Patent Description:
This disclosure relates generally to materials testing, and more particularly, to material testing systems including safety systems requiring intentional function activation.

Universal testing machines are used to perform mechanical testing, such as compression strength testing or tension strength testing, on materials or components. <CIT> discloses a brassiere mold-forming machine. <CIT> discloses an apparatus and method for multiaxial impact testing of materials.

Material testing systems including safety systems requiring intentional function activation are disclosed, substantially as illustrated by and described in connection with at least one of the figures, as set forth more completely in the claims.

Conventional material testing systems use mitigation techniques, such as configuration switches, guarding, limited force controls, motion limiting, and/or protection, to improve operator safety. However, conventional material testing systems frequently do not always comply with international standards. Conventional mitigation techniques require the operator to place the system in the appropriate mode of operation, such as safe interaction or testing. Many conventional safety techniques can be implemented using off-the-shelf safety components, such as programmable logic controllers (PLCs) and/or relays. PLCs and relays typically add significant cost to the material testing system.

Disclosed example material testing systems embed or integrate a safety system complying with international standards within the material testing system. Because the safety system is integrated into the material testing systems, disclosed example material test systems provide safety improvements at a much lower cost than would be accomplished using off-the-shelf parts because the safety system is integrated into the existing electronics, semiconductors, and/or circuit boards of the material testing systems. Integration further improves reliability, which reduces or eliminates external wiring between purchased safety components.

As described in more detail below, disclosed example safety systems for material testing systems include machine state indicators that visually show the state of the testing machine from an operational restriction perspective. Disclosed example safety systems for material testing systems provide high reliability and monitored activation mechanisms at the machine point of control, which may include internal fault checking and/or power supply diagnostics within the material testing systems. In some examples, pneumatic grips are provided with two stage grip pressure control and monitoring. Disclosed example material testing systems are compatible with interlock guarding systems having redundant or diverse contacts. Such guarding systems comply with ISO safety standards by using redundant, diverse, and/or dynamic monitoring in real time. Disclosed example material testing systems include redundant crosshead travel limit monitoring. The material testing system shutdown circuitry of disclosed examples is compliant with international safety standards including ISO <NUM>-<NUM>.

Additionally, conventional off-the-shelf safety relay components used with PLCs use an extra layer of firmware within the PLC to stop the motion of the moving components during an emergency stop event. Disclosed example safety systems for material testing systems are configured to enable the hardware (e.g., an emergency stop button) to directly shutdown a power amplifier drive to the actuator(s), regardless of whether the embedded firmware within the safety processor is running.

Disclosed example material testing systems are compliant with the European Machinery Directive, following the rules set forth in the ISO <NUM>-<NUM> standard, which pertains to the "Safety Related Parts of Control Systems. " The following functions, which are determined by a system risk analysis, are integrated into the material testing system. The safety system provides a disabled drive state to remove energy from the drive crosshead, a disabled drive state to remove energy from the gripping system, and a restricted drive state for operator setup. In the restricted drive state, the example safety systems monitor the crosshead speed to maintain the crosshead speed below an upper speed limit, monitor for intentional manual movement (jogging) of the crosshead, monitor for reduced gripping pressure when closing, and/or monitor for intentional grip closure.

As used herein, a "crosshead" refers to a component of a material testing system that applies directional (axial) and/or rotational force to a specimen. A material testing system may have one or more crossheads, and the crosshead(s) may be located in any appropriate position and/or orientation in the material testing system.

Disabling of circuitry, actuators, and/or other hardware may be done via hardware, software (including firmware), or a combination of hardware and software, and may include physical disconnection, de-energization, and/or a software control that restricts commands from being implemented to activate the circuitry, actuators, and/or other hardware. Similarly, enabling of circuitry, actuators, and/or other hardware may be done via hardware, software (including firmware), or a combination of hardware and software, using the same mechanisms used for disabling. Firmware may include stored instructions such as Safety Rated Embedded Software (SRESW) and/or Safety Rated Application Software (SRASW).

The disclosed example material testing systems further include an unrestricted drive state, which enables the removal of checks in the restricted drive state. In some examples, the unrestricted drive state can be entered via a dual activation mechanism, in which material testing functionality is performed and the operator does not interact with the system.

Disclosed example material testing systems include indicators for different states, such as a disabled state, a setup state (e.g., restricted drive mode), a caution state (e.g., unrestricted drive mode), and a testing state (e.g., unrestricted drive mode) indication on every machine to clearly indicate when the operator may interact and when a hazard is present.

Disclosed example material testing systems include one or more stop functions that are configured to take precedence over the starting and/or continuation of motion of components such as the crosshead or grips. Furthermore, one or more stop functions may be redundantly configured via hardware such that the stop functions are effective to disable the material testing system even when software portions of the safety system are disabled. Examples of such stop functions that may be included in disclosed systems include interlocked guards and/or emergency stop switches.

Some disclosed example material testing systems include selection and enforcement of a single control point for starting the material testing frame and/or gripping system. Some example systems provide power failure monitoring and/or protection to ensure the system stops unrestricted operation and places the material test system into the disabled drive state upon re-establishment of power. In some examples, in response to a power failure, any pneumatic specimen gripping is automatically de-energized.

Disclosed example safety systems and material testing systems include increased internal diagnostics and reporting to the operator of critical errors within the system, such as malfunctions of equipment or conflicts between redundant inputs, outputs, and/or processes. Disclosed example material testing systems enable faster specimen removal and/or insertion, relative to conventional material testing systems, due to the safe setup mode of the testing machine that permits operator activity within the test space without disabling of the material testing system or requiring guard doors. Disclosed example systems further improve operator safety when setting up and configuring the system inside the test space, due at least in part to use of the setup state, which restricts motion of the crosshead and/or limited motion and/or force that can be exerted by the grips.

Disclosed material testing systems and safety systems may be specially configured to be utilized in the disclosed example configurations, to achieve identified risk mitigations. Disclosed material testing systems are significantly more efficient and targeted to materials testing than purchasing general purpose, off-the-shelf, discrete safety components.

Disclosed example material testing systems include: an actuator configured to control an operator-accessible component of the material testing system; an operator interface including a plurality of inputs; and one or more processors configured to: control the actuator based on at least one of a material testing process or an input from the operator interface; and require two or more inputs to be received within a predetermined threshold time to permit at least one operation of the actuator.

In some examples, the one or more processors are configured to require the two or more inputs to initiate each operation of the actuator by the processor. In some examples, the one or more processors are configured to, in response to pausing or cessation of the operation of the actuator, require the two or more inputs to restart the operation or start a different operation. According to the invention, the operator interface includes a button configured to output an unlocking signal while the button is depressed, wherein the one or more processors are configured to use the unlocking signal as one of the two or more inputs.

In some examples, the operator-accessible component includes an automatic grip configured to grip a material under test, wherein the actuator is configured to actuate the automatic grip, and the at least one operation includes applying more than a threshold pressure via the automatic grip. In some examples, the one or more processors are configured to permit control of the actuator to apply less than the threshold pressure via the automatic grip while fewer than the two or more inputs are received. In some examples, the operator-accessible component includes a crosshead configured to move to position a material under test or to apply force to the material under test, and the at least one operation includes at least one of moving of the crosshead or applying the force to the material under test.

