JP4135073B2 - Three-dimensional strain sensor block, three-dimensional external force measurement unit, structure external force measurement method - Google Patents

Description

σx1＝fx1(Ｆ1, Ｐi)、σy1＝fy1(Ｆ1, Ｐi)、σz1＝fz1(Ｆ1, Ｐi)
τxy1＝fxy1(Ｆ1, Ｐi)、τyz1＝fyz1(Ｆ1, Ｐi)、τzx1＝fzx1(Ｆ1, Ｐi)
ここで、｛Ｓt1，Ｓt2，Ｓt3，Ｓt4，Ｓt5，Ｓt6｝は 各応力Ｓt1，Ｓt2，Ｓt3，Ｓt4，Ｓt5，Ｓt6からなる応力群を表し、fx1(Ｆ1, Ｐi)、fy1(Ｆ1, Ｐi)、fz1(Ｆ1, Ｐi)、fxy1(Ｆ1, Ｐi)、fyz1(Ｆ1, Ｐi)、fzx1(Ｆ1, Ｐi)は、
外力Ｆ1が加わった時の位置Ｐiをパラメータとする、夫々σx1、σy1、σz1、τxy1、τyz1、及びτzx1の関数を表す。
【００４６】
ステップＳ３：外力Ｆ2、Ｆ3、・・・、Ｆ6を加えて、ステップＳ２と同様の手段により、各応力群 Σ(Ｆ2, Ｐi)、Σ(Ｆ3, Ｐi)、・・・、Σ(Ｆ6, Ｐi)を得る。すなわち、
Σ(Ｆ2, Ｐi)＝Ｇ｛σx2，σy2, σz2, τxy2, τyz2, τzx2｝--(2)
Σ(Ｆ3, Ｐi)＝Ｇ｛σx3，σy3, σz3, τxy3, τyz3, τzx3｝--(3)
Σ(Ｆ4, Ｐi)＝Ｇ｛σx4，σy4, σz4, τxy4, τyz4, τzx4｝--(4)
Σ(Ｆ5, Ｐi)＝Ｇ｛σx5，σy5, σz5, τxy5, τyz5, τzx5｝--(5)
Σ(Ｆ6, Ｐi)＝Ｇ｛σx6，σy6, σz6, τxy6, τyz6, τzx6｝--(6)
各応力群の構成要素である、σx2、σy2、 σz2、 τxy2、 τyz2、 τzx2、σx3、σy3、 σz3、 τxy3、 τyz3、 τzx3、・・・、σx6、σy6、 σz6、 τxy6、τyz6、τzx6 に対しては、
σx2＝fx2(Ｆ2, Ｐi)、σy2＝fy2(Ｆ2, Ｐi)、σz2＝fz2(Ｆ2, Ｐi)
τxy2＝fxy2(Ｆ2, Ｐi)、τyz2＝fyz2(Ｆ2, Ｐi)、τzx2＝fzx2(Ｆ2, Ｐi)・・・
σx6＝fx6(Ｆ6, Ｐi)、σy6＝fy6(Ｆ6, Ｐi)、σz6＝fz6(Ｆ6, Ｐi)
τxy6＝fxy6(Ｆ6, Ｐi)、τyz6＝fyz6(Ｆ6, Ｐi)、τzx6＝fzx6(Ｆ6, Ｐi)
と記述される。
【００４７】
ステップＳ４： コーシーの座標回転式（岸田敬三著「材料の力学」（１９８７年培風館）参照）に基づいて、各座標軸Ｘ，Ｙ，Ｚの反時計方向回りに各々の角度Ａ,Ｂ,Ｃを回転させて座標変換を行い、角度群 φ｛Ａ，Ｂ，Ｃ｝をパラメータとする事によって、ステップＳ２およびステップＳ３で求めた応力群 Σ(Ｆ1, Ｐi)〜Σ(Ｆ6, Ｐi) の変換座標系での変換後応力群、つまり応力関数Σ´(Ｆ1, Ｐi)〜Σ´(Ｆ6, Ｐi)を得る。すなわち、
Σ´(Ｆ1, Ｐi)
＝Ｇ´｛σx1´，σy1´, σz1´, τxy1´, τyz1´, τzx1´｝ --(7)
Σ´(Ｆ2, Ｐi)
＝Ｇ´｛σx2´，σy2´, σz2´, τxy2´, τyz2´, τzx2´｝ --(8)
Σ´(Ｆ3, Ｐi)
＝Ｇ´｛σx3´，σy3´, σz3´, τxy3´, τyz3´, τzx3´｝ --(9)
Σ´(Ｆ4, Ｐi)
＝Ｇ´｛σx4´，σy4´, σz4´, τxy4´, τyz4´, τzx4´｝ --(10)
Σ´(Ｆ5, Ｐi)
＝Ｇ´｛σx5´，σy5´, σz5´, τxy5´, τyz5´, τzx5´｝ --(11)
Σ´(Ｆ6, Ｐi)
＝Ｇ´｛σx6´，σy6´, σz6´, τxy6´, τyz6´, τzx6´｝ --(12)
変換後の応力群の構成要素となる、σx1´、σy1´、σz1´、τxy1´、τyz1´、τzx1´、σx3、σy3、σz3、τxy3、τyz3、τzx3、・・・、σx6´、σy6´、
σz6´、τxy6 、τyz6´、τzx6´は、
σx1´＝fx1´(Σ(Ｆ1, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_11-F1×A_11-F1×σx1＋A_11-F1×A_12-F1×τxy1＋A_11-F1×A_13-F1×τzx1
＋A_11-F1×A_12-F1×τxy1＋A_12-F1×A_12-F1×σy1＋A_12-F1×A_13-F1×τyz1
＋A_11-F1×A_13-F1×τzx1＋A_12-F1×A_13-F1×τyz1＋A_13-F1×A_13-F1×σz1
σy1´＝fy1´(Σ(Ｆ1, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_21-F1×A_21-F1×σx1＋A_21-F1×A_22-F1×τxy1＋A_21-F1×A_23-F1×τzx1
＋A_21-F1×A_22-F1×τxy1＋A_22-F1×A_22-F1×σy1＋A_22-F1×A_23-F1×τyz1
＋A_21-F1×A_23-F1×τzx1＋A_22-F1×A_23-F1×τyz1＋A_23-F1×A_23-F1×σz1
σz1´＝fz1´(Σ(Ｆ1, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_31-F1×A_31-F1×σx1＋A_31-F1×A_32-F1×τxy1＋A_31-F1×A_33-F1×τzx1
＋A_31-F1×A_32-F1×τxy1＋A_32-F1×A_32-F1×σy1＋A_32-F1×A_33-F1×τyz1
＋A_31-F1×A_33-F1×τzx1＋A_32-F1×A_33-F1×τyz1＋A_33-F1×A_33-F1×σz1
τxy1´＝fxy1´(Σ(Ｆ1, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_11-F1×A_21-F1×σx1＋A_12-F1×A_21-F1×τxy1＋A_13-F1×A_21-F1×τzx1
＋A_11-F1×A_22-F1×τxy1＋A_12-F1×A_22-F1×σy1＋A_13-F1×A_22-F1×τyz1
＋A_11-F1×A_23-F1×τzx1＋A_12-F1×A_23-F1×τyz1＋A_13-F1×A_23-F1×σz1
τyz1´＝fyz1´(Σ(Ｆ1, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_11-F1×A_31-F1×σx1＋A_12-F1×A_31-F1×τxy1＋A_13-F1×A_31-F1×τzx1
＋A_11-F1×A_32-F1×τxy1＋A_12-F1×A_32-F1×σy1＋A_13-F1×A_32-F1×τyz1
＋A_11-F1×A_33-F1×τzx1＋A_12-F1×A_33-F1×τyz1＋A_13-F1×A_33-F1×σz1
τzx1´＝fzx1´(Σ(Ｆ1, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_21-F1×A_31-F1×σ_x1＋A_22-F1×A_31-F1×τxy1＋A_23-F1×A_31-F1×τzx1
＋A_21-F1×A_32-F1×τ_xy1＋A_22-F1×A_32-F1×σy1＋A_23-F1×A_32-F1×τyz1
＋A_21-F1×A_33-F1×τzx1＋A_22-F1×A_33-F1×τyz1＋A_23-F1×A_33-F1×σz1
・・・
σx6´＝fx6´(Σ(Ｆ6, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_11-F6×A_11-F6×σx6＋A_11-F6×A_12-F6×τxy6＋A_11-F6×A_13-F6×τzx6
＋A_11-F6×A_12-F6×τxy6＋A_12-F6×A_12-F6×σy6＋A_12-F6×A_13-F6×τyz6
＋A_11-F6×A_13-F6×τzx6＋A_12-F6×A_13-F6×τyz6＋A_13-F6×A_13-F6×σz6
σy6´＝fy6´(Σ(Ｆ6, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_21-F6×A_21-F6×σx6＋A_21-F6×A_22-F6×τxy6＋A_21-F6×A_23-F6×τzx6
＋A_21-F6×A_22-F6×τxy6＋A_22-F6×A_22-F6×σy6＋A_22-F6×A_23-F6×τyz6
＋A_21-F6×A_23-F6×τzx6＋A_22-F6×A_23-F6×τyz6＋A_23-F6×A_23-F6×σz6
σz6´＝fz6´(Σ(Ｆ6, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_31-F6×A_31-F6×σx6＋A_31-F6×A_32-F6×τxy6＋A_31-F6×A_33-F6×τzx6
＋A_31-F6×A_32-F6×τxy6＋A_32-F6×A_32-F6×σy6＋A_32-F6×A_33-F6×τyz6
＋A_31-F6×A_33-F6×τzx6＋A_32-F6×A_33-F6×τyz6＋A_33-F6×A_33-F6×σz6
τxy6´＝fxy6´(Σ(Ｆ6, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_11-F6×A_21-F6×σx6＋A_12-F6×A_21-F6×τxy6＋A_13-F6×A_21-F6×τzx6
＋A_11-F6×A_22-F6×τxy6＋A_12-F6×A_22-F6×σy6＋A_13-F6×A_22-F6×τyz6
＋A_11-F6×A_23-F6×τzx6＋A_12-F6×A_23-F6×τyz6＋A_13-F6×A_23-F6×σz6
τyz6´＝fyz6´(Σ(Ｆ6, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_11-F6×A_31-F6×σx6＋A_12-F6×A_31-F6×τxy6＋A_13-F6×A_31-F6×τzx6
＋A_11-F6×A_32-F6×τxy6＋A_12-F6×A_32-F6×σy6＋A_13-F6×A_32-F6×τyz6
＋A_11-F6×A_33-F6×τzx6＋A_12-F6×A_33-F6×τyz6＋A_13-F6×A_33-F6×σz6
τzx6´＝fzx6´(Σ(Ｆ6, Ｐi), φ｛Ａ，Ｂ，Ｃ｝)
＝A_21-F6×A_31-F6×σx6＋A_22-F6×A_31-F6×τxy6＋A_23-F6×A_31-F6×τzx6
＋A_21-F6×A_32-F6×τxy6＋A_22-F6×A_32-F6×σy6＋A_23-F6×A_32-F6×τyz6
＋A_21-F6×A_33-F6×τzx6＋A_22-F6×A_33-F6×τyz6＋A_23-F6×A_33-F6×σz6
と記述される。ここで、A_11-Fn〜A_33-Fnとは、外力Ｆn（n＝1〜6）が作用した時の、Ｘ軸に対する回転角度をＡ、Ｙ軸に対する回転角度をＢ、Ｚ軸に対する回転角度をＣとしたときに
A_11-Fn＝cosＢcosＣ、A_12-Fn＝cosＢsinＣ、A_13-Fn＝-sinＢ、
A_21-Fn＝sinＡsinＢcosＣ-cosＡsinＣ、A_22-Fn＝sinＡsinＢsinＣ+cosＡcosＣ、
A_23-Fn＝sinＡcosＢ、A_31-Fn＝cosＡsinＢcosＣ+sinＡsinＣ、
A_32-Fn＝cosＡsinＢsinＣ-sinＡcosＣ、A_33-Fn＝cosＡcosＢ
で定義されるものである。
前記式より解るように、変換後の各応力は、変換前の応力（外力Ｆnと位置Ｐiの関数）に加えて、角度群φ｛Ａ，Ｂ，Ｃ｝の関数となっているため、変換前の応力と比較して自由度が増加し、角度群φ｛Ａ，Ｂ，Ｃ｝で必要条件を満たすよう最適化する事で、Ｆn及びＰiに対する制約条件が緩和されうる事になる。
【００４８】
ステップＳ５： センサ装着候補位置を選定する前提となる外力分離領域と外力分離角度を算定する。選定の方法としては、応力解析及び角度変換に基づいて応力群を得た後の、応力出力が得られ易く、なおかつ、センサを装着する外的条件として好ましい位置となれば良い。
【００４９】
この際、ステップＳ４で求めた応力関数は、角度群φ｛Ａ，Ｂ，Ｃ｝の関数となるため、角度群φ｛Ａ，Ｂ，Ｃ｝をパラメータとして各々の応力を記述する。コーシーの式はから三角関数であるため、合成波として表されることになる。このため、合成波の振幅から、極小／極大値が現れる事になる。この応力関数をそれぞれの角度群φ｛Ａ，Ｂ，Ｃ｝を独立に変化させて得たものが、図３（ａ）、（ｂ）、（ｃ）のグラフである。この図によって、それぞれの外力の分離率のよい位置と角度を求めることも可能である。
また、分離率の良い位置Ｐiを求める方法としては、(7)〜(12)式が
Σ´(Ｆ1, Ｐi)＝Ｇ´｛σx1´，(極小), (極小), (極小), (極小), (極小)｝、
Σ´(Ｆ2, Ｐi)＝Ｇ´｛ (極小)，σy2´, (極小), (極小), (極小), (極小)｝、
Σ´(Ｆ3, Ｐi)＝Ｇ´｛ (極小)，(極小), σz3´, (極小), (極小), (極小)｝、
Σ´(Ｆ4, Ｐi)＝Ｇ´｛ (極小)，(極小), (極小), τxy4´, (極小), (極小)｝、
Σ´(Ｆ5, Ｐi)＝Ｇ´｛ (極小)，(極小), (極小), (極小), τyz5´, (極小)｝、
Σ´(Ｆ6, Ｐi)＝Ｇ´｛ (極小)，(極小), (極小), (極小), (極小), τzx6´｝
となる場合は、応力σx1´を検出する応力センサで外力Ｆ1を、以下同様にしてσy2´でＦ2を、σz3´でＦ3を、τxy4´でＦ4を、τyz5´でＦ5を、τzx6´でＦ6を検出すれば良い事になる。
【００５０】
具体例として、図１は実際の構造体（サスペンション）での適用例である。図１では、３次元歪センサブロック１の中心軸ＳＣが、この構造体（サスペンション）Ｋが主構造体（不図示）に支持される支持支点Ｘと、この構造体Ｋに外力が作用する外力作用点Ｏを結ぶ直線に平行になるようにする事で、τyz´を増大させ、その他の角度変換後応力を低下させ、擬似的ではあるが、上式に近い条件を作り出している事が解った。なお、この角度条件は、具体的な構造体の形状、支持条件に依存して変化するものであるが、一般的な自動車のサスペンションに限定する限り、ほぼそのまま適用可能なものであると考える。
【００５１】
ステップＳ６：こうして得られたそれぞれの外力に対応する外力分離領域ＺＦｘ，ＺＦｙ，ＺＦｚ、ＺＭｘ，ＺＭｙ，ＺＭｚの重複領域ＺＺを算出する。ここで外力分離領域ＺＦｘ・・・については、領域内の各位置について、対応した外力の分離率が良くなる角度も含まれており、その意味で、外力分離領域の重複領域ＺＺには、対応した外力の分離率が良くなる角度を重複して含まれている。
【００５２】
ステップＳ７：ステップＳ６で得られる重複領域ＺＺ内で、更に、応力関数を用いて、応力計測が可能なセンサ素子位置・角度であるかを判断する。
重複領域のうちから、センサ装着位置を決定するにあたっては、サスペンション組付時のセンサ配線の他部材との干渉がない部分を選定し、なおかつ、装着位置へのセンサ装着孔の加工による構造体の強度計算を行なって、最も強度低下が少ない部分にセンサを装着する。
【００５３】
前記方法で位置を決定した後の、センサ装着角度としては、製造時には装着角度誤差が避けられない点を考慮し、例えば図３のグラフから、センサ出力の装着角度誤差マージンが最も広い部分を選定した上で装着角度を決定する。
【００５４】
前記の条件を満たす、応力計測が可能な位置・角度であればこれをセンサ装着位置Ｐs（角度φs）とする。 応力計測が不可能、すなわち、前記の条件を満足しないか、あるいは、外力に対して独立な条件（独立性の条件）が得られず、複数の外力に対して、全ての応力値が同じ値あるいはその倍数となる規則的な傾向を示した場合には、新たなセンサ装着候補位置を選定する。
【００５５】
ここで、外力分離領域を得るための種種の方法を説明する。この方法は、ステップＳ５で用いられるものである。
分離率のよい応力関数を選び出す一般的な方法のひとつとして、(7)、(8)式について、Ｆ1とＦ2で比較して考えた場合、外力Ｆ1と、外力Ｆ2に対しては以下の条件を満たすものを選び出す方法がある。すなわち、各構成要素のうち、例えばσx1´，σy1´, σx2´，σy2´に対して、
「σx１´＝ｋ ×σx2´かつσy1´ ＝ｋ ×σy2´となるｋが存在しない」-(13)
前記（13）は必要条件であり、これは、各構成要素のうち、同種の構成要素が独立であれば良いという条件と等価である。この条件を想定体系全体について記述すれば、
「外力Ｆ1からＦ6のうち、任意の２外力Ｆp、Ｆqに対して、
σxp´＝ｋ×σxq´ かつσyp´＝ｋ×σyq´かつσzp´＝ｋ×σzq´かつ
τxyp´＝ｋ×τxyq´かつτyzp´＝ｋ×τyzq´かつτzxp´＝ｋ×τzxq´
となるｋが存在しない」 --（14）
（p＝1〜6、q＝1〜6、p≠qであり、σxp´、σyp´、σzp´、τxyp´、τyzp´、τzxp´は外力Ｆpが加えられた際の位置Ｐiでの応力群の構成要素、σxq´、σyq´、σzq´、τxyq´、τyzq´、τzxq´は外力Ｆqが加えられた際の位置Ｐiでの応力群の構成要素）
という条件になる。
【００５６】
