Motion Control Dictionary
Find simplified definitions and links to related terms in this easy to use Motion Control Dictionary. This glossary is filled with common terms used in the motion control industry as well as terms you are likely to hear when talking with our technical support and sales staff.
A
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Axis | The components that control each degree of freedom in a machine can be considered an axis. An X-Y-Z machine is a three axis machine where the X and Y axes control movement in the horizontal plane and the Z axis controls up and down motion. Each axis can consist of a controller, drive, motor, and transmission components necessary to couple to the load. | ||
| Axes | Plural of axis. Also plural of ax. | ||
| Attenuate | Reduction or drop in output. A signal that starts with one voltage may end up with a much lower voltage after it has been transmitted over a long line. This signal can be said to have attenuated. | attenuation | |
| ARO | After Receipt of Order. This is a common starting point for quoting lead times. "3 weeks ARO" means the product will be shipped three weeks after we receive the order. | ||
| Analog | The property of having continuous variability in output. | digital | |
| Amplifier | In motion control this is the component that follows the command from a controller and provides power to the motor. In the strictest sense, amplifiers operate in current mode where the output current is proportional to the input command signal. In the motion control industry, the terms amplifiers and drives are often interchanged. | drive | |
| Ampere | Ampere. The basic unit of electric current. | Ampere, Amp, A | current |
| Amperage | The strength of an electric current expressed in amperes. | ||
| Amp | Ampere. The basic unit of electric current. | Ampere, Amp, A | current |
| Alternating current | Alternating Current. Typical power source that comes 'out of the wall'. Single phase and three phase are standard. In the USA the standard values are 120VAC single phase and 240VAC three phase. | AC, alternating current | |
| Actuator | For servo systems, any device (such as a motor) that outputs mechanical motion using electricity as the power source. | ||
| Acceleration feedforward | In the velocity loop, acceleration feedforward acts to inject additional torque/force to compensate for delays inherent during high rates of change in velocity. | acceleration feedforward, feedforward, velocity feedforward | |
| AC line filter | A filter that connects to the incoming AC on a machine. Intended to keep the electrical noise produced in the machine from polluting the AC in the building. | ||
| AC | Alternating Current. Typical power source that comes 'out of the wall'. Single phase and three phase are standard. In the USA the standard values are 120VAC single phase and 208VAC three phase. | AC, alternating current | AC, single phase, three phase |
| A | Ampere. The basic unit of electric current. | Ampere, Amp, A | current |
B
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Bypass capacitor | A capacitor placed near the input of a component to stabilize the voltage source by supplying low impedance power. A bypass capacitor of 1000uF is recommended to be placed across the DC power supply wires within 1 foot (0.3m) of the drive if the length of the power wires exceeds 5 feet (1.5m). | ||
| Bus voltage | The voltage level of the main power supply. | ||
| Bus | A main supply circuit that powers major components in a system. | ||
| Base speed | The highest speed rating of a motor. | base speed, set speed | |
| Bandwidth | A measurement of the responsiveness of a system. The higher the bandwidth the faster and more responsive it is. Bandwidth can be measured by first determining the output given a slow sine wave command. Then increasing the frequency of the sine wave until the output has decreased by a multiple 0.707. The resulting frequency is the bandwidth. | ||
| Band pass filter | A filter that targets a specific frequency or range of frequencies and removes everything else. This type of filter is good when useful frequencies are confined to a specific range and removing the other frequencies is desired. | ||
| Balance pot | A potentiometer used to set the output of a drive so it doesn't have an offset. | balance, balance pot, offset | |
| Balance | The process of equalizing an output so it doesn't favor one direction over another. | offset | balance, balance pot, offset |
| Backlash | The play caused by loose connections between mechanical components. Backlash becomes a problem when an axis changes direction. When a motor turns, it pushes all the gears together in one direction. When the motor reverses direction the gear teeth separate from one side and meet on the other side. The distance between the separation is the backlash. |
C
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Current mode | A drive mode where only the current loop is active. In current mode, the velocity loop and position loop are either disabled, non-existent or closed outside of the drive. | ||
