This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 107142390 filed in the Republic of China on Nov. 28, 2018, the entire contents of which are hereby incorporated by reference.
This disclosure relates to a calculation device of an output torque and a method thereof.
With the development of industrial automation, the types of products that need to be processed at the factory become more diverse, so services that the factory needs to provide are increasingly complex. In order to cope with these complex tasks, in addition to requiring high-precision positioning control of the robot arm in the factory, it is necessary to improve the safety mechanism of the factory.
In order to achieve an accurate positioning of the robot arm, the drive system of the robot arm usually has an encoder, and the information of the encoder is used to correct the positioning error caused by the deformation of the robot arm. On the other hand, the drive system is further equipped with a torque sensor. The data of the torque sensor prevents the robot arm from damage or collision due to an excessive torque of the drive system so as to reduce accidental risks. However, the addition of the torque sensor increases the size of the drive system, increases production costs, and complicates the wire arrangement of the driving system.
Therefore, there is indeed a need for an improved output torque measurement system and a method thereof, which can at least improve the above disadvantages.
According to one or more embodiment of this disclosure, an output torque calculation device is provided, and the output torque calculation device comprises a motor, a first sensor, a transmission device, an elastic device, a second sensor and a processor. The motor has a rotor. The first sensor is connected to the rotor and measures a first angle of the rotor. The transmission device includes a first input portion and a first output portion, and the first input portion is connected to the rotor. The elastic device comprises a second input portion, a second output portion and a rotation axis, the second input portion is connected to the first output portion, and the second output portion is configured to connect to a load. There is a first distance between the second input portion and the rotation axis, there is a second distance between the second output portion and the rotation axis, and the first distance is different from the second distance. The second sensor is connected to the second output portion and measures a second angle of the second output portion. The processor is electrically connected to the first sensor and the second sensor and calculates an output torque carried by a final output end of the output torque calculation device according to the first angle and the second angle.
According to one or more embodiment of this disclosure, an output torque calculation method is provided, the output torque calculation method is performed by a calculation device. The calculation device comprises a first sensor, a second sensor, a rotor, a reducer, a processor and an elastic device. A first input portion of the reducer and a first output portion of the reducer are connected to the rotor and a second input portion of the elastic device respectively. A second output portion of the elastic device is configured to connect to a load, the output torque calculation method comprising: detecting a first angle of the rotor by the first sensor; detecting a second angle of the second output portion of the elastic device by the second sensor; and calculating an output torque carried by a final output end of the calculation device according to the first angle and the second angle by the processor.
The disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present disclosure and wherein:
In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawings.
Please refer to
As shown in
The second input portion 131 of the elastic device 13 is an annular structure with a constant width, the second output portion 132 is a circular structure, and the second input portion 131 surrounds the second output portion 132. The connecting elements 133 are columnar structures and are spaced apart from each other and each of the connecting elements links the second input portion 131 and the second output portion 133, and intervals of the connecting elements 133 are the same. In other embodiments, the shape of the connecting element 133 is not limited and may have other shapes, such as a curved shape or a spiral shape, and the intervals of the connecting elements 133 may be unequal.
The second input portion 131 is provided with a plurality of first fixing elements 135. The first fixing elements 135 may be, for example, screw holes, and the first fixing elements 135 surround the rotation axis 134 and are respectively equidistant from the rotation axis 134. The second output portion 132 is provided with a plurality of second fixing elements 136, and the second fixing elements 136 may be, for example, screw holes, and the second fixing elements 136 surround the rotation axis 134 and are respectively equidistant from the rotation axis 134. There is a first distance D1 between the first fixing element 135 of the second input portion 131 and the rotation axis 134, and there is a second distance D2 between the second fixing element 136 of the second output portion 133 and the rotation axis 134, and the first distance D1 is different from the second distance D2. The first fixing elements 135 of the elastic device 13 respectively lock with the transmission device 12 by a plurality of locking members, and the second fixing elements 136 of the elastic device 13 respectively lock with a load 2 by a plurality of locking members, wherein the locking members may be, for example, screws. Therefore, an angular displacement of the gear reducer can be amplified by the elastic device 13.
