Posts Tagged 'Automation'

5 Tips for a Successful Servo Crossover

Reprint of March 27, 2014, article  by Josh Bellefeuille Sales Application Engineer at Kollmorgen

Kollmorgen Servo Motor FamilyThere are a number of situations that call for crossing over and replacing an existing motor with a newer servo.  These can include: product obsolescence, cost savings, lead time issues, or upgrading to newer technology.  The specifics of each application could lead to an endless number of important factors to consider.  In this post I will try to (briefly) identify those that are most common and their correct order of concern.

1. Healthy Motivations

Whatever the reason for a replacement situation, it is important to understand (and never forget!) the most important aspect of the task.  Mitigating risk.  A good replacement is one that minimizes the potential number of issues that may be experienced amidst the upgrade.  If great care is not taken to manage the potential risk of a replacement, a higher potential for system failure will be introduced.

This means cost should not be the controlling factor for replacements! A good replacement is one that minimizes risk AND reduces the cost of a system, versus reducing cost and accepting a higher potential for risk.

2. Axis Stability

Inertia matching is very important and often overlooked.  A servo replacement should have the same rotor inertia as the existing motor, or be as similar as possible.  The goal is to keep the stability of a system consistent when the new servo is introduced.  This of course assumes the existing system already has the desired stability.

If replacing a lower resolution system (i.e. tachometer, commcoder, or older resolver based system) it is often worthwhile to consider a high resolution sine-encoder feedback device, with resolution ≥ 220 counts per revolution (CPR). Doing so will give more flexibility when matching rotor inertias.  As a general rule, when improving feedback resolution with a high resolution device, the servo replacement should have at least one third of the inertia of the existing motor, though it’s preferred to have one half.  This method has been successfully applied in many applications.

3. Speed and Torque

Speed and torque matching is equally as important.  The performance of the replacement motor should meet or exceed the performance of the existing motor.  It is important to review the catalog values of each (i.e. continuous torque, rated speed) to ensure there are no shortcomings.

It is also critical to compare torque values over the entire speed range of each motor.  Comparing graphically may be a helpful exercise.  This can be done by comparing motor speed/torque curves and manually plotting like-values in a spreadsheet.  For example, at 1000 RPM the continuous torque for motor A = X Nm and motor B = Y Nm, and so on for the entire speed range.

4. Motor Dimensions

Though not critical to the performance of the motor, a retrofit situation becomes streamlined if the mounting dimensions of the replacement servo are identical to the existing motor.  The outline drawings of both motors should be reviewed to ensure consistency.  This is good practice even when replacing motors with industry standard mounts, like NEMA or IEC.  Standards typically have consistent pilot and bolt circle dimensions, but often do not maintain the same shaft dimensions.  Though you are replacing a NEMA 34 motor, one manufacturer’s definition may be drastically different than another’s!

5. Other Considerations

Is the motor the only part of the machine being replaced?  Typically a servo replacement will mean replacing the drives, cables, and in rare instances even the controller.  In this case the difference in motor windings can become a secondary consideration assuming manufacturer recommendations are followed.

However careful review is in order if the replacement motor is intended to be used with an existing drive.  Winding data (including motor constants: Kt and Ke), feedback device type and resolution, and cable pin-outs are just a few of the pieces that must be closely examined and matched.  Furthermore, different servo motor manufacturers often utilize different units and commutation methods for these critical parameters.  This can leave a lack of clear distinction between definitions and units of the motors being compared. As a supplementary resource, this helpful article further details some of the common specification inconsistencies that should be considered during a servo replacement.

Other aspects worthy of comparison may include overall envelope size, environmental ratings, holding brakes, bearing and load life, and specials. As hinted at earlier, this short article is in no way meant to serve as a comprehensive “checklist” of crossover guidelines.  Instead, I hope it serves as a high-level starting point for effective servo crossovers, in which risk is carefully considered and managed.

 

Tags:  Servo Motor, BLDC Motor, Electric Motor, Kollmorgen, Electromate, Servo, Automation

Live Webinar: Designing an Optimal Rotary Motion Joint for Robotics & Factory Automation

 

Space is limited. Reserve your Webinar seat now.

Register now to watch this webinar live or anytime after July 29, 2014.

Harmonic Drive® gearing is a dominant technology used in precision rotary motion applications in the field of robotics and factory automation as well as other industries such as machine tool, semiconductor, and medical equipment.   Basic principles and technical considerations will be reviewed leading to a discussion of rotary actuator joint design optimized for the application requirements while minimizing size & weight.

