# Tag Info

13

You want to use USB for communications with the computer. If you have a number of microcontrollers, you will probably only connect one of the microcontrollers directly to the computer. The other microcontrollers will need to get their commands from the main microcontroller. The communication you choose will depend on a number of factors: required bandwidth ...

11

If I were you, I would first (1) read the LM2576 datasheet. I'm assuming you are using a circuit similar to the schematic and PCB layout on page 23 of the LM2576 datasheet. I'm guessing you've tweaked the circuit slightly, replacing the manually-operated pot shown on the schematic for R2, replaced with some sort of microprocessor-controlled thing that ...

11

That is a very good question, and depends on the design. There are in general two ranges for components which are temperature sensitive. The operational range gives the temperature at which the component can be actively used. Within the survival range the component should generally take no harm but may not be actively used. Often what is even more demanding ...

11

I've found the wikipedia article (as well as its linked articles) on the history of robots to be enlightening: The history of robots has its roots as far back as ancient myths and legends. Modern concepts were begun to be developed when the Industrial Revolution allowed the use of more complex mechanics and the subsequent introduction of electricity made ...

7

The answer is 'yes'. A more detailed answer likely depends on how you define "robotics". But generally, robotics applications are considered to require a very broad spectrum of knowledge. So while most robotics includes some form of mechanical function, you could easily specialize in artificial intelligence, microcontroller design, or any number of ...

6

If I recall correctly Leonardo da Vinci is credited with the earliest design of a robot. My personal favorite is generally referred to as Leonardo's robot. However some accounts place Leonardo's cart as having come first and is generally considered a robot because it could be "reprogrammed" by replacing its cogs.

6

On the Asguard system that we have been working on, we have a lot of shocks due to the wheel geometry. On this system we were also able to reduce the vibrations on the control side as Mark suggested. This was done through synchronising the wheels in optimal patterns. The system also has some mechanical design features that reduces the vibrations. Flexible ...

6

Components should have vibration ratings somewhere. Pretty much anything without moving parts will be fine. Some sensors such as accelerometers and gyroscopes are affected. As an example, quadrotors are an application that is dramatically affected by vibration. The four props produce an absolutely ridiculous amount of vibration and a quadrotor requires ...

6

Partly this depends on where the vibration is coming from. While the two techniques you describe are very valuable, if the vibration is from your own actuators then you may be able to significantly improve things by simply using a different velocity profile for your moves. Traditional trapezoidal velocity profiles are a constant acceleration up to a fixed ...

6

Can I get away with all the ground being common? That's exactly what should be done. Do I need two sets of capacitors? Yes, you usually want to keep all capacitors as they are even if you are cascading voltage regulators. They help keep the regulator stable and avoid sharp voltage variations. Be aware that either regulator might limit the amount of ...

6

It is possibly a bias in the accelerometer. The measured non-zero results (like yours) are the bias. No idea if the magnitude of these biases is right, i.e., you may be experiencing more error than you should expect from a bias. To be clear, you can subtract this bias from your estimate of acceleration. However, you should be sure that the bias doesn't ...

6

There are a variety of reasons to separate the motor power from the "hotel load", including: Reducing the number of wires running between high-power and low-power electronics Redundancy (your homing beacon shouldn't run out of power when the rest of the system does) Preventing heavy current loads from browning out the control system Making the system more ...

6

Actuators that use a worm gear can't generally be back-driven; these are the same gearing mechanisms that let you twist a guitar string to tune it without the tension being able to back-drive (and thus un-tune) the tuning mechanism. Worm gears are nice in that they offer generally pretty huge reductions in speed, with a huge increase in torque. This leads ...

5

According to the datasheet, there are three possibilities: TTL shutdown, thermal shutdown and current limiting. From what I looked up, TTL shutdown means simply that you have a pin you can use to cut-off the regulator output current. My guess is that it is pin 5 and you simply grounded it, as seen in the typical application circuit, so that possibility can ...

5

I can highly recommend CAN for inter processor communications. We use it in our robots, with up to 22 processors on the same bus. With good protocol design, you can use up about 90% of the available bandwidth (about 640kbps when you take into account all of the error checking and inter frame spacing). We're able to servo 10 motors at 1000Hz on one CAN bus. ...

