Controlling method and control system for robotic arm

Abstract

A controlling method of a robotic arm to plug a workpiece into a slot is provided by an aspect of the present disclosure. The method includes defining a search point of the workpiece and a reference point of the robotic arm. The method includes executing a contact process for contacting the workpiece with the plane surrounding the slot. The method includes executing a search process for contacting the workpiece with the long side and the inner side in the slot. The method includes executing a push process for aligning the workpiece to the slot and contacting the search point and the reference point with the bottom of the slot.

Description

Technical Field

[0001] This disclosure relates to a control method for controlling a robotic arm, and more particularly to a control method for controlling the robotic arm to place a workpiece into a slot, and its control system. Prior Technology

[0002] The development of automated production has increased the demand for robotic arms, and their performance, such as control technology, has become a focus for various companies. Previously, when controlling robotic arms to perform insertion tasks, the magnitude of torque and force along each axis was monitored. For example, when inserting a workpiece into a slot, the contact point between the workpiece and the slot could not be determined. This resulted in the robotic arm receiving incorrect feedback information on the force along each axis from the sensors, leading to incorrect insertion responses and reducing the success rate of insertion tasks. Therefore, there is a need for more precise technology to control robotic arms to insert workpieces into slots. Summary of the Invention

[0003] According to the method for controlling a robotic arm to place a workpiece into a slot provided in this disclosure, by defining the search endpoint of the workpiece and the reference endpoint of the robotic arm, and by performing contact, search, and push-in operations on the workpiece relative to the slot respectively, the smoothness of the robotic arm placing the workpiece into the slot can be increased, thereby increasing the success rate of insertion tasks.

[0004] According to the first aspect of this disclosure, a control method is proposed. The control method consists of the following steps: detecting multiple detection signals; and omitting at least one of the multiple detection signals to perform the task of the robotic arm.

[0005] According to a second aspect of this disclosure, a control method is proposed. The control method includes detecting multiple detection signals of a workpiece along multiple axes. The control method also includes omitting at least one of the multiple detection signals to perform a insertion task of a robotic arm.

[0006] According to a third aspect of this disclosure, a control system is proposed. The control system includes a force sensor that detects multiple detection signals along multiple axes. The control system also includes control circuitry coupled to the force sensor, omitting coupling to at least one of the multiple detection signals, to perform insertion tasks on a robotic arm.

[0007] In order to provide a good understanding of the above and other aspects of this disclosure, specific embodiments are described below in conjunction with the accompanying drawings: Simple Explanation of the Diagram

[0008] Figure 1 illustrates a schematic diagram of the control circuit and robotic arm according to an embodiment of the present disclosure. Figure 2 illustrates a schematic diagram of the relative positions of the workpiece and the slot according to an embodiment of the present disclosure. Figure 3 illustrates a schematic diagram of the workpiece and slot in the contact process according to an embodiment of this disclosure. Figure 4 illustrates a schematic diagram of the workpiece and slot in the search process according to an embodiment of this disclosure. Figures 5A and 5B illustrate schematic diagrams of the workpiece and slot in the insertion process according to the embodiments of this disclosure. Figure 6 illustrates a flowchart of controlling a robotic arm to insert a workpiece into a slot according to an embodiment of this disclosure. Implementation

[0009] Figure 1 illustrates a schematic diagram of a control circuit 100 and a robotic arm 200 according to an embodiment of the present disclosure. As shown in Figure 1, the control circuit 100 disclosed herein controls the robotic arm 200 to grip a workpiece 300 and perform the operation of placing the workpiece 300 into a slot 400. The control circuit 100 is coupled to a force sensor 210 of the robotic arm 200 to perform corresponding operations in different programs based on the force sensor 210 detecting a force (or action force) in at least one direction. Furthermore, the control circuit 100 may be part of a control system, which may further include a force sensor 210 and control the movement of the robotic arm 200, wherein the force sensor 210 is electrically connected to the control circuit 100.

