Alpha Rex Rbt Program

Alpha Rex Rbt Program Near Me
Alpha Rex Rbt Program Near Me

FIXED – Pressure, wind, and temperature measurements related to aircraft position in atmosphere.
FIXED – Improved grids for selecting airport data during weather injection.
FIXED – Registration process with missing profile data.
FIXED – Bug of missing data with function during static weather read.
FIXED – Checkerboard cloud patterns and transitions between cloud layers.
FIXED – User profile not loading during second load after initial registration.
FIXED – Temperature and dew point being same value on main weather interface.
FIXED – Ability to add a favorite airport.
FIXED – Selectable area of Favorite Airport banners.
FIXED – Upper-level winds and temperatures not changing when clicking a favorite airport.
FIXED – Cloud coverage.
FIXED – Pressure value being cut off from main interface.
FIXED – Optimized code to search for favorite airport on server end.
FIXED – Optimized code in pulling data for weather injection.
FIXED – Improper handling of Last Update date and time on main window.
FIXED – Issue with lightning to continue to show even when storms were not reported in the metar or remarks.
FIXED – Aircraft and weather point location accuracy points.
FIXED – Live Weather airport weather display accuracy.
FIXED – Extreme cold temperatures aloft.
FIXED – Temperatures to match data from data models.
FIXED – .net error 0xC000014B by updating to latest build of SimConnect.
FIXED – Range of weather search for live weather search and injection.
FIXED – Some favorite airports not being created due to improper characters.
FIXED – Registration errors to confirm data is valid.
FIXED – Clicking favorite airports causing weather reports during Weather Synthesis.
FIXED – Favorite airports loading store airports on server.
FIXED – Favorite airports refresh every 30 minutes.
ADDED – Decoupled winds and temperatures from many injections.
ADDED – Code to prevent a user from switching from Live to DCWS weather during open Weather Synthesis.
ADDED – Sections on application to help inform the user which weather mode they are in.
ADDED – Delete All Airports button to allow user to clear all favorite airports on client and server.
ADDED – Response of “No records found” when searching for an airport or specific weather condition.
ADDED – ICAO weather search show ICAO on top of rest of data surrounding the ICAO.
ADDED – Persistent weather data injection to help reduce frame rate hits during injection.
IMPROVED – Frame rates during transitions.
IMPROVED – Weather search window data elements.
IMPROVED – Rendering of storm and general cloud structures.
CHANGED – Weather presentation to show wind direction in degrees.
CHANGED – Dynamic Changing Weather Scenarios to Dynamic Weather Presets to make more sense.
CHANGED – Security protocol within the application.
REMOVED - Temperature, pressure, and wind controls from main injection so they will read as aircraft is in flight.
SUPPORT - Microsoft Flight Simulator latest version.

Introduction

Free download lego alpha rex program rbt Files at Software Informer. It is an application that allows you to create your own Lego model. You can use it to design any project you have in mind, or modify any of the predesignated. This is a great way to get your alpha rex walking right. This is a great way to get your alpha rex walking right. It’s been a long time since I’ve played with any type of LEGO and through good fortunes, I’ve been given a Lego Mindstorm NXT 2.0 kit and been playing with the humanoid build (Alpha Rex). After going through the basic programming, I thought of building my own using Bricx. I tried mimicking the original program while adding some of my own.

The Alpha Rex comprises probably the most complex of the RoboCenter series of robots, both from the mechanical design perspective and the software programming perspective. The following discussion will concentrate on software programming of the Alpha Rex. The program described below illustrates two advanced programming techniques: state machines and abstraction. A state machine design handles basic movements such as tilting side to side and striding the robot's feet forward and backward. Abstraction handles combining the basic movements into more complex movements, such as walking forward and turning right and left.

The inspiration for this program comes mainly from sources other than the Mindstorms RoboCenter software examples for the Alpha Rex. The RoboCenter examples perform basic movements such as walking forward and turning. However the examples are rather inadequate when it comes to combining basic movements into more complex movements, such as having your Alpha Rex move in a figure eight pattern. Furthermore, including such functionality as having the Alpha Rex walk around avoiding obstacles behooves the application of more advanced programming techniques.

The following sections describe these techniques in much more detail. The final section, following the description of these techniques, presents the development of a complete program for avoiding obstacles.

Basic Movements - State Machine Approach

The Alpha Rex mechanical design falls into a category referred to by robotics hobbyists as a toddler biped. Generally speaking a toddler robot uses only two servos for movement, like the Alpha Rex. One servo shifts the robot's weight from one foot to the other foot. The other servo moves the feet backward and forward. Efficiency and economy in programming dictates that these basic movements link together seamlessly to provide more complex movements, such as walking forward, or turning right. Seamless movement, from a programming perspective, requires that movements do not depend on other movements.