前記（14）の条件は、外力を固定した場合には、応力変換前の関数表記、すなわち位置Ｐiのみの関数表記ではＸ，Ｙ，Ｚの３変数の為、位置Ｐi自体に制約条件が必要となる事は自明であるが、応力変換後の関数表記では、Ｘ，Ｙ，Ｚの３変数に、角度群φ｛Ａ，Ｂ，Ｃ｝の成分であるＡ，Ｂ，Ｃの回転角度変数が加わった６変数であるため、角度Ａ，Ｂ，Ｃに対して制約条件（基準）を加えてやる事で、位置変数の制約条件を緩和できることを示している。
【００５７】
分離率のよい応力関数を選び出す他の方法を以下に示す。
【００５８】
この場合、歪検知素子２（例えば、図１に示した６つの素子）からの歪信号をεa、εb、εc、εd、εe、εfとして、この歪から得られる応力と外力との関係を用いる。
【００５９】
Ａ）応力解析により得られた、すべての位置における応力群 Σ（Ｆn、Ｐi）＝｛σx(n,i)、σy(n,i)、σz(n,i)、τxy(n,i)、τyz(n,i)、τzx(n,i)｝から、各々の歪εx(n,i)、εy(n,i)、εz(n,i)を以下の式にて求める。ここで、
Ｆn（n＝1〜6）は負荷される力（あるいはモーメント）、Ｐi（i＝1〜N）は位置である。
εx(n,i)＝｛σx(n,i)'−ν（σy(n,i)'＋σz(n,i)'）｝／Ｅ
εy(n,i)＝｛σy(n,i)'−ν（σz(n,i)'＋σx(n,i)'）｝／Ｅ
εz(n,i)＝｛σz(n,i)'−ν（σx(n,i)'＋σy(n,i)'）｝／Ｅ
なお、上式での σx(n,i)'、σy(n,i)'、σz(n,i)' とは、各々、センサ体が位置Ｐiに角度φ（Ａ，Ｂ，Ｃ）で配置された場合の、正規座標系Ｘ、Ｙ、Ｚ軸に対しての垂直応力であり、σx(n,i)'、σy(n,i)'、σz(n,i)'と応力群
Σ（Ｆn、Ｐi）との関係は、センサ体の基準線分ΦｓとＸ、Ｙ、Ｚ軸とのなす角度を各々Ａ、Ｂ、Ｃとして、以下で表される。
【００６０】
σx(n,i)＝σx(n,i)’×（１＋cosＡ）／2
σy(n,i)＝σy(n,i)’×（１＋cosＢ）／2
σz(n,i)＝σz(n,i)’×（１＋cosＣ）／2
τxy(n,i)＝σz(n,i)’×sin(2Ｃ)／2
τyz(n,i)＝σx(n,i)’×sin(2Ａ)／2
τzx(n,i)＝σy(n,i)’×sin(2Ｂ)／2
Ｂ）Ａ）で求めた歪は、正規座標系のＸ、Ｙ、Ｚ軸に平行な歪量であるので、これを、歪ゲージを配設する角度として、例えば±45°の角度をつけて配設するとして、ゲージが検出すると予測される歪量 εa〜εfを求める。
【００６１】

ここでΔεx、Δεy、Δεzは、基板厚みを考慮した変動量（有限要素法による応力解析にて決定）、νはポアソン比（材料定数、〜0.3）である。
【００６２】
Ｃ）ある位置Ｐiで外力Ｆnが加わった時に、予想されるセンサ出力Ｓr（Ｆn，Ｐi）（r＝１〜６）は、Ｂ）で求めた予測歪量の１次式で表され、以下となる。
【００６３】

ここで、Ｐiは固定とすると、上式は36個の未知数ｋa1、ｋa2、・・ｋf6を持つ。これらの未知数を決定するため、外力Ｆn（n＝1〜6）全てを考慮した上で
分離率が良い条件式として、次の36個の条件式を設ける。
【００６４】
Ｓ1（Ｆ1，Ｐi）＝ｋa1×εa(1,i)＋ｋb1×εb(1,i)＋ｋc1×εc(1,i)
＋ｋd1×εd(1,i)＋ｋe1×εe(1,i)＋ｋf1×εf(1,i)＝Ｆ1 --(15-1)
ｋa1×εa(2,i)＋ｋb1×εb(2,i)＋ｋc1×εc(2,i)＋ｋd1×εd(2,i)
＋ｋe1×εe(2,i)＋ｋf1×εf(2,i)＜0.01×Ｆ1 --(15-2)
ｋa1×εa(3,i)＋ｋb1×εb(3,i)＋ｋc1×εc(3,i)＋ｋd1×εd(3,i)
＋ｋe1×εe(3,i)＋ｋf1×εf(3,i)＜0.01×Ｆ1 --(15-3)
ｋa1×εa(4,i)＋ｋb1×εb(4,i)＋ｋc1×εc(4,i)＋ｋd1×εd(4,i)
＋ｋe1×εe(4,i)＋ｋf1×εf(4,i)＜0.01×Ｆ1 --(15-4)
ｋa1×εa(5,i)＋ｋb1×εb(5,i)＋ｋc1×εc(5,i)＋ｋd1×εd(5,i)
＋ｋe1×εe(5,i)＋ｋf1×εf(5,i)＜0.01×Ｆ1 --(15-5)
ｋa1×εa(6,i)＋ｋb1×εb(6,i)＋ｋc1×εc(6,i)＋ｋd1×εd(6,i)
＋ｋe1×εe(6,i)＋ｋf1×εf(6,i)＜0.01×Ｆ1 --(15-6)
Ｓ2（Ｆ2，Ｐi）＝ｋa2×εa(2,i)＋ｋb2×εb(2,i)＋ｋc2×εc(2,i)
＋ｋd2×εd(2,i)＋ｋe2×εe(2,i)＋ｋf2×εf(2,i)＝Ｆ2 --(15-7)
ｋa2×εa(1,i)＋ｋb2×εb(1,i)＋ｋc2×εc(1,i)＋ｋd2×εd(1,i)
＋ｋe2×εe(1,i)＋ｋf2×εf(1,i)＜0.01×Ｆ2 --(15-8)
ｋa2×εa(3,i)＋ｋb2×εb(3,i)＋ｋc2×εc(3,i)＋ｋd2×εd(3,i)
＋ｋe2×εe(3,i)＋ｋf2×εf(3,i)＜0.01×Ｆ2 --(15-9)
ｋa2×εa(4,i)＋ｋb2×εb(4,i)＋ｋc2×εc(4,i)＋ｋd2×εd(4,i)
＋ｋe2×εe(4,i)＋ｋf2×εf(4,i)＜0.01×Ｆ2 --(15-10)
ｋa2×εa(5,i)＋ｋb2×εb(5,i)＋ｋc2×εc(5,i)＋ｋd2×εd(5,i)
＋ｋe2×εe(5,i)＋ｋf2×εf(5,i)＜0.01×Ｆ2 --(15-11)
ｋa2×εa(6,i)＋ｋb2×εb(6,i)＋ｋc2×εc(6,i)＋ｋd2×εd(6,i)
＋ｋe2×εe(6,i)＋ｋf2×εf(6,i)＜0.01×Ｆ2 --(15-12)
Ｓ3（Ｆ3，Ｐi）＝ｋa3×εa(3,i)＋ｋb3×εb(3,i)＋ｋc3×εc(3,i)
＋ｋd3×εd(3,i)＋ｋe3×εe(3,i)＋ｋf3×εf(3,i)＝Ｆ3 --(15-13)
ｋa3×εa(1,i)＋ｋb3×εb(1,i)＋ｋc3×εc(1,i)＋ｋd3×εd(1,i)
＋ｋe3×εe(1,i)＋ｋf3×εf(1,i)＜0.01×Ｆ3 --(15-14)
ｋa3×εa(2,i)＋ｋb3×εb(2,i)＋ｋc3×εc(2,i)＋ｋd3×εd(2,i)
＋ｋe3×εe(2,i)＋ｋf3×εf(2,i)＜0.01×Ｆ3 --(15-15)
ｋa3×εa(4,i)＋ｋb3×εb(4,i)＋ｋc3×εc(4,i)＋ｋd3×εd(4,i)
＋ｋe3×εe(4,i)＋ｋf3×εf(4,i)＜0.01×Ｆ3 --(15-16)
ｋa3×εa(5,i)＋ｋb3×εb(5,i)＋ｋc3×εc(5,i)＋ｋd3×εd(5,i)
＋ｋe3×εe(5,i)＋ｋf3×εf(5,i)＜0.01×Ｆ3 --(15-17)
ｋa3×εa(6,i)＋ｋb3×εb(6,i)＋ｋc3×εc(6,i)＋ｋd3×εd(6,i)
＋ｋe3×εe(6,i)＋ｋf3×εf(6,i)＜0.01×Ｆ3 --(15-18)
Ｓ4（Ｆ4，Ｐi）＝ｋa4×εa(4,i)＋ｋb4×εb(4,i)＋ｋc4×εc(4,i)
＋ｋd4×εd(4,i)＋ｋe4×εe(4,i)＋ｋf4×εf(4,i)＝Ｆ4 --(15-19)
ｋa4×εa(1,i)＋ｋb4×εb(1,i)＋ｋc4×εc(1,i)＋ｋd4×εd(1,i)
＋ｋe4×εe(1,i)＋ｋf4×εf(1,i)＜0.01×Ｆ4 --(15-20)
ｋa4×εa(2,i)＋ｋb4×εb(2,i)＋ｋc4×εc(2,i)＋ｋd4×εd(2,i)
＋ｋe4×εe(2,i)＋ｋf4×εf(2,i)＜0.01×Ｆ4 --(15-21)
ｋa4×εa(3,i)＋ｋb4×εb(3,i)＋ｋc4×εc(3,i)＋ｋd4×εd(3,i)
＋ｋe4×εe(3,i)＋ｋf4×εf(3,i)＜0.01×Ｆ4 --(15-22)
ｋa4×εa(5,i)＋ｋb4×εb(5,i)＋ｋc4×εc(5,i)＋ｋd4×εd(5,i)
＋ｋe4×εe(5,i)＋ｋf4×εf(5,i)＜0.01×Ｆ4 --(15-23)
ｋa4×εa(6,i)＋ｋb4×εb(6,i)＋ｋc4×εc(6,i)＋ｋd4×εd(6,i)
＋ｋe4×εe(6,i)＋ｋf4×εf(6,i)＜0.01×Ｆ4 --(15-24)
Ｓ5（Ｆ5，Ｐi）＝ｋa5×εa(5,i)＋ｋb5×εb(5,i)＋ｋc5×εc(5,i)
＋ｋd5×εd(5,i)＋ｋe5×εe(5,i)＋ｋf5×εf(5,i)＝Ｆ5 --(15-25)
ｋa5×εa(1,i)＋ｋb5×εb(1,i)＋ｋc5×εc(1,i)＋ｋd5×εd(1,i)
＋ｋe5×εe(1,i)＋ｋf5×εf(1,i)＜0.01×Ｆ5 --(15-26)
ｋa5×εa(2,i)＋ｋb5×εb(2,i)＋ｋc5×εc(2,i)＋ｋd5×εd(2,i)
＋ｋe5×εe(2,i)＋ｋf5×εf(2,i)＜0.01×Ｆ5 --(15-27)
ｋa5×εa(3,i)＋ｋb5×εb(3,i)＋ｋc5×εc(3,i)＋ｋd5×εd(3,i)
＋ｋe5×εe(3,i)＋ｋf5×εf(3,i)＜0.01×Ｆ5 --(15-28)
ｋa5×εa(4,i)＋ｋb5×εb(4,i)＋ｋc5×εc(4,i)＋ｋd5×εd(4,i)
＋ｋe5×εe(4,i)＋ｋf5×εf(4,i)＜0.01×Ｆ5 --(15-29)
ｋa5×εa(6,i)＋ｋb5×εb(6,i)＋ｋc5×εc(6,i)＋ｋd5×εd(6,i)
＋ｋe5×εe(6,i)＋ｋf5×εf(6,i)＜0.01×Ｆ5 --(15-30)
Ｓ6（Ｆ6，Ｐi）＝ｋa6×εa(6,i)＋ｋb6×εb(6,i)＋ｋc6×εc(6,i)
＋ｋd6×εd(6,i)＋ｋe6×εe(6,i)＋ｋf6×εf(6,i)＝Ｆ6 --(15-31)
ｋa6×εa(1,i)＋ｋb6×εb(1,i)＋ｋc6×εc(1,i)＋ｋd6×εd(1,i)
＋ｋe6×εe(1,i)＋ｋf6×εf(1,i)＜0.01×Ｆ6 --(15-32)
ｋa6×εa(2,i)＋ｋb6×εb(2,i)＋ｋc6×εc(2,i)＋ｋd6×εd(2,i)
＋ｋe6×εe(2,i)＋ｋf6×εf(2,i)＜0.01×Ｆ6 --(15-33)
ｋa6×εa(3,i)＋ｋb6×εb(3,i)＋ｋc6×εc(3,i)＋ｋd6×εd(3,i)
＋ｋe6×εe(3,i)＋ｋf6×εf(3,i)＜0.01×Ｆ6 --(15-34)
ｋa6×εa(4,i)＋ｋb6×εb(4,i)＋ｋc6×εc(4,i)＋ｋd6×εd(4,i)
＋ｋe6×εe(4,i)＋ｋf6×εf(4,i)＜0.01×Ｆ6 --(15-35)
ｋa6×εa(5,i)＋ｋb6×εb(5,i)＋ｋc6×εc(5,i)＋ｋd6×εd(5,i)
＋ｋe6×εe(5,i)＋ｋf6×εf(5,i)＜0.01×Ｆ6 --(15-36)
前記は、分離率１％以下となる条件式であり、これを満たすｋa1、ｋa2、・・・ｋf6の値が存在すれば、Ｐiはセンサ装着位置候補となる。
【００６５】
上式を解くため、通常は上式の不等号を等号として連立方程式を解く。３６の未知数に対する３６の方程式であるため、連立方程式の解は、通常は存在するが、３６の式各々が、その他の３５の式に対して独立でない場合には解が存在せず、この場合には、センサ装着候補位置とならない。
【００６６】
また、前記の解が存在しても、Ｐiが物理的にセンサが装着できない位置であればその位置は、センサ装着候補位置とならない。
【００６７】
なお、歪検知素子が４個の場合においては、４未知数の連立方程式となるため、前式（15-1）から(15-36)の式は、以下の（16-1）から(16-16)の式にて表される。
Ｓ1（Ｆ1，Ｐi)＝ｋa1×εa(1,i)＋ｋb1×εb(1,i)
＋ｋc1×εc(1,i)＋ｋd1×εd(1,i) ＝Ｆ1 --(16-1)
ｋa1×εa(2,i)＋ｋb1×εb(2,i)
＋ｋc1×εc(2,i)＋ｋd1×εd(2,i) ＜ 0.01×Ｆ1 --(16-2)
ｋa1×εa(3,i)＋ｋb1×εb(3,i)
＋ｋc1×εc(3,i)＋ｋd1×εd(3,i) ＜ 0.01×Ｆ1 --(16-3)
ｋa1×εa(4,i)＋ｋb1×εb(4,i)
＋ｋc1×εc(4,i)＋ｋd1×εd(4,i) ＜ 0.01×Ｆ1 --(16-4)
Ｓ2（Ｆ1，Ｐi)＝ｋa2×εa(2,i)＋ｋb2×εb(2,i)
＋ｋc2×εc(2,i)＋ｋd2×εd(2,i) ＝Ｆ2 --(16-5)
ｋa2×εa(1,i)＋ｋb2×εb(1,i)
＋ｋc2×εc(1,i)＋ｋd2×εd(1,i) ＜ 0.01×Ｆ2 --(16-6)
ｋa2×εa(3,i)＋ｋb2×εb(3,i)
＋ｋc2×εc(3,i)＋ｋd2×εd(3,i) ＜ 0.01×Ｆ2 --(16-7)
ｋa2×εa(4,i)＋ｋb2×εb(4,i)
＋ｋc2×εc(4,i)＋ｋd2×εd(4,i) ＜ 0.01×Ｆ2 --(16-8)
Ｓ3（Ｆ1，Ｐi)＝ｋa3×εa(3,i)＋ｋb3×εb(3,i)
＋ｋc3×εc(3,i)＋ｋd3×εd(3,i) ＝Ｆ3 --(16-9)
ｋa3×εa(1,i)＋ｋb3×εb(1,i)
＋ｋc3×εc(1,i)＋ｋd3×εd(1,i) ＜ 0.01×Ｆ3 --(16-10)
ｋa3×εa(2,i)＋ｋb3×εb(2,i)
＋ｋc3×εc(2,i)＋ｋd3×εd(2,i) ＜ 0.01×Ｆ3 --(16-11)
ｋa3×εa(4,i)＋ｋb3×εb(4,i)
＋ｋc3×εc(4,i)＋ｋd3×εd(4,i) ＜ 0.01×Ｆ3 --(16-12)
Ｓ4（Ｆ1，Ｐi)＝ｋa4×εa(4,i)＋ｋb4×εb(4,i)
＋ｋc4×εc(4,i)＋ｋd4×εd(4,i) ＝Ｆ4 --(16-13)
ｋa4×εa(1,i)＋ｋb4×εb(1,i)
＋ｋc4×εc(1,i)＋ｋd4×εd(1,i) ＜ 0.01×Ｆ4 --(16-14)
ｋa4×εa(2,i)＋ｋb4×εb(2,i)
＋ｋc4×εc(2,i)＋ｋd4×εd(2,i) ＜ 0.01×Ｆ4 --(16-15)
ｋa4×εa(3,i)＋ｋb4×εb(3,i)
＋ｋc4×εc(3,i)＋ｋd4×εd(3,i) ＜ 0.01×Ｆ4 --(16-16）
図４は、本発明の３次元外力測定ユニットの一例を示すブロック図である。なお、これよりすでに説明した部分と同じ部分については、同じ符号を付して、重複説明を省略する。
【００６８】
この３次元外力測定ユニット５は、２個の歪検知素子２を交差させたセンサセグメントＳＧを、相互に平行でない３つのベース面に配置した３次元歪センサブロック１と、このセンサブロック１の出力から、必要な外力を測定する信号演算処理回路部３とを備えている。
【００６９】
信号演算処理回路部３は、６つの歪検知素子２（２−１１、２−１２、２−２１、２−２２、２−３１、２−３２）のそれぞれと３つの抵抗Ｒで構成された個別のブリッジ回路３１、それぞれの歪検知素子２から出力される歪信号を増幅する歪増幅回路３２、増幅された歪信号を応力に演算し変換する歪／応力変換部３３と、この歪／応力変換部３３からの応力信号を、３次元歪センサブロック１の設置位置と設置角度について得られた応力関数（位置と角度の関数）を用いて角度変換する応力角度変換部３４と、この応力角度変換部３４の出力から、測定すべき外力（外モーメントを含む。）を演算して出力する外力演算処理部３５を備えている。
【００７０】
３次元歪センサブロック１のそれぞれのベース面１ａに配設される２つの検知素子２は直交している。
【００７１】
この信号演算処理回路部３での演算処理の流れは以下の通りである。
【００７２】
Ａ）各々の素子出力（抵抗変化）は、ブリッジ回路３１を通して電圧変化へと変換される。なお、ブリッジ回路３１は、実際には、３次元歪センサブロック１のベース面１ａ上に対応する歪検知素子２と共に配置されており、これにより、歪検知素子２の温度条件を補償するようにしている。
【００７３】
Ｂ）ブリッジ回路３１を通した出力は、一般的にはμV（マイクロボルト）オーダーの出力であるので、オペアンプ等を用いた歪増幅回路３２にて、後段の処理回路で処理しやすい大きさ（1000倍以上）の歪信号εa、εb、εc、εd、εe、εfとする。
【００７４】
Ｃ）増幅後の歪信号εa、εb、εc、εd、εe、εfは、歪／応力変換部３３に入る。ここで、歪信号が応力へ変換される。ここで、所望の応力、例えば、歪信号からせん断応力、垂直応力への変換が行われる。
【００７５】
Ｄ）歪／応力変換部３３の出力（角度変換前の応力）は、センサブロック１の設置位置と角度について得られる(7)〜(12)の応力関数にて定義される、応力角度変換部３４を通る。
【００７６】
Ｅ）応力角度変換部３４からの応力の出力は、外力演算処理部３５にて外力に変換される。
【００７７】
こうして、この３次元外力測定ユニット５は、信号演算処理回路部３の応力角度変換部３４で、分離率のよい位置と角度の応力関数を用いているので、簡易な計算で、高い感度で、必要な外力をリアルタイムに測定することができる。
【００７８】
この信号演算処理回路部３には、測定すべき外力に応じた複数の出力端子３６を設け、演算した外力をパラレル出力する構成にすることができる。また、共通の出力端子３７を設け、演算した外力を、予め定めた所定の順序で循環的に出力する、いわゆるシリアル出力とすることができる。
【００７９】
また、信号演算処理回路部３を構成する歪増幅回路３２には、演算増幅器Ｂ１、Ｂ２、Ｂ３、Ｂ４、Ｂ５、Ｂ１１、Ｂ１２が、歪／応力変換部３３にはＣ１、Ｃ２が、、応力角度変換部３４には演算増幅器Ｄ、外力計測演算処理部３５には演算増幅器Ｅが用いられており、簡易なハード構成で高速演算処理が可能となり、実装基板はカスタムＩＣ化され得る。
【００８０】
図５は、本発明の３次元歪センサブロックとその設置態様の一例を示すもので、（ａ）はその正面図、（ｂ）は側面図である。
【００８１】
本発明の３次元歪センサブロック１は、その設置位置と姿勢が決まれば、構造体（サスペンション）Ｋの1箇所の位置Ｐｓに埋設設置することができるので、構造体の強度的、機能的性能に支障となることが少ない。
【００８２】
図６は、本発明の３次元歪センサブロックを例示する図である。