In some examples, the operator-accessible component includes a crosshead configured to move to position a material under test or to apply force to the material under test, in which the at least one operation includes moving the crosshead at least a threshold speed. In some examples, the one or more processors are configured to permit control of the actuator to move the crosshead at less than the threshold speed while fewer than the two or more inputs are received. In some examples, the one or more processors are configured to, during operation of the actuator, cease operation of the actuator in response to determining that at least one of the two or more inputs is no longer being received.

In some examples, the one or more processors are configured to, during operation of the actuator, cease operation of the actuator in response to determining that none of the two or more inputs are being received. In some example material testing systems, the one or more processors are configured to, during operation of the actuator, continue operation of the actuator after the two or more inputs are no longer being received. In some such examples, the one or more processors are configured to cease operation of the actuator based on at least one of a conclusion of the material testing process, a pause in the material testing process, or an input from the operator interface.

In some example material testing systems, the one or more processors include: a control processor configured to perform the control of the actuator; and one or more safety processors configured to identify the two or more inputs and to permit at least one operation of the actuator.

Some disclosed example material testing systems include: an actuator configured to control an operator-accessible component of the material testing system; an operator interface including a plurality of inputs; a camera and a video processor configured to: detect an intrusion by processing images output by the camera; and output a non-detection signal in response to determining that an intrusion is not detected; and one or more processors configured to: control the actuator based on at least one of a material testing process or an input from the operator interface; and require two or more inputs to be received to permit at least one operation of the actuator, at least one of the two or more inputs including the non-detection signal.

Some disclosed material testing systems include: an actuator configured to control an operator-accessible component of the material testing system; an operator interface including a plurality of inputs; a pressure sensitive surface configured to: detect the presence of a pressure on the surface; and output a pressure signal in response to detecting the pressure; and one or more processors configured to: control the actuator based on at least one of a material testing process or an input from the operator interface; and require two or more inputs to be received to permit at least one operation of the actuator, at least one of the two or more inputs including the pressure signal.

Some disclosed material testing systems include: an actuator configured to control an operator-accessible component of the material testing system; an operator interface including a plurality of inputs; an operator detection switch configured to output a switch signal while the switch is actuated; and one or more processors configured to: control the actuator based on at least one of a material testing process or an input from the operator interface; and require two or more inputs to be received to permit at least one operation of the actuator, at least one of the two or more inputs including the switch signal.

Some disclosed material testing systems include: an actuator configured to control an operator-accessible component of the material testing system; an operator interface including a plurality of inputs; a presence detector configured to: detect a presence of an operator within a predefined volume; and output a presence signal when an operator is detected within the volume; and one or more processors configured to: control the actuator based on at least one of a material testing process or an input from the operator interface; and require two or more inputs to be received to permit at least one operation of the actuator, at least one of the two or more inputs comprising the presence signal.

Some disclosed material testing systems include: an actuator configured to control an operator-accessible component of the material testing system; an operator interface including a plurality of inputs; a proximity sensor configured to: monitor whether an operator is within a predetermined proximity of the proximity switch; and output a non-proximity signal when an operator is not detected within the predetermined proximity; and one or more processors configured to: control the actuator based on at least one of a material testing process or an input from the operator interface; and require two or more inputs to be received to permit at least one operation of the actuator, at least one of the two or more inputs including the non-proximity signal.

<FIG> is an example material testing system <NUM> to perform mechanical property testing. The example material testing system <NUM> may be, for example, a universal testing system capable of static mechanical testing. The material testing system <NUM> may perform, for example, compression strength testing, tension strength testing, shear strength testing, bend strength testing, deflection strength testing, tearing strength testing, peel strength testing (e.g., strength of an adhesive bond), torsional strength testing, and/or any other compressive and/or tensile testing. Additionally or alternatively, the material testing system <NUM> may perform dynamic testing.

The example material testing system <NUM> includes a test fixture <NUM> and a computing device <NUM> communicatively coupled to the test fixture <NUM>. The test fixture <NUM> applies loads to a material under test <NUM> and measures the mechanical properties of the test, such as displacement of the material under test <NUM> and/or force applied to the material under test <NUM>. While the example test fixture <NUM> is illustrated as a dual column fixture, other fixtures may be used, such as single-column test fixtures.

The example computing device <NUM> may be used to configure the test fixture <NUM>, control the test fixture <NUM>, and/or receive measurement data (e.g., transducer measurements such as force and displacement) and/or test results (e.g., peak force, break displacement, etc.) from the test fixture <NUM> for processing, display, reporting, and/or any other desired purposes.

<FIG> is a block diagram of an example implementation of the material testing system <NUM> of <FIG>. The example material testing system <NUM> of <FIG> includes the test fixture <NUM> and the computing device <NUM>. The example computing device <NUM> may be a general-purpose computer, a laptop computer, a tablet computer, a mobile device, a server, an all-in-one computer, and/or any other type of computing device.

The example computing device <NUM> of <FIG> includes a processor <NUM>. The example processor <NUM> may be any general purpose central processing unit (CPU) from any manufacturer. In some other examples, the processor <NUM> may include one or more specialized processing units, such as RISC processors with an ARM core, graphic processing units, digital signal processors, and/or system-on-chips (SoC). The processor <NUM> executes machine readable instructions <NUM> that may be stored locally at the processor (e.g., in an included cache or SoC), in a random access memory <NUM> (or other volatile memory), in a read only memory <NUM> (or other non-volatile memory such as FLASH memory), and/or in a mass storage device <NUM>. The example mass storage device <NUM> may be a hard drive, a solid state storage drive, a hybrid drive, a RAID array, and/or any other mass data storage device.

A bus <NUM> enables communications between the processor <NUM>, the RAM <NUM>, the ROM <NUM>, the mass storage device <NUM>, a network interface <NUM>, and/or an input/output interface <NUM>.

The example network interface <NUM> includes hardware, firmware, and/or software to connect the computing device <NUM> to a communications network <NUM> such as the Internet. For example, the network interface <NUM> may include IEEE <NUM>. X-compliant wireless and/or wired communications hardware for transmitting and/or receiving communications.

The example I/O interface <NUM> of <FIG> includes hardware, firmware, and/or software to connect one or more input/output devices <NUM> to the processor <NUM> for providing input to the processor <NUM> and/or providing output from the processor <NUM>. For example, the I/O interface <NUM> may include a graphics processing unit for interfacing with a display device, a universal serial bus port for interfacing with one or more USB-compliant devices, a FireWire, a field bus, and/or any other type of interface. The example material testing system <NUM> includes a display device <NUM> (e.g., an LCD screen) coupled to the I/O interface <NUM>. Other example I/O device(s) <NUM> may include a keyboard, a keypad, a mouse, a trackball, a pointing device, a microphone, an audio speaker, a display device, an optical media drive, a multi-touch touch screen, a gesture recognition interface, a magnetic media drive, and/or any other type of input and/or output device.

The example computing device <NUM> may access a non-transitory machine readable medium <NUM> via the I/O interface <NUM> and/or the I/O device(s) <NUM>. Examples of the machine readable medium <NUM> of <FIG> include optical discs (e.g., compact discs (CDs), digital versatile/video discs (DVDs), Blu-ray discs, etc.), magnetic media (e.g., floppy disks), portable storage media (e.g., portable flash drives, secure digital (SD) cards, etc.), and/or any other type of removable and/or installed machine readable media.

