Patent Description:
It is often desirable to mount an object, such as a camera, onto a support platform. In the case when the platform is stationary, such mounting presents no particular issues.

However, when the support platform is movable, such as a on a vehicle, there are significant issues to be overcome in order to maintain the object in a stable condition. In the example of a camera, it is desirable to maintain the camera stable for providing images of a suitable quality. In particular, there are significant challenges presented by mounting a camera on a vehicle that traverses rough ground, on a water-borne vehicle, due to the ever-changing nature of the surface on which the vehicle and camera are supported. Similar issues occur with airborne vehicles, and affect mounting of other objects, such as sensor devices, or projection apparatus. In order to compensate for movement of the vehicle, systems have been proposed that make use of a complex arrangement of multi-axis gimbals and powered actuators.

However, such previous-considered designs have several drawbacks. Firstly, the support structures are cumbersome and heavy, which restricts the possible applications for the resulting system. Secondly, previously-considered designs are not able to maintain an object position with respect to an initial reference position. For example, previously-considered designs are not able to maintain the camera in a substantially fixed, or smoothly changing, vertical position with respect to the horizon in real time. Thirdly, previously considered designs are not suitable for wide angle image capture, since the structure of the support restricts the angle of view.

<CIT> discloses a tracking device for automatically following a moving light source that is detectable in the presence of ambient light. <CIT> discloses a camera crane mobile base has a drive motor assembly at each corner of a chassis.

It is, therefore, desirable to provide a support and stabilisation system that seeks to address the issues of the previously-considered designs.

According to an aspect of the present invention, there is provided a support and stabilisation system as claimed in claim <NUM>.

In one example, the first portion of the telescopic element is rotatably engaged with the base by a first rotational bearing element.

In one example, the first portion of each linear actuator is rotatably engaged with the base by a second rotational bearing element.

In one example, the second portion of each linear actuator is rotatably engaged with the second portion of the telescopic element by a third rotational bearing element.

In one example, the first bearing element is chosen from a group including multi-axis pivot, a gimbal, a two-pivot joint, a ball joint, and a flexible resilient member.

In one example, the second bearing element is chosen from a group including multi-axis pivot, a gimbal, a two-pivot joint, a ball joint, and a flexible resilient member.

In one example, the third bearing element is chosen from a group including multi-axis pivot, a gimbal, a two-pivot joint, a ball joint, and a flexible resilient member.

In one example, the base is provided by a substantially planar base portion.

In one example, the telescopic element defines a longitudinal axis of the system, and the linear actuators define respective actuator longitudinal axes, which are arranged to extend from the base towards the longitudinal axis of the system.

In one example, the linear actuators are engaged with the second portion of the telescopic element at substantially the same axial position on that second portion.

One example system comprises three such linear actuators.

One example system comprises four such linear actuators.

In one example, the control unit is operable to control the linear actuators so as to maintain the linear and angular position of the attachment element with respect to a predetermined reference.

In one example, the predetermined reference is a horizon.

In one example, the control unit is operable to maintain the attachment element at a predetermined height with respect to the predetermined reference.

In one example, the first object is a vehicle. The vehicle may be one of a wheeled vehicle, a tracked vehicle, and a water-borne vehicle.

In one example, the second object is a camera device, an image recording device, or a video or film camera device.

<FIG> and <FIG> illustrate mounting of an object <NUM> on a platform <NUM> in accordance with the principles of the present invention. In the example of <FIG> and <FIG>, the platform <NUM> is illustrated as a moveable wheeled vehicle <NUM>, and the object is an image capture device, such as a camera <NUM>. It will be readily appreciated that the object <NUM> and platform <NUM> are not limited to these examples, which are used for clarity of description below. The principles of the present invention are applicable to the support and stabilisation of any appropriate object, on any appropriate platform. The object and platform may be of any appropriate scale and size. The object may be supported by another stabilisation platform if required.

