原创 机器人

2006-10-23 22:10 6774 9 13 分类: MCU/ 嵌入式
Building The Lynxmotion BRAT

Exploring Humanoid Robotics Has Never Been Easier

Story and photos by Tom Atwood and Harry Mueller

点击看大图


This pictorial shows the assembly of Lynxmotion’s, www.lynxmotion.com, new BRAT, an entry level bipedal robot that is a milestone robot. With a starting price of less than $300, BRAT offers an affordable yet sophisticated entry into the humanoid robotics field. Use Lynxmotion’s powerful sequencing software and you will be able to program the coordinated movement of up to 32 servos (the BRAT biped uses only six servos). The BRAT is a powerful testament to the flexibility of the “servo erector set” product line developed by Lynxmotion. Harry Mueller, who reviews the BRAT in our Winter 2006 issue, notes:


“BRAT, an acronym for Bipedal Robotic Articulating Transport, is the latest creation to come whirring out of the Lynxmotion robotics lab. It promises to be a great addition to the entry-level humanoid robot class. This robotic incarnation can trace its development back to its distant cousin Tao-Pie-Pie of New Zealand, through to SixPac, as described in the Fall 2006 issue of Robot magazine, and up to the first inspirational glimmerings of Jim Frye of Lynxmotion, who created the wonderfully expandable BRAT package.


“In the feature article on the BRAT published in the Winter 2006 issue of Robot, we examine two versions, a bare-bones basic kit and a full-blown “Tarzan-on-steroids” BRAT capable of autonomous operation in addition to great feats of strength. The main difference between the versions is the type of servo used; the basic kit comes with the Hitec HS-422 servos while my hopped up BRAT uses Hitec 5645 digital servos. In addition, my autonomous BRAT uses the optional bot board with an Atom Pro microprocessor. Obstacle detection is achieved with a Sharp GP2D12 analog infrared ranger…


“A number of optional configurations are available for BRAT using different servos and SES components and a few such versions are shown on the Lynxmotion website (www.lynxmotion.com). Once your BRAT has been configured Lynxmotion provides three ways of implementing control.




    • Just use the free terminal program available for the SSC-32.
    • Purchase and use the powerful Sequencer software with the SSC-32.
    • Get a bot board with processor for untethered operation. The Bot Board can also be piggybacked onto the SSC-32 servo controller, in addition to being used alone.”

I assembled the entry level BRAT kit to shed light on the easy steps involved. Putting this research biped together was enormous fun―here are some highlights of the assembly process.



点击看大图
The autonomous BRAT, with infra-red obstacle avoidance, built by Harry Mueller.


点击看大图
The parts are very well organized and are sealed in discrete, well-labeled plastic bags. One of the nice things about the modular Servo Erector Set parts series is that individual brackets come with a standard allotment of screws, nuts, washers and the like, typically more than you’ll need. This put a smile on my face because the assortment of nuts and bolts in my spare parts bin grew as I built the BRAT!


点击看大图
The black anodized aluminum parts almost chime when you put them together, which added to the fun (it feels like you are working with fine metal pieces, something reminiscent of medieval armor). I used bare metal 256 screws when I anchored the multi-purpose brackets to the feet to show the attachment points (black screws come with the kit).


点击看大图
In the second step, L brackets are bolted to C brackets. The instructions illustrate building the left leg. As you build it, simultaneously assemble the right leg as a mirror image.


点击看大图
Multi-purpose brackets are then bolted to the L brackets.


点击看大图
Next, 3mm ID x 8mm OD flanged ball bearings are used to connect the multi-purpose brackets on the feet to the assemblies. Note the bearing and lock washer.


点击看大图
Once assembled, the partial leg assemblies can pivot on the bearings. There is a little play in the joint; this is normal and everything becomes very stable when servos are installed.


点击看大图
Two C brackets are joined.


点击看大图
C brackets are then attached to the leg assembly, and a multi-purpose bracket is attached to the other side of the C bracket. These are bearing-supported, pivoting joints.


点击看大图
Next the U-channel, which will carry the battery, is bolted in place on each leg assembly. The parts are face down and the U-channel is bolted to the left leg.


点击看大图
Both legs are connected to the U-channel; the BRAT is face down.


点击看大图
We are ready to install the first Hitec HS-422 servo. The plastic rivets are easy to use and do a great job attaching the servos to the brackets. Just two self-tapping screws are used to mount the servo wheel to the bracket.


点击看大图
I used a Servo Lab from FMA Direct to center the servos before installation. This is important as you want all the parts to be in proper alignment when the servos are at neutral. Proper alignment results in a better performing robot and makes it easier to share and use projects created by other BRAT owners.


点击看大图
Note the placement of the rivets.


点击看大图
Servos have been installed in both ankle joints.


点击看大图
The knee servos have been installed.


点击看大图
The hip servos are mounted.


点击看大图
It’s beginning to look like a walker!


点击看大图
Use tie wraps to secure the servo cabling. This shows the first of several tie-downs needed.


点击看大图
The power switch has been attached. I later changed the plug from the Tamiya connector shown to an Anderson Power Pole (my workbench standard).


点击看大图
The SSC-32 has been installed with the pins and surface mounted chips on the exterior. This is temporary because after you have trouble-shot the installation, the SSC-32 is flipped over to protect the components. Carefully thread the servo leads (pen is pointing to the lead path through the frame).


点击看大图
Carefully strip and insert the power leads into the VS1 or VS2 terminal. I used the VS2 (both will work with the jumpers properly set). Make sure no tiny strand of wire is poking out of the connection; that could cause a short (and let the dreaded magic smoke out).