| Current loop | The current loop regulates the current in the majority of ADVANCED Motion Controls drives. The current loop is the innermost loop and the foundation for high performing velocity and position loops. Since motor torque is proportional to motor current the current loop is also known as the torque loop. | current loop, torque loop | current loop, position loop, velocity loop |
| Current limit potentiometer | In ADVANCED Motion Controls analog drives this pot controls the output current limit of the drive. | ||
| Current | The flow of electric charge. | Ampere, Amp, A | |
| Critically damped | A system tuned to achieve the fastest response without overshoot/oscillation is considered to be critically damped. In control theory this occurs when the damping ratio ζ = 1. | critical damping | critically damped, over damped, tuning, under damped |
| Coupling | The transfer of energy from one circuit to another by means of the mutual capacitance between them. In feedback and control systems this is considered to be electrical noise and is a common problem. | capacitive coupling, couple, coupling | electrical noise |
| Couple | The transfer of energy from one circuit to another by means of the mutual capacitance between them. In feedback and control systems this is considered to be electrical noise and is a common problem. | capacitive coupling, couple, coupling | electrical noise |
| Contouring | In multi axis machines this is the process of creating smooth and rounded movements using two or more coordinated axes. An X-Y table in a machining application would use contouring to cut a smooth circle. | point to point | |
| Continuous | Constant or unending. In AMC drives the continuous current rating is usually 1/2 the peak rating. | ||
| Commutation | The act of maintaining the correct torque angle on a motor. In brushed motors the commutation is achieved inside the motor via the commutator and brushes. In brushless motors the commutation is achieved by using feedback to determine the motor position and using commutation algorithms to output current to the correct phases. | ||
| Commission | To set up or configure for operation. ex: "Use the setup software to commission the drive." | commission, configure, set up | |
| Cogging | Torque ripple that is centered around specific locations of the motor revolution. When felt by hand the motor feels like it is easier to turn in some positions and more difficult to turn in others. A motor with no cogging would feel very smooth as it is spun by hand. | cogging, detent | |
| Closed loop | Closed loop controls use feedback to correct for errors in the system. Central heating in a building is a common example. The thermostat measures the temperature and turns the heat on or off as necessary. If the temperature is too low the heat turns on, if the temperature is too high the heat turns off. The result is the temperature will hover around the set-point throughout the day regardless external fluctuations like time of day or the weather. Closed loop control in motion control takes the form of a motor, drive, encoder and controller. The encoder is the feedback and senses if the motor is out of position. If out of position the system corrects itself until it is in the correct location. | closed loop, open loop | |
| Capacitor | A device that stores electrical charge. | ||
| Capacitive coupling | The transfer of energy from one circuit to another by means of the mutual capacitance between them. In feedback and control systems this is considered to be electrical noise and is a common problem. | capacitive coupling, couple, coupling | electrical noise |
| Capacitance | The measurement of how much charge can be stored in a capacitor. Capacitance is measured in Farads (F). Since 1F is a very large amount of capacitance, a more common unit is the microfarad or 1/1000000 of a Farad. |
D
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Dual loop | A control scheme where velocity and torque feedback is on the motor (1st loop) and position feedback is on the load (2nd loop). Dual loop control increases accuracy at the load and, compensates for system backlash and stabilizes the system. | ||
| Driver | A device that controls or regulates another device. For example, gate driver controls the output of an IGBT power device, or a line driver can be used to boost an encoder signal. | ||
| Drive | In motion control this component follows the command from a controller and provides power to the motor. A drive can operate in current mode, velocity mode or position mode. It can be commanded by many means such as analog signals, step and direction, encoder following and through network commands among others. | ||
| Directional inhibit | A type of inhibit that disables motion in one direction. Typically used near the end-stops on a machine. This can be used to prevent a load from crashing into the end-stop while allowing the drive to apply power to reverse direction. Can also be used to ensure that a drive does not reverse direction on one-way machines. | directional inhibit, inhibit, negative inhibit, positive inhibit | |
| Direct drive | When the motor is directly coupled to the load with no gearing or other mechanical transmission. | ||
