Medical devices, automotive, robotics, and personal tools like smartphones and tablets have benefited from motion control subsystems with lower cost, lower power, and smaller footprints and packaging due to better miniaturization.
The key to harnessing the complexity of the electronics and embedded software for motion control is understanding and managing the accuracy and precision needed for the positioning, speed, acceleration, and torque requirements.
There may also be a coordinated movement among multiple motors. These key system-level needs will drive many of the system requirements and sensor specifications.
Here is Some Design Advice for Motion Control:
Have Clear Requirements
Requirements define what needs to be done at a level of detail that an engineer can implement. They must be clear and unambiguous.
The engineer should not be required to make decisions that affect the customer. These should be spelled out in the requirements.
Things to Include in Requirements:
- What type of Motion Control is Needed?
A solenoid can provide snap-action movement. It is easy to implement and is lower cost than a motor. For accurate positioning, speed, and acceleration a motor is the best choice.
Types of Motors Include:
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- Servo Motor
Offers very high precision positioning and high torque with low vibration.
- Stepper Motor
Lower cost and easier to implement, but it is less precise and has lower torque than a servo motor.
- AC Motor
When rotary motion with high torque and low precision is needed, an AC motor may be fine.
- DC Motor
For low-cost low-torque applications, a DC motor is simple to use and low cost. Small DC motors used in high volume cost less than one dollar.
- Architecture Selection
The architecture is defined after the requirements are created, but it often leads to changes in requirements, so it is the next step.
For motor control applications, does it make sense to design a motor controller or use one off-the-shelf? There are many controllers with a wide range of features and costs, so it rarely makes sense to design one.
Do you need coordinated motion? To move an object in a circle, for example, requires two motors with coordinated motion.
Coordinated motion in multiple axes is important, for example, when the moving object must pass through a hole or avoid obstacles. Coordinated motion requires a multi-axis motor controller with the ability to coordinate motion.
Software
There will be software in the motor controller, and there is usually firmware or software providing high-level control and a user interface. The software in the motor controller is usually configured with tools provided by the controller manufacturer.
Some advanced controllers can be programmed in C or other languages. Some operate like a PC and can have a user interface.
Firmware in a device typically provides high-level control of the motor controllers, and it interfaces to sensors and other devices. It is typically written in C, but other languages are sometimes used.
The user interface software may be another level of code. Sometimes it runs on a separate processor from the control firmware.
Keep in mind that the difference between firmware that runs on a device and software that runs on a computer may be unclear in some situations. It may be easier just to call all the code software.
Sensors for Motion Control
For some motion control, you only need sensors to detect when the end of travel is reached. These digital sensors tell the motor to stop, so it does not go too far.
Sometimes a rotary encoder is used to measure the position and speed of the motor with great accuracy. This is particularly useful when the motor drives through gears. The rotary encoder can be mounted on the last gear and eliminate errors from backlash in the gears.
Other sensors determine when a part is present to be picked up or dispensed into. The software waits for the part to be present before continuing. These sensors are often connected directly to the motor controller.
There may be sensors measuring motion, such as accelerometers or gyroscopes. Other sensors may not be directly involved in control. These sensors usually require software or firmware to make decisions and then direct the motor controllers to move.
Voler Systems Recent Projects
Voler helps teams identify the right accelerometer, gyroscope, and magnetometer for their application. Here are some recent projects that we have delivered.
Searching how to best control motion for a device or system you are designing? Voler Systems can help.
Voler Systems specializes in developing specifications from your ideas, creating innovative IoT device designs, sensor integration, and producing complex motion control devices. Voler’s team can take on complete responsibility for all aspects of the development of your IoT device or share the responsibility with your in-house team.
About Voler
Located in Silicon Valley and with more than 40 years of electronic design experience, Voler Systems continues to be a leading custom product design consulting company providing highly experienced electrical engineers and firmware developers. Voler Systems ensures delivery of quality products, on time, on budget, and with low risk. All projects are undertaken with good specifications, the right people, quality design, constant communication, and a smooth transfer to manufacturing.
