Test head manipulator configured to address uncontrolled test head rotation

Abstract

An example test head manipulator includes a tower having a base and a track, and an arm capable of supporting a test head, wherein the track is perpendicular relative to the base. The arm is connected to the track to move the test head perpendicularly relative to the tower, and the arm is configured to control rotation of the test head. Each of the arms includes a rotatable cam and at least one plunger in contact with the cam and configured to contact the test head. Rotation of the cam is controllable to move the at least one plunger to counteract uncontrolled rotation of the test head.

Description

Technical Field

[0001] This specification generally relates to a test head manipulator configured to resolve uncontrolled test head rotation. Background Technology

[0002] Automated Test Equipment (ATE) includes a test head that houses test electronics to perform tests on a Device Under Test (DUT). In some ATEs, multiple DUTs are connected to a Device Interface Board (DIB). The test head mates with the DIB to establish electrical connections within the DUT, and various tests are performed through these connections. A manipulator is a device that moves the test head within the test facility. Summary of the Invention

[0003] An example test head manipulator includes a tower having a base and a rail, and an arm capable of supporting a test head, wherein the rail is perpendicular to the base. The arm is connected to the rail to move the test head perpendicularly relative to the tower, and the arm is configured to control rotation of the test head. Each arm includes a rotatable cam and at least one plunger that contacts the cam and is configured to contact the test head. Rotation of the cam is controllable to move the at least one plunger to counteract uncontrolled rotation of the test head. The example test head manipulator may include one or more of the following features (individually or in combination).

[0004] The at least one plunger may include two plungers. These two plungers may be oriented in opposite directions relative to the test head, such that each of the two plungers is configured to contact a different portion of the test head. Rotation of the cam may cause longitudinal movement of the two plungers, which is transmitted to the test head to counteract uncontrolled rotation. The cross-section of the cam may have a radius that varies continuously along at least a portion of each cross-section.

[0005] Two plungers may include a first plunger on a first side of the cam. The first plunger may include a first roller that contacts the cam. Two plungers may include a second plunger on a second side of the cam. The second plunger may include a second roller that contacts the cam. The first and second plungers may be separated by approximately 180°, such that the first plunger is oriented toward the top of the arm of the test head manipulator, and the second plunger is oriented toward the bottom of the arm. A cam may be located between the first and second plungers. The cam may be controllable to rotate relative to the first and second plungers, such that different portions of the cam contact the first and second plungers at different rotation angles.

[0006] The cam may include a first angular structure and a second angular structure rotatable about the same axis. The first angular structure may have a first radius varying along a portion of the first angular structure, and the second angular structure may have a second radius varying along at least a portion of the second angular structure. The first radius may increase in the first angular direction, and the second radius may increase in the second angular direction. The first angular direction may be opposite to the second angular direction. At the maximum radius of the first angular structure, the first angular structure may have a straight-edge discontinuity connecting the maximum radius to the minimum radius of the first angular structure. At the maximum radius of the second angular structure, the second angular structure may have a straight-edge discontinuity connecting the maximum radius to the minimum radius of the second angular structure. The first angular structure and the second angular structure may each be constrained to a rotation of less than 360°. The first angular structure and the second angular structure may each be constrained to a rotation between 0° and 145°.

[0007] The at least one plunger may include a ball configured to contact part of a test head. The ball may be rotatable, at least in the tumbling and θ directions relative to the arm of the test head manipulator. The ball may be supported by a plurality of balls, each of which is rotatable relative to the ball, and the ball may be rotatable relative to each of the plurality of balls.

[0008] The at least one plunger may include a housing containing a ball, a shaft to which the housing is connected, and at least one spring, the at least one spring being at least partially compressible to change the longitudinal dimension of the at least one plunger. The at least one plunger may include a roller in contact with a cam. The roller may be configured to transmit displacement generated by the rotation of the cam to the plunger.

[0009] The test head manipulator may include a handle, at least a portion of which is external to an arm of the test head manipulator. The handle may be mechanically connected to a cam. The handle may be controllable to manually rotate the cam. The cam may be controllable to move at least one plunger to counteract ±1.5° rotation of the test head or less. There may be two arms and two plungers, each arm having one plunger. The test head manipulator may include one or more motors for driving the arms to move along a track.

