After looking at the specifications of each actuator, here is a summary of the actuator characteristics:
- 500mm actuator, 12V DC, 10mm/s, 750N load
- 300mm actuator, 12V DC, 5mm/s, 5000N load
Two main conclusions can be drawn from this:
- 300mm will extend more slowly than the 500mm actuator.
- Our chosen relay and programmable logic controller must be able to handle supplying enough current for 4x 12V DC
For the control of the linear actuators, we can choose between relays, motor controllers, or a combination of both. We probably need a combination of both so we procured relays and motor controllers.
For relays, we have procured the Jayoyi 16 Channel Relay Board Module Optocoupler. It is well-suited for our project as its power supply satisfies the DC 12V range. Also, it is one of the best PLC relay expansion modules available as it comes with 16 channels and has an optocoupler. The perk of an PLC relay expansion module is that it increases the number of safe outputs of another safety relay. These are suitable in applications where several devices need to be stopped. The optocoupler enables electrical signals to be passed between low and high voltage circuits via short optical transmission paths while keeping them electrically isolated. This removes electrical noise from signals, and isolate and protect-voltage devices from high-voltage circuits. Essentially, this ensures that our lifting arm can work properly without erratic operation, which is certainly important for safety!
For motor controller, we have procured the Dual Channel H Bridge Motor Drive Module Controller. It satisfies the DC 12V range, has reversible control and PWM speed control. This means that there can be finer control over our actuators. The actuators should be able to be locked in certain position with the motor controller. This will be helpful for the control of the double actuator configuration.