Humanoid robots is rapidly expanding from research labs to commercial settings, factories, hospitals, and warehouses. One engineering difficulty that is becoming more apparent as these machines get more powerful is motor design.

Humanoids, in contrast to conventional industrial robots, need dozens of small electric motors that provide high torque density, precise motion, low weight, effective thermal management, and long-term dependability while still being able to be produced on a large scale.

It takes more than just upgrading an existing motor to meet those standards. Engineers must adopt new perspectives on packaging, manufacturability, magnetic materials, and motor topology. By enabling motor geometries that are challenging to produce with traditional laminated steel, Soft Magnetic Composites (SMCs), are contributing to the expansion of that design space.

Why Motor Design Is Changing Due to Humanoid Robotics?

Humanoids need to be able to climb stairs, manipulate things, maintain balance, and move with human-like agility, in contrast to standard industrial robots that are frequently stationary or kept apart from people. Compact actuators located in the hips, shoulders, elbows, knees, ankles, wrists, and hands are responsible for those movements.

There is a big opportunity. Humanoid robots have the potential to alleviate labor shortages, assist dangerous or repetitive tasks, and boost productivity in manufacturing, logistics, healthcare, retail, and service sectors. Behind that opportunity lies a challenging engineering reality: innovation within the motor is necessary to make humanoids commercially viable.

Why Motors Are the essential for Humanoid Robots?

The necessity for motor design increases as robots approach human form. A humanoid robot necessitates the simultaneous operation of dozens of coordinated actuators, in contrast to a conventional industrial arm that may repeat a single motion from a fixed base. Each joint has conflicting demands.

A hip actuator needs to produce a lot of torque while being small. A wrist joint requires accurate movement in a little container. Repeated movement, dynamic loading, and balance must all be supported by an ankle motor. Every additional gram has an impact on the robot's overall system efficiency, actuator sizing, and battery demand.

This presents a number of design difficulties:

➤ Compact joints must accommodate motors without making the robot's frame larger.

➤ It is vital to increase torque density without adding more weight.

➤ When operating continuously, heat must be controlled.

➤ Designs need to grow from prototypes to manufacturing that can be repeated.

Developing a better motor is not the only hurdle. It is developing an improved motor that can be produced reliably, fits the robot, supports the motion profile, and controls heat.

Motor Topology: What Is It?

The physical configuration of an electric motor's stator, rotor, windings, air gap, and magnetic circuit is referred to as motor topology. More significantly, it describes the flow of magnetic flux across the apparatus.

Efficiency is not the only factor that topology affects. Torque density, package size, cooling strategy, material choice, manufacturability, and production scalability are all impacted.

One of the first and most crucial motor design choices in humanoid robots is topology selection.

The Significance of Motor Topology

Engineers have been using radial flux motors with laminated steel cores for many years. Because these motors are dependable, tested, and backed by established production techniques, they continue to be useful in a wide range of automotive and industrial applications. However, the packing issues posed by humanoid robots force engineers to consider other options.

Axial flux motors, especially yokeless models, are perfect for joints because they provide more torque density in flatter packages.

Designers can tailor motors for confined locations, such as wrists or ankles, using segmented or modular topologies.

New motor designs that allow for rotational angular movement within a single motor design include spherical and pan tilt motors.

Innovative flux routes can boost productivity and lower heat, both of which are essential for long-duty cycles.

Strong torque density motors can provide manufacturing, assembly, or cooling issues. Easy-to-make motors might not offer the packing flexibility needed for sophisticated robotics. Which topology is optimal overall is not the question. Every topology has trade-offs.

SMC advantages

SMCs are made from insulated iron powder particles compacted into intricate three-dimensional shapes, in contrast to conventional laminated steel. This arrangement helps minimize eddy current losses in intricate flux channels while enabling magnetic flux to move in three dimensions.

That extra design flexibility is important for humanoid robot design.

Instead of making the joint conform to a conventional motor design, SMCs can accommodate stator geometries that follow the joint's natural shapes. Compact cores, segmented stators, pre-wound assemblies, and modular motor designs that are challenging to do with stacked laminations can be made possible by them.

Practically speaking, SMCs can assist engineers in achieving four crucial objectives:

3D net-shaped cores

Geometries that better match small robotic joints, such the hips, wrists, and ankles, can be created by designers.

➤ Reduced losses from eddy currents

SMCs can assist control heat during continuous operation by lowering losses in intricate magnetic circuits.

➤ Enhanced torque density

SMCs can assist deliver higher torque in a smaller volume when combined with the appropriate architecture.

➤ Scalability of manufacturing

Near-net shape manufacture, reproducible parts, and manufacturing processes that can go from prototype to production are all supported by powder metallurgy.

➤ Not all trade-offs in motor design are eliminated by SMCs. They increase the variety of architectures that engineers can really assess.