The example material testing system <NUM> of <FIG> further includes the test fixture <NUM> coupled to the computing device <NUM>. In the example of <FIG>, the test fixture <NUM> is coupled to the computing device via the I/O interface <NUM>, such as via a USB port, a Thunderbolt port, a FireWire (IEEE <NUM>) port, and/or any other type serial or parallel data port. In some other examples, the test fixture <NUM> is coupled to the network interface <NUM> and/or to the I/O interface <NUM> via a wired or wireless connection (e.g., Ethernet, Wi-Fi, etc.), either directly or via the network <NUM>.

The test fixture <NUM> of <FIG> includes a frame <NUM>, a load cell <NUM>, a displacement transducer <NUM>, a cross-member loader <NUM>, material fixtures <NUM>, a control processor <NUM>, and a safety system <NUM>. The frame <NUM> provides rigid structural support for the other components of the test fixture <NUM> that perform the test. The load cell <NUM> measures force applied to a material under test by the cross-member loader <NUM> via the grips <NUM>. The cross-member loader <NUM> applies force to the material under test, while the material fixtures <NUM> (also referred to as grips) grasp or otherwise couple the material under test to the cross-member loader <NUM>. The example cross-member loader <NUM> includes a motor <NUM> (or other actuator) and a crosshead <NUM>. The crosshead <NUM> couples the material fixtures <NUM> to the frame <NUM>, and the motor <NUM> causes the crosshead to move with respect to the frame to position the material fixtures <NUM> and/or to apply force to the material under test. Example actuators that may be used to provide force and/or motion of a component of the material testing system <NUM> include electric motors, pneumatic actuators, hydraulic actuators, piezoelectric actuators, relays, and/or switches.

Example grips <NUM> include compression platens, jaws or other types of fixtures, depending on the mechanical property being tested and/or the material under test. The grips <NUM> may be manually configured, controlled via manual input, and/or automatically controlled by the control processor <NUM>. The crosshead <NUM> and the grips <NUM> are operator-accessible components.

The example control processor <NUM> communicates with the computing device <NUM> to, for example, receive test parameters from the computing device <NUM> and/or report measurements and/or other results to the computing device <NUM>. For example, the control processor <NUM> may include one or more communication or I/O interfaces to enable communication with the computing device <NUM>. The control processor <NUM> may control the cross-member loader <NUM> to increase or decrease applied force, control the fixture(s) <NUM> to grasp or release a material under test, and/or receive measurements from the displacement transducer <NUM>, the load cell <NUM> and/or other transducers.

The example safety system <NUM> provides an additional layer of monitoring and control to the test fixture <NUM>. The safety system <NUM> monitors operator inputs and the state of the test fixture <NUM>. In the example of <FIG>, the safety system <NUM> restricts operation of the test fixture <NUM> by the user so that the test fixture <NUM> is only controllable by the user when the machine is in an appropriate state. In response to detecting one or more conditions, the safety system <NUM> will automatically cause the test fixture <NUM> to go to a restricted state (e.g., a restricted setup state, disable all power and motion that could present a hazardous condition, etc.).

As discussed in more detail below, the safety system <NUM> selectively adds, removes, increases, and/or decreases restrictions on operation of the material testing system based on monitoring input signals from the material testing system <NUM>, input signals from the safety system <NUM>, and/or control signals from the control processor <NUM>. The safety system <NUM> controls operation of the material testing system <NUM> by determining a state, from multiple predetermined states, in which the material testing system <NUM> is to be operated at any given time. Example predetermined states include one or more restricted states, in which one or more operations of the material testing system <NUM> are restricted (e.g., disabled, limited, etc.) and one or more unrestricted states, in which the restrictions of the restricted states are reduced and/or removed. In the example of <FIG>, the safety processor <NUM> attaches to and/or interrupts the control of the cross-member loader <NUM> and/or the fixture(s) <NUM> by the control processor <NUM>. In some other examples, the safety system <NUM> may directly control the cross-member loader <NUM> and/or the fixture(s) <NUM> while enforcing any applicable restrictions on the actuators.

Example restricted states include a setup state and a disabled state. In the setup state, the safety system <NUM> restricts one or more actuators (e.g., the motor <NUM> and/or the grip actuator(s) <NUM>), and controls (or permits control of) the actuators in response to operator inputs. Example restrictions on the motor <NUM> and/or the crosshead <NUM> may include an upper speed limit, and/or an upper or lower position limit of the crosshead <NUM> relative to the test fixture <NUM>. Example restrictions on the grip actuator(s) <NUM> may include an upper pressure limit and/or an upper grip force limit. In the disabled state, the safety system <NUM> restricts the actuators and the control processor <NUM> does not control the actuator in response to operator inputs (e.g., does not attempt to control the motor <NUM> and/or the grip actuator(s) <NUM>, or is prevented from controlling the motor <NUM> and/or the grip actuator(s) <NUM> via de-energization).

Example unrestricted states include a caution state and a testing state. In the example caution state, the safety system <NUM> reduces restrictions on the actuator (e.g., motor <NUM> and/or the grip actuator(s) <NUM>), and does not control the actuator(s) motor <NUM> and/or the grip actuator(s) <NUM>. In the caution state, the control processor <NUM> may control the actuator(s) to perform actions such as high speed jogging of the crosshead <NUM> and/or increasing grip force by the pneumatic grips <NUM>, for which the operator should not be physically proximate the crosshead <NUM> and/or the pneumatic grips <NUM>. In the example testing state, the safety system <NUM> reduces restrictions on the actuator, while the control processor <NUM> controls the actuator(s) to perform testing (e.g., in accordance with a material testing procedure or program executed by the control processor <NUM>).

The example material testing system <NUM> of <FIG> may further include one or more control panels <NUM>, including multiple state indicators <NUM> and one or more mode switches <NUM>. The mode switches <NUM> may include buttons, switches, and/or other input devices located on an operator control panel. For example, the mode switches <NUM> may include buttons that control the motor <NUM> to jog (e.g., position) the crosshead <NUM> at a particular position on the frame <NUM>, switches (e.g., foot switches) that control the grip actuators <NUM> to close or open the pneumatic grips <NUM>, a mode control button that is depressed in conjunction with another button to enable the safety system <NUM> to permit operation in an unrestricted state, and/or any other input devices that could result in operation in an unrestricted state.

The state indicators <NUM> correspond to a set of predetermined states (e.g., the disabled, setup, caution, and testing states described above) to which the safety system <NUM> can set the material testing system <NUM>. As described in more detail below, the safety system <NUM> controls the state indicators <NUM> to provide an indication as to the present state of the material testing system <NUM> as determined by the safety system <NUM>. The state indicators <NUM> may include lights, displays, audio, mechanical systems, and/or any other indication that can be identified by the operator.

<FIG> is a block diagram of an example implementation of the safety system <NUM> of <FIG>. As illustrated in <FIG>, the safety system <NUM> includes a safety processor <NUM>.

