PI vs PC - Which Variant Do You Need?
Assun's DC integrated servo motors are available in two controller variants, differentiated by how the motor receives its position command.
PI Controller Integrated Servo Motor (Traditional Signal Input)
The PI variant accepts traditional analogue voltage or digital pulse input for position control. This is the right choice for single-axis applications, for systems where a central PLC or motion controller outputs analogue or step/dir signals, or for prototyping where simplicity is more important than fieldbus connectivity. The PI variant is also typically lower cost and slightly simpler to integrate for first-time users of integrated servo motors.
PC Controller Integrated + CAN Communication Servo Motor
The PC variant adds CAN Bus communication to the integrated controller, allowing the motor to join a multi-node CAN network. This is the standard choice for collaborative robots, multi-joint manipulator arms, and humanoid robot legs any application where a central controller must coordinate multiple servo axes simultaneously over a bus.
Both PI and PC variants are available across Assun's brushless motor range. Some brushless SKUs are also available in both variants, allowing direct substitution if communication requirements change during development.
Brushless vs Brushed Coreless DC Motor
Assun's integrated servo motor range includes both brushless (BLDC) and brushed coreless DC motor types. The choice between them follows the same logic as in the standalone motor ranges.
Brushless variants the majority of the range. Brushless motors use electronic commutation instead of physical brushes, which eliminates the main wear mechanism and extends service life significantly. They run quieter, produce less electromagnetic noise, and can operate at higher speeds continuously. For applications requiring long duty cycles or low maintenance surgical instruments, collaborative robot joints, and continuously running automation axes brushless is the standard choice.
Brushed variants available in metal brush (M) and graphite brush (G) configurations. Brushed motors are simpler to control and lower cost for the same output power. Metal brush variants suit low-current, low-noise applications. Graphite brush variants handle higher current loads with stronger brush-to-commutator contact. The brushed variants in Assun's integrated servo motor range use the same coreless rotor architecture as the standalone brushed motor range smooth, cogging-free rotation with integrated position control.
How the DC Integrated Servo Motor Differs From the Servo Actuator?
Assun makes two products that both integrate a DC motor and a servo controller. They are related but distinct:
DC Integrated Servo Motor: Motor + integrated controller in one housing. The output is a rotating shaft at motor speed (high RPM, lower torque). If your application requires speed reduction or torque multiplication, you add a separate planetary gearbox. Choose this when you want the integration convenience but need flexibility to specify your own gearbox ratio.
Servo Actuator: Motor + integrated controller + planetary gearbox in one housing. The output shaft delivers geared-down speed with corresponding torque multiplication already achieved. Choose this when you need a complete joint drive module in one part number no separate gearbox sourcing required.
Both are available for direct online purchase. If you are unsure which fits your design, our US engineering team can review your torque, speed, and space requirements.
Where DC Integrated Servo Motors Are Specified?
Assun's DC integrated servo motors are specified across several compact, high-precision motion applications in the US:
- Collaborative Robot Joints: The PC (CAN Bus) variant allows direct integration into CAN-networked robot arms, where each joint motor is a node on the bus receiving synchronised position commands from a central controller. The compact diameters 16mm to 32mm fit within the mechanical structure of smaller collaborative robot arms and humanoid limbs.
- Prosthetics and Exoskeletons: Prosthetic finger, wrist, and elbow joints require integrated actuators that are small enough to fit within the device housing while providing closed-loop position control. The elimination of an external encoder is particularly valuable in prosthetic design, where every wire is a potential failure point and a user comfort issue.
- Medical Devices and Surgical Instruments: Single-axis drives for surgical tool actuation, diagnostic equipment positioning, and laboratory automation use the PI (analogue signal) variant for clean, simple integration into instrument control systems.
- Handheld and Portable Devices: The 16mm and 20mm variants are small enough for motorised tools, camera mechanisms, and compact scientific instruments where an external controller simply will not fit.
FAQs
Q1. What is an integrated servo motor?
An integrated servo motor is a motor that incorporates the servo controller (and often a position feedback sensor) directly into the motor housing, eliminating the need for a separate external drive unit. Instead of wiring a motor, encoder, and controller as three separate components, an integrated servo motor provides all of this in one compact assembly. The result is simpler wiring, a smaller total footprint, and reduced integration risk. Assun's DC integrated servo motors also include the position feedback sensor internally, meaning no external encoder is required.
Q2. What is the difference between a DC integrated servo motor and a regular servo motor?
A regular servo motor is the motor element only to use it in a closed-loop position control system, you must source, mount, and wire an external servo controller (drive) and a separate encoder. A DC integrated servo motor has the controller and position feedback sensor already built inside the motor housing. You connect power and a command signal, and the motor delivers precise position control. This simplifies integration significantly and reduces the total system size.
Q3. Do I need an encoder with Assun's DC integrated servo motor?
No. The position feedback sensor is integrated into the motor housing this is one of the defining features of Assun's product. Unlike standalone servo motors that require a separately mounted and wired encoder, Assun's integrated servo motors have internal feedback. This reduces wiring, enables more compact mechanical designs, and eliminates the encoder mounting and alignment step from your integration process.
Q4. What is the difference between PI and PC integrated servo motor variants?
The PI variant uses traditional analogue voltage or digital pulse input to receive position commands suited for single-axis applications or systems where a PLC generates analogue or step/dir signals. The PC variant adds CAN Bus communication, making it compatible with CANopen networks where multiple servo axes must receive synchronised commands from a central motion controller. Choose PI for standalone or simple systems; choose PC for multi-axis collaborative robots and CAN-networked platforms.
Q5. What motor types are available in Assun's integrated servo motor range?
Assun's DC integrated servo motor range covers both brushless coreless DC motors and brushed coreless DC motors with an integrated servo controller. The brushless variants offer longer service life, lower electrical noise, and higher continuous duty capability. The brushed variants are available in metal brush (low current, low noise) and graphite brush (higher current, stronger contact) configurations. Both types use a coreless rotor design zero cogging torque and rapid start-stop response.
Q6. How does the DC integrated servo motor differ from the servo actuator?
Assun's DC integrated servo motor combines a motor and controller in one housing. The output is a rotating motor shaft at motor speed if speed reduction is needed, a separate planetary gearbox is added. Assun's servo actuator goes one step further by integrating the motor, controller, AND a multi-stage planetary gearbox in a single housing, delivering a geared-down output directly. Choose the integrated servo motor for flexibility in gearbox selection. Choose the servo actuator for a complete joint drive module in one part number.
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