[0010] The robotic arm 200 may be, for example, a six-axis robotic arm, moving the workpiece 300 along the X, Y, and Z axes, and / or rotating it along the X, Y, and Z axes. Therefore, when the robotic arm 200 grips the workpiece 300 and moves it in an ambient space, the force sensor 210 detects the torque and moment along multiple (e.g., six) axes on the workpiece 300. The torque that moves the workpiece 300 along the X, Y, and Z axes can be collectively referred to as the moving force, while the torque that drives the workpiece 300 to rotate in the ambient space can be referred to as the rotating force. In this embodiment, the workpiece 300 may be, for example, a memory chip, a USB flash drive, or an insertable object, and the slot 400 may be correspondingly a memory slot, a USB flash drive socket, or a structure for accommodating items. The force sensor 210 generates multiple detection signals, including an X detection signal, a Y detection signal, a Z detection signal, an MX detection signal, a MY detection signal, and an MZ detection signal, which correspond to the movement state along the X-axis, the movement state along the Y-axis, the movement state along the Z-axis, the rotation state along the X-axis, the rotation state along the Y-axis, and the rotation state along the Z-axis, respectively. In other words, the force sensor 210 can detect the movement force fx and its counter-movement force fx' along the X-axis, the movement force fy and its counter-movement force fy' along the Y-axis, the movement force fz and its counter-movement force fz' along the Z-axis, and the rotation force rfx and its counter-rotation force rfx' along the X-axis, the rotation force rfy and its counter-rotation force rfy' along the Y-axis, and the rotation force rfz and its counter-rotation force rfz' along the Z-axis.

[0011] Figure 2 illustrates a schematic diagram of the relative positions of the workpiece 300 and the slot 400 according to an embodiment of the present disclosure, wherein diagram (a) in Figure 2 is a top view in the Z direction, diagram (b) is a front view in the Y direction, and diagram (c) is a side view in the X direction. As shown in Figure 2, before the robotic arm 200 grips the workpiece 300 and moves it, the workpiece 300 is located above and behind the plane 404 surrounding the slot 400. The control technology provided in this disclosure includes defining a position on the workpiece 300 as a search endpoint 301 (e.g., the black circle on the workpiece 300) to first contact the plane 404 surrounding the slot 400; and defining a reference position (or reference datum) of the robotic arm 200 relative to the workpiece 300 as a reference endpoint 302 (e.g., the white circle on the workpiece 300), which is related to the tool central point (TCP) of the robotic arm 200. Furthermore, the search endpoint 301 can be the first position of the workpiece 300, while the reference endpoint 302 is the second position of the workpiece 300. As seen in Figures 2(b) and (c), in the Z direction, the distance between the reference endpoint 302 and the plane 404 is slightly greater than the distance between the search endpoint 301 and the plane 404, while in the Y direction, as shown in Figure 2(a), the distance between the reference endpoint 302 and the slot 400 is slightly greater than the distance between the search endpoint 301 and the slot 400. Moreover, the degree of tilt of the workpiece 300 is merely an indication of one state during the operation of the embodiment and is not intended to limit the practical application of this disclosure. The slot 400 is generally rectangular, having a long side 401, a short side 402, and a bottom 403; however, other structural shapes can also be chosen to match the shapes of the workpiece 300 and the slot 400. The relevant operating procedures for the robotic arm 200 to control the placement of the workpiece 300 into the slot 400 based on the reference endpoint 302 and the search endpoint 301 will be described next with reference to Figures 3 through 5A.