As shown in
With respect to a formula 1 for the output torque carried by the final output end of the output torque calculation device 1,
(formula 1), wherein T represents the output torque carried by the final output end, θ1 represents the first angle of the rotor 101, θ2 represents the second angle of the elastic device 13, θbacklash represents the backlash of the reducer, Dir represents the current rotation direction of the rotor 101, Gr represents the reduction ratio of the reducer, G1 represents the first shear modulus of the reducer, G2 represents the second shear modulus of the elastic device 13.
Even if the output torque calculation device 1 is not equipped with an additional torque sensor, the output torque carried by the final output end of the output torque calculation device 1 can be accurately estimated by the processor 15 according to the formula 1, θ1, θ2, θbacklash, Dir, Gr, G1 and G2, wherein the output torque carried by the final output end is an output torque applied to the load 2 and generated from the second output portion 132 of the elastic device 13.
Δθ is a mechanical deformation quantity of the reducer, the processor 15 can estimate τ based on the formula 2, G1, and Δθ. As shown in
In view of the above description, a percentage of an error between the output torque estimated by the output torque calculation method of the disclosure and an actual output torque measured by a torque sensor may fall within a tolerable range, so the output torque calculation device does not require to be equipped with an additional torque sensor to measure an actual output torque. On the other hand, an angle of an output portion of the reducer is amplified by the elastic device, so that users can accurately detect angle data by the output torque calculation device without using high-precision angle sensors, and then the output torque calculation device may estimate the output torque carried by the final output end according to the angle data.
Number | Date | Country | Kind |
---|---|---|---|
107142390 A | Nov 2018 | TW | national |
Number | Name | Date | Kind |
---|---|---|---|
7677114 | Deshmukh et al. | Mar 2010 | B2 |
9061420 | Yoo et al. | Jun 2015 | B2 |
9205556 | Magnusson et al. | Dec 2015 | B1 |
9293962 | Park et al. | Mar 2016 | B2 |
9321172 | Johnson | Apr 2016 | B2 |
9534931 | Ueda et al. | Jan 2017 | B2 |
9772240 | Hulse | Sep 2017 | B2 |
20140224057 | Tanaka et al. | Aug 2014 | A1 |
20170136629 | Nagata | May 2017 | A1 |
20170212007 | Li | Jul 2017 | A1 |
Number | Date | Country |
---|---|---|
101677866 | Feb 2012 | CN |
102713217 | Jul 2015 | CN |
104948674 | Sep 2015 | CN |
105518223 | Apr 2016 | CN |
104245242 | Jul 2016 | CN |
106041924 | Oct 2016 | CN |
106644456 | May 2017 | CN |
108733001 | Nov 2018 | CN |
101515455 | May 2015 | KR |
I514100 | Dec 2015 | TW |
2016151360 | Sep 2016 | WO |
2016171799 | Oct 2016 | WO |
Entry |
---|
Nenad M. Kircanski, An Experimental Study of Nonlinear Stiffness, Hysteresis, and Friction Effects in Robot Joints with Harmonic Drives and Torque sensors, Apr. 1997, The International Journal of Robotics Research, vol. 16, No. 2, pp. 214-239 (Year: 1997). |
Tomohiro Kawakami et al., High-fidelity joint drive system by torque feedback control using precision linear encoder, IEEE International Conference on Robotics and Automation, 2010. |
Xing Liu et al., A torque measuring method based on encoder for permanent magnet synchronous machine, 17th International Conference on Electrical Machines and Systems (ICEMS), 2014. |
Byung-jin Jung et al., Joint Torque sensor Embedded in Harmonic Drive Using Order Tracking Method for Robotic Application, Journal of Latex Class Files, 2015, vol. 14, No. 8. |
Hiroshi Kaminaga et al., Measurement Crosstalk Elimination of Torque Encoder Using Selectively Compliant Suspension, IEEE International Conference on Robotics and Automation, 2011. |
Navvab Kashiri et al., On the Sensor Design of Torque Controlled Actuators: A Comparison Study of Strain Gauge and Encoder-Based Principles, IEEE Robotics and Automation Letters, 2017, vol. 2 , No. 2. |
Radoslav Cipin et al., Measurement and evaluation of DC motor starting torque, IEEE, 2017. |
Taiwan Patent Office, “Notice of Allowance”, dated Apr. 30, 2019, Taiwan. |