[0010] An example test head manipulator for transporting a test head includes a tower having a base and a rail, and an arm capable of supporting the test head, wherein the rail is perpendicular to the base. The arm is connected to the rail to move the test head perpendicularly relative to the tower. The arm is configured to control the rotation of the test head. Each arm includes means for counteracting uncontrolled rotation of the test head. The example test head manipulator may include one or more of the following features (individually or in combination).

[0011] A device for counteracting uncontrolled rotation may include two plungers oriented in opposite directions and a rotatable cam, wherein each of the plungers is configured to contact a different portion of the test head. Each of the plungers may be configured to contact the cam. Rotation of the cam may cause longitudinal movement of the plungers, which is transmitted to the test head to counteract the uncontrolled rotation. The test head manipulator may also include a handle, at least a portion of which is outside the arm of the test head manipulator. The handle may be mechanically connected to the cam. The handle may be controllable to manually rotate the cam.

[0012] Any two or more of the features described in this specification (including the content section) may be combined to form specific embodiments not specifically described in this specification.

[0013] At least a portion of the systems and techniques described herein can be configured or controlled by executing instructions stored on one or more non-transitory machine-readable storage media on one or more processing devices. Examples of non-transitory machine-readable storage media include read-only memory, optical disc drives, memory disk drives, and random access memory. At least a portion of the systems and techniques described herein can be configured or controlled using a computing system comprising one or more processing devices and a memory storing instructions that can be executed by the one or more processing devices to perform various control operations. The systems and techniques described herein, as well as their components and variations, can be configured, for example, by design, construction, arrangement, placement, programming, operation, activation, deactivation, and / or control.

[0014] Detailed descriptions of one or more specific embodiments are set forth in the accompanying drawings and the following detailed description. Other features and advantages will become apparent from the details, the drawings, and the claims. Attached Figure Description

[0015] Figure 1 This is an illustration showing a partial transparent perspective view of an example test head manipulator and a test head.

[0016] Figure 2A This is an illustration showing a sectioned front view of a portion of an example arm included in the test head manipulator.

[0017] Figure 2B It is shown Figure 2A An illustration of a cross-sectional side view of a portion of the arm.

[0018] Figure 3A This is a perspective photograph showing a portion of the arm of the test head manipulator.

[0019] Figure 3B , Figure 3C and Figure 3D It shows Figure 2AIllustrations of the front view of the handle on the arm at various rotational positions.

[0020] Figure 4 This is a perspective view illustration of a ball assembly included in a plunger, the plunger being... Figure 2A Part of the arm.

[0021] Figure 5A and Figure 5B This is an illustration showing a perspective view of a component included in an example cam assembly. Figure 2A Part of the arm.

[0022] Figure 5C It is shown that it includes Figure 5A and Figure 5B An exploded view of the components in an example cam assembly.

[0023] Figure 6A This is a perspective view of an example plunger, which is... Figure 2A Part of the arm.

[0024] Figure 6B It is shown Figure 6A An illustration of a cross-sectional side view of an example plunger.

[0025] Figure 6C It is shown Figure 6A An example of an exploded view of a plunger.

[0026] Figure 7A It is shown Figure 2A An illustration of a sectioned front view of a portion of an example arm.

[0027] Figure 7B Includes illustrations showing the plunger and cam at various rotation angles, including a cross-sectional front view.

[0028] Figure 8 This is a perspective view of an example manipulator and an illustration of the controlled movements that can be achieved therefrom.

[0029] Similar reference numerals in different figures indicate similar elements. Detailed Implementation

[0030] This document describes an example implementation of a test head manipulator for transporting test heads. The test head is configured to hold a printed circuit board (PCB) and transport or manipulate the PCB relative to a test system. For example, the manipulator may hold, transport, and manipulate a device interface board (DIB). In this respect, the DIB includes mechanical and electrical interfaces to one or more devices under test (DUTs) being tested or to be tested by a test system such as an automated test equipment (ATE). The example manipulator includes a tower having a base and a rail, and an arm capable of supporting the test head, wherein the rail is perpendicular to the base. The arm is connected to the rail to move the test head perpendicularly relative to the tower. The arm is also configured to control the movement of the test head, such as rotation. Each arm includes a rotatable cam and at least one plunger that contacts the cam and is configured to contact the test head. Rotation of the cam is controllable to move the at least one plunger to counteract uncontrolled rotation of the test head.