In the example of <FIG> and <FIG>, the wheeled vehicle <NUM> has a plurality of ground engaging wheels <NUM> mounted on a chassis <NUM>. The wheels <NUM> engage a ground surface <NUM> and, as is well known and understood, enable the vehicle <NUM> to move across the ground surface <NUM>. A support and stabilisation system <NUM> is mounted on the chassis <NUM>, and the camera <NUM> is mounted on the support <NUM>. It will be appreciated that the support and stabilisation system <NUM> is illustrate schematically in <FIG> and <FIG> for the sake of clarity of these drawings.

The support and stabilisation system <NUM> enables the camera <NUM> to be supported above the chassis <NUM> of the vehicle <NUM>, such that the size of the support and stabilisation system <NUM> is small or non-existent in images generated by the camera <NUM>. In particular, a support and stabilisation system <NUM> embodying the principles of the present invention is mountable within the footprint of the vehicle <NUM> or another platform. As will be described in more detail below, the support and stabilisation system <NUM> extends above the chassis <NUM> sufficiently to enable the camera to capture images that do not include the chassis <NUM> or support and stabilisation system <NUM>, or that contain a minimal view of those components. In addition, the support and stabilisation system <NUM> is designed to have a small footprint such that wide-angle image capture, such as <NUM>° capture, does not result in the chassis <NUM> or support and stabilisation system <NUM> being seen significantly in the resulting images.

As the vehicle <NUM> moves across the ground surface <NUM>, the chassis <NUM> experiences vertical translation T (i.e. translation substantially perpendicular to the ground surface <NUM>), and rotation about a plurality of axes. Two such axes are illustrated by arrows R1 and R2 in the Figures. The support and stabilisation system <NUM> is arranged to enable the camera <NUM> to be maintained in a desirable position relative to the ground surface <NUM>, and to an initial reference position. Where the amount of translation and/or rotation of the vehicle <NUM> exceeds the amount of compensating movement available to the support and stabilisation system <NUM>, then the system <NUM> serves to smooth out such movements, such that the positional changes of the camera <NUM> are typically slower than the positional changes of the vehicle <NUM>.

The camera <NUM> may be mounted on the support and stabilisation system <NUM> using a movable mount to allow the camera to be rotated (about one or more axes) with respect to the support and stabilisation system <NUM>.

<FIG> illustrates a support and stabilisation system <NUM> embodying the present invention. The system <NUM> comprises a support and stabilisation system <NUM> and a control unit <NUM>. The support and stabilisation system <NUM> will be referred to as the "support <NUM>" in the following description. The control unit <NUM> is illustrated as being separate from the support <NUM>, but it will be readily appreciated that the control unit may be located in any convenient position.

The support <NUM> comprises a base <NUM> for attachment to a first object, for example the vehicle or other support object. The base <NUM> is preferably provided by a substantially planar base portion. The base <NUM> is preferably of a substantially rigid material. A telescopic element <NUM> is mounted on the base <NUM>, and defines a longitudinal axis of the system <NUM>. The telescopic element <NUM> has a first portion <NUM> rotatably engaged with the base <NUM>, and a second portion <NUM> linearly slidably engaged with the first portion <NUM>. The second portion <NUM> of the telescopic element <NUM> defines an attachment portion <NUM> adapted for reception of a second object, for example a camera or other device. The second object may be attached directly to the attachment portion, or may be attached via a secondary stabilisation platform or system.

In one example, the first portion <NUM> of the telescopic element <NUM> is attached to the base <NUM> by a multi-axis gimbal <NUM>. The multi-axis gimbal <NUM> is centred on the longitudinal axis, and enables the telescopic element <NUM> to rotate freely in any polar orientation with respect to the base <NUM>, about the centre of the gimbal <NUM>, so as to provide the telescopic element <NUM> with a range of angular movement with respect to the base <NUM>. In a neutral position, as shown in <FIG>, the telescopic element <NUM> extends substantially perpendicularly with respect to the substantially planar base <NUM>.

