Drives for industrial robotics: servo motors, controllers, brakes and couplings
Industrial robotics imposes three conflicting requirements on the drive: high power density (dense torque at minimum rotor mass and stator footprint), millisecond torque response within the servo loop, and positioning accuracy of ±0.02–0.1 mm after the gearbox. On top of this come strict functional safety requirements (ISO 10218-1, STO/SS1/SS2 categories), integration with real-time fieldbuses (EtherCAT, Profinet IRT), and stator heat dissipation under the high cycle dynamics of pick-and-place operations.
Industry-typical tasks
- Axis servo motors for 6-axis articulated robots in arc/spot welding, painting, assembly and machine tending (handling) — 0.05–7 kW per axis
- Drives for palletizers and depalletizers (4-axis robots, wrist payload 50–800 kg) running continuous multi-shift operation
- High-speed pick-and-place machines and delta robots — 150–200 cycles per minute, demanding low rotor inertia and fast brakes
- Gantry systems and linear multi-axis portals (X-Y-Z) for laser cutting, dispensing and inspection — long-stroke axes with rack-and-pinion and gearbox
- AGV/AMR in-plant logistics platforms: traction wheel servo motors, lift drives, steering
- Collaborative robots (cobots) with torque sensors in every joint and ISO/TS 15066 certification — low speeds, safe torque limiting
- Robotic cells: integration of the manipulator with part-feeding conveyors, indexing tables and peripheral drives for shutters and clamps
- Robot control cabinets — servo drives, motion controller, cell PLC, VFDs for auxiliary drives
Servo motors and torque motors
The heart of an industrial robot is a brushless permanent-magnet synchronous servo motor (PMSM) with a built-in 17–23 bit absolute encoder per revolution. The motor characteristics directly drive the rated payload, no-load speed, repeatability and thermal headroom for long duty cycles. Key parameters are specific torque (N·m/kg), rotor inertia (low for dynamic response), peak overload (3–4× rated for 1–3 s), and back-EMF waveform (sinusoidal for accurate vector control).
Axis servo motors for industrial manipulators
Wolong WPM/WGM series — compact PMSM motors built specifically for robotics, with an integrated holding brake (fail-safe, engaged without power) and a 23-bit absolute encoder. The slim, elongated housing with an H-series flange reduces the diameter of the robot joint. The 0.05–7 kW range covers all six axes of manipulators with 5–500 kg payload.
- — 0.05–7 kW per axis, 0.16–47 N·m torque
- — 17–23 bit/rev absolute encoder (multi-turn with hot-swap battery)
- — Integrated electromagnetic brake with ≤ 30 ms engagement time
- — Peak torque 3–4× rated for 1–3 s
- — IP65 shaft sealing with Viton seal
Inovance IS620P and SV630P servo drives for robot controllers
Inovance is the only brand in our portfolio offering a full robotics stack: servo drive (IS620P, SV630P) plus motion controller, PLC and HMI. The SV630P supports EtherCAT with a 125 µs cycle, integrates STO/SS1/SS2 functions per IEC 61800-5-2 and auto-tunes the torque loop. It is used in manipulator control cabinets and in single-axis positioning systems.
- — EtherCAT CoE / CSP (cyclic synchronous position) support
- — Integrated STO, SS1, SS2 safety functions (SIL3 / PLe)
- — Torque loop response ≤ 1 ms
- — Auto-tuning of inertia and torque load
- — Protection: IGBT overheat, encoder fault, torque overload
INVT DA200 servo motors for linear and gantry axes
INVT DA200 — servo motors and drives for XYZ portals, linear modules and feed axes. They support EtherCAT, CANopen and Profinet and pair with INVT PLCs to build a multi-axis cell without a separate motion controller. Used in laser cutting gantries and assembly lines requiring 4–8 axis synchronization.
- — Multi-axis synchronization over fieldbus (EtherCAT/Profinet)
- — Compatible with rack-and-pinion and ball-screw drives
- — Integrated regenerative module or external braking resistor
- — Direct torque/speed/position control modes
- — Single-micron positioning accuracy with 23-bit encoder
Traction and steering servo motors for AGV/AMR platforms
Mobile in-plant logistics platforms (AGV/AMR with 100–1500 kg payload) use low-voltage 24–80 V DC servo drives connected directly to a LiFePO4 battery. Each driven wheel is an independent servo with an integrated gearbox (drive wheel unit) or an external planetary gearbox. Wolong WPM-LV and Inovance IS810N serve as traction and steering drives.
- — 24–80 V DC battery supply (low-voltage series)
- — Regenerative braking with energy return to the battery
- — IP65 protection against shop-floor dust and coolant splashes
- — Dense low-speed torque for starting and maneuvering
- — Encoder resolution sufficient for odometry (≥ 4096 ppr)
Auxiliary motors for the cell
Besides the robot itself, a robotic cell runs feed and discharge conveyors, indexing tables, transfer units, clamps and unloading systems. This is the natural domain of general-purpose Huali Y2/Y3/YE3 motors (0.18–22 kW) and compact IE3/IE4 motors integrated into Boneng K/HB gear motors.