The example safety processor <NUM> includes multiple, redundant processing cores 304a, 304b. The processing cores 304a, 304b execute redundant instructions 306a, 306b and receive redundant inputs, such that the processing cores 304a, 304b should, during normal operation of the test fixture <NUM>, produce substantially identical outputs. The safety processor <NUM> (e.g., via the redundant cores 304a, 304b) monitors the plurality of inputs and determines the state of the material testing system <NUM> based on the inputs. The safety processor <NUM> may compare outputs of the redundant instructions 306a 306b and control the state of the material testing system <NUM> based on the comparison of the outputs.

The example safety processor <NUM> and/or the redundant processing cores 304a, 304b may be include general purpose central processing unit (CPU) from any manufacturer. In some other examples, the safety processor <NUM> and/or the redundant processing cores 304a, 304b may include one or more specialized processing units, such as RISC processors with an ARM core, graphic processing units, digital signal processors, and/or system-on-chips (SoC). The safety processor <NUM> and/or the redundant processing cores 304a, 304b execute machine readable instructions, such as the redundant instructions 306a, 306b that may be stored locally at the processor (e.g., in an included cache or SoC), in a storage device such as a random access memory, a read only memory, and/or a mass storage device.

The redundant processing cores 304a, 304b and the redundant instructions 306a, 306b allow redundant and/or diverse inputs and outputs to be processed by the safety system <NUM>, which provides a highly reliable and predictable system. Thus, while representative inputs and outputs are illustrated in <FIG>, these inputs and/or outputs may be duplicated to support the redundant processing cores 304a, 304b and the redundant instructions 306a, 306b. The redundant instructions 306a, 306b (e.g., embedded software, operating system, and generated code) execute by the safety processor <NUM> is compliant with the processes outlined in international standards, including but not limited to ISO <NUM>-<NUM>, which pertains to "Safety Related Parts of Control Systems. " While the example safety processor <NUM> includes multiple, redundant processing cores, in other examples the safety processor <NUM> may include a single processing core, or multiple, non-redundant processing cores.

The safety system <NUM> of <FIG> further includes an actuator disabling circuit <NUM> that selectively disables a power amplifier <NUM> from providing energy to the motor <NUM> of the crosshead <NUM>. Additionally or alternatively, the actuator disabling circuit <NUM> (or another actuator disabling circuit) may disable the grip actuator(s) <NUM> from providing energy to the pneumatic grip(s) <NUM>. The power amplifier <NUM> receives input power and outputs power to the motor <NUM> to control movement of the crosshead <NUM>. The example actuator disabling circuit <NUM> and the power amplifier <NUM> may be implemented using a safety rated Safe Torque Off (STO) high-reliability servo power amplifier. The control processor <NUM> may control the motor <NUM> and movement of the crosshead <NUM> via a motor control signal <NUM> to the power amplifier <NUM>.

In response to an STO signal <NUM> from the safety processor <NUM>, the actuator disabling circuit <NUM> disables the connected actuator (e.g., the motor <NUM>). For example, the actuator disabling circuit <NUM> may disconnect all energy to the motor <NUM> (and/or other moving parts in the material testing system <NUM>), in less than a certain defined period of time. The example actuator disabling circuit <NUM> may provide an STO feedback signal <NUM> to the safety processor <NUM>, which indicates whether the actuator disabling circuit <NUM> is currently disabling the actuator. The safety processor <NUM> may compare the STO signal <NUM> to the STO feedback signal <NUM> to detect faults.

In the example material testing system <NUM>, the travel of the moving crosshead <NUM> and any internal components is stopped after activation of the STO signal <NUM> as specified by international standards. Most of the subsystems of the safety system <NUM> disclosed herein activate the actuator disabling circuit <NUM> to safely stop the machine. Additionally, the power amplifier <NUM> may include a motor braking circuit <NUM> to decelerate the motor <NUM> before applying the STO signal <NUM>. The motor braking circuit <NUM> allows the motor <NUM> to stop in a more controlled manner by eliminating continued movement by mechanical inertia after shutting down drive power. Using pre-disabling braking reduces or minimizes the motion of the crosshead <NUM> after the motor <NUM> is de-energized. Thus, the example actuator disabling circuit <NUM> and the motor braking circuit <NUM> provide a Category <NUM> stop as defined in the IEC <NUM>-<NUM> standard, which is the "Electrical Safety Standard for Machinery.

The example safety processor <NUM> monitors the motor <NUM> and/or the motor braking circuit <NUM> while pre-disabling braking is occurring to confirm that the motor <NUM> is braking. If the safety processor <NUM> determines that the motor <NUM> is not slowing down during the braking, then the safety processor <NUM> performs a braking failure mitigation to cease the braking and immediately de-energize the motor <NUM>. By implementing braking failure mitigation to the two-stage disabling sequence, the safety processor <NUM> may shorten stopping distance in situations in which the braking is ineffective. While the shortest stopping distance occurs when the pre-disabling braking is operative, when the pre-disabling braking is not completely operative, then a two-stage sequence involving an inoperative pre-disabling braking can have a longer stopping distance than a single-stage sequence (e.g., only disconnection). A secondary advantage of braking failure mitigation is that the mitigation enables more flexibility in implementing the two-stage disabling sequence, in that a wider range of components and systems can be used for high-performance braking with a braking failure mitigation process that can catch failures with the braking system.

The example safety system <NUM> further includes an emergency stop <NUM> (e.g., a button, a switch, etc.) that provides an emergency stop input signal <NUM> to the safety processor <NUM>. The emergency stop <NUM> may be a manually operated emergency stop button, which is a complementary-type safety function. The emergency stop <NUM> includes two channel redundancy for signaling. The emergency stop <NUM> may include an emergency stop switch <NUM>, emergency stop detection circuits <NUM>, and an actuator disabling circuit <NUM>. The emergency stop <NUM> is independently controllable using the hardware and embedded software of the safety processor <NUM>. For example, in response to detecting the emergency stop input signal <NUM> from the emergency stop detector <NUM>, the safety processor <NUM> sets the state of the material testing system <NUM> to the disable state and provides an emergency stop output signal <NUM> to the emergency stop <NUM> (e.g., to the emergency stop switch <NUM>).

The emergency stop switch <NUM>, in response to the emergency stop output signal <NUM>, controls the actuator disabling circuit <NUM> to control the actuator disabling circuit <NUM> and/or the motor braking circuit <NUM> to stop the motor <NUM>. The example actuator disabling circuit <NUM> may have a first connection to the motor braking circuit <NUM>, and second redundant connections to the actuator disabling circuit <NUM>. When the actuator disabling circuit <NUM> is triggered, the actuator disabling circuit <NUM> activates the motor braking circuit <NUM>, delays for a time to permit the braking to occur, and then activates the actuator disabling circuit <NUM> to de-energize the applicable actuator.

In addition or as an alternative to control via the safety processor <NUM>, the emergency stop switch <NUM> may directly actuate the actuator disabling circuit <NUM> within the power amplifier <NUM>, such as by physical interruption of the STO signal <NUM> between the safety processor <NUM> and the actuator disabling circuit <NUM>. The safety processor <NUM> monitors the emergency stop detection circuits <NUM> and acts as a redundant monitor to the hardware. The safety processor <NUM> outputs the STO signal <NUM> to control the actuator disabling circuit <NUM> to continue to disable the motor <NUM> so that, when the emergency stop switch <NUM> is released, the material testing system <NUM> will remain disabled (e.g., in a restricted state) and require user interaction to re-enable operation of the motor <NUM>.