点击看大图
Note the position of the jumpers. These positions are specified on page two of the SSC-32 Ver. 2.0 manual. Read the first two pages of that manual carefully; it describes the layout of the board.


点击看大图
The finished entry level BRAT with the cable in place to connect the SSC-32 to the serial port on my Dell Inspiron laptop. I bought a serial to USB cable from Radio Shack, and had no problem hooking up the BRAT. I did have to toggle through a couple of Com ports to find one that recognized the SSC-32, but this only took seconds.


点击看大图
After connecting to the serial port and applying power, the green light on the SSC-32 illuminates. You then run the Visual Sequencer program. Make sure you have the latest version.


The instructions note that the robot might move swiftly and be prepared. I “knew” all of my servos were properly centered, but when I told the software to center all servos by clicking on the “All="1".5mS” button, my BRAT came alive and kicked me! I had installed one servo 90 degrees out of phase!


点击看大图
You are now ready to set the throw limits and centers on your servos. Here, an ankle servo is set to a 45 degree deflection. Using the Visual Sequencer program, you can then build coordinated, timed sequences of moves that define how your BRAT walks and moves. For more detail on what can be done with the Sequencer, download the sequencer manual at: www.lynxmotion.com/images/data/seq01h.pdf.


点击看大图
This screen grab shows the visual depiction of BRAT’s servos in the Sequencer program. Imagine how this would look if you added additional servos to build this biped into a full-featured humanoid!


点击看大图
Once Harry Mueller added the bot board to his BRAT (see Winter 2006 Robot), switching between the Sequencer and the Atom Pro became something of a chore. A nice fix is to hook up all the pins required to set both the DB9 enable and the TTL serial comm to a 4PST top slide switch. That way you can just flip a couple of switches to go from using the Sequencer to sending things to the Atom Pro and back. Jim from Lynxmotion pointed out that the baud rate can be set permanently to 38.4K for both functions without affecting performance.


点击看大图
Harry’s autonomous BRAT with digital servos executes a Karate kick.


Exploring this software has not only been a hoot, it’s been an inspiration. The power of this software is enormous and one can easily envision “growing” the BRAT to include additional joints and limbs. Want to build your own Robo-One humanoid robot? Start with a BRAT and add a torso, head and arms. See the Winter 2006 issue of Robot to read Harry Mueller’s evaluation of the autonomous Lynxmotion BRAT powered by digital servos. The entry level Biped BRAT Combo Kit for PC (serial port, Brushed or Black Anodized brackets) includes the Sequencer software, SSC-32 Servo Controller, Serial Data cable and four Hitec HS-422 servos. Price: $286.09

文章评论4条评论)

登录后参与讨论

用户851691 2006-10-31 14:14

好象是用比例遥控用的舵机做  构思不错

用户1271842 2006-10-29 00:14

那是公司产品嘛!又不是个人做的。不过网上确实有人自己做机器人的——我是指使用自行购买散件(应该是工业标准的标准件)或加工的零件。

 

用户1063369 2006-10-26 09:21

强,就一个字,酷毕了

用户1053025 2006-10-24 11:13

图片是够酷,就是文字看不懂:P
相关推荐阅读
zhaoliang_0801_926809075 2009-07-28 09:13
基于FPGA和avr单片机的DDS信号发生器
基于FPGA和avr单片机的DDS信号发生器1、项目简介本设计提出了一种使用经济有效的低频信号发生器的设计方法,系统可以实现各种频率各种相位的输出,可以实现ASK、FSK调制信号的输出,其他的调制信号...
zhaoliang_0801_926809075 2009-07-27 23:30
出售msp430uif usb 仿真器
电路板稍有瑕疵,背面需要跳根线,请追求完美的朋友绕到,谢谢 :)此次一共有39块PCBPCB 定价 12元 (瑕疵修改后,定价15元)成品 定价 140元(瑕疵修改后,定价150元)芯片封装:MSP4...
zhaoliang_0801_926809075 2009-07-27 23:15
开源项目-基于FPGA的等精度频率计
开源项目-基于FPGA的等精度频率计1、项目简介:这是本人06年的一个课程设计,当时做完之后,总结了一个片论文发表《电子工程师》有兴趣的朋友可以看看,论文写的比较详细。利用51单片机和FPGA控制实现...
zhaoliang_0801_926809075 2009-07-04 23:38
FPGA入门系列实验教程——实验三 LED流水灯
FPGA入门系列实验教程——实验三 LED流水灯声明:本实验教程编写的目的就是为了指导FPGA初学者轻松入门,让初学者少走些弯路,但由于版主学习FPGA时间不长,水平有限,教程中肯定会出现这样或那样的...
zhaoliang_0801_926809075 2009-07-04 23:37
FPGA入门系列实验教程——实验一 点亮LED
FPGA入门系列实验教程——实验一 点亮LED声明:本实验教程编写的目的就是为了指导FPGA初学者轻松入门,让初学者少走些弯路,但由于版主学习FPGA时间不长,水平有限,教程中肯定会出现这样或那样的错...
zhaoliang_0801_926809075 2009-07-04 23:37
FPGA入门系列实验教程——实验二 LED闪烁灯
FPGA入门系列实验教程——实验二 LED闪烁灯声明:本实验教程编写的目的就是为了指导FPGA初学者轻松入门,让初学者少走些弯路,但由于版主学习FPGA时间不长,水平有限,教程中肯定会出现这样或那样的...
我要评论
4
9
关闭 站长推荐上一条 /2 下一条