- — IE3 or IE4 efficiency class (per customer specification)
- — VFD-rated insulation (Class F)
- — IP55 minimum for shop-floor service
- — Flange-mount execution for gear motor integration
- — PTC or Pt100 thermal protection
Gearboxes and gear motors for cell peripherals
The manipulator itself uses specialized precision gearboxes (harmonic, cycloidal RV), which are outside our portfolio and supplied by the robot manufacturer. Everything around it — feed conveyors, indexing tables, rack-and-pinion gantry axes, AGV platforms and discharge lines — is the domain of industrial gear motors with a servo flange for direct servo motor mounting.
Precision planetary gear motors for gantry axes
X-Y-Z portals and single-axis linear modules use low-backlash planetary gearboxes (≤ 3–8 arcmin) with a servo flange for Wolong WPM or INVT DA200 motors. Ratios i = 3, 5, 10, 25 cover the full feed-rate range. Long rack-and-pinion gantry axes use a planetary gearbox with a preloaded drive pinion.
- — Backlash ≤ 3–8 arcmin (precision / high-precision class)
- — Servo flange for standard motor frame sizes
- — Torsional stiffness ≥ 14 N·m/arcmin
- — Compatible with module m = 2–5 racks
- — Service life ≥ 20,000 h at rated load
Gear motors for part-feeding conveyors
Boneng K (helical-bevel) and HB (industrial bevel-helical) series drive part-feeding conveyors, discharge lines and intermediate buffers around the robot. SF ≥ 1.3 because the duty is continuous S1 in automated operation. They are usually paired with a VFD to match conveyor speed to the robot cycle.
- — K-series (helical-bevel) or HB-series (horizontal industrial)
- — Service factor ≥ 1.3 for S1 duty
- — Compatible with INVT/Inovance VFDs for speed control
- — Optional encoder on the high-speed shaft for robot synchronization
- — IP55 protection
Drives for indexing tables and rotary platforms
Indexing tables and welding positioners use Boneng W/K worm or helical-bevel gear motors, either self-locking (worm pair) or fitted with an additional holding brake. Position accuracy is delivered by a separate mechanical system (Hirth coupling, index pins); the gear motor handles only the transition between positions.
- — Self-locking (worm pair) or integrated brake
- — Ratio 30–80
- — Low vibration at stop
- — Encoder-compatible for position feedback
- — Rigid mounting for vertical load from the table
Gear motors for AGV platforms and linear carts
Compact Boneng HB gear motors and drive wheel units for AGV/AMR with up to 2 t payload. The all-in-one design combines a 24–48 V DC servo motor, a planetary gear stage and a rubber wheel. The ratio is matched to a top speed of 1.2–2.0 m/s.
- — Compact drive wheel unit (motor + gearbox + wheel)
- — Ratio matched to 1.2–2.0 m/s travel speed
- — Low noise (≤ 65 dBA for night-shift logistics)
- — Sealed gear housing against dust and coolant ingress
- — 15,000–20,000 h service life before overhaul
Axis and emergency-stop brakes
In robotics the brake is not a separate heavy unit as on a crane, but a compact electromagnetic disk built into the rear of the servo motor. It acts as a holding brake rather than an active stopping brake: the servo drive decelerates the axis, while the brake only locks the position when power is removed, on a fault, or between cycles. Critical axes (gravity-loaded vertical joints, heavy palletizers) use a dual brake system with external emergency brakes per ISO 10218-1.
Holding brakes for vertical manipulator axes
A fail-safe electromagnetic disk brake (spring-applied, electrically released) is integrated into Wolong WPM/WGM and Inovance MS1 servo motors. When power or the enable signal is lost, the spring presses the friction pads onto the disk within 20–30 ms, holding the robot arm against gravity. Brake torque has a 2× margin over the axis holding torque.
- — Spring-applied (fail-safe per DIN VDE 0580)
- — Brake torque ≥ 2× motor rated torque
- — Engagement time on power loss ≤ 30 ms
- — Service life ≥ 5 million engagement cycles
- — 24 V DC ± 10% coil supply
Emergency brakes for palletizers and heavy manipulators
Palletizers and 200–800 kg manipulators carry a dual brake system: an internal motor brake plus an external electromagnetic disk brake on the gearbox input shaft. Both engage simultaneously on emergency stop (E-Stop, guard door opening, torque overrun). Stop category per ISO 13849-1 is Cat 1 (controlled stop) or Cat 0 (immediate de-energization).
- — Dual brake system (internal + external)
- — ISO 13849-1 stop category 0 or 1
- — Compatible with the drive STO signal
- — Engagement time ≤ 50 ms on the redundant brake
- — SIL2/PLd functional safety certification
Regenerative braking modules and drive resistors
When a servo motor decelerates, the kinetic energy of the moving mass is fed back into the drive DC bus. Without dissipation, DC-bus voltage exceeds the threshold and the drive trips on overvoltage. The solution is an external braking resistor (for moderate cycles) or a regenerative module returning energy to the mains (for intensive pick-and-place machines and palletizers). Both variants are supplied by Inovance and INVT.