| Digital | Expression of discrete numerical values. Digital components communicate and interact using the 1's and 0's of binary code. | ||
| Detent | The magnets in a motor create points that the motor favors, and points that the motor tries to stay away from, these are called detents. As a disconnected motor is turned the detent points can be felt by hand. The less detent there is, the smoother the motor will be when it is put into operation. | cogging, detent | |
| Derivative gain | The derivative gain effects the damping on a system. It determines the contribution of restoring force proportional to the rate of change (derivative) of position error. This force is much like the viscous damping in a shock absorber. | derivative, derivative gain, integrator, integrator gain, proportional, proportional gain | |
| Derivative | The slope or rate of change in a function. The derivative of position is velocity. The derivative of velocity is acceleration. | derivative, derivative gain, integrator, integrator gain, proportional, proportional gain | |
| DC shunt | Usually a calibrated low value resistor used to measure currents that are too high for a volt meter. Also a power resistor used to draw excess voltage off of a power supply. | ||
| DC | Direct Current. A current source that is constant. | AC, alternating current |
E
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Encoder following | A master slave control scheme where the encoder from the master is used to command a second axis (slave). This is a useful feature when it is desired to have one axis follow a second such as in a gantry or conveyor. This feature can be combined with electronic gearing. | electronic gearing, encoder following | |
| Encoder | A high precision feedback device that gives position and velocity data. Resolution ranges from just a few hundred counts per revolution to over a million counts per revolution. | encoder, feedback, resolver | |
| Electronic gearing | Mechanical gears can be replaced with electronic gearing where one motor will follow a second but at a fraction or multiple speed. | electronic gearing, encoder following | |
| EEPROM | Electrically Erasable Programmable Read Only Memory. Non-Volatile Memory that can be erased and reprogrammed. Versus RAM that loses its memory when the device is turned off or permanent memory that can only be written to once. | Double EPROM, E2PROM |
F
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Floating ground | A ground that is not referenced to earth ground. Floating grounds can make dangerous or exciting situations if not handled correctly. For example, when 120VAC is rectified into DC, the ground is considered to be a floating ground. Any attempt to tie the rectified AC ground to earth ground would likely blow a breaker or a fuse. The solution in this case is to first isolate the AC using a transformer before rectification. | ||
| Firmware | Firmware is programming that has been permanently or semi-permanently stored. Firmware is commonly stored in flash or EEPROM memory which both have the ability to keep their information, even when powered off. It is also easy to re-program flash and EEPROM memory when new firmware updates become available. When used in devices that are frequently powered off, firmware allows these devices to turn on again without having to be re-programmed. | firmware, hardware, software | |
| Filter | A component (either hardware, software or firmware) that removes unwanted portions of a signal. | filter, low pass, high pass, band pass, notch | |
| FILO | First In Last Out | ||
| FIFO | First In First Out | ||
| FET | Field Effect Transistor. Used as the output power devices in PWM drives. | FET, IGBT, MOSFET | |
| Ferrite | A ceramic material with magnetic properties. Used in suppression cores to reduce electronic noise emissions. | ferrite, suppression core | |
| Feedforward | Feedforward control gives corrective action before the disturbance affects the output. | acceleration feedforward, feedforward, velocity feedforward | |
| Feedback | Feedback is the measurement of the parameter that is being controlled. For a positioning system to accurately compensate for an error, the actual position must be known relative to the commanded position. In this case, position feedback would be used to provide the actual position. | encoder, feedback, resolver, tachometer |
G
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Gain | Gain is a multiplier between an input and an output. It is defined as the output divided by the input. Unity gain occurs when the output equals the input. A gain of 5 causes 1V input to result in 5V output. A gain of 0.5 causes 2V input to result in 1V output. Units are also associated with gain values. In a velocity mode servo drive the gain could be 100(rpm/Volt). This means 1V input will result in 100rpm output. |
H
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Hz | Abbreviation for Hertz. | Hertz, Hz | |
| Hertz | A unit of frequency in units of 1/s. 60Hertz is 60/s or 60 times per second. 20kHz is 20,000 times/second. | Hertz, Hz | |