The example material testing system <NUM> (e.g., the test fixture <NUM>) is compatible with interlock guarding systems with redundant or diverse contacts. The example safety system <NUM> may include one or more guards <NUM> and guard interlocks <NUM> configured to provide physical and/or virtual barriers to operator access to the material testing system <NUM> while operating in an unrestricted state. For example, the guards <NUM> may include physical barriers that are opened and closed to control access to the volume around the pneumatic grips <NUM> and/or the crosshead <NUM> (and/or other moving components). Example physical barriers include guard doors, which may use redundant safety switches to monitor whether the doors guarding the protected volume are open or closed. Each door switch has mechanically linked normally open and normally closed contacts, which may be dynamically pulsed (e.g., by the guard interlocks <NUM>) and/or otherwise received as inputs. Pulsing permits plausibility diagnostic checking of the guard door switches in real time.

Additionally or alternatively, the guards <NUM> may include virtual guards that monitor the volume around the pneumatic grips <NUM> and/or the crosshead <NUM> for intrusion into the volume. Example virtual guards may include light curtains, proximity sensors, and/or pressure pads. While virtual guarding does not physically prevent access, the virtual guarding outputs guarding signals to the guard interlocks <NUM>, which output interlock signals <NUM> to the safety processor <NUM> and/or actuator disabling circuit <NUM> (e.g., similar to the emergency stop switch <NUM> discussed above).

The interlocks <NUM> may trigger the actuator disabling circuit <NUM> to de-energize the motor <NUM>. In some examples, the safety processor <NUM> controls re-enabling of the power amplifier <NUM> when the guard interlocks <NUM> are no longer triggered, in a similar manner as the emergency stop switch <NUM> discussed above.

Additionally or alternatively, the example safety system <NUM> may default to a restricted "setup" state when an operator enters the protected volume of the material testing system <NUM>. Instead of disabling or de-energizing actuators of the system <NUM>, the setup state enforces restrictions on speed, pressure, or other activities.

The example safety system <NUM> includes multiple state indicators <NUM> and mode switches <NUM>. The example safety processor <NUM> monitors the mode switches <NUM> by, for example, dynamically pulsing the mode switches <NUM> to generate or obtain mode switch input signals <NUM> (e.g., one or more mode switch inputs for each of the mode switches <NUM>). In some examples, the mode switches <NUM> are high-reliability switches. The safety processor <NUM> may test the mode switches <NUM> for short circuits or other faulty conditions periodically, aperiodically, in response to events (e.g., at startup of the material testing machine), on a predetermined schedule, and/or at any other times.

The example safety processor <NUM> controls the state indicators <NUM> to indicate the state of the material testing system <NUM> to the operator. For example, the safety processor <NUM> may output indicator signals <NUM> to the state indicators <NUM>. If the state indicators <NUM> are lights, the output indicator signals <NUM> may, for example, control each of the lights to be on, off, flashing, and/or any other output for the lights. In some examples, the safety processor <NUM> determines the conditions of the indicators via indicator feedback signals <NUM>. Example indicator feedback signals <NUM> may indicate to the safety processor <NUM> whether each of the state indicators <NUM> is on, off, short-circuited, open-circuited, and/or any other status or condition of the state indicators <NUM>. If the processor determines that one or more of the state indicators <NUM> are not in the commanded proper state, the safety processor <NUM> controls the material testing system to be in a restricted state provides a notification to the operator (e.g., via the control panel <NUM> or other notification).

The safety system <NUM> includes a power supply monitor <NUM> to monitor the power supplies (e.g., DC and AC power supplies) that provide power to components of the material testing system <NUM>. The power supply monitor <NUM> provides one or more power supply status signals <NUM> to the safety processor <NUM> and/or to the watchdog circuit <NUM> (described below) to indicate whether the monitored power supplies are within respective voltage and/or current ranges. If the power supply monitor <NUM> determines that one or more of the power supplies are out of tolerance, the safety processor <NUM> and/or to the watchdog circuit <NUM> may disable the material testing system <NUM> and alert the operator.

The example safety system <NUM> further includes one or more speed sensor(s) <NUM>. The example speed sensor(s) <NUM> may be integrated, redundant, and/or diverse speed monitoring sensors. The speed sensor(s) <NUM> provide speed signal(s) <NUM>, which are representative of the crosshead speed, to the safety processor <NUM>. The safety processor <NUM> monitors the speed signal(s) <NUM> to ensure the crosshead <NUM> does not exceed an upper speed limit (e.g., crosshead travel limit(s) <NUM>) as determined by the current operating mode of the machine. For example, the value of the upper speed limit may depend on whether the material testing system <NUM> is in a restricted state or an unrestricted state. In some examples, two speed sensors that operate on different principles may be used in the material testing system <NUM> to prevent the sensors <NUM> from sustaining common cause failures. The speed signal <NUM> of each speed sensor <NUM> is read and compared by the safety processor <NUM> to verify that the speed signals <NUM> are in agreement. If one speed sensor <NUM> indicates a different speed than another speed sensor <NUM>, the safety processor <NUM> disables the material testing system <NUM> (e.g., via the actuator disabling circuit <NUM>).

The example crosshead travel limit(s) <NUM> may include a travel limit that specifies a limit on the position of the crosshead <NUM>. When the crosshead travel limit(s) <NUM> is reached, the safety processor <NUM> stops the motion of the crosshead <NUM>. In some examples, the crosshead travel limit(s) <NUM> are multi-level limits, where the number of limits that are triggered indicate how far the crosshead travel limit(s) <NUM> have been exceeded. In some examples, a first level limit is handled by the safety processor <NUM> to stop operation of the applicable actuator (or all actuators), such as the motor <NUM>. As the crosshead <NUM> continues to move beyond the first level limit and hits a second level limit (e.g., farther outside of the acceptable range than the first level limit), the crosshead travel limit <NUM> may trigger a direct connection (e.g., a hardware connection) to the actuator disabling circuit <NUM> and/or the motor braking circuity <NUM>, and/or to the actuator disabling circuit <NUM>, to trigger the two phase disabling of the motor <NUM>.

In some examples in which the material testing system <NUM> includes automatic gripping (e.g., pneumatically powered grips, hydraulically powered grips, electrically powered grips, electromechanically powered grips, electromagnetically powered grips, etc.), the safety system <NUM> includes a grip controller <NUM> that controls the grip actuators according to a multi-pressure gripping scheme. The multi-pressure gripping scheme reduces (e.g., minimizes, eliminates) the risk of injury to an operator when installing material test specimens in the material testing system <NUM> the pneumatic grips <NUM>.

When the safety processor <NUM> is controlling the material testing system <NUM> in the setup state, the safety processor <NUM> provides a pressure signal <NUM> to the grip controller <NUM>. The grip controller <NUM> controls the upper limit on the pressure that may be applied via the grips <NUM> by controlling the grip actuator(s) <NUM>. The pressure signal <NUM> (which may be directly proportional to specimen gripping force) is limited to allow enough pressure to grip the specimen via the grips <NUM>, but not enough pressure to cause severe injury to the operator. Conversely, when the safety processor <NUM> is controlling the material testing system <NUM> in the caution or testing states, the safety processor <NUM> provides the pressure signal <NUM> to cause the grip controller <NUM> to enable the higher pressure used to grip test specimens during testing. The example grip controller <NUM> may monitor the main system pressure (e.g., via pressure sensor(s) <NUM>) and/or the pressure(s) in the pneumatic grip(s) <NUM> (e.g., upper and lower grips). The grip controller <NUM> feeds the pressure signals <NUM> to the safety processor <NUM> to verify that the commanded pressures are being enforced.

