【正文】 oblems of trajectory tracking and steering to a given configuration are addressed. This second issue is solved by an iterative trajectory tracking. Perturbations are taken into account along the motions. Experimental results on the mobile robot Hilare illustrate the validity of our approach. 1 Introduction Motion control for nonholonomic systems have given rise to a lot of work for the past 8 years. Brockett’s condition [2] made stabilization about a given configuration a challenging task for such systems, proving that it could not be performed by a simple continuous state feedback. Alternative solutions as timevarying feedback [l0, 4, 11, 13, 14, 15, 18] or discontinuous feedback [3] have been then proposed. See [5] for a survey in mobile robot motion control. On the other hand, tracking a trajectory for a nonholonomic system does not meet Brockett’s condition and thus it is an easier task. A lot of work have also addressed this problem [6, 7, 8, 12, 16] for the particular case of mobile robots.All these control laws work under the same assumption: the evolution of the system is exactly known and no perturbation makes the system deviate from its papers dealing with mobile robots control take into account perturbations in the kinematics equations. [l] however proposed a method to stabilize a car about a configuration, robust to control vector fields perturbations, and based on iterative trajectory tracking.The presence of obstacle makes the task of reaching a configuration even more difficult and require 陜西理工學(xué)院畢業(yè)設(shè)計(jì) 第 28 頁 共 63 頁 a path planning task before executing any motion. In this paper, we propose a robust scheme based on iterative trajectory tracking, to lead a robot towing a trailer to a configuration. The trajectories are puted by a motion planner described in [17] and thus avoid obstacles that are given in input. In the won’t give any development about this planner,we refer to this reference for details. Moreover,we assume that the execution of a given trajectory is submitted to perturbations. The model we chose for these perturbations is very simple and very presents some mon points with [l]. The paper is anized as follows. Section 2 describes our experimental system Hilare and its trailer:two hooking systems will be considered (Figure 1).Section 3 deals with the control scheme and the analysis of stability and robustness. In Section 4, we present experimental results. 2 Description of the system Hilare is a two driving wheel mobile robot. A trailer is hitched on this robot, defining two different systems depending on the hooking device: on system A, the trailer is hitched above the wheel axis of the robot (Figure 1, top), whereas on system B, it is hitched behind this axis (Figure l , bottom). A is the particular case of B, for which rl = 0. This system is however singular from a control point of view and requires more plex putations. For this reason, we deal separately with both hooking systems. Two motors enable to control the linear and angular velocities （ vr ， r? ) of the robot. These velocities are moreover measured by odometric sensors, whereas the angle ? between the robot and the trailer is given by an optical encoder. The position and orientation（ xr , yr , r? ） of the robot are puted by integrating the former velocities. With these notations, the control system of B is: c ossi nsi n( ) c os( )r r rr r rrrr r rrttxvyvvlll?????? ? ? ????? ? ? ? （ 1） 陜西理工學(xué)院畢業(yè)設(shè)計(jì) 第 29 頁 共 63 頁 Figure 1: Hilare with its trailer 3 Global control scheme Motivation When considering real systems, one has to take into account perturbations during motion may have many origins as imperfection of the motors, slippage of the wheels, inertia effects ... These perturbations can be modeled by adding a term in the control system (l),leading to a new system of the form ( , )x f x u ??? where? may be either deterministic or a random the first case, the perturbation is only due to a bad knowledge of the system evolution, whereas in the second case, it es from a random behavior of the system. We will see later that this second model is a better fit for our experimental system. To steer a robot from a start configuration to a goal, many works consider that the perturbation is only the initial distance between the robot and the goal, but that the evolution of the system is perfectly known. To solve the problem, they design an input as a function of the state and time that makes the goal an asymptotically stable equilibrium of the closed loop system. Now, if we introduce the previously 陜西理工學(xué)院畢業(yè)設(shè)計(jì) 第 30 頁 共 63 頁 defined term ? in this closed loop system, we don39。感謝大學(xué)四年來所有的任課老師，是他們的辛勤勞動讓我們掌握了良好的專業(yè)基礎(chǔ)知識。皇老師淵博的學(xué)識、敏銳的思維和勤奮踏實(shí)、一絲不茍的工作作風(fēng)、精益求精的治學(xué)態(tài)度，以及真誠正直的為人都給我留下了深刻的印象，時(shí)刻指導(dǎo)和激勵(lì)著我不斷前進(jìn)。 陜西理工學(xué)院畢業(yè)設(shè)計(jì) 第 7 頁 共 63 頁 圖 避障傳感器 手持終端控制機(jī)器人行走的測試 該測試主要測試上位對下位機(jī)器人的控制是否靈活和及時(shí)，是否在機(jī)器人避障存在盲區(qū)的時(shí)候能準(zhǔn)確的避開障礙物，另外，要控制機(jī)器人到達(dá)特定的地方進(jìn)行現(xiàn)場信息的采集。 5 綜合調(diào)試 機(jī)器人行走測試 該階段的測試主要是兩方面，首先，是看軟件避障算法能否實(shí)現(xiàn)準(zhǔn)確的實(shí)現(xiàn)避開位于機(jī)器人前方、左方、右方的障礙物，并且進(jìn)一步確定每種狀態(tài)下機(jī)器人需要規(guī)避多少比較合適。在對手持終端的調(diào) 試過程中遇到了很多問題，其中一個(gè)如圖 所示： 驅(qū)動電機(jī) 電池板 陜西理工學(xué)院畢業(yè)設(shè)計(jì) 第 7 頁 共 63 頁 圖 手持終端調(diào)試 發(fā)送的是 123456,但收到的是一些亂碼。初步設(shè)想如圖 所示： 圖 電池板展開原理圖 而真正實(shí)現(xiàn)起來，就比較難，圖 是開始設(shè)計(jì)的一個(gè)展開機(jī)構(gòu)： 圖 失敗方案實(shí)物圖 問題在于沒有嚴(yán)格咬合的齒輪和齒條，通過測試發(fā)現(xiàn)，這種設(shè)計(jì)會有錯(cuò)齒、越齒現(xiàn)象，最后致使左右展板不對稱，無法達(dá)到理想效果。 第二步：選擇單片機(jī) 第三步：添加文件，然后在文件里進(jìn)行編程即可。下載程序到單片機(jī)后，出現(xiàn)如下界面，給機(jī)器人上電后，單擊在線調(diào)試圖標(biāo)，實(shí)時(shí)讀取各個(gè)參數(shù)和變量的變化，不斷調(diào)整。這里主要對調(diào)試的工具和過程做一簡單介紹。在調(diào)試過程中 測試 串口的連通性從單片機(jī)向電腦發(fā)送字符并用串口助手接受，用電腦串口助手向單片機(jī)發(fā)送字符并用編譯器 IAR 調(diào)試模式查看相應(yīng)參數(shù) 。 BF ASR： ASR狀態(tài)報(bào)告寄存器 讀到數(shù)值為 0x35，可以確定是一次語音識別流程正常結(jié)束，可與（ 0xb2）寄存器的 0x21值配合使用。 B9 ASR：當(dāng)前添加識別句的字符 串長度（拼音字符串） 初始化時(shí)寫入 00H 每添加一條識別句后要設(shè)定一次。 本寄存器代表語音識別時(shí)忽略掉前面 num幀的數(shù)據(jù)。 每1單位， 10毫秒。調(diào)整本參數(shù)也會對識別距離產(chǎn)生影響，數(shù)值越小，越靈敏，距離越遠(yuǎn)。 Default: 0x12H 0 – 關(guān)閉語音段檢測功能， 數(shù)值范圍 :