Drive System Selection – Step 1

There are multiple steps to selecting a drive system. We need to know what the application is and what it is going to do so we can start to develop a drive system that will meet your needs. Learn how to select a motor and what sets the different motors apart in this short video.

Transcript

00:00:01 [Music] this video tutorial gives you an introduction to the process of the selection of drive components we focus here on the evaluation of the application requirements in general and the boundary conditions to respect there is a series of further tutorials covering the calculation of key load parameters and the selection of drive

00:00:28 components such as gear heads motors encoders and controllers the selection can be divided into seven steps that usually have to be performed in the given order as mentioned before there are separate video tutorials for steps two to seven this tutorial covers step 1 the situation analysis where we reviewed the drive as a whole together with its environment the goal is to gain

00:00:53 a good understanding of the requirements of the application at hand these two questions are the basis of all further analysis often I get an inquiry about the special aspect of a drive system without knowing what it's all about how do you expect me to give it profound advice and please give us the background information as well this is why step one of the

00:01:20 selection process is so important and the restaurant date for this tutorial is all the necessary information available to perform a successful selection do we know all the relevant parameters dependencies between the single system components have to be identified a checklist can be a helpful tool to make sure that all aspects have been considered

00:01:46 in addition there are commercial issues to observe in order to get the business case complete which components shall belong to the system to offer just the motor or motor gearhead encoder and controller maybe including mechanical components and housings how big is the sales volume and apprise indications given do we speak of off-the-shelf products with modifications or fully

00:02:14 customized products these eight aspects define a given application quite well from a technical point of view note that they are not independent from each other hence there's no need to go through them in the order presented here first operation duty cycle motion profiles idle duration second ambient conditions think of temperature humidity vacuum vibration

00:02:43 noise electromagnetic susceptibility third electrical supply how much current and voltage is available fourth control concept very important where to the set values commands come from what to control position speed or torque five mounting conditions which are also related to ambient for example cooling but also cable length fixation of the drive six related to mounting is the

00:03:18 mechanical layout what kind of mechanical transformation is used to about our transformation parameters for example reduction efficiency friction but also support of reaction forces seven how does the load look like what are the forces that occur friction feeding forces gravity acceleration forces from a technical point of view the important thing is to observe all

00:03:48 these aspects for getting a thorough understanding of the application as mentioned before there are commercial issues to observe as well looking at the application as a black box can be a reasonable approach for a system whose components have yet to be defined hence the first question to answer is not what is in the box but what are the inputs and what should come

00:04:15 out and how does it work this black box here is a tunable elastic robotic joint it has all kinds of ingredients however during analysis of the application tasks we are rather interested in the interfaces concerning power on the input side of the black box there is the electrical supply with voltage and current for DC power supplies there are different

00:04:44 possibilities including batteries and QS solar panels the output power is given by the required load motion here one can differentiate between linear motion with force and velocity and rotational motion with torque and speed current and voltage must match the needs of the drive system how much voltage is required and how much voltage is available how much current is required

00:05:13 and how much current can be delivered the mechanical concept and the bearing systems are also part of the motion output the drive types adapts the output from motor or motor gearhead to the needs of the load two different drive types can be distinguished linear or translational drive types such as spindle drive rack and pinion and

00:05:39 conveyor belt convert the rotational motion of the motor into a linear motion of the load rotational drive types all kind of gears and belt drives transmit a rotational movement to the load a full mechanical description includes bearings and guidances which must be capable to support all kind of reaction forces they are also important for the estimation of friction forces the

00:06:07 orientation with respect to gravity might also be available information the require motion can lead to different load scenarios basically these four operation modes can be differentiated continuous operation here the drive accelerates once and moves with the constant load for a long period of time examples are laser beam deflection or tattoo gun short-term operation intense

00:06:35 load during a short period of time followed by a very long standstill an example is an insulin pump one shot every few hours cyclic operation is characterized by a relative short variable load profile however continuously repeated typical examples can be found in production equipments such as pick-and-place cycles may also vary as in a strapping tool

00:07:04 on-off operation is a special case of cyclic operation the weakest link in the drive chain limits the power available at the load hence it's not only the torque and speed limits of the motor the limited tort capabilities of the gearhead or the mechanical system must be considered as well or some current limit of motor control or power supply

00:07:31 similarly the achievable speed can be limited by other components such as sensor gears and mechanics or controller the voltage capabilities of controller and power supply might not be sufficient to reach the required speed observe there are constraints imposed by the hardware or by the software the second black box aspect is control what is the motion task positioning

00:08:00 speed or force control where do the commands come from what should be the quality of the motion what is the position accuracy the speed accuracy how fast controlled considered the following points which is my parameter to be controlled and how is it measured accordingly a matching sensor type has to be defined are there additional sensors needed how is the

00:08:28 information passed onto the drive system is there a supervisor or master system if yes how does this higher-level host system communicate with the drive for example wire can open or another field bus or via a serial interface such as rs-232 or USB set values could also simply be given as a digital or analog signal do we need additional in and outputs for example for homing or

00:08:59 temperature monitoring additionally the range and the needed accuracy of the control parameter has to be defined again the weakest link in the drive chain and the combination of it all defines the quality of motion typically you'd say it's the sensor resolution and sensor accuracy that gives the perfect control but this is just one element a lot depends on the

00:09:28 design of the control loops and on communication between components and on the available power for a fast reaction a lot depends also on the mechanics the mass is to be moved and other damping mechanisms but then we also have the ugly things such as backlash mechanical play elastic behavior non constant friction resonances achieving high-end control is a matter

00:09:58 of well balancing all system components in the given ambient based on the tasks and the consideration about control type and communication made so far the possible types of max and controllers can already be defined the Dec is a simple speed controller typically used for applications such as roller-blind drives blower or pumps or cutting and grinding appliances the

00:10:28 Escom is a very versatile dynamic current and speed controller it can be used when the requirements about control performance are higher as in drives for conveyors and all kinds of handheld tools and scanners the APIs is the standard solution for positioning and or if bus communication is required typical applications include all kind of actuators laboratory automation door

00:10:57 drives and similar max Paz is a high dynamic and fast controller requiring a high speed EtherCAT master system it's perfect for demanding multi access controls such as in robotics pick in place and on-the-fly processing the last black box consideration of our application covers environmental aspects and boundary conditions generally the interaction and difference with the

00:11:27 ambient on one hand any system has emissions that influence and even disturbed the environment and surrounding on the other hand any system is susceptible to ambient conditions some special conditions and requirements include temperature noise vibration and truck sterilization ionizing radiation electromagnetic interference space

00:11:56 applications combine a lot of these special ambient conditions including vacuum particular boundary mounting conditions may strongly influence the type and the costs of a drive usually the maximum drive dimensions defines also its maximum power and its price the service life of drives cannot be calculated exactly it strongly

00:12:22 depends on load cycle application and ambient conditions however the service life estimation is possible by means of experience values from similar applications the expected service life is usually given as service hours or number of working cycles having defined all these aspects gives us a very good general picture and understanding of the application from a

00:12:49 technical point of view at the commercial information and you are ready to continue with the next steps of drive selection which is a closer look at the required load forces and speed this is it for step 1 [Music]