Which Parameters Matter for Quadruped Robot Motors? From “Able to Move” to “High-Performance Motion”

From "Able to Move" to "High-Performance Motion": How Motors Are Redefining Quadruped Robots

Over the past few years, quadruped robots (robot dogs) have undergone a significant technological transition:

• From "able to walk" → to "stable walking"

• From "basic motion" → to "high-speed dynamic running"

• From "research prototype" → to "industrial-grade deployment (inspection / security / rescue)"

Throughout this process, one key trend has become increasingly clear:

The core of robotic performance competition is shifting from "algorithmic capability" to "actuation system capability."

Early robot development relied more on:

• Gait planning

• Control algorithms (PID / MPC)

• Perception systems (vision / IMU)

However, as technology has advanced, the industry has gradually recognized a practical reality:

No matter how advanced the algorithm, without sufficiently powerful, fast, and precise actuators, high-performance motion cannot be achieved.

In other words:

• Algorithms determine "how the robot wants to move"

• Motors determine "whether it can actually do so"

Therefore, a core question now faces engineers:

• How to select a motor truly suitable for a robot dog?

• Which parameters are critical?

• How to balance performance and cost?

Why Do Motors Determine Robot Dog Performance?

Many people believe that a robot dog's "intelligence" comes primarily from algorithms.

But in real engineering, a more practical conclusion is:

The performance ceiling of a robot dog is often determined by the motor (actuator), not the algorithm.

I.  Algorithms Only Provide Decisions; Motors Provide Execution

A simple analogy:

• Algorithm → Brain (decides how to move)

• Motor → Muscle (actually executes the movement)

If the "muscle" is not strong enough, fast enough, or precise enough:

• No matter how good the algorithm, it cannot be realized

• Ideal motions cannot be achieved

For example:

• The algorithm commands a jump → insufficient motor torque → cannot jump

• The algorithm requires rapid adjustment → slow response → the robot has already lost balance

Motor capability directly limits the algorithm's potential.

II.  All Motion Is Essentially Motor Operation

Every action of a robot dog depends on the actuators:

• Lifting a leg → motor outputs torque

• Landing → motor absorbs impact

• Balancing → motor continuously makes fine adjustments

• Running → motor responds at high speed

In other words:

When a robot "appears to move," it is essentially the motor continuously outputting control results.

III. Actuator = Power + Control + Perception

Modern robot dogs do not use a "bare motor" but an integrated actuator, typically including:

• Motor (power)

• Gearbox (torque amplification)

• Encoder (position feedback)

• Driver (control execution)

This means:

The motor itself is already part of the control system.

What are the implications?

• Control precision → affects stability

• Response speed → affects dynamic capability

• Torque output → affects load capacity

Actuator performance = Robot motion quality

IV.  Motor Parameters Directly Determine Motion Performance

Different parameters correspond to different capabilities:

• Torque → can it "hold up"?

• Peak torque → can it "explode"?

• Response speed → can it "keep up"?

• Control precision → can it "stay steady"?

If any of these is insufficient:

• The robot will shake

• It will respond sluggishly

• Or it will be unable to perform complex motions

V.  Why Are High-Performance Robots Upgrading Their Actuators?

A clear trend in the industry in recent years is:

Shifting from algorithm optimization → to actuator system upgrades

The reason is simple:

• Algorithms can optimize "strategy"

• Actuators determine "physical capability"

In summary:

Algorithms determine what the robot wants to do, while motors determine how well it can do it.

Core Parameters of Robot Dog Motors

1.  Rated Torque – "Sustained Combat Capability"

Definition: The continuous output capability of the motor under long-term stable operation (Nm)

Why is it critical?

• Determines whether the robot can "stand"

• Determines whether it can operate for extended periods

• Directly affects load capacity

Engineering conclusion: Rated torque = lower limit of basic performance

2.  Peak Torque – "Instantaneous Burst Power"

Definition: The maximum output capability of the motor over a short period

Typical applications:

• Jumping

• Climbing

• Emergency posture adjustment

Peak torque determines limit motion capability

Note:

• Cannot be used continuously

• Typically 2–3 times the rated torque

3.  Gear Ratio – "Balancing Speed and Power"

Core relationship:

• Higher gear ratio → higher torque / lower speed

• Lower gear ratio → higher speed / more responsive

Selection logic:

• Dynamic robots → low gear ratio

• Heavy-load robots → high gear ratio

Essentially a trade-off between power and flexibility

4.  Control Accuracy – "Core of Stability"

Key metrics:

• Encoder precision (14bit / 16bit+)

• Torque control accuracy

Impact:

• Whether the robot shakes

• Whether it can perform fine motions

• Whether it can achieve biomimetic gaits

High accuracy = high stability

5.  Response Speed – "Key to Running Capability"

Definition: Delay from control signal to motion execution

Impact:

• Dynamic balance

• Gait switching

• Obstacle avoidance capability

The faster the response, the "smarter" the robot

6.  Torque Density – "Core Metric for Lightweighting"

Definition: Output capability per unit weight (Nm/kg)

Significance:

• Lighter → more agile

• Lighter → more energy-efficient

• Lighter → longer endurance

One of the core metrics for high-end robots

7.  Voltage & Power

Common:

• 24V: Lightweight applications

• 48V: Industrial grade

Trend:

High-performance robots are gradually migrating to 48V systems (higher efficiency)

8.  Level of Integration (Integrated Actuator)

An integrated actuator includes:

• Motor + driver + encoder + gearbox

Advantages:

• Reduces development complexity

• Improves reliability

• Shortens development cycle

Current mainstream trend in the industry

In-Depth Case Study of Robot Dog Motors

University of Minnesota Agricultural Quadruped Robot – Stability and Reliability in Practice

Project Background

The quadruped robot (OmniAgRobot) from the University of Minnesota Agricultural Robotics Lab is used for:

• Field inspection

• Crop health monitoring

• Soil data collection

This robot can move freely in cornfields, muddy terrain, and irregular terrain – something traditional wheeled robots struggle to achieve.