| Hardware | The physical components in a device such as resistors and capacitors and IC chips. | firmware, hardware, software | |
| High pass filter | A filter that only allows frequencies above a set value to pass. In motion control, high pass filters are not normally seen at the user level. | filter, low pass, high pass, band pass, notch |
I
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| IR compensation mode | This mode is a 'pseudo-velocity' mode because the actual motor velocity is not measured. The velocity loop is closed by estimating motor velocity by using the motor terminal voltage and the motor current. An increase in the motor current is interpreted as the motor slowing down because of an obstruction. Positive feedback into the velocity loop acts as compensation. IR compensation mode can cause the system to become unstable because of the positive feedback, therefore one must be cautious when adjusting the gains.. | ||
| IO | Abbreviation for Inputs and Outputs. '24V I/O' means the inputs and outputs operate at 24V. | I/O, IO | |
| INV | The -INV option on ADVANCED Motion Controls analog drives causes the functionality of the Inhibit lines to be inverted. | INV, negative logic, positive logic | |
| Interpolator | A subroutine that interpolates. AMC drives use 3rd order interpolation positioning. This reduces network traffic by allowing the controller to send fewer position points but still keep smoothness and accuracy between points. | interpolate, interpolator, PVT | |
| Interpolate | To calculate values between two intermediate points. Linear interpolation connects the dots with straight lines with no smoothness. 3rd order interpolation uses smooth curves between points. | interpolate, interpolator | |
| Integrator gain | Integrator gain uses the integrator function to determine the output of a gain stage. This is a time based gain where the magnitude of the output is determined by how much error there is and how long the error has occurred. | derivative, derivative gain, integrator, integrator gain, proportional, proportional gain | |
| Integrator | A mathematical function that determines the area under a curve. | derivative, derivative gain, integrator, integrator gain, proportional, proportional gain | |
| Input | A pin that senses the voltage state of a line. Can be either digital or analog. | input, output, sinking input, sinking output, sourcing input, sourcing output | |
| Inhibit | A logic input on AMC drives that disables the output power. The inhibit line is used to turn off the drive's output while the drive is powered. Often employed in e-stop conditions or when the control system detects improper operation. | directional inhibit, inhibit, negative inhibit, positive inhibit | |
| Inductor | A coiled wire usually wrapped around an iron core. Inductors and the property of inductance are very important to the operation of PWM drives. An inductor resists change in current. This property is useful since it keeps the current from rising too quickly when the PWM is ON and it keeps the current from falling too quickly when the PWM is OFF. The net effect is that it stabilizes the current loop by making the current more manageable and predictable. | ||
| Inductive | An electric property that is related to the resistance to change in current. | ||
| Inductance | An electric property that is related to the resistance to change in current. | ||
| IGBT | Insulated Gate Bipolar Transistor. Used as the output power devices in PWM drives. IGBT's are good for high voltage and high current drives. | FET, IGBT, MOSFET | |
| I/O | Abbreviation for Inputs and Outputs. '24V I/O' means the inputs and outputs operate at 24V. | I/O, IO |
J
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| J1 | On some AMC drives the J1 jumper is a zero ohm surface mount resistor that controls the inhibit logic. With J1 installed, the drive will inhibit when the inhibit line is pulled low. When J1 is removed, the drive will enable when the inhibit line is pulled low. Most AMC drives do not use the J1 jumper, and instead use a switch or are configured in software. |
K
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Kp | Common abbreviation for proportional gain. | ||
| Ki | Common abbreviation for Integral gain. | ||
| Kd | Common abbreviation for derivative gain. |
L
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Low pass filter | A filter that only allows frequencies below a set value to pass. Used to filter the input command and feedback to reduce annoying high frequency buzzing and oscillations. | filter, low pass, high pass, band pass, notch | |
| Loop gain | This refers to the velocity loop on AMC analog drives. | ||
| Legacy | Legacy products are older products that are no longer manufactured. |
M
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| MTBF | Mean Time Before Failure. A measurement of the expected reliability of a component. Measured in millions of hours or years, it is how long the average device will continue to operate before it fails. The MTBF is often estimated by adding up the individual failure rates of all the components used in the device. This method is popular but can be grossly inaccurate. | ||