Webinar Content to Include:
-Overview of Harmonic Drive gearing principles and operation
-Technical considerations of joint performance
-Application design examples
-Design enhancements and customization

Title: Designing an Optimal Rotary Motion Joint for Robotics and Factory Automation
Date: Tuesday, July 29, 2014
Time: 11:00 AM – 12:00 PM EDT
Presenter: Bob Mullins, VP of Sales, Harmonic Drive LLC

 

Tags:  Harmonic Drive, Electromate, Strain Wave Gearing, Rotary Motion, Automation, Motion Control, Webinar, HD, Robotics, Factory Automation

 

 

Highly Dynamic DC Brushless Servo Motor – maxon’s EC-i40

Compact And Powerful

In automation and robotics, many applications are characterized by high energy and high torque at the same time.  Spatial restrictions also mean that drives must be short, have a long service life and be maintenance-free.  The newly redesigned EC-i motors from maxon motors offer solutions that fit these requirements perfectly.

Maxon EC-i40 Brushless Servo Motor

Maxon EC-i40 Brushless Servo Motor

These brushless DC motors have several key advantages: low inertia, minimal detent, robust bearings and compact construction.  The use of high-powered permanent magnets ensures high power density, providing great speed stability under load.

These motors are available in 40 mm diameter and in two lengths, namely 26 mm (50 Watt) and 36 mm (70 Watt).  The modular system with gearheads, encoders and controllers from the maxon delivery program offers a large number of possible combinations.

EC-i motors are ideally suited for applications that require maximum drive in a minimum space.  Typical areas of application are robotics, industrial automation and security technology. 

Click on the link below for more information.

http://www.electromate.com/products/?keyword=EC-i+40&d=102310

EDITORIAL CONTACT:
Warren Osak
sales@electromate.com
Toll Free Phone:   877-737-8698
Toll Free Fax:       877-737-8699
www.electromate.com

Tags:  maxon, maxon motor, maxon DC motor, Electromate, EC-i40, servo motor, BLDC motor, brushless motor, flat motor, pancake motor, automation, electric motor, motion control

 

 

Motion Control for Newbies

Motion Control For Newbies
Check out the latest publication from the maxon academy, Motion Control for Newbies, a practical introduction to motion control.  132 pages.

The basic approach of this textbook, like many, is a practical and experimental one; however, it is reversed from most.  Instead of first explaining the theory of motion control and then applying it to specific examples, here we will start with hands-on experimenting on a real maxon EPOS2 P positioning control system by means of the EPOS Studio software and explain all the relevant motion control principles/features as they appear on the journey.  Therefore, the text contains mainly the exercises and practical work to do.  Background information can be found in the colored boxes.

This is primarily a textbook about motion control and not about programming a PLC. Therefore, the programming part should be considered as an introduction on how to program the motion control aspects.  It is not a full PLC programming course.

Motion control is mechatronics.  It is the combination of mechanics and electronics, of actuators (motors) and sensors all controlled by software.  In this textbook, we identify and define the role, behavior and mutual interaction of the different elements of a motion control system.  However, we need to know the basic internal construction and working principles of the elements only to a limited extent, but rather look at them as a black box.  Given a certain input, what comes out of the box?  How is this output generated and which parameter can be used to influence the output?  For instance, we will not explain how feed forward control must be implemented, but we will explain the basic idea of it and how the parameters will look during axis tuning… click on the link below to download the complete textbook.

http://www.maxonmotorusa.com/medias/sys_master/8812127617054/Motion-Control-for-Newbies.pdf

More information on the minimotors from Maxon Motor AG can be viewed at-

http://www.electromate.com/products/?partner=1072297493

For more information, please contact:

EDITORIAL CONTACT:

Warren Osak
sales@electromate.com
Toll Free Phone:   877-737-8698
Toll Free Fax:       877-737-8699
www.electromate.com

 

Tags:  Maxon, maxon motor, Electromate, Mini Motor, Servo Motor, BLDC Motor, Brushless Motor, EPOS2, Motion Control, Automation, Motor Control, Textbook, motors

 

New Generation of Hexapedal Robots

Whether traversing over the sands of Mars, or walking up a stone path, this robot was designed to move easily and quickly, to jump, and even to flip over.

The biologically inspired robots being designed at the University of Pennsylvania aim to provide new levels of mobility and durability, while providing the capability for rapid behavior development.  The X-RHex (Robot Hexapod) is the latest version of the highly mobile RHex platform.  X-RHex was designed for greater strength, longer runtime, and more mobility than previous versions, plus it is the first RHex to be built to carry a modular payload architecture to support a wide variety of research requirements.

The six legged robot is modeled after insects where three legs are always touching the ground at the same time. As a running robot, the X-RHex provides robust operation in complex, natural, outdoor terrain. The robot is expected to be an effective research machine for in the laboratory as well as outdoors for field tests.