- — Dissipation power sized from the duty cycle (peak and average)
- — PWM-rated braking resistor with thermal protection
- — Regenerative module with EMC filter for mains feedback
- — Drive-compatible interface (shared DC bus)
- — DC-bus overvoltage protection
Brakes for AGV/AMR platforms
Mobile platforms use electromagnetic brakes integrated into the drive wheel unit. They engage when the enable signal drops, when an emergency-stop sensor triggers (bumper, safety laser scanner), or when the battery falls below a critical level. Heavy-payload platforms also carry a parking brake with mechanical lockout for long stops.
- — Fail-safe engagement on power loss
- — Trigger from a safety laser scanner signal
- — Brake redundancy across multiple wheels
- — IP65 protection against shop-floor dust
- — Compatible with AMR control stacks (ROS / VDA 5050)
Couplings in robotic cells
Inside a robot joint there are no couplings in the classical sense — the servo motor mates to the gearbox through a rigid flange. Around the cell, however, couplings are everywhere: on feed conveyors, indexing tables, gantry-axis ball screws and auxiliary drives. Key requirements are compensation of axial, angular and radial misalignment after installation, minimum backlash for precision applications, and tolerance to frequent reversals.
Bellows couplings for precision gantry axes
Ball-screw drives in linear modules and gantry portals use Yongjing bellows couplings with zero backlash and high torsional stiffness. They link the servo motor shaft to the ball-screw. The thin-wall bellows compensates 0.1–0.3 mm / 1–2° of radial and angular misalignment while transmitting torque without loss of positioning accuracy.
- — Zero backlash
- — Torsional stiffness ≥ 5,000 N·m/rad
- — Axial misalignment compensation 0.3–0.8 mm
- — Balanced for speeds > 3,000 rpm
- — Clamp hub with split shaft for fast mounting
Pin-and-bush flexible couplings for feed conveyors
Feed conveyors, discharge lines and rewind spindle drives use classic Jiaohua YOXp / Yongjing LX pin-and-bush flexible couplings. They damp start-up shock loads and compensate 0.2–0.8 mm of misalignment. They are compatible with standard Boneng K / HB gear motors.
- — Torque 5–125 kN·m
- — Radial misalignment compensation 0.2–0.8 mm
- — Elastomer life ≥ 20,000 h
- — Bush replacement without removing the machine
- — Compatible with standard IEC flanges
Jaw-disk couplings for indexing tables
Indexing tables that rotate to fixed positions (90°/180°/index slots) use jaw-disk couplings that absorb misalignment between the gear motor and the table shaft. They transmit high torque during short start/reverse cycles and need no lubrication over their service life.
- — Torque 50–2,000 N·m
- — Angular misalignment compensation up to 1°
- — Lubrication-free polymer elements (PU / Hytrel)
- — Low inertia for fast acceleration and braking
- — Encoder-ready hub on one half
Diaphragm couplings for ball-screw drives
Long ball-screw drives (2–6 m stroke) use diaphragm couplings with a stack of thin steel disks. They transmit high torque at minimum backlash and absorb misalignment from screw thermal expansion. Typical applications are laser-cutting gantry axes and assembly-line linear portals.
- — Zero backlash, high torsional stiffness
- — Axial compensation for screw thermal growth (up to 1 mm)
- — High rotational speed (up to 8,000 rpm)
- — Steel diaphragm life ≥ 50,000 h
- — G2.5 balancing for smooth rotation
Applications gallery
Our solutions for this industry
SDS portfolio brands that cover typical applications in this industry.
- WOLONGbrushless servo motors with 17–23 bit encoders, WPM/WGM series built for robotics, 0.05–7 kW range; low-voltage traction series for AGV/AMR
- INOVANCEfull robotics stack: IS620P and SV630P servo drives, motion controllers, PLCs, HMIs; integrated STO/SS1/SS2 safety functions (SIL3/PLe), EtherCAT with 125 µs cycle
- INVTDA200 servo systems for linear and gantry axes, PLCs for multi-axis EtherCAT/Profinet synchronization, VFDs for auxiliary cell drives
- BONENGK, HB, W gear motors for part-feeding conveyors, indexing tables, AGV platforms and linear carts in robotic cells
- HUALIgeneral-purpose IE3/IE4 motors in the Y2/Y3/YE3 series (0.18–22 kW) for auxiliary cell equipment — conveyors, coolant pumps, ventilation
- YONGJINGzero-backlash bellows and diaphragm couplings for precision gantry axes and ball-screw drives, LX pin-and-bush couplings for conveyors
- JIAOHUAYOXp pin-and-bush flexible couplings for part-feeding conveyors and rewind spindles within the cell
- LONGXUANgear and flexible couplings for cell-periphery and gantry-system drives
- HUAWUelectromagnetic brakes for dual brake systems on heavy manipulators and palletizers with 200–800 kg payload
- ANNENGconductor bar systems and cable management for moving gantry portals and long linear systems
Image credits: Auledas (CC BY 4.0) · KUKA Roboter GmbH, Bachmann (Public domain) · Killgore1138 (CC0) · Marta Veverica (CC BY-SA 4.0) · Rsparks3 (CC0)