| MOSFET | Metal-Oxide Semiconductor Field-Effect Transistor. Used as the output power devices in PWM drives. MOSFET's are good for lower voltage and lower current drives. | FET, IGBT, MOSFET |
N
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| NRE | Non Recurring Engineering or Non Recurring Expense. During the process of designing a custom drive we will sometimes charge an NRE to help pay for the cost of development. As the acronym implies, NRE charges only occur once at the time of development. | ||
| Notch filter | A filter that targets a specific frequency or range of frequencies and removes it. During operation, a machine housing may have a natural frequency that causes it to shake or vibrate. A notch filter set to this natural frequency may be a useful tool to remove the shaking without sacrificing performance. | filter, low pass, high pass, band pass, notch | |
| Noise | Unwanted signals that interfere with normal operation. | ||
| Negative logic | In electronics, logic levels are indicated with voltage levels. In negative logic, the 'true' condition is indicated by the lower voltage and the 'false' condition is indicated by the higher voltage. In 0-5V logic, 0V would be a 'true' and 5V would be a 'false'. In (-5)-0V logic, (-5V) would be a 'true' and 0V would be a 'false'. | INV, negative logic, positive logic | |
| Negative inhibit | A type of inhibit that disables motion in one direction. Typically used near the end-stops on a machine. This can be used to prevent a load from crashing into the end-stop while allowing the drive to apply power to reverse direction. Can also be used to ensure that a drive does not reverse direction on one-way machines. | directional inhibit, inhibit, negative inhibit, positive inhibit |
O
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Over damped | In tuning a system, the response is considered to be over damped when the step response is very slow and there is no overshoot. In control theory this occurs when the damping ratio ζ > 1. | critically damped, over damped, tuning, under damped | |
| Output | A pin that controls the voltage state of a line. Can be either digital or analog. | ||
| Optocoupler | An optocoupler uses an LED and a phototransistor to achieve electrical isolation between two circuits. A signal from the first circuit causes current to flow through the LED. Current through the LED creates light. The light causes the phototransistor to turn on. The activated transistor then causes current to flow through the second circuit. Since there is no electrical path from the first circuit to the second and the signal medium is optical (light), this is called optical isolation. | optical isolation, optocoupler | |
| Open loop mode | A mode option seen on ADVANCED Motion Controls analog drives. In this mode the output duty cycle is proportional to the input command. Open loop mode is similar to voltage mode but with less regulation. | IR compensation, open loop mode, voltage mode | |
| Open loop | An open loop system does not rely on feedback for control. A washing machine is a good example. The machine goes through its cycles based on a timer. It spends a set amount of time on each process then moves to the next. | closed loop, open loop | |
| Offset potentiometer | A potentiometer on AMC analog drives that balances the output to remove any offset. To set this pot, enable the drive and command 0V to the Ref input. The motor may move or favor torque in one direction. Turn the offset potentiometer until the motion or offset torque is set to an acceptable level for your machine. | balance, balance pot, offset | |
| OEM | Original Equipment Manufacturer. An OEM assembles individual components or parts into another component or a completed product. OEM's use AMC products and couple them with motors, controllers and other equipment to make machines. |
P
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| PWM | Pulse Width Modulation. AMC drives use PWM to control the current to the motor. By changing the Pulse Width (duty cycle) the output voltage and current can be controlled. | ||
| PVT | Position Velocity Time. In PVT mode a controller sends Position, Velocity and Time signals to the drive. The drive follows these commands and uses interpolation algorithms to "connect the dots" and create smooth coordinated motion. This network based command greatly reduces network traffic by allowing the drive to interpolate the intermediate points between the PVT points. PVT can tightly coordinate multiple axes with smooth, precise and exactly timed motion. | interpolate, interpolator, PVT | |
| Proportional gain | Proportional gain gives an output that is directly proportional to the error. | derivative, derivative gain, integrator, integrator gain, proportional, proportional gain | |
| Proportional | A mathematical function that relates two variables with a fixed multiplier. | derivative, derivative gain, integrator, integrator gain, proportional, proportional gain | |
| Power supply | The source that supplies voltage and current to the drive. | power supply, supply | |
