This application is the US national phase of international application PCT/SE03/00108 filed 22 Jan. 2003, which designated the US and claims priority to SE Application No. 0200200-4, filed 22 Jan. 2002. The entire contents of these applications are incorporated herein by reference.
The present invention relates in a first aspect to a control system for a powered vehicle.
In a second aspect the present invention relates to a method of controlling a movement of a powered vehicle.
In a third aspect the present invention relates to at least one computer program product for controlling a movement of a powered vehicle.
The theatre has automated much of the equipment used for movement of scenery and lighting. Most of stage activity involves simply moving scenery about the stage. Automated systems for doing this have been limited by poor radio communication, lack of accuracy and navigation, high noise and high costs.
The document U.S. Pat. No. 5,823,884 discloses a powered stage wagon comprising a chassis to which there is mounted a plurality of rolling support means, each of which is located at respective corner of the chassis. The powered stage wagon also comprises a first and a second drive means, both mounted on the chassis in engagement with the surface over which the stage wagon is to move and are mutually spaced. The document describes a method of calculating a travel path along which the stage wagon may be moved from a current position to a desired position. The method comprising the steps of calculating for each of said drive means the bisector of a line joining the current location of said drive means and the location of said drive means when the stage wagon has moved to its desired position; determining the point of intersection of the two bisectors; calculating for each of said drive means the length of an arc centred on said point of intersection and passing through both the current location of said drive means and the location of said drive means when the stage wagon has moved to its desired position; controlling the ratio of the rotational speeds of the first and second drive means in accordance with the ratio of said arc lengths; and controlling the relative orientation of said first and second drive means so that each of said drive means continuously defines a tangent to the respective arc associated with the drive means concerned.
One main disadvantage with the method of calculating a travel path according to the document U.S. Pat. No. 5,823,884 is that it limits paths to certain predefined combinations of translation and rotation. Another disadvantage is that the method does not correct for any physical errors in movement that might occur.
It is an object of the present invention to solve the above mentioned problems.
According to the present invention there is provided in a first aspect a control system for a powered vehicle for describing a desired movement of said vehicle, and communicating said movement to a drive system of said vehicle. The powered vehicle comprising a chassis, at least three rolling means mounted on said chassis for engagement with a surface over which said vehicle is to move. The drive system comprises at least two drive units, each comprising a first driving means and a second driving means, co-operatively operable to provide both propulsion and steering of said drive unit and consequently said vehicle. The control system also comprises a computing means for calculating a desired movement of said vehicle, wherein translation of said vehicle is calculated in said form of a continuous cubic function, and rotation of said vehicle is calculated in the form of a linear function. The control system also comprises a communicating means for transmitting said desired movement to said desired movement to said at least two drive units to move said vehicle in accordance with the desired movement. One advantage with the control system according to the present invention is that it can move a vehicle along any predefined path, with a predefined change in rotation in accordance with a time scale. Another advantage with this control system is that it is scalable, i.e. it can move any number of vehicles simultaneously along different paths. Another advantage with this control system is that it allows vehicles to move in any direction. It makes no assumptions as to one direction being more natural than another. Yet another advantage with this control system is that it uses the same method of describing any type of movement or path.
A further advantage in his context if said control system also comprises a navigation system for determining an actual position of said vehicle, which actual position is transmitted to said computing means for correcting errors between the actual position and a desired position according to said desired movement of said vehicle.
Furthermore, it is an advantage in this context if said continuous cubic function is a Beziér function of a third power.
A further advantage in his context if Beziér function is expressed in accordance with:
x=ap3+bp2+cp+d
y=ep3+fp2+gp+h,
wherein a-h are constants and p is a variable satisfying 0≦p≦1. Furthermore, it is an advantage in this context if said computing means calculates said constants a-h according to the following expressions:
a=x3−3x2+3x1−x0
e=y3−3y2+3y1−y0
b=3x2−6x1+3x0
f=3y2−6y1+3y0
c=3x1−3x0
g=3y1−3y0
d=x0
h=y0,
wherein (X0, y0) is a start position and (x3, y3) is an end position of said movement, and (x1, y1) and (x2, y2) are control positions of said movement.
A further advantage in his context if said movement is made up of at least one segment.
Furthermore, it is an advantage in this context if if said movement is made up of at least two segments, said control system has to apply to the following rules if said vehicle is to move smoothly from one segment to the next:
A further advantage in his context if said computing means also calculates an instantaneous center of said vehicle.
Another object of the invention is to provide a method of controlling, with the aid of a control system, a movement of a powered vehicle. The vehicle comprises a chassis, a drive system, at least three rolling means mounted on said chassis for engagement with a surface over which said vehicle is to move. The drive system comprises at least two drive units, each comprising a first driving means and a second driving means, co-operatively operable to provide both propulsion and steering of said drive unit. The method comprises the following steps:
A further advantage in this context is achieved if said method also comprises the steps of:
Furthermore, it is an advantage in this context if said continuous cubic function is a Beziér function of a third power.
A further advantage in this context is achieved if said Beziér function is expressed in accordance with:
x=ap3+bp2+cp+d
y=ep3+fp2+gp+h,
wherein a-h are constants, and p is a variable satisfying 0≦p≦1.