In some examples, the grip controller <NUM> is controlled via an operator input using a foot pedal switch. For example, the foot pedal switch may include separate switches to apply pressure and to release pressure via the pneumatic grip(s) <NUM>. The switches may be mechanically linked switches, which may be dynamically pulsed to check for plausibility between the switches and/or to monitor for potential faults in the switches (e.g., electrical faults).

The safety processor <NUM> further controls the grip controller <NUM> to de-energize the grip actuator(s) <NUM> when power is disabled to the material testing system <NUM>. For example, the safety processor <NUM> may control the grip actuator(s) <NUM> (e.g., via one or more valves, relays, etc.) to enable pressurization when powered, but to be normally depressurized for pneumatic actuators such that the pneumatic grip(s) <NUM> are prevented from applying grip force when the material testing system <NUM> is unpowered.

The example safety system <NUM> further includes a watchdog circuit <NUM>. The watchdog circuit <NUM> communicates with the safety processor <NUM> periodically, aperiodically, in response to one or more events or triggers, and/or at any other time to verify the operation of the safety processor <NUM>. For example, the safety processor <NUM> may communicate a heartbeat signal, or a response to a challenge from the watchdog circuit <NUM>, to indicate to the watchdog circuit <NUM> that the safety system <NUM> is operating properly. If the watchdog circuit <NUM> does not receive an expected signal from the safety processor <NUM>, the watchdog circuit <NUM> disables the material testing system <NUM> and notifies the operator.

The example safety processor <NUM>, the example emergency stop <NUM>, the example guard interlock <NUM>, the example crosshead travel limit(s) <NUM>, and/or the example watchdog circuit <NUM> are coupled (e.g., connected via hardware) to the actuator disabling circuit <NUM>. When any of the safety processor <NUM>, the emergency stop <NUM>, the guard interlock <NUM>, the crosshead travel limit(s) <NUM>, and/or the watchdog circuit <NUM> determine that a respective condition is satisfied so as to disable the material testing system <NUM> (e.g., activation of the emergency stop switch <NUM>, tripping of the guard <NUM>, exceeding a crosshead travel limit <NUM>, and/or triggering of the watchdog circuit <NUM>), the actuator disabling circuit <NUM> is used to activate the motor braking circuit <NUM> and the actuator disabling circuit <NUM>. The safety processor <NUM> may determine that the state of the material testing system <NUM> is the disabled state.

While the example control processor <NUM> and the safety processor <NUM> are illustrated as separate processors, in other examples the control processor <NUM> and the safety processor <NUM> may be combined into a single processor or set of processors that are not divided into control and safety functions. Furthermore, the control processor <NUM>, the safety processor <NUM>, and/or combined processors may include non-processing circuitry, such as analog and/or digital circuitry to perform one or more specialized functions.

<FIG> illustrates an example operator interface <NUM> that may be used to implement the control panel <NUM> of <FIG> and <FIG>. The operator interface <NUM> may be attached to the example test fixture <NUM>, located proximate to the text fixture, and/or located remotely from the test fixture <NUM>. For example, the operator interface <NUM> may be implemented as a built-in operator panel or switch on a base tray of the test fixture <NUM>.

The example operator interface <NUM> includes multiple input devices (e.g., buttons, switches, etc.) which provide inputs to the control processor <NUM> and/or to the safety system <NUM> of <FIG> and/or <NUM>. The example input devices include a state control button <NUM>, which controls the transition from a restricted state (e.g., the setup state) to an unrestricted state (e.g., the caution state, the testing state), and may be required to be used to perform actions involving the unrestricted states. The state control button <NUM> may be considered as an "unlock" button or safety input that enables use of the material testing system in unrestricted states.

Jog buttons <NUM>, <NUM> control the motor <NUM> to jog the crosshead <NUM> in an up or down (or left and right, or directions based on any other orientation) direction (for directional crosshead movement) and/or in a right-hand or left-hand rotational direction (for rotational crosshead movement). When depressed individually, the jog buttons <NUM>, <NUM> control the crosshead <NUM> to move up or down at a low speed (e.g., determined by the safety processor <NUM>). When a jog button <NUM>, <NUM> is depressed simultaneously with the state control button <NUM>, the safety processor <NUM> may reduce the speed restriction on the motor <NUM> and allow jogging of the crosshead <NUM> at higher speeds. The example jog buttons <NUM>, <NUM> may serve as directional inputs. In examples in which the crosshead <NUM> provides rotational force or motion, directional inputs may include rotational inputs such as right hand rotation and left hand rotation.

As used herein, received "simultaneously" refers to both inputs being activated or depressed at any given time, not necessarily that both buttons have to be initially depressed at exactly the same moment.

A start button <NUM> controls the control processor <NUM> to initiate a material test. A return button <NUM> controls the control processor <NUM> to return the crosshead <NUM> to a predetermined position, which may be accomplished at low speed or high speed. In some examples, the safety processor <NUM> requires that the start button <NUM> and/or the return button <NUM> be depressed in conjunction with the state control button <NUM>. A stop button <NUM> controls the control processor <NUM> to stop or pause a running test. An emergency stop switch <NUM> may be included to implement the emergency stop switch <NUM> of <FIG>.

The operator interface <NUM> further includes state indicators <NUM>-<NUM> to output an indication of a present state of the material testing system <NUM>. The example state indicators <NUM>-<NUM> are lights representative of each of the states of the material testing system <NUM> that may be determined by the safety processor <NUM>. In the example of <FIG>, the operator interface <NUM> includes a disabled state indicator <NUM>, a setup state indicator <NUM>, a caution state indicator <NUM>, and a testing state indicator <NUM>. Each of the state indicators <NUM>-<NUM> is lit when the safety processor <NUM> determines that the material testing system <NUM> is in the corresponding state, while the state indicators <NUM>-<NUM> not corresponding to the present state are unlit.

<FIG> illustrates another example operator interface <NUM> that may be used to implement that control panel <NUM> of <FIG> and <FIG>. The example operator interface <NUM> may be a handset having a limited set of input devices (e.g., buttons, switches, etc.). The operator interface <NUM> may be attached to the example test fixture <NUM>, located proximate to the text fixture, and/or located remotely from the test fixture <NUM>. The operator interface <NUM> includes a state control button <NUM> (e.g., similar or identical to the state control button <NUM> of <FIG>), jog buttons <NUM>, <NUM> (e.g., similar or identical to the jog buttons <NUM>, <NUM>), a start button <NUM> (e.g., similar or identical to the start button <NUM>), and a return button <NUM> (e.g., similar or identical to the return button <NUM>).

The operator interfaces <NUM>, <NUM> may include custom buttons <NUM>, or soft keys, which provide programmable functions to the operator. In some examples, the programmable functions are subject to the restrictions of one or more of the restricted states.

