Camera Direction Controller

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Camera direction controller - is an electronic microcontroller-based board used to control a stereo camera tower pitch/yaw (look-at direction). Based on ATMEL ATMega64A-16 @ 14.7456 MHz. Adaptive control of stepper motors. Position feedback angle sensed by incremental rotary encoder with index and zero tracks is returned to control logic for dynamic compensation.

Stereo vision tower
Sketch of the stereo vision tower
Pitch angle encoder
Rotary encoder for the camera pitch angle. The mechanical drawing. Notice two sensors are allocated in 90 degree shift to determine the direction of rotation. Third sensor (index sensor) is 45 deg rotated, but scans the separate track for index marker, that indicates camera initial position - horizontal.

Contents

Actuators

Bipolar stepper motors (5-12V).

See oz·in→N·m, N·m→kg·cm

Sensors

Optical interrupter VISHAY TCST1202 (preferred) (0.5 mm aperture) or equivalent with higher or lower resolution (TCST1103 - 1.0 mm, TCST1202 - 0.5 mm, TCST1300 - 0.25 mm).

Current sensor is 1.0 Ohm shunt resistors for each coil of motors #2 and #3.


Sensor groups

Vision system

Two Philips spc 2050nc web cameras.

6 FPS @ 1600x1200, 90 FPS @ 640x480
low noise
good image quality at low illumination
(!) sometimes programmatically set focus is lost/stuck due to vibration

Version 6

This version is planned for development.


Schematic capture

File:CDC-Capture-v6.png

PCB Layout

File:CDC-PCB-v6.png

Device photo

File:CDC-Device-Photo-v6.jpg


Version 5

This version is 50% smaller and also fixes most flaws in a revision 4.x.

Schematic capture

The schematic capture of the CDC rev. 5.5

PCB Layout

A PCB Layout of the CDC rev. 5.5

Device photo

A photo of produced PCB with all components soldered of the CDC rev. 5.5

Test results

Flaws

Firmware binding

Version 4

This board is able to control three stepper motors and laser. Capabilities: stepper motor micro-step control, current sense and encoder feedback, laser control. This schematics has some minor design flaws, which will be fixed in future release. However, it performs well all tasks for which it is was designed.

Schematic capture

Camera module schematic (CDC) capture image (revision 4.93). Actual version.

PCB Layout

PCB layout of the CDC rev. 4.93

Device photo

A photo of produced PCB with all components soldered of the CDC rev.4.93.

Version 3

Was not produced, because of missing brake and laser control, and Yaw motor model change to higher-current.

Schematic capture

Camera module schematic capture image version 3.0 (no longer actual).

See also

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