關于瑞典輪機器人——youbot的討論

(轉載請注明作者和出處:https://yangningbocn.github.io 未經允許請勿用于商業用途)
一個老外給出了一個觀點:把他當做平面移動處理,比較貼合我的想法,整體的運動與輪無關,這樣復雜的問題簡單化。

他的原話:

Just a thought, for this robot it may be easier to model the motion of the entire robot instead of modeling the individual wheel. One path could be to use a plugin that accepts twist messages and applies them to the robot base. An example of this is the Planar Move Plugin.

In two dimension (i.e. stage) this might have been called the holonomic plugin.

網址為:

How to simulate a mecanum wheel in Gazebo


也有人提出這樣的觀點:通過添加一個轉動關節軸進行角度改變來模擬瑞典輪

原話如下:

new to all this but thought I could simulate a mecanum wheel by adding a rotational joint about z-axis for each wheel that is restricted to 0, 45 and 90 degrees. this way the base can go forward/backward/45 degree forward/backward and left/right, sideway left/right and rotate left/right. the simulated moves would need to translate into rotational direction sets for the physical movements of the 4 wheel motors? however - how can I have a restricted set of angels for a joint and what needs to be in place to translate it into the physical wheel rotation command? of course the simulation would only provide a logical wheel view and it will also need a special collision handling as the wheels do not really rotate on the z-axis. but in total an easy representation of the possible moves?

網址如下:

Mecanum wheels ok in one direction not the other in Gazebo


還有一個人提出消除掉輪與地面之間的摩擦,然后按照twist來結算每個輪的速度,只是讓輪旋轉,機器人的移動依賴于twist。而不依賴于每個輪的旋轉。我覺得這個思路很好。

原話:

It’s a really interesting simulation issue.

First of all, let’s a look at the wheels. They are not standard wheels, they are mecanum wheels. This kind of wheels help the robot to move and rotate easily in any directions, even in congested area. The movement come from the resulting rotation speeds of the wheels, which are independent. I have found I nice explanation of the relationship between the wheels rotation and the resulting movement on this lego page. On the videos, the youBot looks like gliding on the ground.

From a design point of view, this is convenient, because it is similar to a planar joint + a revolute joint between the base and the ground. Very easy to control.

From a simulation point of view, it is a nightmare.

I doubt that the repo from youBot or WPI-RAIL did the job, because they involve casters. And there is no casters on the real KUKA youBot. If you have a look at their teleop program, you will see that this program align the wheels before the rotation, which is not the design of a mecanum wheel at all. With the mesh of the wheels, you will see it. This not natural (this is also why the wheels solid shape is a sphere). And even worst, the the rotation is therefore not supported. So for me, this model is really poor.

I raised the question on Gazebo answers. Someone suggested to use this planar controller. I considered it as a second choice, but finally, this is very close to the behavior of the real mecanum wheels, as you define the x/y velocity and rotation, which can be directly linked to the wheel individual speeds. I have remove the friction between the wheels and the ground.

On the real robot, this x/y speed and rotation translation to individual wheels speeds would also be very convenient.

A visually better solution would be to add the mesh of the wheels, and rotate them according to the planar messages. No time to work on this.

Finally, if you are looking for a very physical solution, I have found this link, where it has been done in another simulator, by mixing kinematics and dynamics solutions.

That would be really great to have more realistic solution. For my requirement, the planar controller is enough.

網址:

Move the youbot using its wheels

?著作權歸作者所有,轉載或內容合作請聯系作者
平臺聲明:文章內容(如有圖片或視頻亦包括在內)由作者上傳并發布,文章內容僅代表作者本人觀點,簡書系信息發布平臺,僅提供信息存儲服務。
  • 序言:七十年代末,一起剝皮案震驚了整個濱河市,隨后出現的幾起案子,更是在濱河造成了極大的恐慌,老刑警劉巖,帶你破解...
    沈念sama閱讀 229,619評論 6 539
  • 序言:濱河連續發生了三起死亡事件,死亡現場離奇詭異,居然都是意外死亡,警方通過查閱死者的電腦和手機,發現死者居然都...
    沈念sama閱讀 99,155評論 3 425
  • 文/潘曉璐 我一進店門,熙熙樓的掌柜王于貴愁眉苦臉地迎上來,“玉大人,你說我怎么就攤上這事?!?“怎么了?”我有些...
    開封第一講書人閱讀 177,635評論 0 382
  • 文/不壞的土叔 我叫張陵,是天一觀的道長。 經常有香客問我,道長,這世上最難降的妖魔是什么? 我笑而不...
    開封第一講書人閱讀 63,539評論 1 316
  • 正文 為了忘掉前任,我火速辦了婚禮,結果婚禮上,老公的妹妹穿的比我還像新娘。我一直安慰自己,他們只是感情好,可當我...
    茶點故事閱讀 72,255評論 6 410
  • 文/花漫 我一把揭開白布。 她就那樣靜靜地躺著,像睡著了一般。 火紅的嫁衣襯著肌膚如雪。 梳的紋絲不亂的頭發上,一...
    開封第一講書人閱讀 55,646評論 1 326
  • 那天,我揣著相機與錄音,去河邊找鬼。 笑死,一個胖子當著我的面吹牛,可吹牛的內容都是我干的。 我是一名探鬼主播,決...
    沈念sama閱讀 43,655評論 3 444
  • 文/蒼蘭香墨 我猛地睜開眼,長吁一口氣:“原來是場噩夢啊……” “哼!你這毒婦竟也來了?” 一聲冷哼從身側響起,我...
    開封第一講書人閱讀 42,838評論 0 289
  • 序言:老撾萬榮一對情侶失蹤,失蹤者是張志新(化名)和其女友劉穎,沒想到半個月后,有當地人在樹林里發現了一具尸體,經...
    沈念sama閱讀 49,399評論 1 335
  • 正文 獨居荒郊野嶺守林人離奇死亡,尸身上長有42處帶血的膿包…… 初始之章·張勛 以下內容為張勛視角 年9月15日...
    茶點故事閱讀 41,146評論 3 356
  • 正文 我和宋清朗相戀三年,在試婚紗的時候發現自己被綠了。 大學時的朋友給我發了我未婚夫和他白月光在一起吃飯的照片。...
    茶點故事閱讀 43,338評論 1 372
  • 序言:一個原本活蹦亂跳的男人離奇死亡,死狀恐怖,靈堂內的尸體忽然破棺而出,到底是詐尸還是另有隱情,我是刑警寧澤,帶...
    沈念sama閱讀 38,893評論 5 363
  • 正文 年R本政府宣布,位于F島的核電站,受9級特大地震影響,放射性物質發生泄漏。R本人自食惡果不足惜,卻給世界環境...
    茶點故事閱讀 44,565評論 3 348
  • 文/蒙蒙 一、第九天 我趴在偏房一處隱蔽的房頂上張望。 院中可真熱鬧,春花似錦、人聲如沸。這莊子的主人今日做“春日...
    開封第一講書人閱讀 34,983評論 0 28
  • 文/蒼蘭香墨 我抬頭看了看天上的太陽。三九已至,卻和暖如春,著一層夾襖步出監牢的瞬間,已是汗流浹背。 一陣腳步聲響...
    開封第一講書人閱讀 36,257評論 1 292
  • 我被黑心中介騙來泰國打工, 沒想到剛下飛機就差點兒被人妖公主榨干…… 1. 我叫王不留,地道東北人。 一個月前我還...
    沈念sama閱讀 52,059評論 3 397
  • 正文 我出身青樓,卻偏偏與公主長得像,于是被迫代替她去往敵國和親。 傳聞我的和親對象是個殘疾皇子,可洞房花燭夜當晚...
    茶點故事閱讀 48,296評論 2 376

推薦閱讀更多精彩內容

  • rljs by sennchi Timeline of History Part One The Cognitiv...
    sennchi閱讀 7,400評論 0 10
  • 一生瞭望。 塔在頂上。 數不清臺階, 只能 拾起日月虛影, 久久在腦海中烙印 徜徉。 看過了花團錦簇,寂寂蒼茫; ...
    Z0001閱讀 290評論 0 4
  • 【小會有話說】 可能有小伙伴問為什么要費那么大的勁把這本書弄出來呢? 原因是:1.這本書我看過、畫過、也組織過小伙...
    小會2017畫閱讀 644評論 0 2
  • 幸福不是你房子有多大 而是房里的笑聲有多甜 幸福不是你的愛人多漂亮 而是愛人的笑容多燦爛 幸福不是在你成功時的喝彩...
    葉偉鋒閱讀 150評論 0 0