３次元歪センサブロック１Ａ、１Ｂ、１Ｃのベース面１ａに配置した歪検知素子２は、いわゆる歪ゲージと称されるもので、その素材は、熱膨張係数が低く温度特性が良好なＮｉＣｒ、あるいは高いゲージ率を持ち歪感度の高いβ―Ｔａ、あるいは歪感度の高い半導体系材料、もしくはバルク材料よりも高感度である結晶構造制御されたＢａＴｉＯ₃系材料に代表されるセラミクス圧電体、あるいは前記の組合せからなる事が望ましい。
【００８３】
また、歪センサブロック１の本体材料は、想定する歪量に応じて、構造体と同材料の金属、あるいは熱膨張係数が近い他種の金属、あるいは応力伝達効率が高い高弾性率を持つセラミクス、あるいは高い歪出力となるエポキシ、アクリルに代表される高分子材料、あるいは前記の組み合わせからなる事が望ましい。
【００８４】
３次元歪センサブロック１は、図４、５で例示した立方体であってもよいが、求めたい外力が４外力以下の場合において、図６（ａ）に示す３次元歪センサブロック１Ａのように、平板上の互いに平行なベース面１ａに２つの歪検知素子２を交差させたセンサセグメントＳＧをそれそれ配置したものであってもよい。図６（ａ）は、センサセグメントの上記配置態様をきめるのに、そのセンサブロックを埋設する位置及び角度についての応力関数を用いたものであり、これによって、ＡＢＳ制御等を行う上で有効とされる３外力（路面摩擦力、横力、および垂直抗力）と転がり抵抗モーメント（ブレーキトルク）を計測することができ、これらをパラメータとした運動方程式を採用することによって、従来手法のような車輪速度をパラメータとした制御と比してその制御精度を向上することができる。
【００８５】
また、図６（ｂ）に示す３次元歪センサブロック１Ｂのように、互いに平行なベース面１ａにそれぞれセンサセグメントＳＧを配置した平板状のセンサ体１ｂを２個用いて、それぞれのベース面１ａが相互に平行にならないように組み合わせたものであってもよい。図６（ｂ）では、ベース面１ａ上にセンサセグメントＳＧとして４個の歪検知素子を配置する事で、図６（ａ）の場合と同様に４外力を測定でき、もう一方のセンサ体に配置された２個の歪検知素子からなるセンサセグメントＳＧ、あるいはこの他の歪検知素子との組み合わせにて、６外力のうちの残り２外力を測定可能とするものである。
また、図６（ｃ）に示す３次元歪センサブロック１Ｃのように、平板状のセンサ体１ｂ３個を立方体の互いに平行でない面をなすように配置し、各々のベース面１ａの片側だけにそれぞれセンサセグメントＳＧを配置してもよい。
図６（ａ）から（ｃ）の変形例は、６外力の分離率が良い応力方向を平板状のセンサ体１ｂを用いて測定するための手法である。
【００８６】
重要なのは、それぞれのベース面１ａに配置されるセンサセグメントＳＧの配置態様であり、本発明では、それぞれのセンサセグメントＳＧの配置態様を、そのセンサブロックを埋設する位置についての応力関数を用いて決めるようにしている。これは、例えば、センサブロック１Ａについては、センサ体１ｂの相互の交差角の決定に応力関数を用いるという意味であり、センサブロック１Ｃについては、互いに平行なベース面１ａ上にセンサセグメントＳＧを配置するということを、応力関数を用いて決めたということである。
【００８７】
例えば、せん断歪を測定する場合には、応力関数の外トルクとの分離率がよい配置に、垂直応力を測定する場合には、応力関数の外力との分離率がよい配置とすればよい。
【００８８】
これによって、求めたい外力と歪検知素子の歪信号から得られる応力との分離率がよくなり、求めたい外力に対応した歪をより感度良く検知することができる。
【００８９】
なお、本発明の３次元歪センサブロック、３次元外力測定ユニット、構造体の外力測定方法は、ここで説明した車両だけでなく、他の複雑な構造体で複数の外力を受けるものについて、例えば、ロボットアーム、医療用の義肢などにも適用可能である。
【００９０】
【発明の効果】
請求項１に記載の３次元歪センサブロックによれば、センサブロックそのものの構成において、歪検知素子の配置態様をきめるのに、そのセンサブロックを埋設する位置についての応力関数を用いるものである。これによって、求めたい外力と歪検知素子の歪信号から得られる応力との分離率がよくなり、求めたい外力に対応した歪をより感度良く検知することができる。
【００９１】
請求項２に記載の３次元歪センサブロックによれば、請求項１の効果に加え、互いに平行となる２つのベース面の各々に前記センサセグメントを配置し、求めたい外力が４外力以下の場合において、センサセグメントの上記配置態様をきめるのに、そのセンサブロックを埋設する位置及び角度についての応力関数を用いたので、特にＡＢＳ制御等を行なう上で有効とされる３外力（路面摩擦力、横力、および垂直抗力）と転がり抵抗モーメント（ブレーキトルク）を計測することができ、これらをパラメータとした運動方程式を採用することによって、従来手法のような車輪速度をパラメータとした制御と比してその制御精度を向上することができる。
請求項３に記載の３次元歪センサブロックによれば、請求項１の効果に加え、互いに平行とならない複数のベース面の各々に前記センサセグメントを配置したので、異なる複数の応力平面上での応力あるいはその分布を求めることを可能としている。
請求項４に記載の３次元歪センサブロックによれば、請求項１の効果に加え、互いに平行となる２つのベース面の各々に前記センサセグメントを配置したセンサ体を互いに平行とならないように複数個組み合わせることで、異なる平面での平面内応力およびそのセンサセグメントの面外変形による応力を求めることと、２つのセンサ体にて求めた２点での応力から、構造体にはたらく外力、すなわち力およびモーメントを差分あるいはその他の手法によって精度よく求めることを可能としている。
【００９２】
請求項５に記載の３次元外力測定ユニットによれば、３次元歪センサブロックから出力される歪信号の演算処理、つまり、応力角度変換部での演算処理に、応力関数を用いるもので、これにより、歪信号から測定すべき外力に対応した応力を簡単にリアルタイムに算出することができる。
【００９３】
請求項６に記載の３次元外力測定ユニットによれば、請求項５の効果に加え、演算した外力をパラレル出力することができる。
【００９４】
請求項７に記載の３次元外力測定ユニットによれば、請求項５の効果に加え、共通の出力端子を設け、演算した外力を、予め定めた所定の順序で循環的に出力し、いわゆるシリアル出力することができる。
【００９５】
請求項８に記載の３次元外力測定ユニットによれば、請求項５から７の効果に加え、演算増幅器を用いているので、簡易なハード構成で高速演算処理が可能となり、実装基板はカスタムＩＣ化され得る。
【００９６】
請求項１０に記載の構造体の外力測定方法によれば、構造体への３次元歪センサブロックの設置位置、設置角度の決定に、応力分布から角度変換で得られる応力関数（位置と角度の関数）を用いたので、外力分離領域がより広くなり、あるいは、換言すれば、外力分離のための応力関数に角度が変数として導入されたために、分離率のよい場所を選択するための条件が緩和されため、複数の外力に対応した外力分離領域の重複領域が獲得できるようになり、ここに歪センサブロックを設け、さらに外力分離角度に対応させた設置角度とすれば、測定すべき外力全てを感度良く測定できる。
【００９７】
請求項１１に記載の構造体の外力測定方法によれば、請求項１０の効果に加え、３次元歪センサブロックの設置角度を、支持支点と外力作用点とを結ぶ線に対して、センサブロックの中心軸が平行となる角度と具体的に既定したので、具体的な例において、センサブロックの設置角度を容易に決めることができる。
【００９８】
請求項９に記載の３次元外力測定ユニットによれば、上述の３次元歪センサブロック、構造体の外力測定方法と組み合わせて、測定対象の構造体を車両のサスペンションとし、測定外力を最大限、垂直抗力、路面摩擦力、横力、オーバターニングモーメント、転がり抵抗モーメント（ブレーキトルク）、およびセルフアライニングモーメント（トルク）としたものであり、これらの外力を感度良く、リアルタイムに測定することができ、こうして測定された外力を用いて、車両の制動制御などを良好に行うことができ、例えば、ＡＢＳ（Antilock Braking System）の性能を格段に向上させることができる。また、車両運動制御を実現するシステムを考えた場合、従来では車輪速度センサ、加速度センサ、ヨーレイトセンサ等の複数のセンサを組み合わせてシステムを構築しなければならないが、本発明では、単一の３次元歪センサブロックのみを装着するだけで上述の外力を計測可能となるので、そのコストを大きく低減させることができる。
【図面の簡単な説明】
【図１】本発明に係る構造体の外力測定方法の原理を概念的に示すもので、（ａ）は３次元歪センサブロック設置位置の決定方法の説明図、（ｂ）は３次元歪センサブロックの設置角度の決定方法の説明図
【図２】本発明に係る構造体の外力測定方法においてセンサブロック設置位置・角度の決定の手順を示すフローチャート
【図３】本発明に係る構造体の外力測定方法において外力分離領域を得るための応力関数を例示する図
【図４】本発明の３次元外力測定ユニットの一例を示すブロック図
【図５】本発明の３次元歪センサブロックとその設置態様の一例を示すもので、（ａ）はその正面図、（ｂ）は側面図
【図６】本発明の３次元歪センサブロックを例示する図
【図７】従来の構造体の外力測定方法の原理を概念的に示すもので、（ａ）は測定対象の構造体の説明図、（ｂ）はセンサブロック設置位置の決定方法の説明図
【符号の説明】
１ ３次元歪センサブロック
１ａ ベース面
２ 歪検知素子（歪ゲージ）
３ 信号演算処理回路部
３１ ブリッジ回路
３２ 歪増幅回路
３３ 歪／応力変換部
３４ 応力角度変換部
３５ 外力演算処理部
３６ 出力端子
３７ 共通の出力端子
５ ３次元外力測定ユニット
Ａ、Ｂ、Ｃ、Ｄ、Ｅ 演算増幅器
Ｆｚ 垂直荷重
Ｆｘ 路面摩擦力
Ｆｙ 横力
Ｍｙ ねじりトルク
Ｋ 構造体（サスペンション）
ＫＭ 主構造体（車両）
Ｏ 外力作用点（車軸）
Ｐｓ 設置位置
ＳＣ 中心軸
ＳＧ センサセグメント
Ｘ 支持支点
Ｚ 外力分離領域
ＺＺ 重複領域
φｓ 設置角度
Φｓ 線分[0001]
BACKGROUND OF THE INVENTION
The present invention measures all or part of three-dimensional external forces acting on the structure (including external torques around three axes, and a total of six external forces, which are also referred to as “6 component forces”). The present invention relates to a three-dimensional strain sensor block, a three-dimensional external force measurement unit, and a structure external force measurement method.
[0002]
[Prior art]
In order to measure the external force acting on the structure, a strain sensor block with strain sensing elements called strain gauges is installed inside the structure, and stress is applied from the strain signal output from the strain sensor block. A method for obtaining and further calculating an external force is known.
[0003]
At that time, first, as a conventional flow, 1) set the structure, 2) pay attention to the stress in a specific direction along the normal coordinate system of the stress to be obtained, and 3) the structure based on this coordinate system 4) After this, theoretical calculation, stress analysis by the finite element method and other means are performed to calculate three normal stresses and three shear stresses.
[0004]
Next, based on the above calculation results, the strain sensor block is placed inside the structure so as to be arranged at a predetermined angle along the normal coordinate system XYZ direction, and an external force is applied to the strain sensor block. The procedure of measuring the signal output obtained, calculating the stress, and measuring the external force corresponding to this was taken.
[0005]
However, in the conventional method, it was possible to measure about two external forces with one strain sensor block provided in one place, but all six component forces in the three-dimensional direction were measured with high accuracy and in real time. It was not possible to measure it.
[0006]
For example, according to the prior art (Patent Document 1) by the present applicant, a region with a good external force separation rate is calculated from the stress distribution obtained by the finite element method, and a strain sensor block is installed in the region. The external force could be measured.
[0007]
FIG. 7 conceptually shows the principle of the prior art. FIG. 7A is an explanatory diagram of a structure to be measured, and FIG. 7B is an explanatory diagram of a method for determining a sensor block installation position.
[0008]
In this example, as a structure to be measured, a tire T that is supported on a support fulcrum X by a vehicle main body KM that is a main structure and that travels on a road surface G by a bearing portion O that is an external force acting point is rotatably supported. The suspension device and the suspension K are selected.
[0009]
In this structure and suspension K, as shown in FIG. 7B, three external forces Fx, Fy, Fz in the three-dimensional direction and external moments Mx around the three axes corresponding to the three-dimensional direction are provided as external forces. My and Mz act.
[0010]
Here, with respect to this suspension, these three external forces are Fx: force in the vehicle traveling direction (road frictional force, also referred to as braking force / driving force), and Fy: force in the vehicle lateral direction (lateral force). ), Fz: defined as vertical force (load / vertical drag), and three external moments are Mx: moment around the x axis (overturning moment), My: moment around the y axis (rolling resistance moment), Mz: Defined as a moment around the z axis (self-aligning torque).
