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A battery works on the basic principle that electrons tend to move from where they are abundant, or in excess, to where they are scarce. This can happen, if there is a medium that will allow the movement of these electrons.

The part of battery with too many electrons is called the anode which means it is the negative electrode (remember, the charge of an electron is negative). The part of the battery where electrons are scarce is called the cathode, which means it is the positive electrode, which means, there is net positive charge there.

Let’s present Anode and Cathode characteristics as lists, to make things more understandable:

Anode:
• Abundance of electrons
• Negatively charged
• Chemical reaction during discharge: Oxidation
• Material example: Zinc

Cathode:
• Scarcity of electrons
• Positively charged
• Chemical reaction during discharge: Reduction
• Material example: Manganese Dioxide (MnO2)

Between anode and cathode is a barrier material which prevents their direct contact but still allows passing of ions. If this direct contact was not prevented, there would be a short circuit in the battery and it would deplete very rapidly and be useless.

And there is the electrolyte material, such as an alkaline Potassium Hydroxide (KOH) in an alkaline battery.

An ion is an atom where the number of electrons and protons are not equal, therefore it is an atom with a net electrical charge. If electrons are more than protons, it is a negative ion, and if protons are more than electrons it is a positive ion.

When the battery is not in use, there is no flow of electrons. But when an external circuit is connected to the battery, the electrons are released from anode (i.e. Zinc), which travel through the external circuit, does its work in the circuit (such as turning a motor, illuminating a lamp, making a microprocessor work and so on…), and then they arrive at the cathode, which is able to accept those electrons as it was positively charged. But this is not all. For current to keep flowing, the loop of flow must continue, in other words, be closed. This means, inside the battery, there must also be a path to complete this loop. This is where the electrolyte material comes in which serves as this path. It makes possible for ions (see description above) to travel between cathode and anode, in order to complete this loop and keep the current running. Through this electrolyte inside the battery, positive ions travel from anode to cathode (so that cathode can keep being positive and continue to accept electrons when they arrive from external circuit), and negative ions travel from cathode to anode (so that it can keep sending electrons to the external circuit).

The figure above illustrates this process. This is how a battery works. In the figure, electrons traveling inside the battery electrolyte actually represent the free electrons of the negative ions that move from cathode to anode. And for clarity of the figure, positive ions that go from anode to cathode were not shown.

In this post we will take a look at robot simulators and physics engines which should be discussed together.

Robot Simulator:

Basically a robot simulator is a computer program that facilitates building and testing of robots in a virtual environment.

Some key points:

Firstly, robot simulators help save great deal of time and money by elimination of physical prototypes and testing, at least during a major part of the design except the very last stages. Errors can be corrected, the simulations and tests can be reset, and any desired changes can be made far more easier than in real world for all aspects of the robot such as its sensors, actuators, kinematics, operating algorithms and control systems. Benefits are even further multiplied when building and testing multiple robot systems which may also be required to interact with each other and the system behavior must be coordinated.

It is important for a simulator to mimic real world as closely as possible, at least to a degree of simulating real life variables which will affect robots’ operation. This is done by a physics engine which is the core component of a robot simulator. It will be described in more detail below.

The robot simulator must integrate well with the actual operating system ( such as ROS etc…) that the robot will run on in the real world.

There are open source simulators. Using these have the advantages of not only cost but the possibility of being able to receiving inputs or at least discuss the process with far greater number of people.

One of the most beneficial aspects of using a robot simulator is to be able to train the AI far more easier than real world. Such training need a lot of trials and errors which can be performed much faster with a simulator.

Another advantage of using robot simulators is safety. Especially an incomplete robot’s operation may carry higher safety risks, even if all precautions are taken. Using a simulator eliminates such risks.

Real time ( or near real time) simulation and testing is also possible with simulators which means that the simulation runs at the same speed of the actual system.

Pysics Engine:

Simulators include a physics engine which is their key component. A physics engine tries to imitate real world by having virtual objects and environment interact within the boundaries of defined physical laws and constraints. Velocity, acceleration, position, mass of objects, collision detection and response, friction, rotations, kinetic and potential energy, their conversion into each other and conservation of energy concepts must all be represented within certain imposed constraints, with necessary mathematical functions, matrices, differential equations, numerical methods (methods which approximate solution to a complex system by enabling us to avoid very complex differential equations, by dividing the system into much smaller parts all of which can be solved easily and then their solutions are combined), within a coordinate system. As more advanced options, any soft bodies and their deformations, or even fluids may also need to be represented. So basically a physics engine is a mathematical model with variables representing a state of a system at a given instant. The simulation of the state of the system over time is of course ongoing which means all of these are continuously updated over time, which is done by numerical integration methods.

The author of this article, who is a civil engineer, can tell about a similarity here with structural analysis, which might reinforce understanding here. For example in structural analysis, when representing structural behavior under earthquake action over time, the state of the structure is also continuously updated by numerical integration methods, based on the forces on the structure and the structure’s stiffness at that instant (i.e. the equation [F]=[K][X] is continuously updated, where [F] is the global force matrix, [K] is the global stiffness matrix and [X] is the global displacement matrix of the structure. So this matrix is solved continuously within each small time increment ( i.e. 0.1 second). And the constraints as mentioned above in this case are the reaction forces provided by supports ( i.e. foundation) of the structure.

