Stepper Motor Control
Well, I guess the most difficult part is implementing the functions that calculate the Linear/Circular Interpolations and translating those to stepper motion. I've been working on a similar project, however, most of the motion required relies only on absolute positioning. The 6-axis motion controller that I have designed for this project is built around the dSPIN L6470 from STMicroelectronics. ST Provides a decent library to program the device and the integrated motion-engine makes the job a lot easier.However, it turns out that this approach is not as reliable for a CNC or even a 3D printer application, where a simple Go_To(abs_value); command is not sufficient to do the mission. Simply because the trajectory of the motion is unpredictable. Another drawback is the speed, aka the Feed Rate. There's no way to achieve a target speed with each absolute positioning command having its own distance and trajectory. I believe here comes into play what the "planner" does in GRBL and other implementations out there that are based on the same rule of thumb. I tried to understand how GRBL does all of that, but because the functions concerned are distributed across different modules and they are all dependent on each other, I found it waste of time to dig more into this, as my own g-code interpreter follows a different path/approach and I am quite satisfied with the results I have achieved so far. However, I would love to get a clear picture of other implementations and compare the performance with mine and see what is the best in different scenarios
1. Confused on basics of Stepper motor control!?
Yes this controller needs a driver for each motor. It also may need its own power supply. There may be combination drivers with more than one in a package. While the controller function can run as software in a PC, with several axes and limits in PC operation, a separate controller like this is desirable. The controller receives commands from the PC and sends electrical stepping signals to the drivers which power the motors. This controller can apparently calculate diagonal paths with combinations of motors, and has inbuilt limit switch inputs.. It is important to make sure the stepper motors have plenty of torque, as the torque is less at speed and with age. Look up stepper motor torque curves. The drivers need to suit the motors in voltage, current and configuration. They must also suit the controller outputs.
2. Debugging my bipolar stepper motor design
Okay, you have a couple of issues:On dropping small amounts of voltage, a series diode can come in handy to drop between 0.3 and 0.8V or so per diode. But for efficient power regulation, depending on the difference between input and output, linear or switching regulators are the norm, (almost) never voltage dividers for supplying power
3. What are the advantages of a PCBMotor compared to a stepper motor? – PCBMotor
By driving the integration of the motor (including electronics) into the PCB itself, we are facilitating the design of smaller, cheaper and faster applications. PCBMotor uses less space and material. Electronics (driver) and mechanics (motor) are mounted directly on the PCB - so it's totally flat and without gears and connections. PCB enables more design flexibility - multiple motors can be mounted on one board. PCBMotor can generate more power and torque at a lower speed (without gears) than an electric motor of comparable size. PCBMotor has faster start/stop than electrical motors - giving more accuracy to the application. We've actually a written a white paper highlighting the main differences between PCBMotor technology and Stepper motors. Sign up for free and discover: Top 5 Gains you can achieve by employing a PCBMotor
4. Reduce heat dissipation in Stepper motor
60C is not an unusually high temperature for a stepper motor, though it is hot enough to surprise somebody who does not expect it.If you want the motor to run cooler, then you have two options, and you can use both.1) Improve the removal of heat from the motor. Mount it on a heatsink, or blow a fan at it.2) Program the stepper motor driver to deliver less current to it in the hold, this will however reduce the hold torque. If that's not sufficient, program it to deliver less current when stepping, this will however reduce the driving torque. Option 3) Stepper motors are very inefficient, and get hot. Replace it with a conventional motor, either brushed or BLDC, servo-controlled if you need accurate position
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