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Robotic Arm with Servo Motors—A Step Closer to Future

In 1942, when Isaac Asimov first set out three Laws of Robotics, the smart machines co-existing in symbiosis with people seemed more of a fiction than a probable reality. State-of-the-art technology opens up a breathtaking perspective of robots penetrating into our lives. At home, the intelligent devices can do the drudgery we hate—the cleaning and washing. At work, repetitive, dirty, and dangerous tasks are as easy as one-two-three for a robotic arm with servo motors. The type of engine provides accuracy, smoothness, and flexibility of motion comparable to a human limb, while excelling it at repeatability.

Breakfast at Rozum’s

General data: definition and applications

A robotic arm is a programmable mechanism comprising two or more segments linked by means of joints into a kinematic chain. Each joint in the chain is a servo motor or another engine providing either rotation or linear displacement of the segments. The number of linkages in the structure defines how many freedom degrees (DOF) it has—typically, ranging from two to the human limb maximum of seven.

six DOF robotic arm with servo motors

A manipulator is smaller than an industrial robot, enabling flexibility of usage and relocation, as well as optimized floor space utilization. More advanced collaborative models can even work alongside people with no safety cages. Within the general "arm" category, it is also possible to distinguish the following subtypes corresponding to different types of provided movement:

  • Cartesian
  • Cylindrical
  • Spherical
  • Articulated
  • SCARA
  • Parallel
  • Anthropomorphic
  •  

The terminal component in a robot arm is an end effector intended to handle versatile jobs, depending on the type of application. Mostly, these are unvaried and rather dull works, in particular:

  • welding
  • painting
  • material handling
  • assembling
  • palletizing

 

Though requiring little intellectual efforts, the operations demand extra carefulness, unfailing attention, and tirelessness—a challenge when we speak about a human. At least, to maintain over extended periods without rest. Manipulators possess all the necessary qualities to meet the demands, posing viable alternative to human labour. Industry is well aware of the advantages, doing their best to use them to their benefit. According to recent reports, sales of industrial robot arms have risen considerably worldwide and are to continue growing to reach $70,715 billion in the next five years.   

A robotic arm and servo motors

To become functional, a robot arm requires a device to furnish it with force in sufficient quantities to lift joints—an actuator. Though latest progressive findings have resulted in invention of novelty drives, such as biomotors, a typical robotics-oriented actuation mechanism is a stepper or a servo motor.

Though requiring little intellectual efforts, the operations demand extra carefulness, unfailing attention, and tirelessness—a challenge when we speak about a human. At least, to maintain over extended periods without rest. Manipulators possess all the necessary qualities to meet the demands, posing viable alternative to human labour.

Technical details:

Biomotor actuation is different from the servo motor actuation principles and relies on contraction-release effects emerging in a special type of material—biometal—under voltage. Their reaction to a low-voltage impulse is slower than response of a conventional electrical motor, but its motion output possesses a quality of extra value—smoothness. Though bio-inspired materials hold immense potential as a technology to replace bulky actuation hardware, one can find their usage example mostly in research or pilot projects. 

biometal operation principle

Both engines are known to ensure precise positioning over multiple work cycles, which is of critical importance for a manipulator to cope with its usual tasks. Steppers have low price and give little configuration or maintenance problems, whereas servos are more troublesome to set up and pricy. Nevertheless, servo motors boast properties of value in a robotic application: comprehensive motion feedback, outstanding governability, uniform and stable torque production over the entire performance curve.

In PULSE robotic solutions, servomechanisms are behind the following features and benefits:

  • High torque density

    In-built metal-gear gearheads make it possible to multiply torque output of the brushless AC motor by the factor of nearly one hundred without impacting the overall dimensions of servo motors. The underlying strain-wave technology entails the additional advantage of near-zero backlash, minimizing efficiency losses.

  • Movement flexibility

    PULSE robotic arms have six degrees of freedom—almost as many as a person’s upper limb. Embedded into joints, servo motors enable their precise angular displacement within the span from -360 to +360 degrees. Additionally, the engines ensure positioning of the work tool with a thousandth degree accuracy.

    A standard ISO 9409-1-50-4-M6 mechanical interface at the end effector connection facilitates integration. Due to its modular construction, customers have ample options to experiment with designs and configurations, enhancing flexibility.

  • High-precision movement control

    Servo motors rely on feedback from two absolute magnetic encoders reading motion parameters before and after gearing. The sensing devices watch out for change of positions, transferring the collected data to a controller, also seated inside the housing. The controller module acts as an intellectual hub of the robot arm, processing the feedback to find out what needs to be adjusted to achieve desired propulsion.

  • Programmability

    The governing routine is the responsibility of the controllers. The devices are printed board microprocessors, similar to Arduino boards, but of in-house design. The microprocessors communicate with external masters to receive commands and report on their execution by servo motors. Supported communication methods include the CANOpen protocol and an Application Programming Interface (API) in C, Java, and Python. Both methods are easy to set up within minutes, literally taking a few command code strings to launch communication.

  • Reliability and durability

    Most of the basic parts in RDrive servomechanisms are self-designed and self-produced. This translates into continuous quality control throughout stages of a product life cycle and traceability of manufacturing defects, should they occur. The guaranteed life-in-service is 35,000 hours—both for actuators and the PULSE solution as a whole. Modular design makes it possible to replace servos with minimum efforts. The terms of warranty stipulate 1 year of defects liability period.

  • Safety

    Each actuator is fitted out with overtemperature protection based on sensors integrated into their brushless cores. CANOpen and API communication interfaces offer specialized safety features to detect abnormal operation and to stop or set up servos to react to the abnormalities.

As separate products, RDrive models can be customized to drive any other mechanisms: by varying the form factor, modifying basic parts or mountings, changing the communication type, etc. The customization services are available upon request.

Fancy the future

Powering a robotic arm, servo motors aid the humanity in building a better future. In the fancy world of tomorrow, people are supposed to embrace creativity, whereas machines are to act as their fatigueless and ever-attentive collaborators. In other words, people are expected to give birth to ideas, and machines—to nurture them to the adulthood of becoming a tangible asset.

Examples are already abundant when smart machines replace people in dangerous and boring occupations, such as attending assembly lines or working with chemicals. Multiple research report considerable savings achieved through robotization of industrial workflows. Not riding the wave of transformation with a robot arm to boost your productivity might well turn out a strategic mistake in the long run.

mind-guided prosthetics

Evolution of servomechanisms gives rise to new capabilities. Ultra-precise micromotors in robotic hands used as end effectors can already mimic minute flexes of fingers. Introduction of novelty control methods, including the brain-machine interface, hold out the promise of major breakthroughs in heavy-duty manufacturing and prosthetic medicine. Imagine a workshop with no people around, all of them sitting in remote cabins, relaxed in comfortable chairs, and making smart mechanisms lift cargoes with just the power of their thought. Or fancy the disabled getting a chance to enjoy unrestricted movement again!


Join the future now—order an RDrive servo to build a proprietary smart mechanism or buy a ready-made PULSE cobot!

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