[0012] Figure 3 illustrates a schematic diagram of the contact process of the workpiece 300 and slot 400 according to the embodiment disclosed herein, wherein diagram (a) in Figure 3 is a front view in the Y direction and diagram (b) is a side view in the X direction. In the contact process, the robotic arm 200 grips the workpiece 300 at the reference endpoint 302 and moves it in the Z direction (which can be considered as the first direction) until the search endpoint 301 contacts the plane 404. Thus, the force sensor 210 of the robotic arm 200 detects a torque (i.e., the counter-movement force fz') in the Z direction that is greater than or equal to a preset value, for example, 1 N. Therefore, the control circuit 100 can determine that the search endpoint 301 has contacted the plane 404 based on the Z detection signal from the force sensor 210, without needing to receive the other five detection signals, thereby improving the success rate of the task, such as improving the success rate of the insertion task. As shown in Figure 3, only the distance perpendicular to plane 404 in the Z direction is sensed. This means that during the contact process, the control of the robotic arm 200 only responds to the values ​​detected by the force sensor 210 in the Z direction. For example, after the force sensor 210 detects that the torque in the Z direction reaches a preset value, the robotic arm 200 ends the contact process and enters the search process. In other words, during the contact process, the torque and all torque detection results (such as MX, MY, and MZ) of the force sensor 210 in the X and Y axes do not affect the control circuit 100's control of the robotic arm 200. Therefore, during the contact process, the control circuit 100 is coupled to the Z detection signal, but not to the X, Y, MX, MY, and MZ detection signals.

[0013] Figure 4 illustrates a schematic diagram of the workpiece 300 and slot 400 in a search process according to the embodiments disclosed herein, wherein diagram (a) in Figure 4 is a top view in the Z direction and diagram (b) is a side view in the X direction. In the search process, the robotic arm 200 moves the workpiece 300 in the Z direction (which can be referred to as the first direction) and the Y direction (which can be referred to as the second direction) based on the reference endpoint 302. This can be regarded as torque (i.e., the movement force fz and fy) output at the TCP point, which is equivalent to applying the movement force fz and fy to the reference endpoint 302. The rotation of the workpiece 300 in the Z direction can be regarded as torque (i.e., the rotation force rfz) output at the TCP point, which is equivalent to applying the rotation force rfz to the reference endpoint 302. This continues until the search endpoint 301 contacts the inside of the slot 400 (as shown in the rightmost diagram of Figure 4, b). This causes the force sensor 210 to detect that the anti-movement force fy' in the Y direction is greater than or equal to a preset value, such as 1N (or a different value is set according to other embodiments). This indicates that the search endpoint 301 has contacted the inside of the slot 400. Furthermore, when the workpiece 30 is rotated in the Z direction to be parallel to the long side 401 of the slot 400 (as shown in the rightmost diagram of Figure 4(a)), since the search endpoint 301 has already contacted the inside of the slot 400, the workpiece 300 can no longer continue to rotate in the Z direction. Thus, the force sensor 210 of the robotic arm 200 detects that the anti-movement force fy' in the Y direction is greater than or equal to a preset value, for example, 1N, and can determine that the workpiece 300 is parallel to the long side 401 of the slot 400. Referring again to Figure 4, the Y direction is perpendicular to the long side 401 of the slot 400 and parallel to the plane 404. That is to say, in the search process, the control of the robotic arm 200 is based only on the values ​​detected by the force sensor 210 for movement in the Y direction and rotation in the Z direction. For example, after the anti-movement force fy' in the Y direction reaches the preset value, the search process ends and the push-in process begins. Furthermore, during the search process, the detected values ​​of the torques of the X and Z axes and the torques of MX and MY may always exist, but the control circuit 100 of the robotic arm 200 does not control them accordingly, thereby filtering (or omitting) the detection results (or detection signals) that do not require a response, in order to complete the strategy of smoothing the plug-in.

[0014] Additionally, during the search process, when the workpiece 300 touches the inner long side 401 of the slot 400, it will rotate back and forth in the Z direction (i.e., alternating between clockwise and counterclockwise rotation). Therefore, when the workpiece 300 rotates clockwise and the search endpoint 301 touches the inner long side 401, if the counter-movement force fy' in the Y direction is not greater than or equal to a preset value, the workpiece 300 will further rotate counterclockwise until the force sensor 210 detects that the counter-movement force fy' in the Y direction is greater than or equal to the preset value, thus confirming that the workpiece 300 is parallel to the long side 401. In this way, the search process ends and the next push-in process begins.

