MI Miniature joint actuator

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MI Miniature joint actuator covering multiple sizes from φ16mm to φ30mm, it is suitable for various scenarios ranging from precision micro-operation to high-load operations. Integrating three core technologies—axial flux motor, miniature cycloidal reducer, and non-contact encoder—it boasts high torque density, high rigidity, high precision, and superior motion control performance.
With its modular design and advanced manufacturing processes, it is widely used in bionic robots, industrial automation, medical devices, and consumer electronics, providing system-level solutions for precise motion control actuators or fluid (liquid, gaseous, or powder) transfer within compact spaces.

MI series miniature joint actuators quick selection table

		φ16mm			φ20mm			φ25mm		Φ30mm
Single Motor Data	Supply Voltage (V)	12/24			12/24/48			12~18		12~18
	No-Load Speed (Rpm)	≤3000			≤3000			≤3000		≤3000
	Rated Speed (Rpm)	≤2000			≤2000			≤2000		≤2000
	*Continuous Stall Torque (Winding Temperature 145°C) (mNm)	>7.1			>17.2			43		59
	*Starting Torque (Winding Temperature 25°C) (mNm)	>10.3			>24.9			-		-
	*Continuous Stall Phase Current (A)	0.65			0.73			1.2		2.4
Gearhead Data	Reduction Ratio	30	40	50	15	30	50	30	50	30	50
	Backdriving Torque (mNm)	<100	<130	<150	＜95	＜180	＜250	-		-
	Gear Backlash (Arcmin)	20			20			15		15
	Encoder	Absolute Encoder			Absolute Encoder			Absolute Encoder		Absolute Encoder
	Communication Protocol	SPI			SPI			CAN FD		CAN FD
	Total Weight (g)	24.3 (360° Bracket) / 26.1 (L-Type Bracket)			37.2(360° Bracket) / 41.6 (L-Type Bracket)			93 (Rotary Bracket) / 103 (Fixed Bracket)		123 (Rotary Bracket) / 133 (Fixed Bracket)
*Note: Actual values may vary by ±10% from theoretical values.

Product structure

① Stator ② Rotor ③ Stator

Product Features

Axial Flux Motor Technology

Utilizing an axial flux motor design, the actuator achieves significantly higher power density, delivering 2–4 times the torque output of conventional brushless motors within the same volu

High-Density HDI Stator Technology

Employs an ultra-high-density HDI interconnect board to replace conventional stator windings, enhancing thermal performance, improving manufacturing yield, and reducing overall production costs.

Ultra-Precision Cycloidal Gear Technology

Incorporates an ultra-precision cycloidal gear transmission system, enabling a more compact and lightweight structure while delivering higher positioning accuracy and smoother motion control.

Quasi-Direct Drive Technology

Utilizing a quasi-direct drive architecture, the actuator achieves a more compact structure, higher dynamic performance, and more precise motion control.

Compact Structure & Lightweight Design

Highly integrated mechanical design minimizes volume and weight while ensuring high torque density and structural strength. The compact form factor improves integration flexibility and is suitable for robotic joints with strict space and payload requirements.

Poduct Application

Faced with increasingly compact design constraints and demanding performance requirements, our product portfolio delivers a new benchmark in motion solutions. With exceptional reliability, precision, and torque density, these high-performance drive systems are redefining innovation across humanoid robotics, precision surgical devices, consumer electronics, and beyond.

Dexterous Hands

Small humanoid hands

Medical pumps

Drones

		φ16mm				φ20mm				φ25mm		Φ30mm
Single Motor Data	Supply Voltage (V)	12/24				12/24/48				12~18		12~18
	No-Load Speed (Rpm)	≤3000				≤3000				≤3000		≤3000
	Rated Speed (Rpm)	≤2000				≤2000				≤2000		≤2000
	*Continuous Stall Torque (Winding Temperature 145°C) (mNm)	>7.1				>17.2				43		59
	*Starting Torque (Winding Temperature 25°C) (mNm)	>10.3				>24.9				-		-
	*Continuous Stall Phase Current (A)	0.65				0.73				1.2		2.4
	*Maximum Stall Torque (mNm)	＞16.5				＞35.3				120		85
	*Maximum Stall Phase Current (A)	1.5				1.5				3.2		3.2
	*Winding Resistance (Ω)	6				6.6				3.8		1.2
	Three-Phase Resistance Imbalance (%)	≤2				≤2				≤2		≤2
	Winding Inductance (mH)	0.5				1.2				2.1		0.6
	Three-Phase Inductance Imbalance (%)	≤2				≤2				≤2		≤2
	Torque Constant (mNm/A)	13				28.1				42		27.5
	Speed Constant (rpm/V)	734				339				227		347
	Rotor Inertia (gcm2)	0.84				1				6.1		15.8
Gearbox Data	Reduction Ratio	30		40	50	15	30		50	30	50	30	50
	Gear Efficiency (Rated)(%)	72		72	68	65	65		64	70	60	75	60
	Gear Efficiency (Stall Point) (%)	62		62	58	55	55		58	60	55	65	55
	Continuous Stall Torque (Winding Temp 145°C) (mNm)	130		170	200	180	350		450	750	1150	1100	1500
	Starting Torque (Winding Temp 25°C) (mNm)	250		320	400	280	550		800	1500△	1800	14500	2200△
	Backdriving Torque (mNm)	<100		<130	<150	＜95	＜180		＜250	-		-
	Gear Backlash (Arcmin)	20				20				15		15
	Encoder	Absolute Encoder				Absolute Encoder				Absolute Encoder		Absolute Encoder
	Communication Protocol	SPI				SPI				CAN FD		CAN FD
	Total Weight (g)	24.3 (360° Bracket) / 26.1 (L-Type Bracket)				37.2(360° Bracket) / 41.6 (L-Type Bracket)				93 (Rotary Bracket) / 103 (Fixed Bracket)		123 (Rotary Bracket) / 133 (Fixed Bracket)
	Module Inertia (gcm2)	1.77				2.52				12.7		30.4
Thermal Data	Power Loss (W)	2.2	3.7		5.7	3		5	7.8	5	8.3	6.2	10.3
	Motor Operating Temperature (℃)	80	115		145	80		115	145	80	115	80	115
*Note: Actual values may vary by ±10% from theoretical values. △Output torque is limited by mechanical strength.

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