Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1999-04-08
2001-04-24
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S058000, C701S060000, C477S068000, C477S120000
Reexamination Certificate
active
06223111
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to continuously variable transmission, and more specifically to a method and apparatus for generating velocity commands for a continuously variable transmission.
BACKGROUND OF THE INVENTION
Many work machines, particularly earth working machines, use a hydrostatic drive system to drive the traction wheels or tracks of the work machine. The hydrostatic drive system can provide a continuously variable speed output to the wheels or tracks of the work machine. In particular, the speed can be continuously varied by controlling the displacements of either a hydraulic pump or a hydraulic motor which comprise the hydrostatic drive system.
One problem with earth moving machines which use hydrostatic transmissions is that the speed output can be varied rapidly thereby producing a rapid response. This rapid response can result in high, undesirable jerk which can cause discomfort to an operator of the work machine. In addition, the high undesirable jerk can cause the operator to lose control of the machine as the rapid movement of the machine can create unwanted pedal modulations. The unwanted speed pedal modulations create control signals which cause the work machine to move in an unintended manner.
One solution to this problem is pass the control signals from the speed pedal through a low pass filter. Each low pass filter has a selected corner frequency. One corner frequency can provide optimal response during the application of oncoming jerk, i.e. jerk applied to first start accelerating the work machine, but has poor response during the application of off going jerk, i.e. the jerk applied to match the actual speed to the desired speed. On the other hand, another corner frequency will have good response during the application of off going jerk, but will have poor response during the application of oncoming jerk. A drawback of using a low pass filter is that a single filter cannot be selected which provides satisfactory response during both the oncoming jerk and the off going jerk.
Another solution to this problem is to control the oncoming jerk to provide a smooth and rapid response as the machine is accelerated. However, this solution does not control the off going jerk as the actual speed approaches the desired speed. Smoothing the off going jerk is critical for operator comfort and controllability of the work machine. A drawback to controlling only the oncoming jerk is that the response during the application of off going jerk is unsatisfactorily uncomfortable to the operator.
A third solution to this problem is to provide both oncoming and off going jerk shaping to the velocity command. This solution has been applied to work machines having a discrete number of velocity profiles, or speed targets. However, the discrete number of velocity profiles cannot provide the desired response for an infinite number of velocity values that can be commanded by the continuously variable transmission. This scheme does not allow a continuously variable adjustment of the velocity profile to match the continuously variable speed output of the transmission.
What is needed therefore is a method and apparatus for generating velocity commands for a continuously variable transmission which overcomes the above-mentioned drawbacks.
DISCLOSURE OF THE INVENTION
In accordance with a first aspect of the present invention, there is provided a control apparatus for a continuously variable transmission. The control apparatus includes a transmission speed sensor which generates an actual velocity signal in response measuring speed of an output shaft of the continuously variable transmission. The control apparatus further includes a first input device, or speed pedal, which is positionable in one of an infinite number of positions and generates a desired velocity signal corresponding to the position of the pedal. The control apparatus yet further includes a microprocessor controller operable to receive the desired velocity signal (from the speed pedal), receive the actual velocity signal, calculate a commanded acceleration a
c
, and generate a commanded velocity V
c
based on the desired velocity signal, a jerk value j, and the commanded acceleration a
c
.
In accordance with a second aspect of the present invention, there is provided a method of controlling a continuously variable transmission having a transmission speed sensor which generates an actual velocity signal in response measuring speed of an output shaft of the continuously variable transmission. The transmission further has a first input device, or speed pedal, which is positionable in one of an infinite number of positions and generates a is desired velocity signal corresponding to the position. The method includes the steps of receiving the desired velocity signal and receiving the actual speed signal. The method further includes the steps of calculating a commanded acceleration a
c
and generating a velocity command signal. The velocity command signal is based on the desired velocity signal, a jerk value j, and the commanded acceleration a
c
.
REFERENCES:
patent: 4836056 (1989-06-01), Nakawaki et al.
patent: 5417622 (1995-05-01), Asayama et al.
patent: 5478288 (1995-12-01), Sakakibara et al.
patent: 5568748 (1996-10-01), Carlson et al.
patent: 5624339 (1997-04-01), Coutant et al.
patent: 5658217 (1997-08-01), Tsukada
Cronin Michael G.
Kuras Brian D.
Lueschow Kevin J.
Marr Jerry D.
Caterpillar Inc.
Cuchlinski Jr. William A.
Donnelly Arthur D.
Morrison John W.
LandOfFree
Method and apparatus for generating velocity commands for a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for generating velocity commands for a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for generating velocity commands for a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2547941