[0031] As described above, movements or manipulations that can be performed by the manipulator include rotating the test head. For example, refer to Figure 8 The test head manipulator 5 is configured to move the test head 6 up and down, in and out, and left and right. The manipulator 5 is also configured to perform tumbling, theta, torsional, and oscillating rotations on the test head 6. These movements can be controlled, for example, in response to commands or manual movements, to position the test head in a desired location and orientation. For example, the test head can rotate 90°, 180°, 270°, or 360°.

[0032] However, in some cases, uncontrolled angular rotation of the test head may occur. For example, the weight distribution of the DIB or other structures on the test head may be uneven; for instance, the DIB may have additional weight on its leading edge 7 relative to its trailing edge 8. This additional weight may cause uncontrolled rotation of the test head. For example, in... Figure 8 In the illustrated orientation, such uneven weight distribution can produce small and uncontrolled tumbling rotational angular displacements of the test head. In the example where the test head rotates 90°, the uneven weight distribution can produce small and uncontrolled θ rotational angular displacements of the test head. To address these uncontrolled rotations, cams and plungers are configured and controllable to adjust the rotation of the test head. In one embodiment, the cams and plungers are configured to achieve controlled rotation of approximately ±1.5° to counteract or offset uncontrolled rotation. However, the manipulators described herein are not limited to any specific value of angular rotation correction achieved by the cams and plungers. The operation of the cams and plungers can be manually controlled; however, in some specific implementations, their operation can be computer-controlled.

[0033] Figure 1An example specific implementation of the test head manipulator 10 is shown. The manipulator 10 may, but need not, have the same characteristics as... Figure 8 The manipulator 10 has the same structure and capabilities as the manipulator 5. The manipulator 10 includes a tower 15, tracks 13a and 13b, and arms 14a and 14b. The tower 15 includes a base 11 and a track 12. In this embodiment, the base 11 is connected to the track 12 and configured to move along the track 12.

[0034] As noted, the tower section 15 includes two vertical rails 13a, 13b, one on each side of the manipulator 10. Figure 1 As shown, tracks 13a and 13b are arranged along the vertical length of the tower section 15. In some embodiments, tracks 13a and 13b are arranged along the entire vertical length of the tower section, and in other embodiments, tracks 13a and 13b are arranged only along a portion of the vertical length of the tower (e.g., less than the entire vertical height of the tower section). Arms 14a and 14b are mounted on tracks 13a and 13b via support structures 18. In this configuration, for example, support structure 18 is connected to tracks 13a and 13b, and arms 14 are connected to support structure. Support structure 18 is configured to move vertically along tracks 13a and 13b, thus also causing arms 14a and 14b to move vertically along the tower section 15. Support structure 18 is also configured to achieve... Figure 8 The movement is shown in the diagram. In this respect, one or more motors (not shown) are configured and arranged to drive the support structure 18 and thus the arm 14 along tracks 13a and 13b. In some embodiments, arms 14a, 14b are configured and controllable to rotate between 0° and 180° in the direction of arrow 17. In some embodiments, arms 14a, 14b are configured and controllable to rotate between 0° and 360° in the direction of arrow 17. One or more motors (not shown) are configured and arranged to control these rotations and the movement of the arm 14 along tracks 13a and 13b. Figure 8 Other rotations described.

[0035] Arm 14 is configured and controlled to hold the test head 20. As described above, the test head 20 is part of the ATE and may include test electronics for testing the DUT, such as pin electronics, test instruments, etc. In this respect, as described above, in some embodiments, the DUT is connected to a DIB, which provides electrical and mechanical connections between the DUT and the test head. Figure 8 As shown, DIB 9 can be held by the test head. In some implementations, a motor-driven vertical motion brings the test head 20 into contact with the DIB.

[0036] For example, in some cases, the uneven weight distribution of the DIB, or uneven weight distribution on the DIB, can cause the test head to produce small, uncontrolled rotation relative to the arms 14a, 14b and about axis 21. This uncontrolled rotation is undesirable and adversely affects the movement of the DIB within the testing system and its subsequent placement. This uncontrolled rotation is referred to as a “rotational error.” In the embodiments described herein, components within the arms 14a, 14b of the manipulator 10 are configured and arranged to at least partially correct for this rotational error. In some embodiments, the components are located in the front section 22 of each arm 14a, 14b. In some embodiments, the components may be located in the middle or rear of the arm.

