CN106371469A - Camera holder pitch angle control method - Google Patents

Abstract

The invention discloses a method for controlling the pitch angle of a camera platform: when the angle deviation between the angle value measured by the pitch sensor and the target angle value is greater than the allowable error value, if the angle deviation is greater than the critical angle value for coarse and fine adjustment conversion, then Coarse steering gear is used to adjust quickly in a large range according to the proportional adjustment strategy. If the angle deviation is less than the critical angle value of coarse and fine adjustment conversion, the fine tuning steering gear is used for adjustment, and when the angle deviation is greater than the slow adjustment critical value, the fine tuning steering gear is adjusted according to The proportional adjustment method is used for adjustment. When it is less than the slow adjustment threshold value, the fine-tuning servo is adjusted according to the slow adjustment method. The invention has the characteristics of high adjustment precision.

Description

A method for controlling the pitch angle of a camera platform

technical field

The invention relates to a camera pan-tilt system.

Background technique

At present, the automatic stabilized camera gimbal is widely used in aerial photography and other fields, and its goal is to ensure the real-time stability of the camera during shooting, thereby ensuring the stability of the captured image of the camera. However, this type of shooting head has a small load-carrying capacity, and generally the rotation angle is limited, and the center of mass of the camera is required to be consistent with the axis of the adjustment rotation axis. Therefore, it can only support specific models of cameras and cannot load other equipment. The range is relatively narrow, such as DJI Zenmuse series gimbals ^[1] .

references

[1] Zenmuse H3-3D gimbal | DJI Dajiang http://www.dji.com/cn/product/zenmuse-h3-3d

Contents of the invention

The purpose of the present invention is to improve the existing camera platform and provide a pitch angle control method based on the improved camera platform. The adopted technical scheme is as follows:

A method for controlling the pitch angle of a camera platform, the adopted camera platform includes a rotation adjustment device in the roll direction, a rotation adjustment device in the pitch direction, a pitch sensor and a controller for measuring the rotation angle in the pitch direction, and a rotation adjustment device in the pitch direction The adjustment device is fixed on the rotation adjustment device in the balance direction, and the rotation adjustment device in the pitch direction adopts a thick and thin two-stage rotation adjustment structure, including the movable support 1 in the pitch direction, the platform fixed at the end of the movable support 1, the coarse adjustment steering gear 7 and The corresponding coarse adjustment rocker 6, the fine adjustment steering gear 3 and the corresponding fine adjustment rocker 4 are rigidly connected by the pull rod 5 between the coarse adjustment rocker 6 and the fine adjustment rocker 4; the fine adjustment steering gear 3 is fixed on the platform, The horsepower of the steering gear 7 is greater than that of the trimming steering gear 3;

The control method of the pitch angle of the camera gimbal is: preset the allowable error value, the critical angle value of the coarse adjustment conversion, and the slow adjustment critical value. The controller controls the operation of the two servos according to the measurement signal of the pitch sensor: when according to the pitch When the angle deviation between the angle value measured by the sensor and the target angle value is greater than the allowable error value, if the angle deviation is greater than the critical angle value of the coarse adjustment conversion, the coarse adjustment steering gear is used to perform a large-scale rapid adjustment according to the proportional adjustment strategy. If the angle deviation is less than the critical angle value of the coarse and fine adjustment conversion, the fine-tuning steering gear is used for adjustment, and when the angle deviation is greater than the slow adjustment critical value, the fine-tuning steering gear is adjusted according to the proportional adjustment method, and when it is less than the slow adjustment critical value, the fine-tuning steering gear Adjust according to the slow adjustment method.

The present invention has the following advantages due to the adoption of the above technical scheme:

(1) There are no strict requirements for the installation and layout of the bearing equipment, and it is not necessary to strictly adjust the center of gravity of the equipment to be consistent with the axis of the Y axis, thereby improving the flexibility of the layout of the bearing equipment while ensuring the bearing capacity.

(2) The pitch angle adopts a fine two-level adjustment structure, coupled with software strategy cooperation, which can ensure the accuracy of platform movement and realize high-precision platform movement and rotation.

Description of drawings

Figure 1: Structural diagram of the two-stage rotation adjustment of the gimbal

Figure 2: Flow chart of software feedback control strategy

detailed description

The present invention will be further described in detail with reference to the accompanying drawings and embodiments. The specific embodiments described here are only used to explain the present invention, and are not used to limit the protection scope of the present invention.

The high-inclination, high-load, self-balancing high-precision camera platform technology provided by the present invention includes two aspects, one is the design and layout of the hardware, and the other is the automatic balance feedback control software based on the above-mentioned hardware equipment.

(1) Design and layout of hardware: a high-precision camera head with large inclination angle, high load, and self-balancing. The key structural design is to use two-stage rotation adjustment structure in the pitch direction.

The thick and fine two-stage rotation adjustment structure includes a bracket 1 in the pitch direction, a coarse-adjustment steering gear 7 (large steering gear) and the corresponding rocker arm 6, a fine-tuning steering gear 3 (small steering gear) and the corresponding rocker arm 4. There is also a connecting part between the two rocker arms - pull rod 5

Among them, the steering gear used for coarse adjustment is a large steering gear. The steering gear is characterized by large horsepower, which can drive the rotation of high-load equipment on the platform, and the adjustable range is also large. The disadvantage of large steering gears is that the accuracy is slightly Low, and at this time there is no need to rotate in a large range, so we use small servos for fine-tuning servos, and make small-scale high-precision adjustments for the errors left by large servos.