[0011]
In this prior art, in order to measure each external force Fx, Fy, Fz, Mx, My, and Mz, the stress generated in the structure K by each of these external forces is calculated by the finite element method, and the external force and A region in which the correspondence with a specific stress is good (T, for example, when an external force Fx is applied, only the stress σx appears prominently and no other stress occurs. This is referred to as an “external force separation region”). By installing a strain sensor block, it was possible to detect the stress and measure the corresponding external force with high sensitivity.
[0012]
However, in this method, as shown in FIG. 7B, the external force separation regions (ZFx, ZFy, ZFz, ZMx, ZMy, ZMz) may overlap each other, but usually do not overlap. In order to measure each external force, it is necessary to provide a dedicated strain sensor block in each external force separation region. That is, there was a constraint of one external force and one sensor block.
[0013]
Therefore, in this example, for braking control of the structure (suspension) to be measured, among the 6 component forces, 4 of road friction force Fx, lateral force Fy, vertical drag Fz, and rolling resistance moment My Since it is necessary to measure two external forces, the strain sensor block must be provided in each of the four external force separation regions ZFx, ZFy, ZFz, and ZMy in the figure.
[0014]
In addition to the above, the present applicant has proposed, in Patent Document 2, Patent Document 3, etc., prior art for measuring a plurality of external forces that act on a complex support structure having a complicated shape with high sensitivity. In order to solve each technical problem, the problem has been left as a problem before.
[0015]
[Patent Document 1]
JP 2002-22579 A (paragraph 0054, paragraph 0055, FIG. 3, FIG. 4)
[Patent Document 2]
JP-A-7-248272
[Patent Document 3]
Japanese Patent No. 2784711
[Problems to be solved by the invention]
The present invention has been conceived under the circumstances described above, and has an external force acting on a structure having a complicated shape and having a plurality of different supporting fulcrums from different directions. It is an object of the present invention to provide a three-dimensional strain sensor block, a three-dimensional external force measurement unit, and an external force measurement method for a structure that can be measured with high sensitivity by embedment and installation in one place inside the body.
[0016]
[Means for Solving the Problems]
In order to solve the above problems, the present inventor added a stress distribution of the structure obtained by the finite element method used in the past, and a structure calculated by coordinate rotation, that is, angle conversion, from the obtained stress distribution. The stress function (position and angle function) for each of the positions of the three-dimensional strain sensor block is arranged in the three-dimensional strain sensor block, the calculation processing in the three-dimensional external force measurement unit, the three-dimensional strain sensor block in the structure external force measurement method The idea was to maximize the use of each for determining the installation position and angle, and the results were obtained.
[0017]
Here, when simply referred to as an external force, it refers to the 6 component force described above and includes three external forces and three external moments.
[0018]
The three-dimensional strain sensor block according to claim 1, For measuring external forces acting on the structure A three-dimensional strain sensor block that forms the outer surface Different On the base surface Arranged With strain sensing element Consist of multiple With sensor segments, When an external force to be measured is applied to the structure, an analysis based on a stress function obtained by applying a three-dimensional rotational coordinate transformation to the distribution of stress acting on the position and angle in the structure The external force separation area where the external force is independent and separated from other external forces and the area where the external force separation angle overlaps are obtained, and the burying position is determined from the obtained result in consideration of the angle in the structure. Embedded in such a manner that the sensor segment is located there. It is characterized by that.
[0019]
In this structure, in the configuration of the sensor block itself, a stress function regarding the position and angle at which the sensor block is embedded is used to determine the arrangement of the sensor segment. As a result, the separation rate between the external force to be obtained and the stress obtained from the strain signal of the strain sensing element is improved, and the strain corresponding to the external force to be obtained can be detected with higher sensitivity.
[0020]
The three-dimensional strain sensor block according to claim 2 is the three-dimensional strain sensor block according to claim 1, wherein the sensor segments are arranged on each of two base surfaces that are parallel to each other. In the case of four or less external forces, the stress function for the position and angle at which the sensor block is embedded is used to determine the arrangement of the sensor segments. As a result, it is possible to measure three external forces (road friction force, lateral force, and vertical drag) and rolling resistance moment (brake torque) that are effective in performing ABS (Antilock Braking System) control, etc. By adopting the equation of motion as a parameter, the control accuracy can be improved as compared with the control using the wheel speed as a parameter as in the conventional method.
The three-dimensional strain sensor block according to claim 3 is the three-dimensional strain sensor block according to claim 1, wherein the sensor segments are arranged on each of a plurality of base surfaces that are not parallel to each other, and a plurality of different stresses. It is possible to obtain the stress on the plane or its distribution.
The three-dimensional strain sensor block according to claim 4 is the three-dimensional strain sensor block according to claim 1, wherein the sensor bodies in which the sensor segments are arranged on each of two parallel base surfaces are not parallel to each other. As a result, the external force acting on the structure is obtained from the in-plane stress on different planes and the stress due to out-of-plane deformation of the sensor segment, and the stress at the two points obtained by the two sensor bodies. That is, it is possible to obtain the force and the moment with high accuracy by the difference or other methods.
[0021]
The three-dimensional external force measurement unit according to claim 5 is: Any of the above A three-dimensional strain sensor block; A plurality of bridge circuits each including the strain sensing elements of the plurality of sensor segments as a part, and an electric signal of each of the plurality of bridge circuits Distortion signal Calculate Convert to stress plural A strain / stress converter, Using the stress function, the plurality of Obtained at strain / stress converter For stress Angle conversion by installation position and installation angle of the 3D strain sensor block I do A stress angle converter, The The external force to be measured is determined from the output of the stress angle converter. Calculate An external force calculation processing unit for outputting is provided.