A. Tuter

Effective power management is essential for effectively distribute, store and control power in electrical circuits of any size and purpose. By this, energy waste is reduced, and components within the circuit are also protected from being exposed to overcurrent and getting overheated. Our attention as always are not macro power systems but micro systems such as in robotics, computers and small electronic devices.

Let’s list certain components and aspects of power management.

Voltage Regulators: Obviously the most fundamental components of a circuit to manage proper power distribution are voltage regulators. These provide necessary voltage as needed in a circuit. Voltage regulators are of different types.

Power rails: It is a path in the circuit that provides a given voltage to multiple components in the circuit which serves as a reference voltage in the circuit.

Current and Voltage sensors are used to meeasure if the distribution is working properly and to identify possible faults or inefficiencies.

Fans, heat sinks and thermal cutoffs are used to prevent overheating and damage.

Capacitors are used to temporarily store energy.

Power Management Integrated Circuit (PMIC): This can be considered as the brains, the central control of this whole operation, meaning, coordinating and optimizing power management in the circuit and also protecting it when necessary. A PMIC can be as a single chip, which helps efficient utilization of space constraints in electronic devices. The tasks of a PMIC include:

Monitoring the voltage, temperature and current levels of the system, to ensure they work within required values and activating overcurrent protection, thermal shutdown, and under-voltage lockout mechanisms when necessary.

Managing voltage regulators that we mentioned above, to make sure each part of the circuit receives proper voltage.

It turns power on an off to various parts of the circuit to manage power effectively and save power and also to turn them on and offin required sequence by the needs of the system.

Monitoring and optimizing usage of energy storage components like batteries and capacitors which includes charging rates, protection against overcharging.

Dynamic Voltage and Frequency Scaling (DVFS) adjusts the voltage and frequency of controlling components to optimize and save power.

An inverter is a device to change DC current to AC. It can be used for example to run devices during electric outages or remote areas without electrical service. For example at a remote area if you have solar panel to supply electricity, it would be a DC voltage. You need an inverter to modify this current to an AC current, to power your tools, devices, appliances or equipment, most of which are made to run on AC current, due to its inherent efficiency over DC current when transmitting electricity to power or homes, offices and factories.

An inverter changes the DC current direction, to match the sinusoidal waveform and frequency (as in 50 Hz) of an AC current.

In one sentence, how does an inverter work?

An inverter, has especially arranged paths of current to flow, and does this conversion by rapidly turning on and off the switches on these paths to generate current in wave form, (AC), from steady current (DC).

The components used in an inverter typically are:
Capacitors: They are a passive component of a circuit, which store and release energy when needed in order to smooth out fluctuations.
Transistors: Acts as an on or off switch to control the output
Inductors: Also a passive component like capacitor, an inductor helps stabilizing current and voltage fluctuations, working together with capacitors, by complementing each other.
Controller: It controls the on and off status if switches in a desired pattern, to generate the frequency of AC current we want.

Note that, above we said capacitors and Inductors both help stabilize voltage and current. So how do they exactly differ here, in other words why do we need both ?

Capacitors and Inductors basically complement each other here, for overall efficiency and stability of the circuit.

Capacitors store energy in their electric field. This makes them inherently good for dealing with abrupt voltage changes or fluctuations in other words, voltage regulation, to maintain steady voltage. This change can happen quickly because capacitors have low impedance at high frequencies, and this makes capacitors good at filtering high-frequency noise.

On the other hand inductors are very good at dealing with current changes because they store energy in their magnetic field during current flow. When the current changes, it is countered by the already existing current because of the magnetic field of the inductor, which tends to resist this change at first, and then gradually, smoothly allows it. In other words, inductors are used in current regulation to maintain a steady output of current. This ensures that unstable loads and current spikes are prevented. Because of the inherent slow synchronization nature of inductors with changes in current, in other words because inductors have low impedance at low frequencies, they are good at filtering low frequency noises.

Therefore, together, capacitors and inductors filter noise in voltage and current and smooth those out. This improves the efficiency of the inverter, significantly reduce power losses and ensures that the inverter can deliver stable voltage and current, which is safe to use.

Carnegie Mellon University Robotics Institute Researchers have developed a robot that can crawl inside natural gas pipelines to map them, while also detecting and repairing their leaks when necessary.

The research project, which is near completion, was sponsored by the U.S. Department of Energy (DOE) through the Advanced Research Projects Agency-Energy (ARPA-E) and its Rapid Encapsulation of Pipelines Avoiding Intensive Replacement (REPAIR) program. Upon its application, use of this system will drastically reduce the costs of pipeline leak detection and leak repair processes. 

The repair is made by the robot applying resin coating from inside, to seal the crack and can be applied for pipes of any material. The robot has a modular configuration which can be modified, which means flexibility for each application. 

For more details, see source at: 

https://www.cs.cmu.edu/news/2024/pipe-repair-robots