GB2523807A

GB2523807A - Single axis stabilization mounting

Info

Publication number: GB2523807A
Application number: GB1403960.6A
Authority: GB
Inventors: Kin Leung
Original assignee: MASTORTECH Ltd
Current assignee: MASTORTECH Ltd
Priority date: 2014-03-06
Filing date: 2014-03-06
Publication date: 2015-09-09
Also published as: GB201403960D0

Abstract

A stabilization mount (10) for a camera (23) has automatic roll axis compensation, so that the camera gives a steady image when in motion. In one embodiment the mount is hand-held. The mount has a slidable counterweight (24), a roll motion sensor, and a motor (31), responsive to a controller, to provide roll stability.

Description

Single Axis Stabilization Monnting

TECHNICAL FIELD

This invention relates to a single axis stabilization mounting for a camera or the like, in particular to allow a camera to be insulated from movements associated with the camera support.

BACKGROUND TO THE INVENTION

One problem with hand-held cameras is the effect of vibration and movement on the viewing direction. Typically a hand-held camera is subject to instability because of the difficulty of holding the camera still. A moving camera, for example a vehicle mounted camera, is subject to instability due to movement of the vehicle out of the viewing plane. A hand-held camera on a moving vehicle suffers both kinds of instability, and this instability is exacerbated in a video image. Moving the camera, for example in a panning shot, tends to emphasize instabilities.

Stabilization techniques, for example camera mounting platforms having movement sensors and corresponding electric motors, have been proposed to counter movements in the pitch, roll and yaw (pan) axes. These kinds of stabilized platforms tend to be bulky, complex, heavy and relatively expensive.

What is required is an improved camera mounting capable of maintaining a horizontal viewing plane, with simplicity of constmction, light weight and relatively low cost.

SUMMARY OF THE INVENTION

According to the invention, there is provided a platform assembly for a camera, and comprising a camera mounting for mounting a camera thereto, and a support, the mounting being connected to the support with capability for relative movement in roll about a roll axis, the mounting including a roll motion sensor, and a motor being provided on the platform assembly to counter roll motion about said axis in response to output of said sensor, wherein a counterweight is provided on said mounting, said counterweight being radially adjustable with respect to said axis to balance the mass of a camera, in use.

The roll axis is defined in one embodiment by an axle and bearing in combination; the bearing may be plain or may include rolling elements such as balls or rollers.

A platform assembly according to the invention provides for stabilization about the roll axis, and the adjustable counterweight ensures that the tendency for roll motion can be minimized. In particular the counterweight can be positioned below the axis (in use) to ensure stability of a camera above the axis.

The counterweight comprises a housing within which is housed a counterweight mass.

In one embodiment the housing also contains a roll motion sensor and electronic circuitry associated with the motion sensor. A rechargeable battery may be included in the housing.

t5 The motor is preferably a brushless DC motor, and is mounted so as to drive relative movement between the support arid camera mounting. The axis of the motor may be coincident with the roll axis.

Electrical wiring to the motor may be contained within a channel or hollow section of the camera mounting.

A limb of the camera mounting carries a platform to which a camera may be directly attached. An adaptor plate may be provided suitable for any kind of camera, including a camera phone or a video camera.

The platform assembly may further include a pitch sensor to block motion of said motor when the assembly is pitched outside a predetermined pitch range. The pitch range may be +60, and in one embodiment is +45°. The output of the pitch sensor may be provided to a microprocessor associated with the roll motion sensor whereby motion of the motor is controlled. The pitch sensor may be contained in a housing for the counterweight.

Aspects of the invention will be apparent from the claims appended hereto.

BRIEF DESCRIPTION OF DRAWINGS

Other features of the invention will be apparent from the following description of a preferred embodiment illustrated by way of example only in the accompanying drawings in which: Fig. 1 comprises au elevation of one side of a platform assembly according to the invention, and including a camera thereon, Fig. 2 is a front elevation corresponding to Fig. 1, Fig. 3 is an elevation of the other side of the platform assembly, corresponding to Fig. 1, Fig. 4 is a perspective view from the front of the platform assembly, corresponding to Fig. 1.