[0015] Figures 5A and 5B illustrate schematic diagrams of the workpiece 300 and slot 400 in the insertion process according to the embodiments of the present disclosure, wherein Figure 5A is a side view in the X direction, and Figure 5B shows (a) a front view in the Y direction and (b) a side view in the X direction. Referring to Figure 5A, the robotic arm 200 controls the workpiece 300 to move in the Z direction (i.e., the first direction) and rotate in the X direction (which can be regarded as the third direction) according to the reference endpoint 302. This can be regarded as applying a force of Z-direction movement and X-direction rotation to the reference endpoint 302 until the workpiece 300 (including both the search endpoint 301 and the reference endpoint 302) is perpendicular to the plane 404 and aligned with the slot 400 (as shown in the right side view of Figure 5A). Therefore, the counter-movement force fz' in the Z direction between the search endpoint 301 and the inside of the slot 400 decreases, causing the force sensor 210 of the robotic arm 200 to detect that the counter-movement force fz' in the Z direction is less than a preset value, such as 1N. This indicates that the workpiece 300 has been aligned with the slot 400. The X direction is parallel to the long side 401 of the slot 400.

[0016] Next, referring to Figure 5B, after controlling the workpiece 300 (including both the search endpoint 301 and the reference endpoint 302) to face the bottom 403 (or hollow position) of the slot 400, the robotic arm 200 clamps the workpiece 300 and moves it in the Z direction (which can be referred to as the first direction) and rotates the workpiece 300 in the Y direction until the search endpoint 301 and the reference endpoint 302 contact the bottom 403 of the slot 400 (as shown in the rightmost diagram of Figures (a) and (b) of Figure 5B), so that the force sensor 210 of the robotic arm 200 detects that the anti-movement force fz' in the Z direction is greater than or equal to a preset value. The same or different preset values ​​can be set for different parts of the slot 400 (or the parts that can hold items) or when executing different programs. For example, the preset values ​​can include a first preset value, a second preset value, and so on. This setting method is not limited to the embodiment. Furthermore, since the workpiece 300 has completely contacted the bottom 403 of the slot 400 and can no longer rotate in the Y direction, the force sensor 210 detects that the counter-movement force fz' in the Z direction is greater than or equal to a preset value. This indicates that the workpiece 300 has completely contacted the bottom 403 of the slot 400, completing the insertion process. In other words, during the insertion process, the control of the robotic arm 200 mainly responds to the detection values ​​of the force sensor 210 in the X-direction rotation, Z-direction movement, and Y-direction rotation. For example, when the workpiece 300 is rotated in the X-direction so that the counter-movement force fz' in the Z direction is less than a preset value (aligning with the slot), the workpiece 300 continues to move in the Z direction and rotate along the Y direction until the force sensor 210 detects that the counter-movement force fy' in the Y direction and the counter-movement force fz' in the Z direction reach the preset values. Then, it is determined that the workpiece 300 has completely contacted the bottom 403 of the slot 400, and the insertion process ends. During the process of pushing workpiece 300 into slot 400, the control of robotic arm 200 can be adjusted according to the six axial reaction forces detected by force sensor 210 to fine-tune the final insertion smoothness. Furthermore, in different (e.g., three) programs, a continuous Z-direction moving force is applied to workpiece 300, and then different axial detection results are added according to different programs. Therefore, the total number of detection signals coupled to control circuit 100 varies in different programs to improve task success rate and smoothness. In other words, during task execution, control circuit 100 (or robotic arm 200) omits at least one of the six axial detection signals.

