A robot actuator is a core component that generates the motion of a robot’s joints and drive units. It is generally composed of a motor, reducer, sensor, and controller, and serves to convert electrical energy into the actual rotational or linear motion of the robot. In systems where multiple joints must move in an organic way, such as humanoids, collaborative robots, and service robots, the performance of the actuator is directly tied to the motion quality of the robot as a whole. In this article, we look step by step at the definition of an actuator, its main components, and the characteristics of the Bonsystems actuator lineup.
Table of Contents
The Definition of a Robot Actuator
Key Summary An actuator is a system-level component that combines the elements needed for drive, such as the motor, reducer, sensor, and controller, to generate the motion of a robot’s joints and drive units.
A robot actuator means a component that generates the actual motion at a robot’s joints or drive units. It works in a structure where the motor generates rotational motion, the reducer converts that rotation into torque the robot can use, and the sensor and controller detect and adjust position, speed, and force.
A single motor alone makes it hard to realize the accurate motion and sufficient force that a robot joint requires. It is therefore appropriate to understand an actuator as a drive system in which the motor, reducer, sensor, and control elements work together.
Thanks to this structure, a system designer can design the robot’s joint section at the actuator level, instead of combining each component individually. Especially when many joints are needed within a single robot, as in humanoids or collaborative robots, the actuator becomes a core unit that raises system design and assembly efficiency.
The Role of the Motor: the Source of Rotational Motion
Key Summary The motor converts electrical energy into mechanical rotational motion and serves as the starting point of motion within the robot actuator.
Within a robot actuator, the motor serves to convert electrical energy into mechanical rotational motion. BLDC motors or servo motors are used in actuators for robot joints as needed, and accurate position control and fast responsiveness are required as important factors.
However, the rotation a motor generates generally occurs at high speed with low torque. In this state as is, it is hard to generate enough force for a robot arm to lift an object or for a joint to support itself stably.
The motor’s rotational motion must therefore pass through a reducer to be converted into a speed and torque suited to the robot joint. In this process, the reducer takes on the important role of determining the output characteristics of the actuator.
The Role of the Reducer: Converting Rotational Force into Torque
Key Summary The reducer converts the fast rotational motion the motor generates into slow but strong rotational motion, forming the torque the robot joint needs.
The reducer is the component that turns the fast rotational motion generated by the motor into slow but strong rotational motion. For a robot joint to lift an object with a constant force, maintain a posture, or stably perform repeated motions, sufficient torque is needed. At this point the reduction part of the actuator converts the motor’s rotational force into force the robot can actually use.
There are several reduction methods, and among them the cycloidal reduction method is one of the structures drawing attention in robot joint drive units. A cycloidal reducer can realize a wide range of reduction ratios within a single-stage structure, and through a surface-contact structure it has favorable characteristics for distributing external shock loads.
These characteristics align well with application fields that require accurate operation and durability at the same time, such as humanoids, collaborative robots, and industrial robots. Bonsystems has developed its BSR cycloidal reducer lineup based on a Pinless cycloidal structure and slim package design, and the product family that extends this reduction technology into an actuator form is the BCSA lineup.
Sensor and Controller: Devices for Accurate Motion Output
Key Summary The sensor and controller are elements that check the state and adjust the drive so that the robot actuator moves according to the target position and speed.
In a robot actuator, the controller serves to adjust the motor’s movement based on the target position, speed, and drive conditions conveyed from an external system or the robot’s control section. In other words, it judges in which direction and how much the actuator should move and drives the motor accordingly.
The sensor serves to confirm how the actual motion is taking place in this process. For example, it detects information such as the motor’s rotational position and speed and the movement of the output shaft, so that the controller can grasp the current state.
The controller compares the actual state confirmed by the sensor with the target value and corrects the drive when necessary. In this way, the controller and sensor work together in a flow of executing commands, confirming the actual motion, and adjusting again. The sensor configuration and control method can differ depending on the applied product or design approach, but fundamentally they can be seen as elements that help the robot joint move within the intended range.
The Robot Actuator and the Bonsystems Lineup
Key Summary The Bonsystems BCSA integrates cycloidal reducer technology into a single-module actuator form, enabling the adoption of system-level components in humanoid and collaborative robot joint applications.
A robot actuator is not simply a product that puts several components into one package. It is a system-level component in which the motor’s output, the reducer’s structure, the sensor’s detection method, and the control interface must be designed together to suit a single drive purpose.
Using an actuator lets the system designer reduce the process of selecting and combining the motor and reducer individually. In addition, the assembly process, wiring structure, part count, and verification process become simpler, yielding advantages in robot development and mass production as well.
Especially in systems where actuators are repeatedly applied to many joints, as in humanoids or collaborative robots, the advantages of modularization grow further. Because the same design unit can be applied to many joints, the consistency of system configuration and the efficiency of maintenance can be raised.
FAQ
Q: How is an actuator different from a reducer?
A: A reducer means the power-transmission component itself that turns the motor’s rotation into large torque, while a robot actuator means a system-level component that integrates the motor, reducer, and, as needed, the control section into a single module.
Q: What are the core components inside an actuator?
A: Generally, the motor, reducer, and controller are the core components. The motor generates rotational motion, the reducer converts rotational force into torque, and the controller adjusts the drive force based on this information.
Q: Why is the cycloidal reduction method suitable for robot actuators?
A: The cycloidal reduction method can realize a wide range of reduction ratios within a single-stage structure, and through a surface-contact structure it has favorable characteristics for distributing external shock loads. These structural features make it a suitable basis for humanoid, collaborative, and industrial robot joint actuators that require accurate motion and durability together.
Q: What is the Bonsystems actuator lineup?
A: Bonsystems has the BCSA lineup based on cycloidal reducer technology. The BCSA series is a product family in the form of a reduction part combined with a motor, a modular component designed with robot joint and drive-unit application in mind. The control section configuration can be reviewed flexibly depending on the application environment and system configuration.
Q: Why introduce a robot actuator as an integrated module?
A: Because introducing the motor, reducer, sensor, and controller as a module rather than combining them separately yields value such as system-level part-count reduction, reduced wiring and adjustment burden, and stronger mass-production stability.
