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Hello All....
I am looking for opinions on a suitable inertial-mismatch ratio for our system.
I am a vfx supervisor for films and television. We are designing a multipurpose high-speed camera dolly. It’s a semi-autonomous, RF controlled, battery powered dolly that travels back and forth on a single 6" I -beam rail system. The dolly will have four modes of operation:
1. Manual Control (by that I mean being pushed by hand)
2. Motorized Control, via an RF link
3. Repeat Learn mode, wherein the microcontroller remembers and plays back moves
4. Programmable Moves
The first two modes were easy to design for in terms of motors and gear train. Our first design had 48-volt motors with synchronous belt reduction with plenty of torque and speed.
For the 3rd and 4th modes however, a red flag has been thrown up by the 89:1 inertial mismatch ratio of those above motors.
We are selecting new motors/drivers with higher inertia and to reduce the ratio, but I am polling for people’s opinions on a suitable ratio for this system. Obviously weight and size is of primary concern.
Requirements:
1.) The most important aspect of control is smooth starts and stops… there cannot be any jitter or the camera will see it. We will not be jerking the rig around like an industrial robot. Its all about smooth and gentle (but fast) two point moves.
2.) We’d like the drive mechanism to stay absolutely quiet as possible. (thus the synchronous belts)
3.) Need decent controlability down around 1 to 2 RPS of motor shaft, where much of our operation will be.
Specs:
Speed: 25 mph top speed
Range: 50 to 300 feet typical
Number of motors/drive wheels: 4
Weight: 150 pounds total weight of vehicle/motors/batts/camera/payload
Peak Acceleration: 14.66 ft/sec^2
Drive Wheels: 4.5” dia. low d. urethane treadled running on alum beam.
Gearing (current) 2.5:1 via rubber synchronous belt (for quietness)
Peak Torque at motor shaft: 301 in-oz
Peak RPM of motor: 4660 rpm
Feedback: 10/m/s Linear Barcode Reader with .15mm resolution, encoders on motor shafts.
I am looking for opinions on a suitable inertial-mismatch ratio for our system.
I am a vfx supervisor for films and television. We are designing a multipurpose high-speed camera dolly. It’s a semi-autonomous, RF controlled, battery powered dolly that travels back and forth on a single 6" I -beam rail system. The dolly will have four modes of operation:
1. Manual Control (by that I mean being pushed by hand)
2. Motorized Control, via an RF link
3. Repeat Learn mode, wherein the microcontroller remembers and plays back moves
4. Programmable Moves
The first two modes were easy to design for in terms of motors and gear train. Our first design had 48-volt motors with synchronous belt reduction with plenty of torque and speed.
For the 3rd and 4th modes however, a red flag has been thrown up by the 89:1 inertial mismatch ratio of those above motors.
We are selecting new motors/drivers with higher inertia and to reduce the ratio, but I am polling for people’s opinions on a suitable ratio for this system. Obviously weight and size is of primary concern.
Requirements:
1.) The most important aspect of control is smooth starts and stops… there cannot be any jitter or the camera will see it. We will not be jerking the rig around like an industrial robot. Its all about smooth and gentle (but fast) two point moves.
2.) We’d like the drive mechanism to stay absolutely quiet as possible. (thus the synchronous belts)
3.) Need decent controlability down around 1 to 2 RPS of motor shaft, where much of our operation will be.
Specs:
Speed: 25 mph top speed
Range: 50 to 300 feet typical
Number of motors/drive wheels: 4
Weight: 150 pounds total weight of vehicle/motors/batts/camera/payload
Peak Acceleration: 14.66 ft/sec^2
Drive Wheels: 4.5” dia. low d. urethane treadled running on alum beam.
Gearing (current) 2.5:1 via rubber synchronous belt (for quietness)
Peak Torque at motor shaft: 301 in-oz
Peak RPM of motor: 4660 rpm
Feedback: 10/m/s Linear Barcode Reader with .15mm resolution, encoders on motor shafts.