[0037] Figure 2A It shows from Figure 1 The front view of the front section 22 of arm 14a cut off in the direction of arrow 4. Figure 2B It shows from Figure 1 The side view of a portion of the front section 22 of arm 14a, taken in the direction of arrow 3. Arm 14b may have the same... Figure 2A and Figure 2B Similar or identical constructions are shown. Therefore, only the construction of arm 14a is described herein. Arm 14a includes a cam 23. In this embodiment, cam 23 is part of a cam assembly including a rotatable object configured to transmit its rotational motion to plungers 24 and 25. This causes at least a portion of one or both plungers to move linearly in the direction of arrow 2. In some specific embodiments, each arm 14a, 14b includes Figure 2A and Figure 2B The diagram shows a cam and two plungers in the configuration. In some specific embodiments, each arm may include a cam and a single plunger (not shown in the diagram).

[0038] In this embodiment, the cam 23 contacts the plungers 24 and 25 in a configuration where each plunger 24, 25 is located on a different side of the cam 23. For example, the plunger 24 is arranged at a 180° angle relative to the plunger 25. Thus, the plungers 24 and 25 face opposite directions; therefore, each plunger contacts a different portion of the test head 20, for example, Figure 1 The top 100 and bottom 101 of the groove or recess 103 in the test head 20 shown. For example, as Figure 2A and 2B As shown, plunger 24 is oriented towards the top of arm 14a, and plunger 25 is oriented towards the bottom of arm 14a. Here, "top" and "bottom" refer to the orientation at the top of arm 14a. Figure 1 The configuration shown is part of arm 14a and is not intended for limitation. The oppositely arranged plunger is used to correct rotational errors at different orientations of the test head, such as when the test head is inverted.

[0039] As shown in the figure, in this embodiment, cam 23 is located between and in direct physical contact with plungers 24 and 25. In this respect, plunger 24 includes a roller 26 that contacts cam 23, and plunger 25 includes a roller 27 that contacts cam 23. Plunger 24 also includes a roller 71 that contacts portion 100 of test head 20, and plunger 25 includes a roller 72 that contacts portion 101 of test head 20. Each roller 26, 27 may include rollers with… Figure 4 The spherical assembly shown is constructed as described. Figure 4 As shown, the example roller 26 includes a ball 71, which is supported, for example, by direct contact with a plurality of balls 69 (six in this embodiment) within the housing 68. Each of the plurality of balls 69 is rotatable relative to the ball 71, and the ball 71 is rotatable relative to each of the plurality of balls 68. Similarly, the ball 71 is in direct contact with the test head 20, but this contact is not fixed. That is, the ball 71 can rotate as the test head moves, thereby allowing the plunger to correct the angular position of the test head 14a as described herein. For example, the plunger can apply a force to the test head via the ball 71. This force can cause angular movement of the test head, during which the ball 71 rotates to allow continuous angular movement of the test head.

[0040] Return to reference Figure 2A and Figure 2B Cam 23 is also mechanically connected to handle 30, which is also in Figure 3A , Figure 3B , Figure 3C and Figure 3D As shown in the diagram. Through this mechanical connection, the handle 30 can be manually rotated to control the rotation of the cam 23, thereby controlling the tension in the plunger and the rotation of the test head 20. Therefore, as... Figures 3B to 3D As shown, by rotating the handle 30 to various angles, the cam 23 also rotates relative to the plunger, causing different parts of the cam 23 to contact the plunger at different rotation angles, resulting in different longitudinal movements of the plungers 24 and 25. When the plungers 24 and 25 contact the test head 20, this longitudinal movement is transmitted to the test head 20, causing angular movement of the test head 20. Figures 3A to 3D In the specific implementation shown, the handle 30 is outside the arm 14a.

[0041] Figure 5A An exemplary construction of the cam assembly is shown. Figure 5B and Figure 5C The cam 23, connected to the handle 30, is shown in both the assembled and disassembled positions. As shown, the cam 23 includes an angular structure 28 with a radius 31 and an angular structure 29 with a radius 32, wherein the radius 31 varies along a portion of the angular structure 28 to reach a maximum radius 31', and the radius 32 varies along a portion of the angular structure 29 to reach a maximum radius 32'. Figures 5A to 5CAs shown, radius 31 increases in angular direction 33, while radius 32 increases in angular direction 34. In this embodiment, angular direction 33 is opposite to angular direction 34. Therefore, the cross-section of cam 23 has a radius that changes continuously along a portion of each cross-section.