| Power | Energy per unit time, E/t. Common units are: Watts (W) and Horse Power (HP). Electrical power can be calculated using these equations: V*I, I^2*R, V^2/R. Mechanical power can be calculated using these equations: Torque*speed, F*V. | ||
| Potentiometer | A device that uses a variable resistor to control the voltage output. | pot, potentiometer | |
| Pot | Short for potentiometer. | pot, potentiometer | |
| Positive logic | In electronics, logic levels are indicated with voltage levels. In positive logic, the 'true' condition is indicated by the higher voltage and the 'false' condition is indicated by the lower voltage. In 0-5V logic, 0V would be a 'false' and 5V would be a 'true'. In (-5)-0V logic, (-5V) would be a 'false' and 0V would be a 'true'. | INV, negative logic, positive logic | |
| Positive inhibit | A type of inhibit that disables motion in one direction. Typically used near the end-stops on a machine. This can be used to prevent a load from crashing into the end-stop while allowing the drive to apply power to reverse direction. Can also be used to ensure that a drive does not reverse direction on one-way machines. | directional inhibit, inhibit, negative inhibit, positive inhibit | |
| Position loop | The position loop regulates the position of the motor or system. The position loop uses feedback such as an encoder to ensure that the actual position is equal to the commanded position. The position loop will compensate for position errors by applying more torque to push the system back into position. | current loop, position loop, velocity loop | |
| Peak | Peak current in AMC drives typically lasts for about 1 second. After the peak time duration has been exceeded the drive automatically 'folds back' to the continuous current setting of the drive. The peak current is typically rated to twice the continuous current. | ||
| PDO | Programmable Digital Output. A digital output that can be configured to indicate the status for many conditions such as: In Position, At Velocity, Over Speed, Fault, etc. | ||
| PDI | Programmable Digital Input. A digital input that can be configured for many functions such as: Inhibit, Home, Reset Fault, etc. | ||
| PAO | Programmable Analog Output. An analog output that can be configured and scaled to indicate different conditions such as: Output Current, Motor Speed, Motor Position, Temperature, etc. | ||
| PAI | Programmable Analog Input. An analog input that can be configured and scaled for different functions such as: Commanded Torque, Commanded Speed, Commanded Position, Current limit, etc. |
Q
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Quiescent power | The amount of power consumed when the drive is turned on but disabled. The quiescent power is used to keep the drive logic operational. This is of interest to designers of battery powered systems where there is a limited supply of power. Otherwise most users consider this to be negligible. | standby power |
R
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Run away | In control systems, Run Away occurs when feedback is lost or inverted. When there is no feedback the system detects that the velocity is zero or the position is stationary. If the system is trying to reach a velocity or position other than what it is detecting, the system will try to compensate. However with no feedback it will appear to the system that the load is not moving so the system will try to add more power. The end result is a system that is outputting full power that causes the load to spin out of control and possibly crash into something. | ||
| RMS | Root Mean Square. This is the standard method of characterizing the average output of cyclical, periodic and/or repeating functions. RMS calculations are especially useful when determining the output of a symmetrical wave centered around zero. If straight averaging was used on a sine wave the result would be 0 since half of the waveform is above 0 and the other half is below. If your electric company used straight averaging to determine your bill then you would be getting your power for free! The RMS for some common waveforms can be calculated using a multiplier and the amplitude. For sine waves the multiplier is 0.707, square waves 1, and triangle waves 0.577. | ||
| RMA | Return Materials Authorization. AMC uses RMA numbers to track returns. An RMA number can be obtained from the returns department or from anyone in customer service. Please call 805-389-1935 or request an RMA number using the customer service contact form. | ||
| Resolver | A high resolution feedback device that is an alternative to encoders. Resolvers are suited to harsh environments such as high temperatures and severe vibration since they do not rely on optical sensors or glass disks which can fail in these conditions. Resolvers use inductive coupling to determine rotor position. Since resolver signals are not discrete, resolution is determined by the amount of interpolation used in the interface circuitry in the drive or controller. Typical resolutions range from 1000 to 65000 counts / revolution. | encoder, feedback, resolver | |