The payload specifications include a 5V, 12V, and battery voltage (37V to 42V) power interface, and a USB and Ethernet connection.  Payloads are attached to the robot using mil-spec Picatinny rail mounted standard interface.  While typical payloads are often smaller in mass than the X-RHex itself, the robot has been tested for carrying up to 12kg on its back, which is significantly heavier than the weight of the robot. Payloads can include webcams, GPS units, and a secondary computer for fast processing of sensor data.

The X-RHex body is 57 x 39 x 7.5 cm, with a ground clearance of 12.5 cm (12 cm when inverted).  Each leg has a diameter of 17.5 cm, and the unit weights 9.5 kg with both batteries installed.  One of the main objectives for the mechanical design of X-RHex was to improve its frame durability in both resistance to fatigue and impact, as well as serviceability while achieving better performance than past models of RHex.

Leg design, on the other hand, was preserved.  The leg mounts are nearly centered on the thinner body, which means the robot operates with greater ground clearance even when in an inverted state.  The motors were chosen after careful analysis of the performance of past RHex robots.  The team chose to use flat brushless motors designed and manufactured by maxon motor USA. Each motor offers 84 Watts of continuous power, has a gear ratio of 28:1, and a maximum robot power density of 240 W/kg.

UPenn robot_2The X-RHex is designed around four subsystems, including a main computer, electronics stacks, batteries, and motor assemblies.  While the main computer handles all high-level control and communications; the electronics stacks house the motor controller, control interface board, and the battery management board used for power distribution, regulation, protection, and monitoring.  Mounted to the outer side of each stack is a lithium polymer batter and interface board.  A motor assembly, which contains the brushless motor and related sensors, is located at each of the six hips.

X-Rhex travels at a high speed of about four body lengths per second (about two meters per second).  The motors used are maxon EC 45 brushless motors.  There is one located at each of the six C-legs (the leg is shaped like a C).  The C-legs are basically springs, which are compliant in both vertical and rotational direction.  This means that the legs can push even though they rotate.  Brushless motors are perfect for this type of application because they are high-efficiency motors, they have no friction due to the brushes, and produce no sparks while in operation.

maxon designs and manufactures their complete line of both brush and brushless motors in-house.  They also provide gearheads, encoders, and other accessories for their motors, including a wide array of electronics.  The company’s EC flat brushless motors are available in power ratings from 12 to over 70 watts, and come standard with Hall sensors.  The motors are also available in a variety of operating voltages, as well as speeds and torques. maxon motors offer long life and quiet operation.

There are two phases to each leg’s operation: the ground phase and the aerial phase.  Like an insect, three legs are in each phase of operation at any particular time.  This provides static stability for the robot.  The gait is called an alternating tripod gait, and is the most stable operation for a six-legged machine.

The ground phase of the rotation has to move at a slower speed and requires a higher torque rating.  The aerial phase of the rotation needs to move at a faster speed, but requires lower torque.  This is because the legs are on the ground for only about 60 to 90 degrees of rotation, while they are in the air the other 270 to 300 degrees of rotation.

Further, friction is created while the C-leg is in its ground phase no matter what the terrain.  Since the X-RHex can travel over rocks, sand, dirt, grass, the floor of a building, etc., the time the leg spends in the ground phase versus the aerial phase is variable.  Note that not all gaits have to be tripod based, either. But, to be as flexible as possible, different algorithms must be created for each gait dependent upon where the robot is expected to travel.

For more information, contact:
maxon precision motors, inc.
101 Waldron Rd
Fall River, MA 02720                                                          
T: +1 508 677 0520
F: +1 508 677 0530
www.maxonmotorusa.com

Kod*Lab
University of Pennsylvania
http://kodlab.seas.upenn.edu/Main/HomePage

Tags:  maxon, maxon motor, Hexapedal Robot, Robot, Motion Control, Automation, Mars, Servo Motor, Brushless Motor, Brushless Servo Motor

See Electromate at the MMTS Show on May 12-14th


Are you attending the Montreal Manufacturing Technology Show (MMTS) on May 12-14, 2014? 


If so, stop by and say hello! Electromate is exhibiting it’s Robotic and Mechatronic Products in Booth #30.

Click on the link below to Register Now.

http://www.mmts.ca/attend/register-now

Tags:  Robotics, Mechatronics, Automation, Motion Control, Trade Show, Motor Control, Machine Control

Live Webinar on May 13: The Evolution of Ethernet in Motion Control


Electromate’s Website

Archives

Subscribe to this blog by entering your email address below.

Join 337 other followers

Hey there! Electromate is using Twitter.

Presentation Playlist

Flickr Photos

Motion & Automation Controllers

Stepper Motors & Drives

Servo Motors & Drives

Servo Motors

Servo Drives

Stepper Motors

Stepper Drives

Positioning Systems & Actuators

Motion Control Made Simple Textbook

Power Transmission Products (2)

More Photos

Follow

Get every new post delivered to your Inbox.

Join 337 other followers