[0022]
This uses a stress function for the calculation process of the strain signal output from the three-dimensional strain sensor block, that is, the calculation process in the stress angle conversion unit, and thus corresponds to the external force to be measured from the strain signal. The calculated stress can be easily calculated in real time.
[0023]
The three-dimensional external force measurement unit according to claim 6 is the three-dimensional external force measurement unit according to claim 5, wherein the signal calculation processing circuit unit is provided with a plurality of output terminals corresponding to the external force to be measured, and is calculated. The external force is output in parallel.
[0024]
The three-dimensional external force measurement unit according to claim 7 is the three-dimensional external force measurement unit according to claim 5, wherein the signal calculation processing circuit unit is provided with a common output terminal, and the calculated external force is determined in advance by a predetermined value. The output is cyclic in this order.
[0025]
The three-dimensional external force measurement unit according to claim 8 is the three-dimensional external force measurement unit according to any one of claims 5 to 7, wherein a strain / stress conversion unit and a stress angle conversion unit that constitute the signal arithmetic processing circuit unit. The external force measurement calculation processing unit is configured by combining operational amplifiers.
[0026]
Claim 10 The external force measurement method for the structure described in An external force measurement method using any one of the above-described three-dimensional strain sensor blocks, wherein the structure is: Supported by the main structure and concentrated on one point from the outside to receive external force A structure, the structure Act on Different external forces in different directions The measurement is performed in real time from stresses separated and measured by a single three-dimensional strain sensor block provided in the structure.
[0027]
In this measurement method, a stress function (a function of position and angle) obtained by angle conversion from the stress distribution is used to determine the installation position and installation angle of the three-dimensional strain sensor block on the structure.
[0028]
As a result, the external force separation region becomes wider, or in other words, since the angle is introduced as a variable in the stress function for external force separation, the conditions for selecting a place with a good separation rate are relaxed, An overlapping region of external force separation regions corresponding to the external force can be acquired. If a strain sensor block is provided here, all external forces to be measured can be measured with high sensitivity.
[0029]
Therefore, the strain sensor block is a three-dimensional strain sensor block in which a plurality of strain sensing elements are arranged so that a plurality of external forces can be measured, and the three-dimensional strain sensor block is installed in the overlapping region, and the installation angle is determined. Also, a stress function is used.
Claim 11 The external force measurement method for the structure described in In claim 10 In the structure external force measurement method described above, as an example of a result obtained as an installation angle of the three-dimensional strain sensor block, a support fulcrum on which the structure is supported by the main structure and an external force acts on the structure. The three-dimensional strain sensor block is installed so that the central axis of the three-dimensional strain sensor block is parallel to the line connecting the external force action points.
[0030]
Claim 9 The three-dimensional external force measurement unit according to claim 5 is a three-dimensional external force measurement unit according to any one of claims 5 to 8, The structure is Suspension as a support member for supporting and connecting a vehicle wheel And The maximum external force to be measured is a vertical drag acting on the ground contact surface between the wheel and the traveling road surface, a road surface friction force applied in the traveling direction of the vehicle, a lateral force acting perpendicular to the traveling direction of the vehicle, An overturning moment, a rolling resistance moment, and a self-aligning moment applied to the vehicle
[0031]
This three-dimensional external force measurement unit is combined with the above-described three-dimensional strain sensor block and structure external force measurement method, and the structure to be measured is a vehicle suspension, and the measurement external force is vertical drag, road friction force, lateral force, These are overturning moment, rolling resistance moment (brake torque), and self-aligning moment (torque), and these external forces can be measured in real time with high sensitivity. Using the 6 external forces thus measured The vehicle braking control can be performed satisfactorily. For example, the performance of an ABS (Antilock Braking System) can be significantly improved. Further, when considering a system that realizes vehicle motion control, conventionally, a system must be constructed by combining a plurality of sensors such as a wheel speed sensor, an acceleration sensor, and a yaw rate sensor. Since the above-described external force can be measured only by mounting only the dimensional strain sensor block, the cost can be greatly reduced.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below, but what is described here is an example of a preferred embodiment, and the scope of the present invention is not limited to the embodiment shown here.
[0033]
FIG. 1 conceptually shows the principle of an external force measuring method for a structure according to the present invention, where (a) is an explanatory diagram of a method for determining a three-dimensional strain sensor block installation position, and (b) is a three-dimensional strain sensor. FIG. 2 is an explanatory diagram of a method for determining an installation angle of a block, FIG. 2 is a flowchart showing a procedure for determining a sensor block installation position / angle in the external force measurement method for a structure according to the present invention, and FIG. It is a figure which illustrates the stress function for obtaining an external force isolation | separation area | region in a measuring method.
[0034]
As in the conventional example of FIG. 7, this external force measurement method uses a vehicle suspension as a structure K, and three external forces, road surface friction force Fx, lateral force Fy, vertical drag Fz, three external moments, and overturning moment Mx. The rolling resistance moment My and the self-aligning torque Mz are to be measured by a single three-dimensional strain sensor block 1 installed at one location in the structure K.
[0035]
Although the details will be described later, the main point is not to use the stress distribution calculated by the finite element method as in the prior art to obtain the external force separation regions ZFx, ZFy, ZFz, ZMx, ZMy, and ZMz. The point is to use a coordinate function, that is, a stress function (position and angle function) obtained by angle conversion for each distributed stress.
[0036]
In this way, it is possible to obtain an overlap region ZZ of all the external force separation regions ZFx, ZFy, ZFz, ZMx, ZMy, ZMz, and in this overlap region ZZ, the external forces Fx, Fy, Fz, Mx to be measured respectively. , My and Mz have stresses (vertical stress and shear stress) that correspond to each other with a good separation rate. If the three-dimensional strain sensor block 1 is installed here, the external force to be measured can be measured with high sensitivity. Can do.
[0037]
In FIG. 1, the symbol Ps indicates the installation position of the three-dimensional strain sensor block 1 determined as the point where the external force can be measured with the highest sensitivity in the overlapping region ZZ, and the line segment Φs intersects the symbol Ps. In addition, the installation angle of the three-dimensional strain sensor block 1 determined as the direction in which the external force can be measured with the highest sensitivity in the overlapping region ZZ is shown. Reference numeral 2 denotes a strain sensing element 1a disposed in the three-dimensional strain sensor block 1. Is a base surface constituting the outer surface of the three-dimensional strain sensor block 1, and SC is a central axis corresponding to the detection center of the base surface unit of the strain sensing element 2 arranged in the three-dimensional strain sensor block 1.
[0038]
Further, a set of strain sensing elements 2 arranged so as to intersect with one base surface 1a is referred to as a sensor segment SG. This intersection angle is generally determined by the direction of the main stress and the shear corresponding to the main stress. The angle is set to 90 degrees or 45 degrees based on the angular relationship with the stress.
[0039]
Further, as shown in FIG. 1B, after determining the installation position of the three-dimensional strain sensor block 1 as the installation position Ps in the overlapping region ZZ, the central axis SC of the three-dimensional strain sensor block 1 is What is necessary is just to determine so that the installation angle which corresponds with line segment (PHI) s may be taken.
[0040]
In the case of this embodiment, the structure (suspension) K is mainly used in the direction of the line segment Φs at which the independence of the external force and the separation rate are the best in the stress function, that is, the direction of the central axis SC. It is parallel to a straight line connecting a support fulcrum X supported by a structure (not shown) and an external force application point O at which an external force acts on the structure K.
[0041]
In determining the installation posture and the installation angle of the three-dimensional strain sensor block 1, the external force to be measured is maximized from the maximum and minimum values of the stress function when the angle is used as a parameter in the stress function as described later. In addition, a condition that minimizes the external force that is not the purpose is used, so that the necessary external force can be measured with high sensitivity. From this, the stress measuring method of this invention is demonstrated in more detail mainly using the flowchart of FIG.
[0042]
As shown in this flowchart, the sensor block installation position / angle determination method in the stress measurement method of the present invention is configured by the procedure from step S1 to step S7.
[0043]
Step S1: A structure system to which an external force is applied is set. As the structure, a vehicle may be selected as a measurement object, and in addition to a structure having an axle, a structure having no axle or a structure having a complicated shape may be set. The front-rear direction is the X direction, the wheel rotation axis direction is the Y direction, and the vertical direction is the Z direction (normal coordinate system). At the same time, a structure fixing method (constraint condition) is set. As the external force, a total of 6 external forces including a force in a three-dimensional direction and a torque around three axes are assumed.
[0044]
In the following, for the sake of explanation, three external force road surface frictional forces Fx, lateral force Fy, normal reaction force Fz, three external moments, overturning moment Mx, and rolling resistance moment My acting on the structure described in FIG. The self-aligning moment Mz is simply indicated as external forces F1, F2, F3,.
[0045]
Step S2: An external force F1 is applied and a stress analysis is performed by a finite element method to obtain a stress distribution of the structure as a function of the position P (X, Y, Z) in the normal coordinate system. Here, in the three-dimensional normal coordinate system, vertical stresses σx, σy, σz and shear stress τxy, τyz, τzx when an external force is applied as stress groups for each position Pi (i = 1 to N). A stress group Σ (F1, Pi) is applied to all positions. Note that the number N of positions Pi is determined by the number of microelements defined by the finite element method, and the finite element method is already a well-known technique. Shall be omitted.

σx1 = fx1 (F1, Pi), σy1 = fy1 (F1, Pi), σz1 = fz1 (F1, Pi)
τxy1 = fxy1 (F1, Pi), τyz1 = fyz1 (F1, Pi), τzx1 = fzx1 (F1, Pi)
Here, {St1, St2, St3, St4, St5, St6} represents a stress group composed of each stress St1, St2, St3, St4, St5, St6, and fx1 (F1, Pi), fy1 (F1, Pi). , Fz1 (F1, Pi), fxy1 (F1, Pi), fyz1 (F1, Pi), fzx1 (F1, Pi) are
This represents a function of σx1, σy1, σz1, τxy1, τyz1, and τzx1 with the position Pi when the external force F1 is applied as a parameter.
[0046]
Step S3: Applying external forces F2, F3,..., F6, and using the same means as in Step S2, each stress group Σ (F2, Pi), Σ (F3, Pi),. Pi). That is,
Σ (F2, Pi) = G {σx2, σy2, σz2, τxy2, τyz2, τzx2}-(2)
Σ (F3, Pi) = G {σx3, σy3, σz3, τxy3, τyz3, τzx3}-(3)
Σ (F4, Pi) = G {σx4, σy4, σz4, τxy4, τyz4, τzx4}-(4)
Σ (F5, Pi) = G {σx5, σy5, σz5, τxy5, τyz5, τzx5}-(5)
Σ (F6, Pi) = G {σx6, σy6, σz6, τxy6, τyz6, τzx6}-(6)
Σx2, σy2, σz2, τxy2, τyz2, τzx2, σx3, σy3, σz3, τxy3, τyz3, τzx3, ..., σx6, σy6, σz6, τxy6, τyz6, τzx6 The
σx2 = fx2 (F2, Pi), σy2 = fy2 (F2, Pi), σz2 = fz2 (F2, Pi)
τxy2 = fxy2 (F2, Pi), τyz2 = fyz2 (F2, Pi), τzx2 = fzx2 (F2, Pi)
σx6 = fx6 (F6, Pi), σy6 = fy6 (F6, Pi), σz6 = fz6 (F6, Pi)
τxy6 = fxy6 (F6, Pi), τyz6 = fyz6 (F6, Pi), τzx6 = fzx6 (F6, Pi)
Is described.
[0047]
Step S4: Based on Cauchy's coordinate rotation type (see Keizo Kishida, “Mechanicals of Materials” (Baifukan, 1987)), the respective angles A, B, C are set in the counterclockwise directions of the coordinate axes X, Y, Z. By rotating and performing coordinate transformation and using angle group φ {A, B, C} as parameters, transformation of stress groups Σ (F1, Pi) to Σ (F6, Pi) obtained in steps S2 and S3 The transformed stress group in the coordinate system, that is, the stress functions Σ ′ (F1, Pi) to Σ ′ (F6, Pi) is obtained. That is,
Σ '(F1, Pi)
= G '{σx1', σy1 ', σz1', τxy1 ', τyz1', τzx1 '}-(7)
Σ '(F2, Pi)
= G '{σx2', σy2 ', σz2', τxy2 ', τyz2', τzx2 '}-(8)
Σ '(F3, Pi)
= G '{σx3', σy3 ', σz3', τxy3 ', τyz3', τzx3 '}-(9)
Σ '(F4, Pi)
= G '{σx4', σy4 ', σz4', τxy4 ', τyz4', τzx4 '}-(10)
Σ '(F5, Pi)
= G '{σx5', σy5 ', σz5', τxy5 ', τyz5', τzx5 '}-(11)
Σ '(F6, Pi)
= G '{σx6', σy6 ', σz6', τxy6 ', τyz6', τzx6 '}-(12)
Σx1 ′, σy1 ′, σz1 ′, τxy1 ′, τyz1 ′, τzx1 ′, σx3, σy3, σz3, τxy3, τyz3, τzx3,..., Σx6 ′, σy6 ′ ,
σz6´, τxy6, τyz6´, τzx6´
σx1 ′ = fx1 ′ (Σ (F1, Pi), φ {A, B, C})
= A _11-F1 × A _11-F1 × σx1 + A _11-F1 × A _12-F1 × τxy1 + A _11-F1 × A _13-F1 × τzx1
+ A _11-F1 × A _12-F1 × τxy1 + A _12-F1 × A _12-F1 × σy1 + A _12-F1 × A _13-F1 × τyz1
+ A _11-F1 × A _13-F1 × τzx1 + A _12-F1 × A _13-F1 × τyz1 + A _13-F1 × A _13-F1 × σz1
σy1 ′ = fy1 ′ (Σ (F1, Pi), φ {A, B, C})
= A _21-F1 × A _21-F1 × σx1 + A _21-F1 × A _22-F1 × τxy1 + A _21-F1 × A _23-F1 × τzx1
+ A _21-F1 × A _22-F1 × τxy1 + A _22-F1 × A _22-F1 × σy1 + A _22-F1 × A _23-F1 × τyz1
+ A _21-F1 × A _23-F1 × τzx1 + A _22-F1 × A _23-F1 × τyz1 + A _23-F1 × A _23-F1 × σz1
σz1 ′ = fz1 ′ (Σ (F1, Pi), φ {A, B, C})
= A _31-F1 × A _31-F1 × σx1 + A _31-F1 × A _32-F1 × τxy1 + A _31-F1 × A _33-F1 × τzx1
+ A _31-F1 × A _32-F1 × τxy1 + A _32-F1 × A _32-F1 × σy1 + A _32-F1 × A _33-F1 × τyz1
+ A _31-F1 × A _33-F1 × τzx1 + A _32-F1 × A _33-F1 × τyz1 + A _33-F1 × A _33-F1 × σz1
τxy1 ′ = fxy1 ′ (Σ (F1, Pi), φ {A, B, C})
= A _11-F1 × A _21-F1 × σx1 + A _12-F1 × A _21-F1 × τxy1 + A _13-F1 × A _21-F1 × τzx1
+ A _11-F1 × A _22-F1 × τxy1 + A _12-F1 × A _22-F1 × σy1 + A _13-F1 × A _22-F1 × τyz1
+ A _11-F1 × A _23-F1 × τzx1 + A _12-F1 × A _23-F1 × τyz1 + A _13-F1 × A _23-F1 × σz1
τyz1 ′ = fyz1 ′ (Σ (F1, Pi), φ {A, B, C})
= A _11-F1 × A _31-F1 × σx1 + A _12-F1 × A _31-F1 × τxy1 + A _13-F1 × A _31-F1 × τzx1
+ A _11-F1 × A _32-F1 × τxy1 + A _12-F1 × A _32-F1 × σy1 + A _13-F1 × A _32-F1 × τyz1
+ A _11-F1 × A _33-F1 × τzx1 + A _12-F1 × A _33-F1 × τyz1 + A _13-F1 × A _33-F1 × σz1
τzx1 ′ = fzx1 ′ (Σ (F1, Pi), φ {A, B, C})
= A _21-F1 × A _31-F1 × σ _x1 + A _22-F1 × A _31-F1 × τxy1 + A _23-F1 × A _31-F1 × τzx1
+ A _21-F1 × A _32-F1 × τ _xy1 + A _22-F1 × A _32-F1 × σy1 + A _23-F1 × A _32-F1 × τyz1
+ A _21-F1 × A _33-F1 × τzx1 + A _22-F1 × A _33-F1 × τyz1 + A _23-F1 × A _33-F1 × σz1
...
