请阅读latex 2 插图指南：
http://www.ctex.org/documents/latex/graphics/

谢谢！

用png吧。jpeg压缩多了本来质量就不好。

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[t]
\begin{center}
\includegraphics[scale=0.7]{自平衡机器人说明书3.jpg}
\end{center}
\caption{车体受力图}
\label{wheelbody150828}
\end{figure}