20

A differential is a mechanical device designed to do exactly what you propose. It will allow the two motors to spin at slightly different rates while still combining the power. The most common use of a differential is in the drivetrain of an automobile in which it is used to power both wheels from one engine while still allowing the wheels to spin at ...


19

While a mechanical differential does what you ask, you don't really need it. You can connect two identical electric motors together on the same shaft. There is no "slipping out of sync" because there isn't a issue of sync in the first place. Drive the two motors the same and both will develop close to the same torque. One will have slightly more torque ...


9

Radians and unit analysis The comment by MrYouMath is correct. For the purposes of dimensional analysis, the radian is considered a dimensionless quantity and therefore does not need to be included. This is because the radian is defined by an arc length (L) divided by a radius (also L) to give (L/L). The units of the Laplace domain complex number, $s$, are ...


7

This is not a definitve answer, but since I went to the trouble to look it up I thought i might as well post what I found: Pretty sure there's no onboard pump As you can see this is a normal firehose, not a suction hose with reinforcing spirals. this is relevant because it means water has to be supplied to Colossus at pressure, from a fire engine with a ...


6

The main problem which I can see in your idea, that your system will have a cumulative error. Only calculating this won't be enough, you will have to find alternate solutions, too. In similar (but maybe bigger) scenarios, for example for drones, there is a similar problem. The solution is using the wheel rotation counters to get a fast, real-time, but ...


6

Taking this in stages, initially lets consider only a single front wheel, with no slip in any direction, where we have an accurate continuous measure of both rotational position and absolute angle. In this case calculating current position (relative to our starting point) is a relatively straightforward trigonometry and calculus problem. Unfortunately we ...


5

While pneumatic systems can be controlled in a non-discrete manner as GisMofx mentioned, that is generally not the norm because the control system to achieve that movement is more expensive that comparative electric actuators. The result is still less precise and less responsive. This is the reason that all CNC machines are electric. Pneumatic systems are ...


4

PID, LQR, and LQG feedback control laws are only small pieces of the solution. Alone, these methods generally cannot solve the problem of balanced bipedal walking. The reason why is because these aforementioned control laws are designed to send the dynamics to a single, stable equilibrium point. If our goal is only to keep the robot balanced while standing,...


4

You do not need full vacuum to accomplish your goal. A small amount of vacuum pressure adds up really quick over a large surface area. Try to make the entire footprint of your robot under vacuum; your sealing perimeter increases linearly with diameter, but area increases with diameter squared. Basically this means the problem is easier to solve the larger ...


4

I can say using accelerometers to detect displacement won't work. These devices have so much of inherent noise that discerning very slow acceleration from remaining immobile is about impossible. You won't be able to detect acceleration of order of 0.1 mm/s2 and it takes just a several seconds at such acceleration to exceed your 5mm. You'd have a hard time ...


4

The correct way to do this is by using what is known as a particle filter. The maths for estimating your next position is quite simple and other answers have already provided that, but this is how you deal with the uncertainty. This video explains the basic principle rather well. You will notice that you need to take a measurement of some aspects relating ...


3

I think going optical is the only best solution. How about handheld interferometer? The reflection from interfoerometers are the best, as they give nanometer precision. If you could mount reflective surfaces on the object that moves, by simply capturing the reflected interferrometer patterns you can find the path difference and feedback to the displacement ...


3

The basic equation would be $$\text{Distance traveled}=2 \pi r \times n$$ where $r$ is the radius of the wheel and $n$ is the number of revolutions of the wheel. This assumes, though, that there's no slipping. This question says that for the car to move, $$F_k>f_cG_k$$ where $F_k$ is the force applied that's moving the far, $f_c$ is the coefficient of ...


3

Knowing the diameter of the wheels and the number of times the wheels turn over in a time interval will give both distance travelled and average speed for that time interval. You would have to have a continual monitoring system which would record time, wheel revolutions and the angle of the wheels used for steering, most likely relative to the central ...