<FIG> is a flowchart representative of example machine readable instructions <NUM> which may be executed by the safety system <NUM> of <FIG> and <FIG> to control actuation of the material testing system <NUM> of <FIG> in an unrestricted mode. The example instructions <NUM> enforce a dual activation requirement in which multiple inputs are required within a timeout period to enable transitions from restricted states to unrestricted states.

The example instructions <NUM> may be executed to determine a state of the material testing system from a plurality of predetermined states, enforce restrictions on the actuator, and automatically set the state of the material testing system to one of the restricted states in response to completion of an action involving controlling the actuator.

At block <NUM>, the material testing system <NUM> and/or one or more subsystems may be powered on. If the material testing system <NUM> is not powered on, block <NUM> iterates until the material testing system <NUM> is turned on. When the material testing system <NUM> is powered on (block <NUM>), at block <NUM> the safety system <NUM> sets the state of the material testing system <NUM> to a disabled state and disables one or more actuator(s) (e.g., the motor <NUM>, the grip actuator(s) <NUM>). For example, the safety system <NUM> may default the actuator disabling circuit <NUM> to de-energizing the motor <NUM>.

At block <NUM>, the safety processor <NUM> is initialized. For example, the safety processor <NUM> may perform fault checks (e.g., checking inputs, outputs, and/or attached devices for open circuits and/or closed circuits), redundancy checks (e.g., determining that redundant inputs and/or redundant outputs are in agreement), and/or other initialization processes.

At block <NUM>, the safety processor <NUM> determines whether any faults are detected in the safety system <NUM> (e.g., detected during the initialization process). If faults are detected (block <NUM>), at block <NUM> the safety processor <NUM> outputs a fault alert (e.g., via the control panel <NUM>, via the computing device <NUM>, etc.). The example instructions <NUM> may then end.

When faults are not detected (block <NUM>), at block <NUM> the safety processor <NUM> determines whether an operator input has been received to transition the material testing system <NUM> from the disabled state to a setup state. For example, the safety processor <NUM> may require one or more specified inputs (e.g., pressing an unlock button) to transition from the disabled state. If the operator input has not been received (block <NUM>), block <NUM> iterates while the material testing system <NUM> remains in the disabled mode to await the operator input.

When the operator input is received (block <NUM>), at block <NUM> the safety processor <NUM> sets the state of the material testing system <NUM> to a setup state. In accordance with setting the setup state, the safety processor <NUM> enables the actuator(s) (e.g., the motor <NUM>), restricts the actuator(s), and indicates the state as the setup state (e.g., via the state indicators <NUM>). In some examples, the safety processor <NUM> controls one or more visual indicators on the control panel <NUM> to selectively emphasize corresponding ones of the operator selectable inputs (e.g., mode switches <NUM>) based on the state of the material testing system <NUM> being the setup state. For example, the safety processor <NUM> may control the visual indicators to emphasize the inputs that may be used by the operator in the setup mode and deemphasize the inputs that may not be used in the setup mode.

At block <NUM>, the safety processor <NUM> monitors input signals of the safety system <NUM> (e.g., sensor signals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), feedback signals (e.g., feedback signals <NUM>, <NUM>, <NUM>), control signals (e.g., signals from the control processor <NUM>), and/or interlock signals (e.g., the guard signal <NUM> from the guard interlock <NUM>). The safety processor <NUM> may monitor the signals to, for example, identify operator commands and/or conditions that would cause the safety processor <NUM> to recognize a change in the state of the material testing system <NUM>.

At block <NUM>, the safety processor <NUM> determines whether a first operator input is received. An example first operator input may include a mode switch <NUM> (e.g., an Unlock key, button, or switch), a presence sensor (e.g., a proximity sensor, a pressure sensitive surface, a motion sensor, a light curtain, a mechanical guard door, a camera and processing circuitry, etc.), or any other source of operator input. The first operator input may include determining a presence in a first location in which the operator is incapable of accessing a protected volume and can access a second operator input. Additionally or alternatively, the first operator input may include the lack of presence within the protected volume itself. If the first operator input has not been received (block <NUM>), control returns to block <NUM> to continue monitoring.

When a first operator input is received (block <NUM>), at block <NUM> the safety processor <NUM> initializes a timeout timer. The timeout timer may be a software timer, a dedicated hardware timer, or any combination of hardware and software. In some examples, the first operator input may cause the safety processor <NUM> to determine the state to be in a caution state, and indicate that the caution state is the current state (e.g., via the state indicators <NUM>).

At block <NUM>, the safety processor <NUM> determines whether a second operator input has been received. The example second operator input may include a mode switch <NUM> (e.g., an Unlock key, button, or switch), a presence sensor (e.g., a proximity sensor, a pressure sensitive surface, a motion sensor, a light curtain, a mechanical guard door, a camera and processing circuitry, a room entry detector, etc.), or any other source of operator input. The safety processor <NUM> may require that the combination of the first input and the second input include both of a desired operation (e.g., jog the crosshead <NUM> at a speed higher than a restricted setup speed, start a material test, return the crosshead <NUM> to a desired position, actuate the pneumatic grips <NUM> at a pressure higher than a threshold pressure) and an intention-indicating input (e.g., an unlock button, a lack of presence in the protected volume, a presence at a location away from the protected volume).

In some examples, the safety processor <NUM> may require that the desired operation input and the intention-indicating input be received in a required order (e.g., the desired operation input before the intention-indicating input or the intention-indicating input before the desired operation input).

If the second operator input has not been received (block <NUM>), at block <NUM> the safety processor <NUM> determines whether the timeout timer has expired. For example, the timeout timer may be set to expire after running for a predetermined threshold time period, within which the two operator inputs must be received to indicate an operator intention to perform the action (e.g., to avoid unintentional actuation). If the timeout timer has not expired (block <NUM>), control returns to block <NUM> to continue monitoring for a second operator input. If the timeout timer has expired (block <NUM>), the first operator input times out and control returns to block <NUM> to continue monitoring.

When the second operator input is received prior to expiration of the timeout time (block <NUM>), at block <NUM> the safety processor <NUM> sets the material testing system <NUM> to the state corresponding to the operator inputs (e.g., an unrestricted state, such as the caution state or the testing state). For example, the safety processor <NUM> may transition the material testing system <NUM> to the caution state and then the testing state when the first and second operator inputs correspond to a test start (e.g., the state switch button <NUM> and the start button <NUM>). The safety processor <NUM> also reduces and/or removes restrictions associated with the set state to perform the action corresponding to the operator inputs.

At block <NUM>, the control processor <NUM> performs the action corresponding to the first and second operator inputs. For example, the control processor <NUM> may perform a programmed material test, control the motor <NUM> to jog the crosshead and/or return the crosshead to a desired position, apply a high gripping or clamping pressure, and/or any other action corresponding to the operator inputs. At block <NUM>, the safety processor <NUM> determines whether the action is completed. The action may be completed when, for example, either of the first or second inputs are no longer being received, if the control processor <NUM> has completed a programmed material test, if an interlock is triggered. In some examples, the safety processor <NUM> ceases operation of the actuator in response to determining that one of the two inputs is no longer being received. In some other examples, the safety processor <NUM> permits the operation of the actuator to continue while at least one of the inputs is received, and ceases operation of the actuator in response to determining that none of the two or more inputs are being received. In some examples, the safety processor <NUM> permits the operation of the actuator to continue even when the inputs are no longer received (e.g., for extended-duration testing), and ceases operation of the actuator in response to conclusion of the material testing process, a pause in the material testing process, or an input from the operator interface (e.g., pressing the stop button <NUM> of <FIG>).