| Regeneration | Regeneration is when the motor begins to act as a generator. This occurs when the motor torque is in the opposite direction as the motor velocity. Regeneration can become a problem if the power supply is unable to absorb the extra energy. In some cases the drive can shut down due to over voltage or the power supply can be damaged. For example a motor can apply a torque to the wheels on an electric cart. The cart will then accelerate to a velocity. To decelerate, an opposite torque would be used to slow down the wheels. Since the cart is already moving and it has momentum, it may take several seconds of negative torque to bring the cart to a stop. During this time the motor velocity is in the opposite direction as the motor torque and therefore the system is in regeneration. | regeneration, shunt regulator, shunt resistor | |
| Regen | short for regeneration | ||
| Reference gain potentiometer | On AMC analog drives the reference gain is adjusted using the Reference Gain Potentiometer | ||
| Ref gain | Reference Gain. The Reference Gain is the first gain stage after the reference input or command input. This gain adjusts the overall gain of the amplifier. |
S
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Switcher | Typically refers to PWM switching to control current, as opposed to linear control. | ||
| Suppression core | Used for electrical noise suppression. Suppression cores are made out of a ceramic ferrite material. They have inductive properties that target specific frequencies to attenuate (reduce) electrical noise without adversely affecting performance. | ferrite, suppression core | |
| Supply | The source that supplies voltage and current to the drive. | power supply, supply | |
| Stepper | A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. The shaft or spindle of a stepper motor rotates in discrete step increments when electrical command pulses are applied to it in the proper sequence. Advantages: Affordable solution for low torque and low/medium performance positioning. Disadvantages: Lower efficiency and performance than servos. | ||
| Step and direction | A type of command that uses two digital lines to control motion. One line is used to increment position or velocity, the other line is used to indicate direction. Originally developed to control stepper motors AMC has adapted this type of control to control servo motors. | ||
| Standby Power | The amount of power consumed when the servo drive is turned on but disabled. The standby power is used to keep the servo drive logic and feedback operational in order to track position changes, monitor I/O and receive commands and communication. This is of interest to designers of battery powered systems where there is a limited supply of power. Otherwise most users consider this to be negligible. | ||
| Sourcing output | An output where the direction of current flows out of the output. Sourcing outputs are compatible with sinking inputs. | input, output, sinking input, sinking output, sourcing input, sourcing output | |
| Sourcing input | An input where the direction of current flows out of the input. Sourcing inputs are compatible with sinking outputs. A sourcing input works by internally pulling the input line high through a pull-up resistor. The output however is able override this voltage and pull it low. | input, output, sinking input, sinking output, sourcing input, sourcing output | |
| Software | Computer programs that make hardware work. ADVANCED Motion Controls provides software that loads onto Windows based PC's to communicate and configure AMC digital drives. | firmware, hardware, software | |
| Sinusoidal | This often refers to motor commutation. Instead of the six distinct states of trapezoidal commutation, sinusoidal commutation uses smooth transitions from state to state. When viewing a complete cycle or cycles the result is a sine-wave pattern. | sinusoidal, trapezoidal | |
| Sinking output | An output where the direction of current flows into the output. Sinking inputs are compatible with sourcing inputs. A sinking output works by pulling low a line that is pulled up with a pull up resistor. | input, output, sinking input, sinking output, sourcing input, sourcing output | |
| Sinking input | An input where the direction of current flows into the input. Sinking inputs are compatible with sourcing outputs. | input, output, sinking input, sinking output, sourcing input, sourcing output | |
| Single phase | AC power that comes from two wires. Single phase AC has more voltage ripple and less output power compared with three phase AC power. | AC, single phase, three phase | |
| Shunt resistor | The power resistor in a shunt regulator. The shunt regulator directs excess energy into the shunt resistor to 'burn off' extra voltage. | regeneration, shunt regulator, shunt resistor | |
| Shunt regulator | A device that clamps the power supply voltage from exceeding rated values. Shunt regulators are very useful in dealing with problems with regeneration. | regeneration, shunt regulator, shunt resistor | |
| Shunt | An alternate path for current to flow. | ||