The coarse adjustment steering gear 7 is connected with the corresponding rocker 6. When the coarse adjustment steering gear controller receives the sent control command, it sends a signal to the steering gear and drives the coarse adjustment steering gear to move, so that the equipment is pitching After the predetermined threshold is reached, the two steering gears are connected through the connecting part between the two rocker arms—the pull rod 5. When the fine-tuning steering gear controller receives the control command sent to the steering gear The signal drives the fine-tuning servo to move, so as to achieve the function of fine-tuning the rotation.

(2) Automatic balance feedback control software

In order to realize the real-time automatic balance of the camera pan/tilt, the present invention needs to adjust the balance state of the X-axis and the Y-axis according to the state of the current angle sensor in real time. The adjustment strategy is as follows:

a) Filter the sensor data. Due to factors such as the working environment of the sensor, its own state, and the transmission process, the data generated by the sensor will be unstable to a certain extent, resulting in the generation of wrong data, which will interfere with the stability of the system. Filter processing to eliminate data errors caused by accidental factors. Preferably, the present invention uses a combination of limiting filtering and Kalman filtering to filter the data to eliminate erroneous data and ensure the correctness of the data.

b) Adjust the X-axis balance state. In design, the X-axis (rolling direction) balance is adjusted by a single steering gear. When the difference between the sensor angle value and the preset angle in the X-axis direction, that is, the angle deviation is less than the X-axis allowable error value E (ie accuracy) , the steering gear stops adjusting in the X direction. When the angle deviation value measured by the sensor in the X-axis direction is greater than the allowable error value, if the deviation is large, the proportional adjustment strategy (see the description below) is used for adjustment; if the deviation is small (less than the slow adjustment critical value T), The slow adjustment strategy is adopted to adjust at a slow speed to ensure the stability of the adjustment.

c) Adjust the Y-axis balance state. The balance of the Y-axis (pitch direction) is adjusted by combining two servos. When the difference between the angle value of the Y-axis direction sensor and the preset angle, that is, the angle deviation is less than the allowable error value (ie, accuracy) of the Y-axis, the servo will Stop tuning. When the angle deviation measured by the sensor in the Y-axis direction is greater than the allowable error value, if the sensor angle deviation is large (greater than the critical angle value S for coarse and fine adjustment conversion), use a large steering gear and perform large-scale rapid adjustment according to the proportional adjustment strategy , if the sensor angle deviation is small (less than or greater than the critical angle value S for coarse and fine adjustment conversion), the small steering gear is used for adjustment, and when the sensor angle is greater than the slow adjustment critical value, the small steering gear is adjusted according to the proportional adjustment method, and when it is less than When the threshold value is adjusted slowly, the small servo will be adjusted in the slow adjustment mode.

d) Repeat the above three processes until a balanced state is reached (that is, the angular errors of the angle sensor in both directions of the X and Y axes are within the accuracy range).

The proportional adjustment strategy is to multiply the difference between the angle value sensed by the sensor and the preset angle, that is, the angle deviation (the angle deviation should be 0 in balance) and the ratio K to obtain the steering gear pulse width modulation value to be changed (△ PWM value), as the variation of the pulse width value (PWM) of the steering gear, is added to the original pulse width value of the steering gear to form a new pulse width value, thereby adjusting the steering gear.

The slow adjustment strategy is to set the pulse width value △PWM for each change to a small fixed value, which is only related to the positive or negative angle deviation, and has nothing to do with the angle deviation, so that the steering gear can be controlled at a relatively stable slow speed. Mode of operation adjustment.

The automatic balance feedback control software can be implemented on a general-purpose personal computer platform, and can also be implemented under an embedded single-chip microcomputer system.

Claims (2)

1. A method for controlling the pitch angle of a camera platform, the adopted camera platform includes a rotation adjustment device in a roll direction, a rotation adjustment device in a pitch direction, a pitch sensor and a controller for measuring the rotation angle in a pitch direction, and a pitch sensor in a pitch direction The rotation adjustment device in the balance direction is fixed on the rotation adjustment device in the balance direction, and the rotation adjustment device in the pitch direction adopts a coarse and fine two-stage rotation adjustment structure, including the movable bracket in the pitch direction, the platform fixed at the end of the movable bracket, the coarse adjustment steering gear and the Corresponding coarse adjustment rocker, fine adjustment servo and corresponding fine adjustment rocker, The coarse adjustment rocker arm and the fine adjustment rocker arm are rigidly connected by a tie rod; the fine adjustment steering gear is fixed on the platform, and the coarse adjustment steering gear has a higher horsepower than the fine adjustment steering gear. The control method of the pitch angle of the camera gimbal is: preset the allowable error value, the critical angle value of the coarse adjustment conversion, and the slow adjustment critical value. The controller controls the operation of the two servos according to the measurement signal of the pitch sensor: when according to the pitch When the angle deviation between the angle value measured by the sensor and the target angle value is greater than the allowable error value, if the angle deviation is greater than the critical angle value of the coarse adjustment conversion, the coarse adjustment steering gear is used to perform a large-scale rapid adjustment according to the proportional adjustment strategy. If the angle deviation is less than the critical angle value of the coarse and fine adjustment conversion, the fine-tuning steering gear is used for adjustment, and when the angle deviation is greater than the slow adjustment critical value, the fine-tuning steering gear is adjusted according to the proportional adjustment method, and when it is less than the slow adjustment critical value, the fine-tuning steering gear Adjust according to the slow adjustment method. 2. The control method according to claim 1, characterized in that the measurement data of the pitch sensor is filtered by a combination of limiting filtering and Kalman filtering.