If the action is not completed (block <NUM>), control returns to block <NUM> to continue performing the action. When the action has completed (block <NUM>), control returns to block <NUM> to return to the setup state. The safety processor <NUM> may then reapply the corresponding restrictions.

<FIG> illustrates an example material test system <NUM> including a camera <NUM> and a video processor <NUM> configured to provide input signals to the safety system <NUM> to operate the material test system <NUM>. The example material test system <NUM> includes the material testing system <NUM> of <FIG>, including the safety system <NUM>, and the operator interface <NUM> of <FIG>.

A camera <NUM> monitors a protected volume <NUM> (e.g., a volume adjacent the test fixture <NUM>). The video processor <NUM> detects an intrusion by processing images output by the camera <NUM>, and outputs a non-detection signal to the safety system <NUM> in response to determining that an intrusion is not detected. The safety system <NUM> may, for example, poll the input from the video processor <NUM> to determine a value representative of detection or non-detection. The example safety system <NUM> may then use the non-detection signal as the first input signal or the second input signal (e.g., in the instructions <NUM> of <FIG>) to enable some operations of the material testing system <NUM>. When an operator or object is detected by the camera <NUM> and the video processor <NUM> as within the volume <NUM>, the video processor <NUM> stops providing the non-detection signal (or provides a detection signal) to the safety system <NUM>, which then disables operation of the material test system <NUM>. The operator interface <NUM> may provide the additional signal to indicate which operator is desired.

<FIG> illustrates an example material test system <NUM> including a pressure sensitive surface <NUM> configured to provide input signals to the safety system <NUM> to operate the material test system <NUM>. The example material test system <NUM> includes the material testing system <NUM> of <FIG>, including the safety system <NUM>, and the operator interface <NUM> of <FIG>.

The pressure sensitive surface <NUM>, such as a pressure pad, detects the presence of a pressure (e.g., an operator) on the surface <NUM>. When the presence of the pressure is detected, the pressure sensitive surface <NUM> outputs a pressure signal to the safety system <NUM>. The pressure sensitive surface <NUM> may be located such that, when the presence is detected, the operator standing on the pressure sensitive surface <NUM> is out of reach or otherwise incapable of reaching the protected volume. The safety system <NUM> may, for example, poll the input from the pressure sensitive surface <NUM> to determine a value representative of detection or non-detection. The example safety system <NUM> may then use the pressure signal as the first input signal or the second input signal (e.g., in the instructions <NUM> of <FIG>) to enable some operations of the material testing system <NUM>. When an operator or object is no longer detected by pressure sensitive surface <NUM>, the pressure sensitive surface <NUM> stops providing the detection signal (or provides a non-detection signal) to the safety system <NUM>, which then disables operation of the material test system <NUM>. The operator interface <NUM> may provide the additional signal to indicate which operator is desired.

<FIG> illustrates an example material test system <NUM> including an operator detection switch <NUM> configured to provide input signals to the safety system <NUM> to operate the material test system <NUM>. The example material test system <NUM> includes the material testing system <NUM> of <FIG>, including the safety system <NUM>, and the operator interface <NUM> of <FIG>.

The operator detection switch <NUM>, such as a deadman switch, detects the presence of the operator by triggering of the switch, where failure to continuously depress the switch <NUM> automatically causes release of the switch <NUM>. When the depression of the switch occurs, the operator detection switch <NUM> outputs a switch signal to the safety system <NUM>. The operator detection switch <NUM> may be located such that, when the switch <NUM> is depressed, the operator depressing the switch <NUM> is out of reach or otherwise incapable of reaching the protected volume. The safety system <NUM> may, for example, poll the input from the operator detection switch <NUM> to determine a value representative of detection or non-detection. The example safety system <NUM> may then use the switch signal as the first input signal or the second input signal (e.g., in the instructions <NUM> of <FIG>) to enable some operations of the material testing system <NUM>. When the switch <NUM> is no longer depressed, the operator detection switch <NUM> stops providing the switch signal (or provides a signal indicative of non-activation of the switch <NUM>) to the safety system <NUM>, which then disables operation of the material test system <NUM>. The operator interface <NUM> may provide the additional signal to indicate which operator is desired.

<FIG> illustrates an example material test system <NUM> including a presence detector <NUM> configured to provide input signals to the safety system <NUM> to operate the material test system <NUM>. The example material test system <NUM> includes the material testing system <NUM> of <FIG>, including the safety system <NUM>, and the operator interface <NUM> of <FIG>.

The presence detector <NUM>, such as a room entry detector, a presence sensor or a motion sensor, detects the presence of the operator in a particular area. When detection occurs by the presence detector <NUM>, the presence detector <NUM> outputs a presence signal to the safety system <NUM>. The presence detector <NUM> may be located such that, when the presence detector <NUM> recognizes the presence of an operator, the operator is out of reach or otherwise incapable of reaching the protected volume. The safety system <NUM> may, for example, poll the input from the presence detector <NUM> to determine a value representative of detection or non-detection. The example safety system <NUM> may then use the presence signal as the first input signal or the second input signal (e.g., in the instructions <NUM> of <FIG>) to enable some operations of the material testing system <NUM>. When the presence detector <NUM> no longer detects a presence, the presence detector <NUM> stops providing the presence signal (or provides a signal indicative of no presence) to the safety system <NUM>, which then disables operation of the material test system <NUM>. The operator interface <NUM> may provide the additional signal to indicate which operator is desired.

<FIG> illustrates an example material test system <NUM> including a proximity sensor <NUM> configured to provide input signals to the safety system <NUM> to operate the material test system <NUM>. The example material test system <NUM> includes the material testing system <NUM> of <FIG>, including the safety system <NUM>, and the operator interface <NUM> of <FIG>.

The proximity sensor <NUM> monitors a protected volume <NUM> (e.g., a volume adjacent the test fixture <NUM>) and outputs a non-proximity signal to the safety system <NUM> in response to determining that proximity of an operator is not detected. The safety system <NUM> may, for example, poll the input from the proximity sensor <NUM> to determine a value representative of proximity or non-proximity. The example safety system <NUM> may then use the non-proximity signal as the first input signal or the second input signal (e.g., in the instructions <NUM> of <FIG>) to enable some operations of the material testing system <NUM>. When an operator or object is detected by proximity sensor <NUM> as within the volume <NUM>, the proximity sensor <NUM> stops providing the non-detection signal (or provides a detection signal) to the safety system <NUM>, which then disables operation of the material test system <NUM>. The operator interface <NUM> may provide the additional signal to indicate which operator is desired.

Claim 1:
A material testing system (<NUM>), comprising:
an actuator configured to control an operator-accessible component of the material testing system (<NUM>);
an operator interface (<NUM>) comprising:
a plurality of inputs; and
a button configured to output an unlocking signal while the button is depressed; and
one or more processors (<NUM>) configured to:
control the actuator based on at least one of a material testing process or an input from the operator interface (<NUM>); and
require two or more inputs to be received within a predetermined threshold time to permit at least one operation of the actuator; and
use the unlocking signal as one of the two or more inputs.