The support <NUM> further comprises a plurality of linear actuators <NUM>; in the example of <FIG>, four linear actuators <NUM> are shown. Preferably, at least three linear actuators <NUM> are provided. The linear actuators <NUM> may be electrical (for example driven by a motor or other electrical component), hydraulic, or pneumatic.

Each linear actuator <NUM> has a first portion rotatably engaged with the base <NUM>, and a second portion <NUM> linearly slidably engaged with the first portion <NUM> of the actuator <NUM> concerned. The second portion <NUM> of each linear actuator <NUM> is rotatably engaged with the second portion <NUM> of the telescopic element <NUM>. The linear actuators <NUM> define respective longitudinal axes, and each linear actuator <NUM> is operable to drive the second portion <NUM> thereof linearly along its longitudinal axis with respect to the first portion <NUM> thereof. Accordingly, extension and retraction of the second portions <NUM> of the linear actuators <NUM> causes the second portion <NUM> of the telescopic element <NUM> to move linearly with respect to the first portion <NUM>, and rotationally with respect to the base <NUM> in a controlled manner.

The first portions <NUM> of the linear actuators <NUM> are attached to the base <NUM> by respective first two-axis pivoting joints <NUM>. The second portions <NUM> of the linear actuators <NUM> are attached to the second portions <NUM> of the telescopic element <NUM> by respective second two-axis pivoting joints <NUM>. In the example of <FIG>, the second portions <NUM> of the linear actuators <NUM> are shown extending from inside the first portions <NUM>. It will be readily appreciated that the opposite configuration is also possible, with the second portions <NUM> extending around the first portions <NUM>. The first portions <NUM> of the linear actuators <NUM> may be attached to the planar base <NUM>, or may be attached to the base <NUM> via suitable mounting portions.

Each of the first two-axis pivoting joints <NUM> allow the respective first portions <NUM> of the linear actuators <NUM> to rotate with respect to the base <NUM> about two axes. The first axis extends substantially parallel to the plane of the base <NUM>, and the second axis extends substantially transversely to the longitudinal axis of the linear actuator <NUM> concerned.

Each of the second two-axis pivoting joints <NUM> allow the respective second portions <NUM> of the linear actuators <NUM> to rotate with respect to the respective second portions <NUM> of the telescopic element <NUM> about two axes. The first axis extends substantially tangentially to the respective second portion <NUM> of the telescopic element <NUM>, and the second axis extends substantially transversely to the longitudinal axis of the linear actuator <NUM> concerned.

The linear actuators <NUM> may be electrically, hydraulically or pneumatically actuated, and are controlled by the control unit <NUM>. The control unit <NUM> is connected to receive sensor information, and operates to use that sensor information to supply control signals to the linear actuators. This control of the linear actuators <NUM> adjusts the relative linear position of the second portions <NUM> with respect to the first portions <NUM> of the respective linear actuators, thereby controlling the linear and polar position of the telescopic element <NUM>.

Sensors are provided on or in the support and stabilisation system <NUM>, and operate to provide the sensor information to the control unit. The sensors may be provided by any suitable combination of sensors. For example, a six-axis inertial measurement unit (IMU) may be provided. As is well known and understood, an IMU is an electronic device that measures and reports specific force, angular rate, and sometimes the magnetic field surrounding an object, using a combination of accelerometers and gyroscopes, sometimes also magnetometers. Other possible sensors include a linear position sensor for the telescopic element <NUM> and/or for each linear actuator <NUM>, an angular position sensor for the telescopic element <NUM>, a multi axis accelerometer, a gravity sensor for determining a vertical direction, and an altimeter. Additional sensors and feedback devices may be provided on the vehicle or other platform for supplying additional information to the control unit <NUM>. Furthermore, the control unit <NUM> may make use of additional information, such as positional information derived from Global Positioning System (GPS) data (or similar), for control of the support and stabilisation system <NUM>.