σx6 ′ = fx6 ′ (Σ (F6, Pi), φ {A, B, C})
= A _11-F6 × A _11-F6 × σx6 + A _11-F6 × A _12-F6 × τxy6 + A _11-F6 × A _13-F6 × τzx6
+ A _11-F6 × A _12-F6 × τxy6 + A _12-F6 × A _12-F6 × σy6 + A _12-F6 × A _13-F6 × τyz6
+ A _11-F6 × A _13-F6 × τzx6 + A _12-F6 × A _13-F6 × τyz6 + A _13-F6 × A _13-F6 × σz6
σy6 ′ = fy6 ′ (Σ (F6, Pi), φ {A, B, C})
= A _21-F6 × A _21-F6 × σx6 + A _21-F6 × A _22-F6 × τxy6 + A _21-F6 × A _23-F6 × τzx6
+ A _21-F6 × A _22-F6 × τxy6 + A _22-F6 × A _22-F6 × σy6 + A _22-F6 × A _23-F6 × τyz6
+ A _21-F6 × A _23-F6 × τzx6 + A _22-F6 × A _23-F6 × τyz6 + A _23-F6 × A _23-F6 × σz6
σz6 ′ = fz6 ′ (Σ (F6, Pi), φ {A, B, C})
= A _31-F6 × A _31-F6 × σx6 + A _31-F6 × A _32-F6 × τxy6 + A _31-F6 × A _33-F6 × τzx6
+ A _31-F6 × A _32-F6 × τxy6 + A _32-F6 × A _32-F6 × σy6 + A _32-F6 × A _33-F6 × τyz6
+ A _31-F6 × A _33-F6 × τzx6 + A _32-F6 × A _33-F6 × τyz6 + A _33-F6 × A _33-F6 × σz6
τxy6 ′ = fxy6 ′ (Σ (F6, Pi), φ {A, B, C})
= A _11-F6 × A _21-F6 × σx6 + A _12-F6 × A _21-F6 × τxy6 + A _13-F6 × A _21-F6 × τzx6
+ A _11-F6 × A _22-F6 × τxy6 + A _12-F6 × A _22-F6 × σy6 + A _13-F6 × A _22-F6 × τyz6
+ A _11-F6 × A _23-F6 × τzx6 + A _12-F6 × A _23-F6 × τyz6 + A _13-F6 × A _23-F6 × σz6
τyz6 ′ = fyz6 ′ (Σ (F6, Pi), φ {A, B, C})
= A _11-F6 × A _31-F6 × σx6 + A _12-F6 × A _31-F6 × τxy6 + A _13-F6 × A _31-F6 × τzx6
+ A _11-F6 × A _32-F6 × τxy6 + A _12-F6 × A _32-F6 × σy6 + A _13-F6 × A _32-F6 × τyz6
+ A _11-F6 × A _33-F6 × τzx6 + A _12-F6 × A _33-F6 × τyz6 + A _13-F6 × A _33-F6 × σz6
τzx6 ′ = fzx6 ′ (Σ (F6, Pi), φ {A, B, C})
= A _21-F6 × A _31-F6 × σx6 + A _22-F6 × A _31-F6 × τxy6 + A _23-F6 × A _31-F6 × τzx6
+ A _21-F6 × A _32-F6 × τxy6 + A _22-F6 × A _32-F6 × σy6 + A _23-F6 × A _32-F6 × τyz6
+ A _21-F6 × A _33-F6 × τzx6 + A _22-F6 × A _33-F6 × τyz6 + A _23-F6 × A _33-F6 × σz6
Is described. Where A _11-Fn ~ A _33-Fn When the external force Fn (n = 1 to 6) is applied, the rotation angle with respect to the X axis is A, the rotation angle with respect to the Y axis is B, and the rotation angle with respect to the Z axis is C.
A _11-Fn = CosBcosC, A _12-Fn = CosBsinC, A _13-Fn = -SinB,
A _21-Fn = SinAsinBcosC-cosAsinC, A _22-Fn = SinAsinBsinC + cosAcosC,
A _23-Fn = SinAcosB, A _31-Fn = CosAsinBcosC + sinAsinC,
A _32-Fn = CosAsinBsinC-sinAcosC, A _33-Fn = CosAcosB
Is defined by
As can be seen from the above equation, each stress after conversion is a function of the angle group φ {A, B, C} in addition to the stress before conversion (function of external force Fn and position Pi). The degree of freedom is increased as compared with the previous stress, and the constraint on Fn and Pi can be relaxed by optimizing the angle group φ {A, B, C} to satisfy the necessary conditions.
[0048]
Step S5: An external force separation region and an external force separation angle, which are preconditions for selecting a sensor mounting candidate position, are calculated. As a selection method, the stress output after obtaining the stress group based on the stress analysis and the angle conversion can be easily obtained, and the position may be a preferable position as an external condition for mounting the sensor.
[0049]
At this time, since the stress function obtained in step S4 is a function of the angle group φ {A, B, C}, each stress is described using the angle group φ {A, B, C} as a parameter. Since Cauchy's formula is a trigonometric function, it is expressed as a composite wave. For this reason, the minimum / maximum value appears from the amplitude of the synthesized wave. The stress function obtained by independently changing each angle group φ {A, B, C} is the graph of FIGS. 3A, 3B, and 3C. From this figure, it is also possible to obtain a position and an angle with good separation rate of each external force.
As a method for obtaining the position Pi having a good separation rate, the equations (7) to (12) are as follows.
Σ ′ (F1, Pi) = G ′ {σx1 ′, (minimum), (minimum), (minimum), (minimum), (minimum)},
Σ ′ (F2, Pi) = G ′ {(Minimum), σy2 ′, (Minimum), (Minimum), (Minimum), (Minimum)},
Σ ′ (F3, Pi) = G ′ {(Minimum), (Minimum), σz3 ′, (Minimum), (Minimum), (Minimum)},
Σ ′ (F4, Pi) = G ′ {(Minimum), (Minimum), (Minimum), τxy4 ′, (Minimum), (Minimum)},
Σ ′ (F5, Pi) = G ′ {(Minimum), (Minimum), (Minimum), (Minimum), τyz5 ′, (Minimum)},
Σ '(F6, Pi) = G' {(Minimum), (Minimum), (Minimum), (Minimum), (Minimum), τzx6 '}
In this case, the external force F1 is detected by a stress sensor that detects the stress σx1 ′, and similarly, σy2 ′ is F2, σz3 ′ is F3, τxy4 ′ is F4, τyz5 ′ is F5, and τzx6 ′ is F6. It will suffice if it is detected.
[0050]
As a specific example, FIG. 1 is an application example in an actual structure (suspension). In FIG. 1, the central axis SC of the three-dimensional strain sensor block 1 is a support fulcrum X at which the structure (suspension) K is supported by a main structure (not shown), and an external force at which an external force acts on the structure K. By making it parallel to the straight line connecting the point of action O, τyz 'is increased, and the stress after other angle conversion is decreased, and it is understood that a condition close to the above equation is created although it is pseudo. It was. The angle condition changes depending on the specific structure shape and support conditions, but it is considered that the angle condition can be applied as it is as long as it is limited to a general automobile suspension.
[0051]
Step S6: The overlapping regions ZZ of the external force separation regions ZFx, ZFy, ZFz, ZMx, ZMy, ZMz corresponding to the external forces thus obtained are calculated. Here, the external force separation region ZFx... Includes the angle at which the corresponding external force separation rate is improved at each position in the region, and in this sense, corresponds to the overlapping region ZZ of the external force separation region. The angle that improves the separation rate of the external force is included.
[0052]
Step S7: In the overlapping region ZZ obtained in Step S6, it is further determined whether or not the sensor element position / angle is capable of stress measurement using a stress function.
In determining the sensor mounting position from the overlapped area, select the part that does not interfere with other members of the sensor wiring during suspension assembly, and the structure of the structure by processing the sensor mounting hole at the mounting position Intensity calculation is performed, and a sensor is attached to a portion where the intensity decrease is least.
[0053]
As the sensor mounting angle after determining the position by the above method, considering that the mounting angle error is unavoidable at the time of manufacture, for example, the portion with the widest mounting angle error margin of the sensor output is selected from the graph of FIG. After that, determine the mounting angle.
[0054]
If it is a position / angle that satisfies the above conditions and allows stress measurement, this is defined as a sensor mounting position Ps (angle φs). Stress measurement is impossible, that is, the above conditions are not satisfied, or independent conditions for external force (independent conditions) cannot be obtained, and all stress values are the same for multiple external forces Or when the regular tendency which becomes the multiple is shown, a new sensor mounting candidate position is selected.
[0055]
Here, various methods for obtaining the external force separation region will be described. This method is used in step S5.
As one of the general methods for selecting a stress function with a good separation rate, the following conditions are applied to the external force F1 and the external force F2 when the equations (7) and (8) are compared with F1 and F2. There is a way to select one that meets the requirements. That is, among each component, for example, σx1 ′, σy1 ′, σx2 ′, σy2 ′,
“There is no k such that σx1 ′ = k × σx2 ′ and σy1 ′ = k × σy2 ′”-(13)
The above (13) is a necessary condition, which is equivalent to the condition that among the components, the same type of components need only be independent. If this condition is described for the entire assumption system,
“Of the external forces F1 to F6, for any two external forces Fp and Fq,
σxp ′ = k × σxq ′ and σyp ′ = k × σyq ′ and σzp ′ = k × σzq ′ and
τxyp ′ = k × τxyq ′ and τyzp ′ = k × τyzq ′ and τzxp ′ = k × τzxq ′
K does not exist "-(14)
(P = 1 to 6, q = 1 to 6, p ≠ q, and σxp ′, σyp ′, σzp ′, τxyp ′, τyzp ′, τzxp ′ are stresses at the position Pi when the external force Fp is applied. Group components, σxq ′, σyq ′, σzq ′, τxyq ′, τyzq ′, τzxq ′ are the components of the stress group at the position Pi when the external force Fq is applied)
It becomes the condition.
[0056]
The condition (14) is that when an external force is fixed, the function notation before stress conversion, that is, the function notation of only the position Pi has three variables of X, Y, and Z, and therefore the position Pi itself needs a constraint condition. Although it is obvious that in the function notation after stress conversion, the rotation angle variables of A, B, and C, which are components of the angle group φ {A, B, C}, are added to the three variables of X, Y, and Z. This indicates that adding the constraint condition (reference) to the angles A, B, and C can ease the constraint condition of the position variable.
[0057]
Another method for selecting a stress function with a good separation rate is shown below.
[0058]
In this case, the strain signals from the strain sensing element 2 (for example, the six elements shown in FIG. 1) are assumed to be εa, εb, εc, εd, εe, εf, and the relationship between the stress obtained from this strain and the external force is used. .
[0059]
A) Stress group obtained by stress analysis at all positions Σ (Fn, Pi) = {σx (n, i), σy (n, i), σz (n, i), τxy (n, i) , Τyz (n, i), τzx (n, i)}, the respective strains εx (n, i), εy (n, i), and εz (n, i) are obtained by the following equations. here,
Fn (n = 1 to 6) is the applied force (or moment), and Pi (i = 1 to N) is the position.
εx (n, i) = {σx (n, i) ′ − ν (σy (n, i) ′ + σz (n, i) ′)} / E
εy (n, i) = {σy (n, i) ′ − ν (σz (n, i) ′ + σx (n, i) ′)} / E
εz (n, i) = {σz (n, i) ′ − ν (σx (n, i) ′ + σy (n, i) ′)} / E
It should be noted that σx (n, i) ′, σy (n, i) ′, and σz (n, i) ′ in the above equation are respectively the angle φ (A, B, C) of the sensor body at the position Pi. Stresses perpendicular to the normal coordinate system X, Y, and Z axes when arranged, σx (n, i) ', σy (n, i)', σz (n, i) 'and stress group
The relationship with Σ (Fn, Pi) is expressed below with the angles formed by the reference line segment Φs of the sensor body and the X, Y, and Z axes as A, B, and C, respectively.
[0060]
σx (n, i) = σx (n, i) ′ × (1 + cosA) / 2
σy (n, i) = σy (n, i) ′ × (1 + cosB) / 2
σz (n, i) = σz (n, i) ′ × (1 + cosC) / 2
τxy (n, i) = σz (n, i) '× sin (2C) / 2
τyz (n, i) = σx (n, i) '× sin (2A) / 2
τzx (n, i) = σy (n, i) '× sin (2B) / 2
B) Since the strain obtained in A) is a strain amount parallel to the X, Y, and Z axes of the normal coordinate system, this is set at an angle of ± 45 °, for example, as an angle for disposing the strain gauge. Strain amounts εa to εf that are expected to be detected by the gauge are determined.
[0061]

Here, Δεx, Δεy, Δεz are fluctuation amounts considering the substrate thickness (determined by stress analysis by the finite element method), and ν is a Poisson's ratio (material constant, ˜0.3).
[0062]
C) When an external force Fn is applied at a certain position Pi, the expected sensor output Sr (Fn, Pi) (r = 1 to 6) is expressed by a linear expression of the predicted distortion amount obtained in B). It becomes.
