In many applications, Roboteq controllers drive high powered motors that move parts and equipment at high speed and/or with very high force. If a malfunction occurs, potentially enormous forces can be applied at the wrong time or in the wrong place. An error or malfunction can potentially cause serious damage to property and harm to operators and bystanders. While Roboteq controllers operate very reliably and failures are very rare, as with any other electronic equipment, an unforeseen failure is a possibility. If there is any danger that a loss of motor control can cause damage or injury, you must plan for that possibility in order to minimize the potential consequences, Roboteq certainly has. This article outlines some of the many precautions designed into our products to ensure the safety of our customers. Please read the below sections carefully so that you fully understand the potential risks in order best protect yourself, your equipment and bystanders.
Over/Under Limits Protections
Users should always keep in mind is that even a battery-operated system has a large amount of energy running through it. This is why Roboteq controllers always run below the maximum allowed current limit. This allows for a safe cushion for error without pushing design limits. Robteq controllers actively monitor the motor's current consumption and automatically reduce the power output to keep the current within allowed limits. This keeps the motor and the wiring safe. Further, controllers automatically disconnect a motor from its power source if the voltage rises above the maximum threshold or dips below minimum threshold. Roboteq controllers also closely monitor their own heat output. Once a controller’s temperature rises above 70oC, power to the motor is scaled back. If the temperature exceeds 75oC, power to the motor is completely cut off.
Multiple safe guards are designed into the firmware Roboteq’s controllers to help ensure the highest possible level of safety. If pulse commands are not repeated regularly or if no new command is received via the Serial, USB or CAN bus within a preset amount of time, the controller will cut-off all power to the motor. Additionally, when using analog commands, a motor using a Roboteq controller and a joystick will not start if the joystick is not centered. Should the command voltage rise above or fall below the safety thresholds, the motor will automatically stop.
Motor Stops if Unsafe Conditions are Detected
Users can also set their own current thresholds. If the current should rise above user-defined threshold for too long, the controller will cut power to the motor. Power to the motor is also cut if limit switches are reached. To allow Roboteq users as many safety options as possible, any digital input can be used as a safety stop (controlled ramp stop) or emergency stop (motor disconnect). If a loop error condition error continues, for instance if the motor cannot reach a programmed speed or position for a sustained period of time, power to the motor is cut off. Roboteq’s stall detection disengages the motor if power is applied to the motor but no motion is detected. Further, if you have fitted your motor with an electromechanical break, Roboteq controllers will engage it, automatically.
Safe Torque Off (STO) on selected Roboteq Controller models, coming later in 2018!
Hardware Fault Protections
In the unlikely event that the firmware operating the motor controller’s microcomputer unit (MCU) should fail, Roboteq controllers feature the ability to automatically detect and recovery the MCU. An optional, separate power supply keeps the controller responding if power levels in the main battery pack become too low. Roboteq controllers feature a digital output for driving external contactors. By measuring for abnormal battery current draw while the motor is off, Roboteq controllers can detect transistor shorts in the power stage.
Additional Safety Functions Thanks to MicroBasic Scripting
Roboteq’s MicroBasic scripting allows the user to write programs that are permanently saved into, and run from the controller’s Flash Memory. This powerful ability also allows users to set application-specific fault conditions that can be detected and acted upon thanks to Roboteq’s MicroBasic scripting. One example of this would be activating an external alarm buzzer when motor speed is outside its low or high range. The MicroBasic scripting feature gives users the capability to fully customize the functionality of their Roboteq controller and program safety features based on their unique requirements.