R01AN5644EJ0100 Rev.1.00
Page 42 of 62
Jan 22, 2021
Reference Guide for a 2-Axis Robot Arm with 2-Phase Stepping
Motors Incorporating Resolvers
RX24T, RX72M,
RAA3064002GFP/RAA3064003GFP
•
Central coordinates of an arc
Calculate the central coordinates of a circle passing through three points and then calculate the radius from
the obtained central coordinates.
�
(
𝑥𝑥
1
− 𝑥𝑥𝑦𝑦
)
2
+ (
𝑦𝑦
1
− 𝑦𝑦𝑦𝑦
)
2
=
𝑟𝑟
2
𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝑡𝑡𝐸𝐸𝐸𝐸𝐸𝐸
1
(
𝑥𝑥
2
− 𝑥𝑥𝑦𝑦
)
2
+ (
𝑦𝑦
2
− 𝑦𝑦𝑦𝑦
)
2
=
𝑟𝑟
2
𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝑡𝑡𝐸𝐸𝐸𝐸𝐸𝐸
2
(
𝑥𝑥
3
− 𝑥𝑥𝑦𝑦
)
2
+ (
𝑦𝑦
3
− 𝑦𝑦𝑦𝑦
)
2
=
𝑟𝑟
2
𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝑡𝑡𝐸𝐸𝐸𝐸𝐸𝐸
3
Calculate under the condition that equation 1 is equal to equation 2.
(
𝑥𝑥
1
− 𝑥𝑥𝑦𝑦
)
2
+ (
𝑦𝑦
1
− 𝑦𝑦𝑦𝑦
)
2
= (
𝑥𝑥
2
− 𝑥𝑥𝑦𝑦
)
2
+ (
𝑦𝑦
2
− 𝑦𝑦𝑦𝑦
)
2
(
𝑥𝑥
1
+
𝑦𝑦
1
−
2
𝑥𝑥𝑦𝑦
)(
𝑥𝑥
1
− 𝑥𝑥
2
) + (
𝑦𝑦
1
+
𝑦𝑦
2
−
2
𝑥𝑥𝑦𝑦
)(
𝑦𝑦
1
− 𝑦𝑦
2
) = 0
Similarly, calculate under the condition that equation 2 is equal to equation 3.
�
(
𝑥𝑥
1
− 𝑥𝑥
2
)
𝑥𝑥𝑦𝑦
+ (
𝑦𝑦
1
− 𝑦𝑦
2
)
𝑦𝑦𝑦𝑦
=
1
2
{(
𝑥𝑥
1
2
− 𝑥𝑥
2
2
) + (
𝑦𝑦
1
2
− 𝑦𝑦
2
2
)}
(
𝑥𝑥
2
− 𝑥𝑥
3
)
𝑥𝑥𝑦𝑦
+ (
𝑦𝑦
2
− 𝑦𝑦
3
)
𝑦𝑦𝑦𝑦
=
1
2
{(
𝑥𝑥
2
2
− 𝑥𝑥
3
2
) + (
𝑦𝑦
2
2
− 𝑦𝑦
3
2
)}
On the assumption of
𝑋𝑋
𝑖𝑖
=
𝑥𝑥
𝑖𝑖
2
+
𝑦𝑦
𝑖𝑖
2
, perform substitution to form a determinant.
�
𝑥𝑥
1
− 𝑥𝑥
2
𝑦𝑦
1
− 𝑦𝑦
2
𝑥𝑥
2
− 𝑥𝑥
3
𝑦𝑦
2
− 𝑦𝑦
3
� �
𝑥𝑥𝑦𝑦
𝑦𝑦𝑦𝑦
�
=
1
2
�
𝑋𝑋
1
− 𝑋𝑋
2
𝑋𝑋
2
− 𝑋𝑋
3
�
On the assumption of
�𝐸𝐸 𝑏𝑏
𝑦𝑦 𝑑𝑑�
=
�
𝑥𝑥
1
− 𝑥𝑥
2
𝑦𝑦
1
− 𝑦𝑦
2
𝑥𝑥
2
− 𝑥𝑥
3
𝑦𝑦
2
− 𝑦𝑦
3
�
, calculate the inverse matrix.
�
𝑥𝑥𝑦𝑦
𝑦𝑦𝑦𝑦�
=
1
2 ×
1
𝐸𝐸𝑑𝑑 − 𝑏𝑏𝑦𝑦
×
� 𝑑𝑑
−𝑏𝑏
−𝑦𝑦
𝐸𝐸 �
×
�
𝑋𝑋
1
− 𝑋𝑋
2
𝑋𝑋
2
− 𝑋𝑋
3
�
P
1
(x1,y1)
P
2
(x2,y2)
P
c
(xc,yc)
●
●
✖
R
P
3
(x3,y3)
●