Seamless movement means that a composite movement, such as tilting left and moving the right foot forward, may be combined together without the programmer needing to concern themselves with the details of servo position, direction of rotation, and amount of rotation. The composite movement routines, described below, make use of two basic building blocks: a routine for tilting the robot side to side, and a routine to move the robot's feet back and forth.

For a complete discussion on how these two movements can be combined into composite movements see pages 33-37, 56-57, and 65-66 of the Parallax manualAdvanced Robotics with the Toddler, by Bill Wong and Ken Gracey. The reader is pointed to the above reference for a detailed understanding of toddler movements, and since the Alpha Rex is a toddler type robot these considerations apply. I highly recommend reading the above pages before continuing with the rest of this discussion.

Tilting from Side to Side

The C motor (plugged into port C) moves the robot from side to side. Unlike the RoboCenter example, the following subroutine uses the C motor as a servo (as opposed to a simple motor). Using a motor as a servo means that the primary function of the motor is to move, or actuate a lever arm over a limited distance (or travel). Moving a limited distance means that the motor does not rotate an unlimited amount, rather the motor rotates only that amount necessary to move the lever, or connected mechanical component the required amount. In the case of the Alpha Rex the components are the robot's two legs, which have two degrees of freedom in the way they can move: shifting the weight of the robot from one leg to the other, and moving one leg forward at the same time moving the other leg backward. The rotation sensors built into the NXT motors allow them to work very nicely as servo motors.

Tilting the Alpha Rex side to side may be broken down into nine separate cases defining the C motor action necessary to implement a basic movement. The following table lists these cases, or states. The first column provides a numerical identifier that the software can use to identify each possible state. The second column gives the movement from the previous position to the new position, such as the robot moving from tilting to the right to tilting to the left. The last two columns describe the required C motor action to perform the movement in the second column. You will note included in the table certain trivial movements, such as moving center to center. These are essentially 'do nothing' states that may occur because a previous movement left us in the state in which we already desire to be.

Table 1
State	Movement	Number of Rotations	Direction of Rotation
0	Center to Center	none	none
1	Right to Center	0.75	↑
2	Left to Center	0.75	↓
3	Center to Right	0.75	↓
4	Right to Right	none	none
5	Left to Right	1.5	↓
6	Center to Left	0.75	↑
7	Right to Left	1.5	↑
8	Left to Left	none	none

The tilt subroutine makes use of a single state variable to contain the previous position state of the robot: left, right, or center. Table 2 associates each of three possible tilt movements and tilt states (previous position) with a unique identifier number.

Table 2
ID#	Movement	Previous Position
0	Tilt back to the center position	Center
1	Tilt to the robot's right side	Right tilt
2	Tilt to the robot's left side	Left tilt

Thus the most previous position may be represented by a number 0, 1, or 2. And the new movement we are about to perform by a number 0, 1, or 2. Hence we may use a simple formula for determining the state in table 1 above: State ID equals three times the new movement plus the previous position, or

StateID = 3 * NM + PP
where StateID is the State ID in table 1,
NM, the new movement, and
PP, the pervious position

For example, if the previous position is â€œcenterâ€ and we want to tilt left, then

StateID = 3 * 2 + 0 = 6

Looking at table 1, the associated movement (in the same row) as StateID 6 is 'center to left', as expected.

The NXT-G code shown below implements the tilt subroutine. The code uses a state variable 'Tilt_Previous' to maintain the previous tilt position of the robot. A switch statement handles all the cases in table 1. The subroutine has only one input parameter: one of the numbers from the first column of table 2. Hence, when using this subroutine as a My Block we only need to know what tilt position we wish the robot to assume: left, center, or right. We do not need to know anything about the servo positions or how to move them. This abstraction removes these details from the programmer who uses the tilt subroutine in a higher level program.

Striding Forward and Backwards

The B motor (plugged into port B) moves the Alpha Rex feet forward and backward. The development of the striding subroutine follows very closely the development of the tilting subroutine described above. Similar to tilting the robot side to side, moving the robot's feet backward and forward may be broken down into nine separate cases as shown in table 3.