| Set speed | The speed at which the system is commanded. | base speed, set speed | |
| Servo drive | The servo drive is the link between the controller and motor. Also referred to as servo amplifiers, their job is to translate the low energy reference signals from the controller into high energy power signals to the motor. | servo amplifier, servo drive | |
| Servo amplifier | The servo drive is the link between the controller and motor. Also referred to as servo amplifiers, their job is to translate the low energy reference signals from the controller into high energy power signals to the motor. | servo amplifier, servo drive | |
| Servo | Servo control, which is also referred to as "motion control" or "robotics" is used in industrial processes to move a specific load in a controlled fashion. | ||
| Scaling | A ratio that relates one thing to another. In velocity mode the scaling could be 2000rpm/V. This means for 1V input on the command the output would be 2000rpm. Then for 2V input with the same scaling the output would be 4000rpm. Scaling is commonly seen on such things as the current monitor, the velocity monitor, amplifier output and tachometers. |
T
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Turnkey | A system or product that has been fully configured and installed and is ready for operation. AMC offers OEM solutions rather than turnkey solutions. | ||
| Tuning | To adjust the gain stages in a control loop to achieve optimal performance. | tune, tuning | critically damped, over damped, tuning, under damped |
| Tune | To adjust the gain stages in a control loop to achieve optimal performance. | tune, tuning | critically damped, over damped, tuning, under damped |
| Trapezoidal | A commutation scheme for brushless motors that can affordably provide good servo performance in most applications. Trapezoidal commutation directs current through the three motor phases in 6 steps per electrical cycle. | sinusoidal, trapezoidal | |
| Trap | Short for trapezoidal. | ||
| Transconductance | The relationship of voltage to current in an electronic device. In servo systems, transconductance specifically refers to a current mode drive. The value of the transconductance is the gain in units of A/V. A drive with a transconductance of 2A/V would output 10A with a 5V input command. | ||
| Torque loop | The current loop regulates the current in the majority of ADVANCED Motion Controls drives. The current loop is the innermost loop and the foundation for high performing velocity and position loops. Since motor torque is proportional to motor current the current loop is also known as the torque loop. | current loop, torque loop | current loop, position loop, velocity loop |
| Torque | A rotational force. Torque is measured in N*m, lb*in, lb*ft, etc. 1 N*m is the torque produced by 1N of force applied to a lever arm that is 1m long. | ||
| Toroid | A geometrical shape similar to a doughnut. Ferrite suppression cores are often in the shape of a toroid. | ||
| Three phase | AC power that comes from three wires. Three phase AC power has less voltage ripple and more power compared with single phase AC power. | AC, single phase, three phase | |
| Tachometer mode | A drive mode that uses tachometer feedback to close the velocity loop. | ||
| Tachometer | A velocity feedback device that outputs a voltage that is proportional to velocity. Similar to a small generator mounted to the motor shaft. |
U
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Unstable | Not able to hold a commanded value because of poor tuning. Characterized by large oscillations that may increase in magnitude for each successive oscillation. | ||
| Under damped | In tuning, the response is considered to be under damped when there is overshoot or oscillations in the step response. In control theory this occurs when the damping ratio ζ < 1. | critically damped, over damped, tuning, under damped |
V
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Voltage mode | A servo drive mode where the output voltage is directly proportional to the input command. | ||
| Voltage | The strength of an electric potential expressed in volts. | ||
| Volt | SI unit of electric potential. The volt is the fluid equivalent of pressure or the mechanical equivalent of force. | V, volt | |
| Velocity mode | A servo drive configured for velocity mode turns the motor at a velocity that is proportional to the command. Small commands will generate small velocities and large commands large velocities. | ||
| Velocity loop | The velocity loop is the control loop that regulates velocity. | current loop, position loop, velocity loop | |
| Velocity feedforward | In the position loop, velocity feedforward acts to inject additional velocity to compensate for delays inherent during high rates of change in position. | acceleration feedforward, feedforward, velocity feedforward | |
| VDC | Abbreviation for Volts DC. | ||
| V | SI unit of electric potential. The volt is the fluid equivalent of pressure or the mechanical equivalent of force. | V, volt |
W
| Term | Definition | Synonyms | Related Terms |
|---|---|---|---|
| Wattage | SI unit of power. | ||
| Watt | SI unit of power. |