The control unit <NUM> operates to maintain the telescopic element <NUM> in a desired position and orientation relative to a predetermined reference, within the range of movement provided by the support and stabilisation system <NUM>. In this manner, the attachment portion can be maintained in a desired position and orientation with respect to the predetermined reference, thereby maintaining the camera <NUM> in a desired position and orientation. The predetermined reference may be internal to the vehicle <NUM> and support <NUM>, or may be external to the system, such as the horizon.

Where the amount of translation and/or rotation of the vehicle <NUM> exceeds the amount of compensating movement available to the support and stabilisation system <NUM>, then the system <NUM> serves to smooth out such movements, such that the positional changes of the camera <NUM> are typically slower than the positional changes of the vehicle <NUM>.

Preferably, the control unit <NUM> operates in real time in order to maintain the camera <NUM> in the desired position and orientation in real time. The system can then be described as "active" system.

This predetermined reference may be set upon initial calibration of the support and stabilisation system <NUM>. Following attachment of the camera <NUM> to the system <NUM>, the user sets an initial position for the camera <NUM> and system <NUM>, and calibrates the control system <NUM> in order to set the predetermined reference. For optimum performance, this initial calibration can also include mechanical balancing of the system <NUM>.

<FIG> shows a simplified side view of another support and stabilisation system embodying the present invention. The <FIG> embodiment is a generalised version of the <FIG> embodiment, and is of the same overall structure. The <FIG> embodiment differs from the <FIG> embodiment by virtue of the general nature of the mounting rotational mounting of the telescopic element <NUM> and the linear actuators <NUM>.

In <FIG>, the first portion <NUM> of the telescopic element <NUM> is mounted on the base <NUM> by way of a first bearing element <NUM>. The first bearing element <NUM> may be a multi axis pivot, such as a gimbal as in <FIG>, a two-pivot joint, a ball joint, a flexible resilient member, or any other appropriate bearing element that allows the first portion <NUM> of the telescopic element <NUM> to rotate with respect to the base <NUM>. Different first bearing elements <NUM> allow for different respective axes of rotation of the telescopic element. For example, a two-axis gimbal allows for rotation about two axes, each of which is substantially perpendicular to the longitudinal axis of the telescopic element <NUM>. A ball joint would allow this two-axis rotation, and also allow for rotation of the telescopic element <NUM> about the longitudinal axis thereof.

Also illustrated in <FIG>, respective second bearing elements <NUM> attach the linear actuators <NUM> to the base <NUM>, and respective third bearing elements <NUM> attach the linear actuators <NUM> to the second portion <NUM> of the telescopic element <NUM>. The second and third bearing elements <NUM> and <NUM> may be of the same type, or may be of different types. The second and third bearing elements <NUM> and <NUM> may be provided by any suitable rotational element, such as a multi-axis pivot, such as a gimbal, a two-pivot joint, a ball joint, a flexible resilient member, or any other appropriate bearing element that allows the linear actuator <NUM> to rotate with respect to the base <NUM> and second portion <NUM> of the telescopic element <NUM>.

In <FIG>, the second portion <NUM> of the telescopic element <NUM> extends outside of first portion thereof. <FIG> illustrates the opposite situation in which the second portion <NUM> of the telescopic element <NUM> extends within the first portion <NUM> thereof. The remaining configuration and operation of the example of <FIG> is substantially the same as that for <FIG>, with the same reference numerals used in each of <FIG> and <FIG>.

<FIG> illustrates, in partial cross-sectional simplified schematic side view, another support and stabilisation system embodying the present invention. The system of <FIG> Is similar in overall concept to the embodiments shown in, and described with reference to, the previous Figures. In the example of <FIG>, the linear actuators extend to a side of the base opposite to that of the attachment portion for the object being supported.

In <FIG>, a support <NUM> comprises a base <NUM> for attachment to the platform. A telescopic element <NUM> extends through the base <NUM>, through an aperture <NUM> defined in the base <NUM>. The telescopic element <NUM> comprises a first portion <NUM>, arranged for rotational engagement with the base <NUM>, and a second portion <NUM> which extends through the first portion <NUM>, and through the aperture <NUM> in the base <NUM>. The second portion <NUM> of the telescopic element <NUM> is arranged for linear movement with respect to the first portion <NUM>. The second portion of the telescopic element <NUM> provides an attachment portion <NUM> for the attachment of the object to the support <NUM>.