5

If you are interested in real and fictional robots (for concepts), the CMU Robot Hall of Fame may be useful.

5

Since you're running directly from a battery I would say it's safe to just add as much decoupling (in other words caps across your input power) as possible, since the only real downside (that I think is relevant to your setup) to adding a lot of capacitance is increased in-rush current (since the capacitor naturally acts as a short-circuit during charge-up). ...

5

It sounds like you're experiencing a "brown out" caused when the excessive current draw from the battery causes a drop in the supply voltage. This is due to the fact that batteries have internal resistance (a.k.a output impedance). In this example, if the load drops to $0.2\Omega$, the internal resistance of the battery will cause the output voltage to be ...

5

I must agree with the other two answers, however the main issue is that you do not have enough voltage into your regulator (I see from your comment to Ian that you are using a Pololu D15V35F5S3 Regulator). If you refer to the Pololu D15V35F5S3 Product Description, down at the bottom you will find the following graph: Looking at the red line for 5V output: ...

4

You can find some nice presentations on prezi about robotic history (and about many other topics). For example this or this or this presentations mention the ancient greek Archytas's robotic pigeon well before Leonardo's work around 350 B.C. and the klepsydra from around 300 B.C. having a feedback control system.

4

This site gives a great time line of robotics. Keep in mind the origins of robots come well before electricity. As the article describes, the early egyptians designed and constructed simple automatons, which are considered the earliest type of robot. Another starting point worth mentioning is the materials that early robots were made from and continue to ...

4

It may be practical to adapt some ink-jet printer heads to dispense water. An ink-jet printer head projects a stream of droplets. Droplet volume varies widely among printers; typically, it's smaller in newer printers. Eg, a fairly-comprehensive 1998 inkjet tutorial at imaging.org says early HP 800-series ink-jets produced 6000 drops per second with 32 ...

4

Working in robotics doesn't mean that you must understand (or enjoy) all the relevant disciplines. It simply means that you must understand that you are one part of a team that produces a robotic system. On the other hand, what skills you have will determine which teams will find you valuable as a member -- smaller teams require everyone to bring multiple ...

4

Is it possible? Certainly. Is it worthwhile? Depends on how sensitive you need it to be. Dog urine has a strong ammonia component (or maybe it's just my dogs that stink so bad) that could be used as the primary analyte to look for. Unfortunately, calibrated electronic ammonia sensors are expensive. I was actually looking into this just a week ago because I ...

4

As a professional robotics engineer (with an Electrical and Computer Eng bachelors, although I focused more on the CE side), this depends entirely on what aspect of a robotic system you'd like to work on. Robots are interdisciplinary systems by definition, and you will always need a team with a broad skill-set to build one. That being said, there are places ...

4

Robots tend to be portable devices powered by batteries. Portable battery operated devices tend to use embedded processors with limited power and memory. Compiled code has several advantages over interpreted code in such applications: Compiled code usually takes up less space. So you can have more code in the same amount of space. Compiled code usually ...

3

You can also add between the controller power an electrolytic capacitor of about 500 or even 1000 microfarads x 12 volts and a diode in series with it, so when the trigger pull much current source with a corresponding drop in voltage will be avoided that Power down controller please and even free you from unwanted noise (about 10 turns of cable around a ...

3

I don't know any "rules", but for complex bots, I create separate "power" unit. It basically consists of the battery, as well as some 7805s/7809s. The 78xx series takes a 12V input and gives an xx V output. Most ICs work well on 5V, and an Arduino needs 9V, so that's what I end up using (Note: the 5V/3V output pins on the Arduino are not really meant to be ...

3

First a bit about motors. Stall current is the current drawn by the motor when the recommended voltage is applied and the motor is not turning due to a load. Alternatively, the no load speed is the speed the motor will spin at under no load. In this state it will draw a minimum current. Here is an example torque/speed current for a DC motor: Source: ...

3

I have used small solenoid valves with a fixed displacement to dispense small droplets. For example, the valve I used consistently pumped 0.5 uL from one orifice to the other every time it was switched. That particular valve was not intended to be used as a pump, but there was no reason it couldn't be. There are other solenoids which are intended to be used ...

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