[0063]

Here, if Pi is fixed, the above equation has 36 unknowns ka1, ka2,. To determine these unknowns, all external forces Fn (n = 1-6) are taken into account
The following 36 conditional expressions are provided as conditional expressions with good separation rate.
[0064]
S1 (F1, Pi) = ka1 × εa (1, i) + kb1 × εb (1, i) + kc1 × εc (1, i)
+ Kd1 * [epsilon] d (1, i) + ke1 * [epsilon] e (1, i) + kf1 * [epsilon] f (1, i) = F1-(15-1)
ka1 × εa (2, i) + kb1 × εb (2, i) + kc1 × εc (2, i) + kd1 × εd (2, i)
+ Ke1 × εe (2, i) + kf1 × εf (2, i) <0.01 × F1-(15-2)
ka1 × εa (3, i) + kb1 × εb (3, i) + kc1 × εc (3, i) + kd1 × εd (3, i)
+ Ke1 × εe (3, i) + kf1 × εf (3, i) <0.01 × F1-(15-3)
ka1 × εa (4, i) + kb1 × εb (4, i) + kc1 × εc (4, i) + kd1 × εd (4, i)
+ Ke1 × εe (4, i) + kf1 × εf (4, i) <0.01 × F1-(15-4)
ka1 × εa (5, i) + kb1 × εb (5, i) + kc1 × εc (5, i) + kd1 × εd (5, i)
+ Ke1 × εe (5, i) + kf1 × εf (5, i) <0.01 × F1-(15-5)
ka1 × εa (6, i) + kb1 × εb (6, i) + kc1 × εc (6, i) + kd1 × εd (6, i)
+ Ke1 × εe (6, i) + kf1 × εf (6, i) <0.01 × F1-(15-6)
S2 (F2, Pi) = ka2 × εa (2, i) + kb2 × εb (2, i) + kc2 × εc (2, i)
+ Kd2 × εd (2, i) + ke2 × εe (2, i) + kf2 × εf (2, i) = F2− (15-7)
ka2 × εa (1, i) + kb2 × εb (1, i) + kc2 × εc (1, i) + kd2 × εd (1, i)
+ Ke2 × εe (1, i) + kf2 × εf (1, i) <0.01 × F2-(15-8)
ka2 × εa (3, i) + kb2 × εb (3, i) + kc2 × εc (3, i) + kd2 × εd (3, i)
+ Ke2 × εe (3, i) + kf2 × εf (3, i) <0.01 × F2-(15-9)
ka2 × εa (4, i) + kb2 × εb (4, i) + kc2 × εc (4, i) + kd2 × εd (4, i)
+ Ke2 × εe (4, i) + kf2 × εf (4, i) <0.01 × F2-(15-10)
ka2 × εa (5, i) + kb2 × εb (5, i) + kc2 × εc (5, i) + kd2 × εd (5, i)
+ Ke2 × εe (5, i) + kf2 × εf (5, i) <0.01 × F2-(15-11)
ka2 × εa (6, i) + kb2 × εb (6, i) + kc2 × εc (6, i) + kd2 × εd (6, i)
+ Ke2 × εe (6, i) + kf2 × εf (6, i) <0.01 × F2-(15-12)
S3 (F3, Pi) = ka3 × εa (3, i) + kb3 × εb (3, i) + kc3 × εc (3, i)
+ Kd3 × εd (3, i) + ke3 × εe (3, i) + kf3 × εf (3, i) = F3− (15-13)
ka3 × εa (1, i) + kb3 × εb (1, i) + kc3 × εc (1, i) + kd3 × εd (1, i)
+ Ke3 × εe (1, i) + kf3 × εf (1, i) <0.01 × F3-(15-14)
ka3 × εa (2, i) + kb3 × εb (2, i) + kc3 × εc (2, i) + kd3 × εd (2, i)
+ Ke3 × εe (2, i) + kf3 × εf (2, i) <0.01 × F3-(15-15)
ka3 × εa (4, i) + kb3 × εb (4, i) + kc3 × εc (4, i) + kd3 × εd (4, i)
+ Ke3 × εe (4, i) + kf3 × εf (4, i) <0.01 × F3-(15-16)
ka3 × εa (5, i) + kb3 × εb (5, i) + kc3 × εc (5, i) + kd3 × εd (5, i)
+ Ke3 × εe (5, i) + kf3 × εf (5, i) <0.01 × F3-(15-17)
ka3 × εa (6, i) + kb3 × εb (6, i) + kc3 × εc (6, i) + kd3 × εd (6, i)
+ Ke3 × εe (6, i) + kf3 × εf (6, i) <0.01 × F3-(15-18)
S4 (F4, Pi) = ka4 × εa (4, i) + kb4 × εb (4, i) + kc4 × εc (4, i)
+ Kd4 × εd (4, i) + ke4 × εe (4, i) + kf4 × εf (4, i) = F4— (15-19)
ka4 × εa (1, i) + kb4 × εb (1, i) + kc4 × εc (1, i) + kd4 × εd (1, i)
+ Ke4 × εe (1, i) + kf4 × εf (1, i) <0.01 × F4-(15-20)
ka4 × εa (2, i) + kb4 × εb (2, i) + kc4 × εc (2, i) + kd4 × εd (2, i)
+ Ke4 × εe (2, i) + kf4 × εf (2, i) <0.01 × F4-(15-21)
ka4 × εa (3, i) + kb4 × εb (3, i) + kc4 × εc (3, i) + kd4 × εd (3, i)
+ Ke4 × εe (3, i) + kf4 × εf (3, i) <0.01 × F4-(15-22)
ka4 × εa (5, i) + kb4 × εb (5, i) + kc4 × εc (5, i) + kd4 × εd (5, i)
+ Ke4 × εe (5, i) + kf4 × εf (5, i) <0.01 × F4-(15-23)
ka4 × εa (6, i) + kb4 × εb (6, i) + kc4 × εc (6, i) + kd4 × εd (6, i)
+ Ke4 × εe (6, i) + kf4 × εf (6, i) <0.01 × F4-(15-24)
S5 (F5, Pi) = ka5 × εa (5, i) + kb5 × εb (5, i) + kc5 × εc (5, i)
+ Kd5 × εd (5, i) + ke5 × εe (5, i) + kf5 × εf (5, i) = F5— (15-25)
ka5 × εa (1, i) + kb5 × εb (1, i) + kc5 × εc (1, i) + kd5 × εd (1, i)
+ Ke5 × εe (1, i) + kf5 × εf (1, i) <0.01 × F5-(15-26)
ka5 × εa (2, i) + kb5 × εb (2, i) + kc5 × εc (2, i) + kd5 × εd (2, i)
+ Ke5 × εe (2, i) + kf5 × εf (2, i) <0.01 × F5-(15-27)
ka5 × εa (3, i) + kb5 × εb (3, i) + kc5 × εc (3, i) + kd5 × εd (3, i)
+ Ke5 × εe (3, i) + kf5 × εf (3, i) <0.01 × F5-(15-28)
ka5 × εa (4, i) + kb5 × εb (4, i) + kc5 × εc (4, i) + kd5 × εd (4, i)
+ Ke5 × εe (4, i) + kf5 × εf (4, i) <0.01 × F5-(15-29)
ka5 × εa (6, i) + kb5 × εb (6, i) + kc5 × εc (6, i) + kd5 × εd (6, i)
+ Ke5 × εe (6, i) + kf5 × εf (6, i) <0.01 × F5-(15-30)
S6 (F6, Pi) = ka6 × εa (6, i) + kb6 × εb (6, i) + kc6 × εc (6, i)
+ Kd6 × εd (6, i) + ke6 × εe (6, i) + kf6 × εf (6, i) = F6— (15-31)
ka6 × εa (1, i) + kb6 × εb (1, i) + kc6 × εc (1, i) + kd6 × εd (1, i)
+ Ke6 × εe (1, i) + kf6 × εf (1, i) <0.01 × F6-(15-32)
ka6 × εa (2, i) + kb6 × εb (2, i) + kc6 × εc (2, i) + kd6 × εd (2, i)
+ Ke6 × εe (2, i) + kf6 × εf (2, i) <0.01 × F6-(15-33)
ka6 × εa (3, i) + kb6 × εb (3, i) + kc6 × εc (3, i) + kd6 × εd (3, i)
+ Ke6 × εe (3, i) + kf6 × εf (3, i) <0.01 × F6-(15-34)
ka6 × εa (4, i) + kb6 × εb (4, i) + kc6 × εc (4, i) + kd6 × εd (4, i)
+ Ke6 × εe (4, i) + kf6 × εf (4, i) <0.01 × F6-(15-35)
ka6 × εa (5, i) + kb6 × εb (5, i) + kc6 × εc (5, i) + kd6 × εd (5, i)
+ Ke6 × εe (5, i) + kf6 × εf (5, i) <0.01 × F6-(15-36)
The above is a conditional expression with a separation rate of 1% or less. If there are values of ka1, ka2,..., Kf6 that satisfy this condition, Pi becomes a sensor mounting position candidate.
[0065]
In order to solve the above equation, the simultaneous equations are usually solved by using the inequality sign in the above equation as an equal sign. Since there are 36 equations for 36 unknowns, there are usually solutions to simultaneous equations, but there is no solution if each of the 36 equations is not independent of the other 35 equations, in this case Does not become a sensor mounting candidate position.
[0066]
Even if the above solution exists, if Pi is a position where a sensor cannot be physically mounted, that position is not a candidate position for sensor mounting.
[0067]
When there are four strain sensing elements, there are four unknown simultaneous equations, so the equations (15-1) to (15-36) can be changed from (16-1) to (16- It is expressed by the formula of 16).
S1 (F1, Pi) = ka1 × εa (1, i) + kb1 × εb (1, i)
+ Kc1 × εc (1, i) + kd1 × εd (1, i) = F1− (16-1)
ka1 × εa (2, i) + kb1 × εb (2, i)
+ Kc1 × εc (2, i) + kd1 × εd (2, i) <0.01 × F1-(16-2)
ka1 × εa (3, i) + kb1 × εb (3, i)
+ Kc1 × εc (3, i) + kd1 × εd (3, i) <0.01 × F1-(16-3)
ka1 × εa (4, i) + kb1 × εb (4, i)
+ Kc1 × εc (4, i) + kd1 × εd (4, i) <0.01 × F1-(16-4)
S2 (F1, Pi) = ka2 × εa (2, i) + kb2 × εb (2, i)
+ Kc2 × εc (2, i) + kd2 × εd (2, i) = F2-(16-5)
ka2 × εa (1, i) + kb2 × εb (1, i)
+ Kc2 × εc (1, i) + kd2 × εd (1, i) <0.01 × F2-(16-6)
ka2 × εa (3, i) + kb2 × εb (3, i)
+ Kc2 × εc (3, i) + kd2 × εd (3, i) <0.01 × F2-(16-7)
ka2 × εa (4, i) + kb2 × εb (4, i)
+ Kc2 × εc (4, i) + kd2 × εd (4, i) <0.01 × F2-(16-8)
S3 (F1, Pi) = ka3 × εa (3, i) + kb3 × εb (3, i)
+ Kc3 × εc (3, i) + kd3 × εd (3, i) = F3-(16-9)
ka3 × εa (1, i) + kb3 × εb (1, i)
+ Kc3 × εc (1, i) + kd3 × εd (1, i) <0.01 × F3-(16-10)
ka3 × εa (2, i) + kb3 × εb (2, i)
+ Kc3 × εc (2, i) + kd3 × εd (2, i) <0.01 × F3-(16-11)
ka3 × εa (4, i) + kb3 × εb (4, i)
+ Kc3 × εc (4, i) + kd3 × εd (4, i) <0.01 × F3-(16-12)
S4 (F1, Pi) = ka4 × εa (4, i) + kb4 × εb (4, i)
+ Kc4 × εc (4, i) + kd4 × εd (4, i) = F4-(16-13)
ka4 × εa (1, i) + kb4 × εb (1, i)
+ Kc4 × εc (1, i) + kd4 × εd (1, i) <0.01 × F4-(16-14)
ka4 × εa (2, i) + kb4 × εb (2, i)
+ Kc4 × εc (2, i) + kd4 × εd (2, i) <0.01 × F4-(16-15)
ka4 × εa (3, i) + kb4 × εb (3, i)
+ Kc4 × εc (3, i) + kd4 × εd (3, i) <0.01 × F4-(16-16)
FIG. 4 is a block diagram showing an example of the three-dimensional external force measurement unit of the present invention. In addition, about the same part as the part already demonstrated from this, the same code | symbol is attached | subjected and duplication description is abbreviate | omitted.
[0068]
The three-dimensional external force measurement unit 5 includes a three-dimensional strain sensor block 1 in which sensor segments SG in which two strain sensing elements 2 are crossed are arranged on three base surfaces that are not parallel to each other, and an output of the sensor block 1. And a signal arithmetic processing circuit unit 3 for measuring a necessary external force.
[0069]
The signal arithmetic processing circuit unit 3 is composed of each of six strain sensing elements 2 (2-11, 2-12, 2-21, 2-22, 2-31, 2-32) and three resistors R. The individual bridge circuit 31, the strain amplification circuit 32 that amplifies the strain signal output from each strain sensing element 2, the strain / stress conversion unit 33 that calculates and converts the amplified strain signal into stress, and the strain / stress A stress angle converter 34 that converts the stress signal from the converter 33 using a stress function (function of position and angle) obtained for the installation position and installation angle of the three-dimensional strain sensor block 1, and the stress angle An external force calculation processing unit 35 that calculates and outputs an external force (including an external moment) to be measured from the output of the conversion unit 34 is provided.
[0070]
The two detection elements 2 arranged on the respective base surfaces 1a of the three-dimensional strain sensor block 1 are orthogonal to each other.
[0071]
The flow of arithmetic processing in the signal arithmetic processing circuit unit 3 is as follows.
[0072]
A) Each element output (resistance change) is converted into a voltage change through the bridge circuit 31. Note that the bridge circuit 31 is actually arranged with the corresponding strain sensing element 2 on the base surface 1a of the three-dimensional strain sensor block 1, so that the temperature condition of the strain sensing element 2 is compensated. ing.
[0073]
B) Since the output through the bridge circuit 31 is generally an output on the order of μV (microvolt), the distortion amplifier circuit 32 using an operational amplifier or the like has a size that can be easily processed by a subsequent processing circuit ( Distorted signals εa, εb, εc, εd, εe, and εf.
[0074]
C) The amplified strain signals εa, εb, εc, εd, εe, εf enter the strain / stress converter 33. Here, the strain signal is converted into stress. Here, a desired stress, for example, a strain signal is converted into a shear stress or a normal stress.
[0075]
D) The output of the strain / stress converter 33 (stress before angle conversion) is defined by the stress function of (7) to (12) obtained with respect to the installation position and angle of the sensor block 1. 34.
[0076]
E) The stress output from the stress angle conversion unit 34 is converted into an external force by the external force calculation processing unit 35.