The first column gives the State ID used by the software. The second column gives the movement of the robot's feet. To understand the movement column, think of the movement as saying which foot in front has to move to a new position. For example, 'right to center' means that the right foot has to move from in front to the center position directly below the robot. 'Left to right' means that the left foot has to move from in front to the rear of the robot. 'Right to left' means that the right foot has to move from in front to the rear of the robot. Keep in mind that the feet move concurrently. That is, when the right foot moves forward, to the front of the robot, the left foot moves, simultaneously, to the rear of the robot. The last two columns describe the required B motor action to perform the movement in the second column.

Table 3
State	Movement	Number of Rotations	Direction of Rotation
0	Center to Center	none	none
1	Right to Center	0.75	↓
2	Left to Center	0.75	↑
3	Center to Right	0.75	↑
4	Right to Right	none	none
5	Left to Right	1.5	↑
6	Center to Left	0.75	↓
7	Right to Left	1.5	↓
8	Left to Left	none	none

Similar to the tilt subroutine, the stride subroutine makes use of a single state variable to contain the previous stride state of the robot: left foot forward, right foot forward, or both feet in the center position. Table 3 associates each of three possible stride movements and stride positions with a unique number.

Table 4
ID#	New Movement	Previous Position
0	Both feet to the center position	Feet centered
1	Right foot to forward position, left back	Right foot forward, left back
2	Left foot to forward position, right back	Left foot forward, right back

Similar to the tilt subroutine, we may use a simple formula for determining the state in table 3 above: State ID equals three times the new movement plus the previous position, or

StateID = 3 * NM + PP
where StateID is the state ID in table 3,
NM, the new movement, and
PP, the previous movement

The NXT-G code shown below is very similar to the tilt subroutine. The code uses a state variable 'Stride_Previous' to maintain the previous stride position of the robot. A switch statement handles all the cases in table 3. The subroutine has only one input parameter: one of the numbers from the first column of table 4. Hence, when using this subroutine as a My Block we only need to know what stride position we wish the robot to assume: left foot forward, both feet centered, or right foot forward.

Composite Movements

Walking forward and backward, turning from left to right and right to left may be accomplished by simply combining together tilt and stride My Blocks in the correct sequence. For example, to walk forward we must accomplish the following: tilt left, move right foot forward, tilt right, move left foot forward. Conversely we may walk forward by: tilting right, moving the left foot forward, tilting left, and moving the right foot forward. The NXT-G code for walking forward is shown below.

Turning the Alpha Rex involves an added principle: friction. That is, the robot does not so much turn as it pivots. It pivots by centering its weight over both feet (center tilt position) and moving one foot forward and the other backward. For example, if the right foot moves from the forward position to rear position (concurrently the left foot moves forward), the robot will pivot to the left.

Scanning for obstacles

The Alpha Rex uses motor A to both move the robot's arms up and down (rather functionally useless) and for panning the ultra-sonic (US) sensor back and forth. The NXT-G subroutine shown below rotates the US sensor to the left and takes a reading, then it rotates the US sensor to the right and takes a reading. The readings are stored in two variables: one for the left reading and one for the right reading. The main program uses these readings to determine what to do when the US sensor 'sees' an obstacle in front of the Alpha Rex. You may note that the NXT-G code inserts a pause between the motor block and the read US sensor block. This pause allows the mechanical movement of the US sensor to stabilize before the sensor gets read, thus increasing the reliability of the reading.

Avoiding obstacles

The NXT-G code shown below ties all the ideas and code previously discussed into a practical program for the Alpha Rex. The code below comprises the main routine programmed into the Alpha Rex. In software parlance the main routine sometimes gets referred to as the 'executive routine' or the program 'entry point', because this where the program first starts when executed.

The program works by first executing the 'AR_US_Scan' My Block. The execution of this block stores the reading from the US sensor, taken when pointed to the left, in the variable US_Reading_L. Conversely, the reading from the right gets stored in US_Reading_R. The main routine then checks to see if either reading indicates that the robot sees an obstacle closer than 15 inches. If so, then the program compares the two readings to determine whether the robot has seen the obstacle to its left or right side. If the robot sees the obstacle to its right, then it turns left to avoid the obstacle. Conversely if the robot sees the obstacle to its left, then it turns right to avoid the obstacle. If the robot does not see an obstacle on either side, then it walks forward.

The AR_US_Scan My Block and the movement My Blocks indeed hide a great deal of painstaking complexity from the programmer creating the code for the main routine. He does not need to know the details of how the sensor works or takes its reading. He does not need to know the details of how to make the robot walk or turn. He only needs to drop the appropriate My Block in the correct position. By now you should be able to see the power of abstraction in software design. Abstraction eliminates the need to know the details and makes the code very simple and straight forward.

(click on image for enlarged view