Furthermore, it is an advantage in this context if said method also comprises the steps of
A further advantage in this context is achieved if said method also comprises the steps of:
Furthermore, it is an advantage in this context if said method also comprises the steps of:
Another object of the invention is to provide at least one computer program product directly loadable into the internal memory of at least one digital computer. The at least one computer program product comprises software code portions for performing the steps of the method according to the present invention, when said at least one product is/are run on at least one computer. One advantage with the computer program product(s) according to the present invention is that it/they can move a vehicle along any predefined path, with a predefined change in rotation in accordance with a time scale. Another advantage with this product is that it is scalable, i.e. it can move any number of vehicles simultaneously along different paths. Another advantage with this product is that it allows vehicles to move in any direction. It makes no assumptions as to one direction being more natural than another. Yet another advantage with this product is that is uses the same method of describing any type of movement or path.
It should be emphasised that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, steps or components but does not preclude the presence of one or more other features, integers, steps, components or groups thereof.
Embodiments of the invention will now be described with a reference to the accompanying drawings, in which:
In a preferred embodiment of the control system 70 according to the present invention the continuos cubic function is a Beziér function of a third power.
In a preferred embodiment of the controlsystem 70 according the present invention the Beziér function is expressed in accordance with:
x=ap3+bp2+cp+d
y=ep3+fp2+gp+h,
wherein a-h are constants and p is a variable satisfying 0≦p≦1.
In a preferred embodiment of the control system 70 according to the present invention the constants a-h are calculated in accordance with the following expressions:
a=x3−3x2+3x1−X0
e=y3−3y2+3y1−y0
b=3x2−6x1+3x0
f=3y2−6y1+3y0
c=3x1−3x0
g=3y1−3y0
d=x0
h=y0
wherein (x0, y0) is a start position and (y3, y3) is an end position of said movement, and (x1, y1) and ((x2, y2) are control positions of said movement.
In a preferred embodiment of the control system 70 according to the present invention the movement is made up of at least one segment.
In a preferred embodiment of the control system 70 according to the present invention, if said movement is made up of at least two segments, the control system 70 has to apply the following rules if said vehicle 72 is to move smoothly from one segment to the next:
In a preferred embodiment of the control system 70 according to the present invention, the computing means 74 also calculates an instant aneous center of said vehicle 72. The movement of any point on the vehicle 72 can always be described as a rotation about the instantaneous center is calculated errors in the vehicles position along the curve and its rotation as reported by the navigation system 78 may be accounted for.
The drive unit 10 comprises a rolling means 12 intended to be in frictional engagement with a surface over which said drive unit 10 is intended to move. Preferably, said rolling means 12 is a wheel 12. The drive unit 10 also comprises a first driving means 14, and a second driving means 16, co-operatively operable to provide both propulsion and steering of said drive unit 10. The first driving means 14 is arranged on a rotatable support means 18 rotatable about a center axis, c.a.
The first driving means 14 is operable to rotate said rolling means 12 about a rolling axis. The rolling axis is perpendicular to said center axis, c.a. As is apparent from
This vehicle 50 comprises two drive units 10, of the same kind disclosed in
In
The method continues at block 88 with the step: with a communication means comprised in the control system, to transmit said desired movement to said at last two drive units to move said vehicle in accordance with said desired movement. The method is completed at block 90.
In a preferred embodiment of the method according to the present invention, the method also comprises the steps of:
In a preferred embodiment of the method according to the present invention, the continuos cubic function is a Beziér function of a third power.
In a preferred embodiment of the method according to the present invention, the Beziér function is expressed in accordance with:
x=ap3+bp2+cp+d
y=ep3+fp2+gp+h,
wherein a-h are constants, and p is a variable satisfying 0≦p≦1.
In a preferred embodiment of the method according to the present invention, the method also comprises the steps of:
to calculate said constants a-h according to the following expressions:
a=x3−3x2+3x1−x0
e=y3−3y2+3y1−y0
b=3x2−6x1+3x0
f=3y2−6y1+3y0
c=3x1−3x0
g=3y1−3y0
d=x0
h=y0
wherein (x0, y0) is a start position and (x3, y3) is an end position of said movement, and wherein (x1, y1) and (x2, y2) are control positions of said movement.
In a preferred embodiment of the method according to the method according to the present invention, the method also comprises the steps of:
In a preferred embodiment of the method according to the present invention, the method also comprises the steps of:
In
One advantage with the present invention is that it can move a vehicle or robot along any predefined path, with a predefined change in rotation in accordance with a time scale.
Another advantage is that it can move any number of vehicles synchronously, that is move several vehicles as though they were one, transparently to the user and without any mechanical connection or any cables between the vehicles.
Another advantage is that it allows vehicle to be of any size while using the same set of components.
Another advantage with the present invention is that it allows the operator to control the speed of the movements dynamically, while the relation positions of all vehicles under his/her control remain the same.
The invention is not limited to the embodiments described in the foregoing. It will be obvious that many different modifications are possible within the scope of the following claims.
Number | Date | Country | Kind |
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0200200 | Jan 2002 | SE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/SE03/00108 | 1/22/2003 | WO | 00 | 11/9/2004 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO03/062935 | 7/31/2003 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
5416477 | Shibata | May 1995 | A |
5456332 | Borenstein | Oct 1995 | A |
5823884 | Ager | Oct 1998 | A |
6289270 | Baumgarten | Sep 2001 | B1 |
Number | Date | Country |
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7-13622 | Jan 1995 | JP |
Number | Date | Country | |
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20050065676 A1 | Mar 2005 | US |