistance parameter are described. In order to adjust the motor resistance parameter, power is applied the electric motor while the controlled vehicle is stopped and its brake is set so that the vehicle remains stopped while a measurement is taken that can be used to determine motor resistance. A new motor resistance value is then generated based at least in part upon the measurement(s) and the motor resistance parameter is set to the new motor resistance value. The new motor resistance parameter may then be used in the control of the electric motor. In some embodiments, the measurements are taken after the controller receives a brake release request but before actually releasing the brake. The described arrangement can be used in a wide variety of motor controllers and is especially well suited for use in low cost controllers that control motors that are susceptible to wide variations in their resistance such as brushed permanent magnet DC motors.