ARRIS CM2000 Brushless Gimbal
With many compact brushless gimbal systems hitting the market, I decided to test out the new ARRIS CM2000 brushless GoPro gimbal. The gimbal is available to purchase from hobby-wing for $250 with the purchase of a $50 off coupon. I placed my order with EMS shipping on May 2nd and my order was shipped out on May 10th, arriving to Arizona on May 15th.
The gimbal was packaged in a branded cardboard box protected within another box.
Inside the box the gimbal, CD and strap were loosely packed, but undamaged. A mini USB cable (not included) is required to program the gimbal.
The CD contains the FTDI drivers, SimpleBGC software, PDF manual and a short video clip recorded from the test flight. The test video is matched to the corresponding number labeled on the gimbal and the CD.
The gimbal and CD are individually numbered to correspond with the test flight footage. Four rubber dampers hold the top and bottom 2mm carbon plates together, protecting the control board and isolating it from vibrations. The power cable uses a JST connector and each motor is wired to the control board with a 3 pin servo cable. The IMU is mounted just beside the GoPro on the base plate, and it is soldered to the control board with several thin-flexible wires. A long signal cable is included to manually control the pitch and roll of the gimbal from a receiver or flight controller. The top plate has two 5mm wide slots seperated 50mm center to center. It also has a centered 40mm square hole pattern with another set of two 40mm spaced holes shifted forward about 5mm from center.
The pitch motor seems to be upgraded from the pictures on the product page. The new motor is slightly larger, but should provide more torque. It appears to be of higher quality than the pitch motor on the product page. The gimbal is assembled primarily with nylon hardware. The bolts appear to be collected from miscellaneous hardware as many of the bolts vary in size or are shortened.
Removing the top plate from the rubber dampers reveals the control board. At the front are the manual control pins and mini USB port. To the left the IMU cables are directly soldered to the board. The motor and power connections are located at the back of the board. Nylon bolts are used at each corner of the control board, but only two of the bolts are secured into place with a nut.
The board I received functions well, but appears to be defective. Judging by the removal of pin A2 from the board and the rerouting of a cable to the micro controller, it would appear that the trace for the manual pitch control was damaged and had to be replaced by a wire This appears to be an intentional design modification. I was very impressed with the quality of the gimbal until I came across this modification as a result of poor quality control, but, nevertheless, it works.
Everything was already setup and functioned quite well after powering up the gimbal for the first time. The original PID settings on my board were as follows:
Roll – P: 24 I: 0.29 D: 11 Power: 83 Poles: 14
Pitch – P: 15 I: 0.32 D: 4 Power: 64 Poles: 16-Inverted
After looking at the motors it would appear that each has 12 poles, so I began by correcting this setting in the software. After experimenting with the software, I ended up modifying the PID settings as follows, however, some additional tuning may still be necessary:
Roll – P: 26 I: 0.32 D: 10 Power: 86 Poles: 12
Pitch – P: 20 I: 0.30 D: 4 Power: 68 Poles: 12-Inverted
For software updates and additional tuning and programming information, I recommend consulting the simpleBGC downloads page.
Ultimately, I am very impressed with this gimbal. With the exception of my defective control board, the gimbal is strong and well constructed. It performs very well compared to a servo gimbal, however, I found that there are some disadvantages to brushless gimbal technology. Brushless gimbals have much less torque than a traditional servo gimbal, therefore, they may begin self-induced oscillations during aggressive maneuvers if not properly tuned or balanced. Since the gimbal must use a feedback system with an IMU to maintain stability, it is vital that all vibrations are removed from the gimbal, but this gimbal’s included dampers do a great job at handling that. The movements are very smooth and can quickly react to disturbances.
Pros:
- Solid construction
- Excellent vibration isolation
- Well balanced and tuned out of the box
- Great attention to the testing and assembly of each product
- Much faster response and smoother operation than a traditional servo gimbal
Cons:
Poor control board quality controlThis appears to be an intentional design modification- Less torque than a traditional servo gimbal
- Motors operate at an audible high frequency
More updates, including flight test videos, will be posted to this page when I finish testing my settings…
Review of the Fat Shark Predator FPV Goggles
Recently I decided to purchase a set of Fat Shark Predator FPV Goggles, available from hobbyking. The package, including an extra 700mAh battery, arrived promptly and in good condition.
Within the box, each item, along with the instruction manual, is packaged in plastic bags in a cardboard tray.
This set includes the video transmitter, CCD Killer video camera, TX power harness, two dipole antennas, an RCA cable for composite video input, a Turnigy 9X compatible head tracker cable, 700mAh LiPo battery and the Fatshark Predator video goggles in a nice protective hard case.
The video transmitter, although rather large at approximately 60mm x 35mm x 14mm excluding 8mm SMA connector, weighs only 17 grams. The kit includes a balance plug adapter for a 2S or 3S LiPo. The CCD Killer video camera is quite small, at about 20mm square, and weighs only 12 grams. The camera has two microphones for stereo sound and a 3.6mm IR coated 87 degree FOV lens with lens cap. The supplied cable has rather thin wires on either end that are exposed from the cable covering and terminate to a 5 pin molex connector.
The rubber eye cups fit quite well and keep out all light from the screens. Optional lenses can be purchased separately and inserted by removing the rubber eye cups. These lenses are designed for nearsighted users that have trouble viewing distant objects.
The bottom side of the goggles include a port for the head tracker output, a switch to turn on or off the receiver module and a 3.5mm headphone jack for audio out.
The right side of the goggles have a battery port and an input port for use with the supplied RCA composite cable. Atop the goggles are four buttons used for volume and channel control as well as a four position switch used for contrast and brightness adjustment. The center button can also be used to manually reset the center position of the head tracker. Along the right side of the head strap there is a convenient pocket for holding the battery in place.
The monitors of the Fatshark Predator Goggles have a 25 degree field of view, slightly smaller than the field of view offered by other products. This is my first set of FPV goggles, that being said, I had not problem with the narrower field of view. Although difficult to get a clear picture, here I attempted to show what kind of view to expect from the goggles. I can’t say it is as enveloping as I had expected, but I probably had high expectations for a type of video goggle that I had never used. It feels more like looking at a computer or television screen in a blacked out room than a theater.
The build quality exceeded my expectations and the battery life on a 700mAh battery was much better than expected, at nearly an hour per charge. I was concerned about the inability to adjust the IPD of the goggles, however, I ran into no problems there. The monitors and lenses within the goggles are designed such that they are suitable for a range of IPDs. Being a nearsighted user with a very light prescription, I had very little difficulty reading the goggles although the displays are not the most sharp with my eyesight. The goggles are convenient and easy to use as an all in one package. I have no complaints about the video quality or frame rate. I never tried to push the range of the goggles, but the supplied 100mW transmitter module and supplied dipole antennas seem to be suitable for park flying within a couple hundred feet. The functions of the head tracker work well and were easy to setup on my Turnigy 9x with ER9X firmware. Ultimately, I really like the goggles and I would recommend them.