The first portion <NUM> of the telescopic element <NUM> is mounted on the base <NUM> by way of a first bearing element <NUM>. The first bearing element <NUM> may be a multi axis pivot, such as a gimbal, a two-pivot joint, a ball joint, a flexible resilient member, or any other appropriate bearing element that allows the first portion <NUM> of the telescopic element <NUM> to rotate with respect to the base <NUM>. Different first bearing elements <NUM> allow for different respective axes of rotation of the telescopic element. For example, a two-axis gimbal allows for rotation about two axes, each of which is substantially perpendicular to the longitudinal axis of the telescopic element <NUM>. A ball joint would allow this two-axis rotation, and also allow for rotation of the telescopic element <NUM> about the longitudinal axis thereof.

A plurality of linear actuators <NUM> are attached between the base <NUM> and the second portion <NUM> of the telescopic element <NUM>. Respective second bearing elements <NUM> attach the linear actuators <NUM> to the base <NUM>, and respective third bearing elements <NUM> attach the linear actuators <NUM> to the second portion <NUM> of the telescopic element <NUM>. The second and third bearing elements <NUM> and <NUM> may be of the same type, or may be of different types. The second and third bearing elements <NUM> and <NUM> may be provided by any suitable rotational element, such as a multi-axis pivot, such as a gimbal, a two-pivot joint, a ball joint, a flexible resilient member, or any other appropriate bearing element that allows the linear actuator <NUM> to rotate with respect to the base <NUM> and second portion <NUM> of the telescopic element <NUM>.

A control unit <NUM> is provided, and operates as the control unit described above.

The example system of <FIG> allows the object being supported to be closer to the base of the support system, whilst retaining the advantages of an embodiment of the present invention.

One particular example of the use of a support and stabilisation system embodying the present invention would be mounting a camera <NUM> to the roof of a vehicle <NUM>. The vehicle <NUM> can then drive over bumpy and angled terrain and the support and stabilisation system is able to control the position the camera <NUM> such that, for example, the camera remains substantially level with respect to the horizon. The system is able to control the position of the camera so as to remove or reduce any sudden vertical displacements or rotations that might create undesirable output from the camera <NUM>.

If the base <NUM> is located at the centre of the vehicle <NUM>, the stabiliser system is able to reduce displacement as a result of the vehicle pitching or rolling.

Claim 1:
An active stabilisation system (<NUM>) for mounting an object to a movable platform, the stabilisation system comprising:
a base (<NUM>) for attachment to a moveable platform (<NUM>);
a telescopic element (<NUM>) having a first portion (<NUM>) rotatably engaged with the base (<NUM>), and a second portion (<NUM>) linearly slidably engaged with the first portion (<NUM>) and having an attachment portion (<NUM>) adapted for reception of an object (<NUM>);
a plurality of linear actuators (<NUM>), each linear actuator (<NUM>) having a first portion (<NUM>) rotatably engaged with the base (<NUM>), and a second portion (<NUM>) linearly slidably engaged with the first portion (<NUM>) of the actuator concerned, and rotatably engaged with the second portion (<NUM>) of the telescopic element, the plurality of linear actuators (<NUM>) being operable to drive the second portion (<NUM>) of the telescopic element linearly with respect to the first portion of the telescopic element (<NUM>) and rotationally with respect to the base (<NUM>);
a plurality of sensors on or in the stabilisation system, and operable to provide sensor data relating to a position of the attachment portion; and
a control unit (<NUM>) operable to receive the sensor data and to supply real time control signals to the linear actuators (<NUM>) in response to reception of the sensor data, thereby to control the relative linear positions of the second portions (<NUM>) of the linear actuators with respect to the first portions (<NUM>) of the respective linear actuators.