DESCRTPTON OF AN EMBODIMENT OF THE INVENTION

With reference to the drawings a platform assembly 10 comprises a camera mounting 11 pivotably connected to a support 12 about a roll axis 13. Relative roll motion is in the plane defined by an orthogonal axis 14 which is substantially vertical in use.

The camera mounting 11 is tee-shaped and consists of a horizontal limb 15 and oppositely directed vertical limbs 16, 17. The upwardly directly limb 16 supports a camera platform 18 which is pivotable about a pitch axis 19 by virtue of a screw-threaded clamp 21 having a finger nut 22. The pitch axis 19 and the roll axis 13 coincide, but need not. In use the finger nut may be loosened to adjust the pitch of the platform 18, and tightened to lock the platform at a desired relative pitch angle.

A camera 23 illustrated on the platfonn 18. The camera may be retained in any convenient manner, A conventional digital still camera is illustrated, but the platfonu may be adapted to mount any kind of device incorporating a camera, such as a mobile phone or video camera.

The depending limb 17 has slidable thereon a counterweight 24 consisting of a two-part shell housing 25 defining within an enclosed space. The limb 17 enters the housing 25, and the housing may be frictionally clamped in any position on the limb by means of the pivoting over-centre clamp arm 26. The clamp arm is of conventional kind, is released by upward pivoting (as viewed in Fig. 3), and clamped by downward pivoting.

Within the housing 25 is provided a counterweight mass, for example a block of metal, and a motion sensor for sensing roll motion, as will be further described below.

The housing itself may be moulded of plastic material, or pressed from aluminium sheet. The counterweight mass may be variable to suit the mass of the camera; for example the counterweight mass may comprise a plurality of individual mass elements which can be added or removed to obtain a desired counterbalance. tS

The housing 25 may also incorporate a power supply, such as a rechargeable dry cell battery, for which an on/off switch 27 is provided (Fig. 2) in the wall of the housing.

The support 12 is generally vertically disposed and carries at the lower end a single-hand grip 28, which in the illustrated embodiment is attached by a horizontal axis clamp screw 29. The clamp screw 29 may be loosened to adjust the relative angle of the hand grip 28, and also permits removal of the hand grip entirely for mounting of the assembly on another device, such as the handle bar of a cycle, the dashboard of a car, a helmet, the deck of a boat or an aircraft.

A motor 3] is provided on the axis 13 to control relative movement between the mounting 11 and support 12. The motor may be provided on either element, and drive the other by means ot for example, a pinion and arcuate rack gear. As illustrated, the motor is on the support 11, and a gear housing 32 is provided on the mounting 11, The motor 31 is bi-directional, and is responsive to the roll motion sensor to counter roll motion and thereby maintain the camera stable about the roll axis notwithstanding relative motion of the hand grip 28 (or other device) which is represented by arrow 33 (Fig. 2). A charging socket 34 (Fig. 3) may be provided on the motor, on axis 13.

In use, in hand-held mode, the relative angle of the hand grip 28 and of the camera platform may be adjusted by clamps 22, 29 to ensure that the camera is orientated in the desired direction whilst being comfortable in the hand. The vertical position of the counterweight 24 is adjusted to properly balance the camera, particularly to avoid excessive turning moments due to the overbalancing tendency; suitable markings may be provided on the limb 17 to guide a user to the correct position according to the mass or type of camera.

When switched on, the roll motion sensor controls the motor 3] to counter roll motion 33, so that the camera remains stable about the roll axis to capture good quality images in motion (such as when walking or running). I5

The handgrip may also be moved about a pitch and yaw (pan) axis. In the pitch axis, the roll motion sensor may become ineffective at a predetermined pitch angle (up or down); the angle may for example be 45° pitch.

In a refinement, a tilt sensor may be incorporated within the housing 25 so as to prevent movement of the motor 3 1 above the predetermined pitch angle. Such a tilt sensor may for example block or fix the output of the roll motion sensor. This facility permits a user to tilt (pitch) the camera to any desired degree without inducing instability or tremble due to the roll motion sensor being out of a specified operational range (e.g. +45° pitch), The limbs of the camera mounting 11 may be hollow or channelled to permit wired connection between the motor 3 1 and electronic circuitry contained within the housing 25.

