From Hydraulic Drive to Permanent Magnet Motor Drive,Revolution in Robot Drive Technology

The use of permanent magnet motors in robot has become an ideal way to improve performance and cost-effectiveness.

On April 16th this year, Boston Dynamics released a video of the decommission of its Atlas robot equipped with a hydraulic system through social media. This decommissioned Atlas relies on a dedicated battery for power supply and uses a hydraulic system. However, due to the high manufacturing costs and low energy efficiency of the hydraulic system, the hydraulic version of Atlas is difficult to achieve large-scale commercial application.

Atlas电驱版
New motor-driven Atlas

Less than a day later, Boston Dynamics released its new Atlas powered by electric motors. Like Tesla’s Optimus robot, Boston Dynamics’ new Atlas is fully powered by electric motors, which not only brings significant changes in appearance, but also greatly improves the overall performance of the robot. From the appearance, the new Atlas has a more flexible mechanical design and multiple joints that can rotate freely, which are direct advantages brought by electric motor.

So,what made Boston Dynamics give up the hydraulic drive that it had explored for many years and switch to motor drive?

On the one hand, the commercialization of hydraulic drive solutions is very difficult, and the high cost is difficult for customers to accept. On the other hand, Boston Dynamics chose hydraulic drive because of its higher torque output. Thanks to the continuous improvement of permanent magnet motor technology in the electric vehicle industry in recent years, the use of permanent magnet motors is currently better than hydraulic drive.

Overall, motor drive has become the main direction of robot development.

Why is hydraulic drive replaced by permanent magnet motor drive?

Energy efficiency

Robot drives powered by motors, particularly those utilizing permanent magnet motors, typically offer higher energy efficiency.Motors directly convert electrical energy into mechanical energy, a process that incurs significantly less energy loss than hydraulic systems.The efficiency of permanent magnet motors typically exceeds 80%, and high-quality motors can even achieve efficiencies exceeding 95%.

The energy efficiency of hydraulic systems is relatively low because hydraulic oil loses energy due to friction and heat exchange during flow. In addition, hydraulic systems require complex piping networks, pumps, valves, and cooling systems, which increase the energy consumption and weight of the system.

Permanent Magnet Motor
Motor-driven robots and previous hydraulic-driven robots

You can see the comparison of the appearance of Boston Dynamics’ previous generations of hydraulic-driven robots and the latest motor-driven robots. The application of permanent magnet motors greatly reduces the weight and volume of the robots.

Control accuracy and response speed

Motor drive can achieve higher control accuracy and faster response speed. Through precise current control and advanced control algorithms, precise control of motor speed and position can be achieved.

In precision instrument assembly or surgical operations, every action of the robot needs to be accurate to the millimeter or even micrometer level. The electronic control system of the motor can easily achieve this level of accuracy, while the hydraulic system is difficult to achieve similar accuracy due to its inherent leakage and elasticity problems.

The efficiency and response speed of hydraulic actuators and motors are affected by various factors, including fluid flow resistance and temperature changes. The greater the flow resistance, the more severe the energy loss, thereby reducing the output efficiency of the actuators and motors. A decrease in temperature can lead to an increase in hydraulic oil viscosity and a decrease in fluidity, thereby slowing down the response speed of the actuators and motors.

Noise and vibration

Laboratory robot

Compared to hydraulic systems, motor drives produce lower noise and vibration during operation, which is particularly important for robots that need to work in quiet environments. Such robots are widely used in precision assembly, laboratory automation, and medical equipment, where the need for low noise and low vibration is critical to ensure accuracy and environmental comfort.

Reliability

Due to the vulnerability of robots to external shocks during operation, the seals of the hydraulic system can become deformed and fail, often resulting in leakage of hydraulic oil.

asf3k so4g8

Once the hydraulic oil leaks, the system pressure will drop, which will cause the hydraulic cylinder and hydraulic motor to operate slowly or stop working completely. In addition, the leaking hydraulic oil may damage the electronic components inside the robot, further affecting the normal operation of the robot.

abtpl geb1n

Cost

The hydraulic system contains many precision components, such as hydraulic pumps, valves, cylinders, and motors, some of which need to be customized. For example, the hydraulic version of Atlas has 28 hydraulic cylinders throughout its body, and the bionic design of its leg skeleton requires the use of metal 3D printing for manufacturing.

The complexity of hydraulic systems leads to high manufacturing and maintenance costs, making it difficult to achieve large-scale commercialization. Although high-performance hydraulic systems have advantages in certain applications, from a cost perspective, motor-driven systems are more competitive.

Flexibility
Hydraulic-driven joints not only lack precision, but also have limited rotational angles. However, electric-driven robots use rotary motors as joints, which can achieve 360°rotational motion. This highly flexible design enables robots to perform complex movements and tasks.

In the introduction video of Boston Dynamics’ latest electric-driven version Atlas, you can see a humanoid robot with all joints rotating, although it may seem a little strange.

Most industrial robots currently require manual intervention when they malfunction. If the robot can stand up again after falling, there will be less need for manual intervention. On the other hand, robots can simply dust themselves off and resume work through this action, which will greatly improve productivity.

Flexibility

Hydraulic-driven joints not only lack precision, but also have limited rotational angles. However, electric-driven robots use rotary motors as joints, which can achieve 360°rotational motion. This highly flexible design enables robots to perform complex movements and tasks.

In the introduction video of Boston Dynamics’ latest electric-driven version Atlas, you can see a humanoid robot with all joints rotating, although it may seem a little strange.

Atlas机器人电驱版02

Most industrial robots currently require manual intervention when they malfunction. If the robot can stand up again after falling, there will be less need for manual intervention. On the other hand, robots can simply dust themselves off and resume work through this action, which will greatly improve productivity.

Send Inquiry: Send Inquiry | HQ Magnet (hq-magnet.com)

Our YouTube channel: HQ Magnet – Neodymium Magnets Factory Wholesale – YouTube