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The Hacksmith: Power Loader Safety System

2021-08-26 | By The Hacksmith

License: See Original Project

This project was created by Engineering Superheroes of Hackmith Industries.

DO NOT ATTEMPT to Re-Create

Hacksmith Industries is no stranger to the Alien movie franchise. The team has been constructing a power loader over the past three years, with each new video addressing different aspects of the machine. In the previous installment, Hacksmith team member, Bogdan, tackled the safety features within the power loader’s control system.

The power loader’s mechanical arms and treads have many movement options, and users can use a remote to control it. Piloting such a heavy machine with strong hydraulic arms can be dangerous, and remotely controlling it runs the risk of running into things if the user isn’t paying attention. So for this installment, Bogdan, Ben, and Anmol set out to add extra safety features and make the power loader even smarter. See how it works in the video below!

 

How Does it Work?

The first safety feature added to the power loader was a kill-switch system, which can stop the power loader in a few different ways:

  1. Wireless e-stop: The power loader can be immediately stopped remotely with a big e-stop button.
  2. Drop detection: If the remote controller is dropped, the power loader will immediately stop all motion.
  3. Loss of signal: If the signal is lost, the power loader will immediately stop.

The kill-switch system will stop the power loader from running away, but more systems are needed to keep the pilot safe. The power loader has a much wider range of movement and a much smaller safety cage than a forklift or tractor, so it’s critical to path out movements, so the driver doesn’t get squashed by the hydraulic arms. The Hacksmith team programmed the control system to have proprioception, also known as the ability to keep track of where one’s limbs are without seeing them, for added safety measures. Proprioception is sometimes referred to as the “sixth sense.” To test your proprioception, try closing your eyes and clapping your hands. The body automatically tracks where its limbs are, meaning they don’t have to be visible to know where they are.

Humans come equipped with proprioception, but it isn’t so easy for robots. The power loader’s closed-loop feedback system or “proprioception” must be programmed into its operating system and needs sensors to let the brains know where the hydraulic arms are. For this system, the sensors used are rope potentiometers. These send signals to the brain based on the length of their rope, similar to an electronic tape measure. Each joint on the power loader is equipped with a rope potentiometer that keeps track of joints’ angles and lengths. The joints are placed into a position to automate those positions, the angles and lengths are measured, and reverse kinematics is used to make instructions for the brain to recreate them. ROS, the Robot Operating System, was used for this project.

Finally, the Hacksmith team upgraded the hydraulic system to be more precise. Originally, the hydraulics operated on a basic ON/OFF system, which meant full power or no power, so the movement was jerky. This made it hard for the power loader to move things gently and difficult for the pilot to control safely. The new system uses proportional valves that can move fluid in much smaller increments, making the joints much smoother. They also allow the arms to do multiple movements at the same time!

Schematic and BOM

 

 

More Hacksmith Movie Creations on Maker.io

Check out the previous installment of the Power Loader Control System on Maker.io and check out the power loader’s progress from the beginning on YouTube.

Also, view more Hacksmith movie projects on Maker.io:

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