[0077]
In this way, the three-dimensional external force measuring unit 5 uses the stress function of the position and angle with a good separation rate in the stress angle conversion unit 34 of the signal arithmetic processing circuit unit 3, and therefore with a simple calculation and high sensitivity, Necessary external force can be measured in real time.
[0078]
The signal calculation processing circuit unit 3 can be provided with a plurality of output terminals 36 corresponding to the external force to be measured, and the calculated external force can be output in parallel. In addition, a common output terminal 37 is provided, and the calculated external force can be a so-called serial output that cyclically outputs in a predetermined order.
[0079]
The distortion amplifier circuit 32 constituting the signal arithmetic processing circuit unit 3 includes operational amplifiers B1, B2, B3, B4, B5, B11, and B12, the strain / stress conversion unit 33 includes C1 and C2, and stress. An operational amplifier D is used for the angle conversion unit 34, and an operational amplifier E is used for the external force measurement calculation processing unit 35. High-speed calculation processing is possible with a simple hardware configuration, and the mounting board can be made into a custom IC.
[0080]
FIG. 5 shows an example of the three-dimensional strain sensor block of the present invention and its installation mode, where (a) is a front view and (b) is a side view.
[0081]
Since the three-dimensional strain sensor block 1 of the present invention can be embedded and installed at one position Ps of the structure (suspension) K if its installation position and posture are determined, the strength and functional performance of the structure is obtained. Is less likely to interfere with
[0082]
FIG. 6 is a diagram illustrating a three-dimensional strain sensor block of the present invention.
The strain sensing element 2 arranged on the base surface 1a of the three-dimensional strain sensor blocks 1A, 1B, 1C is called a so-called strain gauge, and the material thereof is NiCr having a low thermal expansion coefficient and good temperature characteristics, or Β-Ta with a high gauge factor and high strain sensitivity, or a crystal-controlled BaTiO with higher sensitivity than semiconductor materials or bulk materials with high strain sensitivity _Three It is desirable to be made of a ceramic piezoelectric material typified by a system material, or a combination thereof.
[0083]
The main body material of the strain sensor block 1 is a metal of the same material as that of the structure, another kind of metal having a similar thermal expansion coefficient, or a ceramic having a high elastic modulus with high stress transmission efficiency, depending on an assumed strain amount. Alternatively, it is desirable to be made of a polymer material typified by epoxy or acrylic, or a combination of the above, which provides high strain output.
[0084]
The three-dimensional strain sensor block 1 may be the cube illustrated in FIGS. 4 and 5, but when the external force to be obtained is 4 or less, as in the three-dimensional strain sensor block 1 </ b> A illustrated in FIG. 6A. The sensor segments SG in which two strain sensing elements 2 intersect each other may be arranged on base surfaces 1a parallel to each other on a flat plate. FIG. 6 (a) uses the stress function for the position and angle at which the sensor block is embedded to determine the arrangement of the sensor segments, and this is effective in performing ABS control and the like. 3 external forces (road friction force, lateral force, and vertical drag force) and rolling resistance moment (brake torque) can be measured. By adopting an equation of motion using these as parameters, wheels like the conventional method The control accuracy can be improved as compared with control using speed as a parameter.
[0085]
Further, like the three-dimensional strain sensor block 1B shown in FIG. 6B, two flat sensor bodies 1b each having a sensor segment SG arranged on a base surface 1a parallel to each other are used, and each base surface 1a. They may be combined so that they are not parallel to each other. In FIG. 6 (b), by arranging four strain sensing elements as sensor segments SG on the base surface 1a, four external forces can be measured as in the case of FIG. 6 (a). The remaining two external forces out of the six external forces can be measured by the sensor segment SG composed of the two strain detection elements arranged in combination, or a combination with other strain detection elements.
Further, as in the three-dimensional strain sensor block 1C shown in FIG. 6C, three flat sensor bodies 1b are arranged so as to form cubes that are not parallel to each other, and only on one side of each base surface 1a. The sensor segment SG may be arranged.
6 (a) to 6 (c) is a method for measuring a stress direction with a good separation rate of six external forces using the flat sensor body 1b.
[0086]
What is important is the arrangement mode of the sensor segments SG arranged on each base surface 1a. In the present invention, the arrangement mode of each sensor segment SG is determined using a stress function for the position where the sensor block is embedded. I am doing so. This means, for example, that for the sensor block 1A, a stress function is used to determine the mutual crossing angle of the sensor bodies 1b, and for the sensor block 1C, the sensor segments SG are arranged on the base surfaces 1a parallel to each other. This is because the stress function is used to decide to do.
[0087]
For example, when measuring shear strain, an arrangement having a good separation rate from the external torque of the stress function may be arranged, and when measuring a normal stress, an arrangement having a good separation rate from the external force of the stress function may be adopted.
[0088]
As a result, the separation rate between the external force to be obtained and the stress obtained from the strain signal of the strain sensing element is improved, and the strain corresponding to the external force to be obtained can be detected with higher sensitivity.
[0089]
The three-dimensional strain sensor block, the three-dimensional external force measurement unit, and the structure external force measurement method according to the present invention are not limited to the vehicle described here, and other complex structures that receive a plurality of external forces, for example, It can also be applied to robot arms and medical prostheses.
[0090]
【The invention's effect】
According to the three-dimensional strain sensor block of the first aspect, in the configuration of the sensor block itself, the stress function for the position where the sensor block is embedded is used to determine the arrangement of the strain detection elements. As a result, the separation rate between the external force to be obtained and the stress obtained from the strain signal of the strain sensing element is improved, and the strain corresponding to the external force to be obtained can be detected with higher sensitivity.
[0091]
According to the three-dimensional strain sensor block of the second aspect, in addition to the effect of the first aspect, the sensor segment is arranged on each of two base surfaces that are parallel to each other, and an external force to be obtained is 4 or less. In order to determine the arrangement of the sensor segments, the stress function for the position and angle at which the sensor block is embedded is used, so that three external forces (road surface frictional force, Lateral force and vertical drag) and rolling resistance moment (brake torque) can be measured. By adopting an equation of motion using these as parameters, it is compared with the control using wheel speed as a parameter as in the conventional method. The control accuracy can be improved.
According to the three-dimensional strain sensor block of the third aspect, in addition to the effect of the first aspect, the sensor segments are arranged on each of the plurality of base surfaces that are not parallel to each other. It is possible to determine the stress or its distribution.
According to the three-dimensional strain sensor block of the fourth aspect, in addition to the effect of the first aspect, a plurality of sensor bodies in which the sensor segments are arranged on each of two parallel base surfaces are arranged so as not to be parallel to each other. By combining them, the external force acting on the structure, that is, the force, is obtained from the in-plane stress in different planes and the stress due to out-of-plane deformation of the sensor segment, and the stress at two points obtained by the two sensor bodies. And the moment can be accurately obtained by a difference or other methods.
[0092]
According to the three-dimensional external force measurement unit of claim 5, the stress function is used for the calculation process of the strain signal output from the three-dimensional strain sensor block, that is, the calculation process in the stress angle conversion unit. Thus, the stress corresponding to the external force to be measured can be easily calculated in real time from the strain signal.
[0093]
According to the three-dimensional external force measurement unit of the sixth aspect, in addition to the effect of the fifth aspect, the calculated external force can be output in parallel.
[0094]
According to the three-dimensional external force measuring unit according to claim 7, in addition to the effect of claim 5, a common output terminal is provided, and the calculated external force is cyclically output in a predetermined order, so-called serial. Can be output.
[0095]
According to the three-dimensional external force measurement unit according to claim 8, since the operational amplifier is used in addition to the effects of claims 5 to 7, high-speed arithmetic processing is possible with a simple hardware configuration, and the mounting board is a custom IC. Can be
[0096]
Claim 10 According to the described external force measurement method for a structure, a stress function (position and angle function) obtained by angle conversion from the stress distribution is used to determine the installation position and installation angle of the three-dimensional strain sensor block on the structure. Therefore, the external force separation region becomes wider, or in other words, because the angle is introduced as a variable in the stress function for external force separation, the conditions for selecting a place with a good separation rate are relaxed. Overlapping areas of external force separation areas corresponding to multiple external forces can be acquired, and if a strain sensor block is provided here and the installation angle is set to correspond to the external force separation angle, all external forces to be measured can be measured with high sensitivity. it can.
[0097]
Claim 11 According to the external force measurement method of the structure described in Claim 10 In addition to the above effect, the installation angle of the three-dimensional strain sensor block is specifically defined as an angle at which the central axis of the sensor block is parallel to the line connecting the support fulcrum and the external force application point. In the example, the installation angle of the sensor block can be easily determined.
[0098]
Claim 9 According to the three-dimensional external force measurement unit described in the above, in combination with the above-described three-dimensional strain sensor block and the structure external force measurement method, the structure to be measured is a vehicle suspension, the measurement external force is maximized, the vertical drag, Road friction force, lateral force, overturning moment, rolling resistance moment (brake torque), and self-aligning moment (torque), and these external forces can be measured with high sensitivity in real time. The braking force of the vehicle can be satisfactorily performed using the external force applied, and for example, the performance of ABS (Antilock Braking System) can be remarkably improved. Further, when considering a system that realizes vehicle motion control, conventionally, a system must be constructed by combining a plurality of sensors such as a wheel speed sensor, an acceleration sensor, and a yaw rate sensor. The above-mentioned external force can be achieved simply by mounting the dimensional strain sensor block. Measurable Therefore, the cost can be greatly reduced.
[Brief description of the drawings]
FIG. 1 conceptually shows the principle of an external force measurement method for a structure according to the present invention, wherein (a) is an explanatory diagram of a method for determining a three-dimensional strain sensor block installation position, and (b) is a three-dimensional strain sensor. Illustration of how to determine the block installation angle
FIG. 2 is a flowchart showing a procedure for determining a sensor block installation position and angle in the structure external force measurement method according to the present invention;
FIG. 3 is a diagram illustrating a stress function for obtaining an external force separation region in the external force measurement method for a structure according to the present invention.
FIG. 4 is a block diagram showing an example of a three-dimensional external force measurement unit according to the present invention.
FIGS. 5A and 5B show an example of a three-dimensional strain sensor block according to the present invention and an installation mode thereof, wherein FIG. 5A is a front view and FIG. 5B is a side view.
FIG. 6 is a diagram illustrating a three-dimensional strain sensor block according to the present invention.
FIGS. 7A and 7B conceptually illustrate the principle of a conventional structure external force measurement method, where FIG. 7A is an explanatory diagram of a structure to be measured, and FIG. 7B is an explanatory diagram of a method for determining a sensor block installation position;
[Explanation of symbols]
1 3D strain sensor block
1a Base surface
2 Strain sensing element (strain gauge)
3 Signal processing circuit
31 Bridge circuit
32 Distortion amplifier circuit
33 Strain / stress converter
34 Stress angle converter
35 External force calculation processor
36 Output terminal
37 Common output terminals
5 3D external force measurement unit
A, B, C, D, E Operational amplifier
Fz vertical load
Fx Road friction force
Fy lateral force
My torsion torque
K structure (suspension)
KM main structure (vehicle)
O External force acting point (axle)
Ps installation position
SC center axis
SG sensor segment
X Support fulcrum
Z External force separation area
ZZ overlap area
φs Installation angle
Φs line segment

Claims (11)

A three-dimensional strain sensor block for measuring an external force embedded in a structure and acting on the structure ,
Comprising a plurality of sensor segments composed of strain sensing elements arranged on different base surfaces constituting the outer surface;
When an external force to be measured is applied to the structure, an analysis based on a stress function obtained by applying a three-dimensional rotational coordinate transformation to the distribution of stress acting on the position and angle in the structure The external force separation area where the external force is independent and separated from other external forces and the area where the external force separation angle overlaps are obtained, and the burying position is determined from the obtained result in consideration of the angle in the structure. The three-dimensional strain sensor block is embedded so that the sensor segment is positioned there . The three-dimensional strain sensor block according to claim 1,
A three-dimensional strain sensor block, wherein the sensor segments are arranged on each of two base surfaces that are parallel to each other. The three-dimensional strain sensor block according to claim 1,
A three-dimensional strain sensor block, wherein the sensor segments are arranged on each of a plurality of base surfaces that are not parallel to each other. The three-dimensional strain sensor block according to claim 1,
A three-dimensional strain sensor block, wherein a plurality of sensor bodies in which the sensor segments are arranged on each of two base surfaces parallel to each other are combined so as not to be parallel to each other. A three-dimensional strain sensor block according to any one of claims 1 to 4 ,
A plurality of bridge circuits each including a part of the strain sensing elements of the plurality of sensor segments;
A plurality of strain / stress converters for calculating a strain signal to be an electrical signal of each of the plurality of bridge circuits and converting it into stress;
A stress angle conversion unit that performs angle conversion based on an installation position and an installation angle of the three-dimensional strain sensor block with respect to the stress obtained by the plurality of strain / stress conversion units using the stress function ;
3D force measuring unit, characterized in that the output of said stress angle conversion unit, and a force arithmetic processing unit which calculates and outputs the external force to be measured. The three-dimensional external force measurement unit according to claim 5,
A three-dimensional external force measurement unit provided with a plurality of output terminals corresponding to each of the external forces calculated by the external force calculation processing unit and configured to output the calculated external forces in parallel. The three-dimensional external force measurement unit according to claim 5,
A three-dimensional external force measurement unit configured to provide a common output terminal for outputting all the external forces calculated by the external force calculation processing unit and to cyclically output the calculated external forces in a predetermined order. In the three-dimensional external force measurement unit according to any one of claims 5 to 7,
The strain / stress conversion unit, the stress angle conversion unit, and the external force measurement calculation processing unit are three-dimensional external force measurement units configured by combining operational amplifiers. In the three-dimensional external force measurement unit according to any one of claims 5 to 8,
The structure is a suspension that is a support member that supports and connects the wheels of the vehicle.
The maximum external force to be measured is a vertical drag acting on the ground contact surface between the wheel and the traveling road surface, a road surface friction force applied in the traveling direction of the vehicle, a lateral force acting perpendicular to the traveling direction of the vehicle, A three-dimensional external force measurement unit characterized by an overturning moment, a rolling resistance moment, and a self-aligning moment applied to the vehicle. An external force measurement method using the three-dimensional strain sensor block according to any one of claims 1 to 4,
The structure is a structure that is supported by the main structure and receives an external force concentrated on one point from the outside ,
A method for measuring an external force of a structure , wherein external forces in different directions acting on the structure are measured in real time from stresses separated and measured by a single three-dimensional strain sensor block provided in the structure. In the external force measuring method of the structure according to claim 10 ,
The installation angle of the three-dimensional strain sensor block is
The central axis of the three-dimensional strain sensor block is parallel to a line connecting a support fulcrum on which the structure is supported by the main structure and an external force acting point at which an external force acts on the structure. A method for measuring the external force of the structure.

Images