The roll angle sensor, in one embodiment, comprises a solid state acceleration sensor and gyroscopic sensor. A 32 bit microprocessor is incorporated within the housing 25 and is adapted to both provide corrective control to the motor 3 1 and to achieve an element of prediction so as to avoid overshoot. Feedback control of motor position may be included.

The motor typically has a corrective speed response of ± 1800 per second, a position accuracy of +0.05 degree, and a working current in the range I 50-200mA, A feature of the disclosed embodiment is that 360 degree rotation of the support 12 is possible with respect to the mounting. Such rotation is in the plane of axis 14 (Fig. ) so that for example unobstructed hand movement is possible, and the platform assembly may be held with the hand grip upwardly or sideways facing.

In use, initial switching on of the mounting will result in a short stabilization cycle during which the roll sensor sets a default orientation for the camera, typically horizontal. Further relative roll motion of the hand grip results in speed and angle outputs from the roll sensor which are compared with initialization data to generate a corrective signal for the motor 31. The microprocessor includes a PID (proportional-integral-derivative) controller to control position and speed of the motor, with continuous high speed detection and compensation. The motor 31 is preferably brushless, Improvements and alternatives are possible within the scope of the appended claims.

Claims

Claims I. A platform assembly for a camera, and comprising a camera mounting for mounting a camera thereto, and a support, the mounting being connected to the support with capability for relative movement in roll about a roll axis, the mounting including a roll motion sensor, and a motor being provided on the platform assembly to counter roll motion about said axis in response to output of said sensor, wherein a counterweight is provided on said mounting, said counterweight being radially adjustable with respect to said axis to balance the mass of a camera, in use.
2. An assembly according to claim I wherein said mounting comprises a depending leg, said counterweight is slidably mounted on said leg, and a releasable locking mechanism is provided to fix said counterweight to said leg.
3. An assembly according to claim 2 wherein said locking mechanism comprises a pivotable over-centre clamp arm adapted to urge said counterweight and leg into intimate contact.
4. An assembly according to claim 3 wherein said counterweight is infinitely adjustable with respect to said leg.
5. An assembly according to any preceding claim wherein said counterweight comprises a housing having a mass element housed therein.
6. An assembly according to claim 5 wherein said housing contains said roll motion sensor.
7. An assembly according to claim S or claim 6 wherein said housing contains a power supply for said motor.
8. An assembly according to claim 7 wherein said power supply comprises one or more dry cell batteries.
9. An assembly according to any preceding claim wherein said support comprises a charging socket for said power supply.
10. Mi assembly according to any preceding claim wherein said counterweight is substantially rectangular in elevation, and is mounted symmetrically on said leg.
11. An assembly according to ay preceding claim wherein said mounting is tee-shaped, and comprises one limb on said roll axis, and orthogonally thereto oppositely directed limbs for said camera mounting and for said counterweight.
12. An assembly according to claim 11 wherein the rotational axis of said motor is co-axial with said roll axis.
13. An assembly according to claim 11 or claim 12 wherein said mounting comprises an internal conduit for electrical wiring connecting said motor and motion sensor.
14. An assembly according to any of claims 11-13 wherein the camera mounting limb has a camera platform pivotable thereon about a platform pitch axis, in use.
15. An assembly according to claim 14 wherein said platform pitch axis comprises a releasable screw clamp for maintaining said camera platform in a fixed orientation with respect to the camera mounting limb,
16. Mi assembly according to any preceding claim wherein said support comprises a depending single-held grip.
17. An assembly according to claim 16 wherein said handgrip is detachable.
18. An assembly according to claim 16 or claim 17 wherein said handgrip is pivotable about a handle pitch axis, in use.
19. An assembly according to claim 18 wherein said handle pitch axis comprises a removable clamp screw.
20. An assembly according to any preceding claim wherein said support is mounted for rotation about said roll axis with respect to said mounting.
21. An assembly according to any preceding claim and further including a pitch sensor, the output of said pitch sensor being adapted to block rotation of said motor when pitch is outside a predetermined pitch range.
22. An assembly according to claim 21 wherein said pitch range is +45° with respect to the horizontal.
23. An assembly according to claim 21 or claim 22 wherein said pitch sensor is t5 provided in a housing of said counterweight.
24. An assembly according to any of claims 1-23 and including a camera on said mounting.
25. A platfonn assembly substantially as described herein with reference to the accompanying drawings.