Why a Quadruped Structure?

Compared to wheeled robots or drones:

• Muddy ground → wheeled robots easily get stuck

• Between crop rows → wheeled robots cannot enter

• Irregular terrain → insufficient stability

Quadruped robots offer:

• Greater terrainability

• Higher stability

• More precise path control

Motor Selection: The Key Role of the AK70-10

The project ultimately chose the AK70-10 integrated actuator for the following core reasons:

① High Integration

• Motor + gearbox + driver integrated

• Simplifies mechanical structure and wiring

• Improves system reliability

② High-Precision Control

• Supports CAN communication

• Supports multi-motor synchronization

• Enables complex gait coordination

③ High Torque Output

• Adapts to muddy ground, slopes, and other complex environments

• Provides stable support

④ High Reliability and Ease of Deployment

• Easy to install

• Efficient debugging

• Shortens development cycle

Actual Engineering Performance

During testing, the robot achieved:

• Synchronized coordination of multiple motors

• High-frequency position and torque control

• Stable walking in complex terrain

Research team feedback:

High integration + high torque significantly improved system stability and development efficiency

Core Conclusion

The core requirements for agricultural robots are not "extreme performance" but:

• Stability

• Reliability

• Sustainable operation

Essential needs:

Medium-high torque + high precision + high reliability

KLEIYN – Vertical Climbing Quadruped Robot Pushing Limits

Project Highlights:

• Can climb between narrow walls of 800–1000mm

• Motion speed increased approximately 50-fold

• Adapts to complex environments (e.g., chimneys/shafts)

Motor Configuration Breakdown

Why Can It Climb?

Three key factors:

1. High rated torque

• Ensures continuous adhesion without falling

2. High peak torque

• Provides burst power for leg lifting and propulsion

3. Low-latency response

• Quickly adjusts contact points (prevents slipping / loss of balance)

Engineering conclusion:

Extreme motion = Torque + Response + Control, all three combined

Kemba – Precision-Driven Robot

Project Characteristics

• High-precision gait control

• Strong force control capability

• Used for research and control algorithm validation

Motor Capability Requirements

• Precise foot placement control

• Torque variation control (compliance control)

• High-bandwidth response

Engineering Significance

In research robots:

• High torque ≠ good performance

• Controllability is the core

Core Conclusion

Future robot trend = Precision-driven + Force control integration

Bottom-Line Logic for Robot Dog Motor Selection – Derived from Case Studies

After understanding the core parameters and real-world cases, the most critical next step is:

Selecting the actuator solution that truly fits your project.

From the three typical cases – KLEIYN, the agricultural robot, and Kemba – we can identify a crucial pattern:

Different application scenarios correspond to fundamentally different "motor parameter combination strategies."

No single parameter is the strongest; the key is the right combination.

I.  Extreme Motion Scenario (KLEIYN)

Keywords: Dynamic capability / Burst power / Response speed

Core needs:

• High peak torque (burst)

• High response speed (rapid adjustment)

• Medium-high rated torque (sustained support)

Why?

• Climbing, jumping, and fast movement all require substantial instantaneous power

• Simultaneously, rapid adjustment is essential to avoid losing balance

Essential logic:

Prioritize "response + burst," then sustained capability

II.  Agricultural / Industrial Scenario (University of Minnesota Robot)

Keywords: Stability / Reliability / Continuous operation

Core needs:

• Stable rated torque

• High reliability (long operation hours)

• High integration (reduces system complexity)

Why?

• Farm environments are complex but the pace is relatively slow

• Requires long-duration operation, not extreme performance

Essential logic:

Prioritize "stability + reliability," not extreme performance

III. Research / Control Scenario (Kemba)

Keywords: Precision / Force control / Repeatability

Core needs:

• High-precision encoder

• Fine torque control

• High-bandwidth control system

Why?

• Need to validate algorithms

• Need repeatable experimental results

Essential logic:

Prioritize "controllability," not just raw power

Comparison of the Three Scenario Types

Robot Dog Motor Product Recommendations and Selection Advice

Quick Decision Guide

Conclusion

The transition of quadruped robots from “able to move” to “high-performance motion” is no longer driven by algorithms, but by motor actuators. Algorithms determine how a robot “wants to move,” while motors determine how well it “can perform.” Modern integrated actuators are themselves the core of the control system, directly defining the performance ceiling of quadruped robots.

Different application scenarios correspond to completely different motor parameter combination strategies. Extreme motion scenarios prioritize response speed and peak torque, agricultural and industrial scenarios prioritize rated torque and reliability, while research and education scenarios prioritize control accuracy and force control capability. There is no “strongest” motor—only the most suitable parameter configuration.

Motor selection is not a competition of a single parameter, but a system-level balance among torque, response, precision, weight, and cost. Dynamic quadruped robots focus on response and burst power, industrial and agricultural scenarios emphasize stability and continuous operation, heavy-load applications require high torque reserves, and research and education place greater importance on controllability and ease of development.

The key to advancing quadruped robots from “able to move” to “high-performance motion” is not how powerful the algorithm is, but whether the motor can support, keep up, and control accurately. Only by choosing the right motor can a quadruped robot truly run fast, stand stable, and perform precise tasks.