Adept SmartMotion Systems: Power Sequencing
The timing diagrams in the following sections illustrate the power-on/power-off sequences for the enable- and disable-power process. These processes consist of several stages, from controlling the relay to supply power to the amplifiers (toggling high power), to toggling the brake signals. The sequence by which the process occurs is governed by the user-configurable parameters described in this documentation. For details on how these parameters are used under different conditions, click on a link in the list below, or scroll down to review the timing diagrams. For parameter descriptions, and information on specifying the parameter values, see the Robot Initialization Specifications menu.
Enable Power Sequence with uncalibrated robot
Enable Power Sequence for calibrated robot
Disable Power Sequence resulting from an E-Stop
Disable Power Sequence initiated by V+ DISABLE POWER program instruction
Enabling Power
The Enable Power sequence is different depending on whether or not the robot has been calibrated. Both sequences are described in the following sections.
Enable Power Sequence for robots that have not been calibrated
If the robot is not calibrated, enabling power asserts the high-power signal to the amplifiers, but does not assert drive enable or brake release. This allows the system builder to safely enable one drive at a time from within the interactive servo tuning menu in the SPEC program. The following timing diagram illustrates the enable power sequence for an uncalibrated robot.
Timing Diagram: Enable Power when Robot is Not Calibrated
Enable Power Sequence for calibrated robots
When power is enabled for a calibrated robot, the system asserts high-power to the amplifiers, enables the drive, and releases the brake. A number of parameters control the operation of this sequence, which is illustrated in the Timing Diagram below:
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The Time required for clutch to engage parameter (see Data 221) determines the amount of time provided for the clutch to engage before the high-power sequence continues.
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The Delay from high power on to amp enable (sec) parameter (Data 220/3) determines the amount of time the V+ operating system will wait after high-power is enabled before enabling the amplifiers.
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After enabling the amplifiers, the Max time to wait for amp enable parameter (Data 220/2) determines the amount of time the V+ operating system will wait for the servos to report that amp faults are clear and that the amp is enabled.
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Max time to wait for high power (sec) parameter (see Data 222) specifies the maximum amount of time V+ should wait after the servos have been enabledbefore reporting a successful startup. (See in the figure below)
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The Time required for brakes to release parameter (see Data 220/4) specifies the amount of time that the V+ operating system should wait after the brakes have been released before performing any motions. Setting a delay prevents the robot from moving when the brakes are still engaged.
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The Time required for brakes to engage parameter (see Data 220/5) specifies the amount of time to wait after the brakes have been enabled before disabling the amplifier. Setting this delay provides time for the brakes to engage when the power is disabled.
Two parameters are provided to filter out noise during the enable-power sequence: Machine signal fault configuration and Axis error time delay:
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The Machine Signal filter configuration parameter (see Data 1230) specifies a time period during which the axis signals must be asserted before the signal is recognized by the servo board. Note that this parameter applies to every input signal on the servo board (drive fault; Switch 1, previously labeled Overtravel; Switch 2, previously labeled Home. For more detailed information on the servo board inputs, see the Adept SmartMotion Installation Guide) During this time period an Error Block is enabled. This acts to filter out noise for axis signals during the enable-power sequence.
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The Axis error time delay parameter (see Data 1231) specifies a time period following the assertion of drive enable during which axis errors will not be recognized as asserted. This acts as a filter for noise errors caused by powering up the amplifier.
NOTE: The Axis error time delay parameter is configured from the Motor Amplifier Specifications menu.
The following timing diagram illustrates the enable-power sequence for a calibrated robot. Each time period in which a parameter is in effect is indicated by a label. For example, the label Data 221 indicates when the Time required for clutch to engage parameter is used. To view details about a Data label, click on the label name or review the description above.
Timing Diagram: Enable Power when Robot is Calibrated
Disabling Power
Power-down sequencing in Adept controllers is controlled with a combination of hardware and software interlocks. For safety reasons, an E-Stop, overtravel, or axis fault immediately disables power (engaging the brakes and disabling the drives as well) via a hardware interlock, while disabling power using the V+ POWER system switch initiates the sequence through software. In the case of an overtravel or axis fault orginating on the servo board, the error is reported to V+, which powers down any other servo boards in the system.
Disable Power Sequence for E-STOP
In the case of an E-Stop fault, all servo boards in the system power down simultaneously. As shown in the figure below, the hardware sequence is much more abrupt than the software sequence, which disables power with a more controlled, step-by-step method as shown in the Timing Diagram: Disable Power initiated from program. The power-down sequence is controlled by the parameter Time required for brakes to engage: (see Data 220/5) which specifies the amount of time to wait after the brakes have been enabled before disabling the amplifier. Setting this delay provides time for the brakes to engage when the power is disabled.
Timing Diagram: Disable Power Sequence for E-STOP
Disable Power Sequence initiated from a program
When power is disabled under program control (i.e., via the DISABLE POWER program instruction), the software power-down sequence begins. In this sequence, the Robot Initialization parameter Time Required for Brakes to Engage (see Data 220/5) indicates how long the robot should continue to servo in position after engaging the brakes before disabling power to the amplifiers. This gives time for the brakes to engage so that gravity-loaded joints don't drop during power-down.
Timing Diagram: Disable Power initiated from program