[0017] In some implementations, after the push-in process ends, because the robotic arm 200 controls the workpiece 300 to rest against one side of the slot 400, a reaction force will affect the detection result of the force sensor 210. Therefore, it is necessary to control the robotic arm 200 to a gravity state or release the control of the robotic arm 200 (to release stress), so that the robotic arm 200 is carried (or bounced back) by the workpiece 300 to a position without reaction force before releasing the workpiece 300, so as to avoid the force sensor 210 detecting the reaction force, which would cause the control system (or control circuit 100) to make an error in determining the position of the reference endpoint 302.

[0018] Figure 6 illustrates a flowchart of controlling a robotic arm to insert a workpiece into a slot according to an embodiment of the present disclosure. In step S610, for example, using the control circuit 100 in Figure 1, the position where the workpiece 300 first touches the plane 404 surrounding the slot 400 is defined as the search endpoint 301, and the robotic arm 200 calculates the position for gripping the workpiece 300 based on the reference endpoint 302. Wherein, if the slot 400 is a memory slot on a computer motherboard, then the plane 404 should be the plane of the outer edge of the memory slot itself; or, if a plane contains a recessed slot 400 (or opening, etc., not limited to the embodiment) that can accommodate an object, then the plane 404 should be the plane of the surrounding environment of the slot 400, that is, a plane not contained within the slot 400 itself (such as a USB flash drive port).

[0019] In step S620, the control circuit 100 executes a contact program, controlling the robotic arm 200 to move the workpiece 300 in the Z direction until the force sensor 210 of the robotic arm 200 detects a counter-movement force fz' in the Z direction that is greater than or equal to a preset value. Then, it determines that the search endpoint 301 is in contact with the plane 404, where the Z direction is perpendicular to the plane 404. Furthermore, before executing the contact program, a vision system (such as a camera and its associated vision control circuitry) can be used to confirm the approximate location of the slot 400 before starting the program. Alternatively, the contact program can include content confirming the approximate location of the slot 400; this is an optional design.

[0020] In step S630, the control circuit 100 executes a search program, controlling the robotic arm 200 to move the workpiece 300 in the Z and Y directions, and rotate the workpiece 300 in the Z direction until the force sensor 210 of the robotic arm 200 senses an anti-movement force fy' in the Y direction that is greater than or equal to a preset value, thereby determining that the search endpoint 301 contacts the inner side of the slot 400 and the workpiece 300 is parallel to the long side 401 of the slot 400. The Y direction is parallel to the plane 404 and perpendicular to the long side 401 of the slot 400.

[0021] In step S640, the control circuit 100 executes the push-in procedure, controls the robotic arm 200 to rotate the workpiece 300 in the X direction until the workpiece 300 is perpendicular to the plane 404 and aligned or fully facing the slot 400, and controls the robotic arm 200 to move the workpiece 300 in the Z direction and rotate the workpiece 300 along the Y direction until the force sensor 210 of the robotic arm 200 detects that the anti-movement force fz' in the Z direction is greater than or equal to a preset value, so as to determine that the search endpoint 301 and the reference endpoint 302 contact the bottom 403 of the slot 400, wherein the X direction is parallel to the long side 401 of the slot 400.

[0022] In certain settings, when the search program determines that the workpiece 300 is parallel to the long side 401 of the slot 400, the force sensor 210 can sense that the Z-direction rotation causes the Y-direction counter-movement force fz' to be greater than or equal to a preset value.

[0023] In some specific settings, during the push-in (or placement) procedure, if the workpiece 300 is determined to be perpendicular to the plane 404 and aligned with the slot 400, the force sensor 210 can sense that the counter-movement force fz' in the Z direction is less than the preset value.

[0024] In certain settings, during the push-in process, if the search endpoint 301 contacts the bottom 403 of the slot 400, the force sensor 210 can detect that the counter-movement force fy' of the Y-direction rotation is greater than or equal to a preset value.