3

An important point in the fluid dynamics design is about control points. A simple experiment - hold your hand over a hose on the vacuum cleaner, you'll notice a light vacuum pulling on it, but hold your hand right on the top of the hose, and it feels like it is pulling significantly harder. This is because fans operate on a load response curve, and when ...


3

Yes, it's possible. See here: Position Control of a Pneumatic Actuator and this youtube video here: Pneumatic Actuator With Position Control on YouTube Many solutions use a servo controlled pneumatic valve in conjunction with a position sensor on the actuator to control pressures on both sides of the piston to maintain a specific position or motion ...


3

Potentially yes. There are a lot of homemade toys which use a reaction between vinegar and bicarbonate of soda to make simple CO2 jet engines. However if you want to use this sort of reaction to generate more controllable mechanical power for actuators or motors you are giving yourself a lot of problems. Fighting robots often use compressed CO2 to power ...


3

Let’s consider gears as being represented by a pitch circle on which lie several equally spaced dots with a number equal to the number of teeth. These dots can either represent the teeth or the gaps between teeth, and they follow the rule that, as a pair of meshing gears rotate, the dots of one gear will coincide with the dots of the other gear as the dots ...


3

I believe the key here is not the material, but the manufacturing method. I would not recommend a small cnc machine, which seems to be what you're considering. Those are cool and fun, but you will have to dick around with it for dozens of hours, and it may never produce good results, and if it does, it will be slow. 25 bucks a set for parts is actually quite ...


3

Total reach is usually the straight line length of each member added together, do work centre to centre. The manufacturer will specify the total load at a spcific configuration so check the detail.


2

It heavily depends on the caster that the suspension is set at. Caster makes the wheels go back to neutral position. The more caster, the more torque is needed to keep the wheel at a position. Scrub radius will also make a difference. Google these terms and get familiar with them to get the idea. It will wildly vary per car. Use a scale like Muze mentioned ...


2

The forces of breaking a motor by shorting its electrical connections are the same as starting the motor with full voltage applied. Actually, they'd only be the same in a ideal motor. In any real motor the breaking forces would be a little less due to the less than 100% efficiency of the motor. Motor torque is proportional to the current. During ...


2

The robot likely has a body accelerometer & integrates it to use a velocity tracking controller with some sort of explicit or implicit proportional & integral control for the body. - This would keep the robot moving at the same speed as the weight it is dragging goes up. The balance of the robot body can be measured 2 ways: 1) the most ...


2

Clearly there are a lot of different potential solutions to this depending on the application and design approach. Also, as is clear from the video, bipedal robots are still a long way from achieving the level of elegance in walking that most humans manage with little conscious effort. As the most important comparison is with humans, it's worth looking at ...


2

In general terms what you really want from CNC machines is to repeat the same actions exactly the same every time, while you may need to monitor and account for things like tool wear, temperature changes, small variations in material properties etc this is still in the realms of fairly straightforward feedback control. Ultimately lathes aren't the best ...


2

I find I have to make a pretty large device to have anywhere near the same power as the human hand. Is the human hand, cubic centimeter for cubic centimeter just really strong compared to a machine? Keep in mind that power and strength (force) are very much separate things. It is easy to make a very strong and small gripper, by using worm gearing to magnify ...


2

I would like to commented this on the question (but I can't due to the 50rep requirement) I don't know if wheels are obligated or there a other options? Tracks should give more friction to the ground, so you will be able to have a smaller chasis with more traction than a long one with wheels. If the design must be wheel based, this is also a option. Also ...


2

The act of calculating the angles of a robot from the position of the end eflector is called inverse kinematics. Incidenttally the reverse, calculating end efflector position from angles is called forward kinematics. Kinematics being the study of motion of interconnected bodies. Now there are many ways to attack kinematics problems, and the exact solution ...


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