[0025] In some specific configurations, the control of the robotic arm 200 is released, allowing the workpiece 300 to bring the robotic arm 200 back to a position free from reaction force, thereby relieving the stress on the robotic arm; then, the robotic arm 200 is controlled to release the workpiece 300.

[0026] The technical terms used in this specification are based on common terminology in the field. Where this specification provides explanations or definitions for certain terms, the interpretation of those terms shall be based on the explanations or definitions provided in this specification. Each embodiment disclosed herein has one or more technical features. Where feasible, those skilled in the art may selectively implement some or all of the technical features in any embodiment, or selectively combine some or all of the technical features in these embodiments. For example, the process of the three procedures—contact procedure, search procedure, and push procedure—described in this disclosure can be modified to be included in two procedures, or even integrated into a single procedure; this disclosure is not limited to being split into three procedures. Alternatively, the execution and control of the three procedures can be carried out by three different independent circuits operating sequentially, or by two circuits operating in conjunction; this is not limited to a single control circuit.

[0027] The above disclosure provides different ways of implementing or exemplifying this disclosure. Specific examples of components and configurations described above (e.g., mentioned values ​​or names) are used to simplify / illustrate some embodiments of this disclosure. Of course, these components and configurations are merely examples and are not intended to be limiting. Furthermore, reference numerals and / or letters may be repeated in various instances of some embodiments of this disclosure. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0028] Although the present disclosure has been illustrated above with reference to embodiments, it is not intended to limit the scope of the disclosure. Those skilled in the art to which this disclosure pertains may make various modifications and refinements without departing from the spirit and scope of the disclosure. Therefore, the scope of protection of this disclosure shall be determined by the appended claims.

[0029] 100: Control Circuit 200: Robotic Arm 210: Force sensor 300: Workpiece 301: Search Endpoint 302: Reference endpoint 400: Slot 401: Long side 402: Short side 403: Bottom 404: Plane S610~S640: Steps fz, fy, fx: Moving forces rfz, rfy, rfx: Rotational forces fz', fy', fx': Reaction forces rfz',rfy',rfx': Reverse rotational force X: Detection signal Y: Detection signal Z: Detection signal MX: Detection Signal MY: Detection signal MZ: Detection signal

Claims

1. A control method comprising the following steps: detecting a plurality of detection signals; omitting at least one of the detection signals to perform a task of a robotic arm; after completing the task, releasing the control of the robotic arm to allow a workpiece on the robotic arm to spring back to a position free from reaction force, thereby relieving the stress on the robotic arm; and controlling the robotic arm to release the workpiece.

2. A control method, comprising: Detect multiple detection signals of a workpiece in multiple axes; omit at least one of these detection signals to perform a plug-in task of a robotic arm; After completing the plug-in task, release the control of the robotic arm, allowing the workpiece to spring back to the robotic arm and return to a position without reaction force, thereby relieving the stress on the robotic arm; And control the robotic arm to release the workpiece.

3. The control method as described in claim 2, for controlling the robotic arm to insert a workpiece into a slot, wherein the slot is recessed in a plane and has a long side, a short side, and a bottom, the method comprising: A control circuit defines a first position of the workpiece as a search endpoint and a second position of the workpiece as a reference endpoint; The control circuit executes a contact procedure, which includes controlling the robotic arm to move the workpiece toward a first direction until a force sensor of the robotic arm detects a first counter-movement force in the first direction that is greater than or equal to a first preset value, and then determining that the search endpoint is in contact with the plane, wherein the first direction is perpendicular to the plane; The control circuit executes a search procedure, which includes controlling the robotic arm to move the workpiece toward the first direction and a second direction, and rotating the workpiece in the first direction until a force sensor of the robotic arm detects a second counter-movement force in the second direction that is greater than or equal to a second preset value, and then determining that the search endpoint is in contact with the inner side of the slot and the workpiece is parallel to the long side of the slot, wherein the second direction is parallel to the plane and perpendicular to the long side of the slot; The control circuit executes an insertion procedure, which includes: controlling the robotic arm to rotate the workpiece in a third direction until the workpiece is perpendicular to the plane and aligned with the slot, wherein the third direction is parallel to the long side of the slot; and controlling the robotic arm to move the workpiece toward the first direction and rotate the workpiece in the second direction until the force sensor of the robotic arm detects that the first counter-movement force in the first direction is greater than or equal to the first preset value, and determining that the search endpoint and the reference endpoint contact the bottom of the slot to complete the insertion task.

4. The control method as described in claim 3, wherein in the search procedure, determining that the workpiece is parallel to the long side of the slot is determined by the force sensor detecting that the second anti-movement force is greater than or equal to the second preset value when rotating in the first direction.

5. The control method as described in claim 4, wherein in the pushing procedure, determining that the workpiece is perpendicular to the plane and aligned with the slot is achieved by the force sensor detecting that the first anti-movement force is less than the first preset value.

6. The control method as described in claim 4, wherein in the push-in procedure, determining that the search endpoint contacts the bottom of the slot is achieved by the force sensor detecting that the first counter-movement force is greater than or equal to the first preset value when controlling the workpiece to rotate in the second direction.

7. A control system comprising: a force sensor for detecting a plurality of detection signals along a plurality of axes; and a control circuit coupled to the force sensor, omitting at least one detection signal coupled to the detection signals, for performing a insertion task of a robotic arm, wherein the control circuit controls the robotic arm to insert a workpiece into a slot to complete the insertion task, and after the robotic arm completes the insertion task, releases control of the robotic arm to cause the workpiece to spring back to a position without reaction force, thereby relieving stress on the robotic arm, and controls the robotic arm to release the workpiece.

8. The control system as described in claim 7, wherein the control circuit is coupled to the force sensor of the robotic arm and is used to control the robotic arm to insert the workpiece into the slot, wherein the slot is recessed in a plane and has a long side, a short side and a bottom; the control circuit defines a first position of the workpiece as a search endpoint and defines a second position of the workpiece as a reference endpoint; the control circuit controls the robotic arm to move the workpiece toward a first direction until the force sensor of the robotic arm detects a first counter-movement force in the first direction that is greater than or equal to a first preset value, and determines that the search endpoint contacts the plane, wherein the first direction is perpendicular to the plane; The control circuit controls the robotic arm to move the workpiece toward the first direction and a second direction, and rotate the workpiece in the first direction until the force sensor of the robotic arm detects a second counter-movement force in the second direction that is greater than or equal to a second preset value, and determines that the search endpoint is in contact with the inner side of the slot and the workpiece is parallel to the long side of the slot, wherein the second direction is parallel to the plane and perpendicular to the long side of the slot; and the control circuit controls the robotic arm to rotate the workpiece along a third direction until the workpiece is perpendicular to the plane and aligned with the slot, wherein the third direction is parallel to the long side of the slot; and the control circuit controls the robotic arm to move the workpiece toward the first direction and rotate the workpiece in the second direction until the force sensor of the robotic arm receives a first counter-movement force in the first direction that is greater than or equal to the first preset value, and determines that the search endpoint and the reference endpoint are in contact with the bottom of the slot.

9. The control system as described in claim 8, wherein the control circuit determines that the workpiece is parallel to the long side of the slot by means of the force sensor detecting that when rotating in the first direction, the second counter-movement force in the second direction is greater than or equal to the second preset value.

10. The control system as claimed in claim 9, wherein the control circuit determines that the workpiece is perpendicular to the plane and aligned with the slot by means of the force sensor detecting that the first anti-movement force is less than the first preset value.

11. The control system as described in claim 9, wherein the control circuit determines that the search endpoint contacts the bottom of the slot by means of the force sensor detecting that the workpiece rotates in the second direction, resulting in the first counter-movement force in the first direction being greater than or equal to the first preset value.

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