[0042] Angular structure 28 includes a straight-edge discontinuity 38 connecting the maximum radius 31' to the minimum radius 31. The straight-edge discontinuity 38 of angular structure 28 is located at the maximum radius 31'. Similarly, angular structure 29 includes a straight-edge discontinuity 39 connecting the maximum radius 32' to the minimum radius 32'. The straight-edge discontinuity 39 of angular structure 29 is located at the maximum radius 32'. Angular structures 28 and 29 are rotatable about the same axis 36. In some embodiments, angular structures 28 and 29 are each rotatable between 0° and 360°. In some embodiments, angular structures 28 and 29 are each constrained to rotate between 0° and 145°. In some embodiments, rotation is constrained so as not to move through each straight-edge discontinuity; that is, so that the corresponding plunger does not fall off the discontinuity.

[0043] Cam 23 is connected to handle 30 via rod 35 and plate 40. Rod 35 includes a cylindrical structure 37 having a ring 43 connected to its end 42. Ring 43 is fixedly attached to rod 35 at end 42. In some embodiments, ring 43 is configured to move along axis 36 on the outer surface of cylinder 37. Rod 35 passes through a central tubular hole 41 via cam 23 such that end 44 of rod 35 passes through central tubular hole 41, hole 46 of plate 40, and into through hole 45 of handle 30. Central tubular hole 41 of cam 23 is along longitudinal axis 36 and may extend from corner structure 28 through corner structure 29. In this embodiment, plate 40 is located between cam 23 and handle 30 to connect cam 23 and handle 30 to an arm of manipulator, such as arm 14a. Plate 40 includes hole 48 to attach handle 30 to arm 14a using pin 53. As described above, in order to secure the handle 30 to the arm and the cam 23, the rod 35 passes through the through hole 41 of the cam 23, the hole 46 of the plate 40, and enters the through hole 45 of the handle 30. The pin 49 passes through the hole 50 of the handle 30 and the hole 51 of the rod 35 to secure the rod 35 to the handle 30.

[0044] Figures 6A to 6C An example embodiment of plungers 24, 25 is shown. Each plunger 24, 25 may have the same structure and function. Therefore, only one plunger 24 is described herein. Plunger 24 includes a housing 70 for receiving... Figure 4 The described ball component. Also refer to... Figure 1The ball 71 of the ball assembly is configured to rotate in multiple degrees of freedom, including but not limited to the directions of arrows 17 and 19. The plunger 24 includes a shaft 72. The shaft 72 includes a top end 77 and a bottom end 78. The top end 77 includes a shoulder 76 connected to the housing 70 via a rod 79. The rod 79 has a top end 81 and a bottom end 82. The top end 81 includes a step 83, which includes a hole 85. When the plunger 24 is assembled, the step 83 is positioned within the housing 70. An O-ring 80 and a pin 84 pass through holes 90 and 85 in the housing 70 to secure the housing 70 to the rod 79 and the plunger 24. The housing 70' is connected to the bottom end 78 of the shaft 72 via a structure 86. The structure 86 includes a rod and a ring 87 fixedly attached to the structure. The rod includes a top portion 88 and a bottom portion 89. The top portion 88 has a radius greater than that of the bottom portion 89. The ring 87 is located at the top of the rod and between the top portion 88 and the bottom portion 89. The bottom portion 89 can be secured to the housing 70' by an O-ring 80' and a pin 84' inserted into through holes 85' and 90'. When the plunger 24 is assembled, the ring 87 is located at the end 78 of the shaft 72 near the cam 23, and the top portion 88 is located within the spring 74 along the longitudinal direction of the spring 74.

[0045] like Figures 6A to 6C As shown, shaft 72 houses a plurality of springs 74—two springs in this embodiment. Springs 74 are at least partially compressible to change the longitudinal dimension of plunger 24. Springs 74 are positioned along the longitudinal axis of shaft 72. Plate 75 is located between the two springs 74. Figures 6A to 6C In some embodiments, the two springs 74 are identical in structure and length. In some specific embodiments, the springs 74 are not identical. In some specific embodiments, the plunger 24 includes only one spring 74 or more than two springs.

[0046] As described above, the tension on the handle 30 is transmitted to the cam 23. The cam 23 transmits the displacement generated by its rotation to the plunger 24 via its roller 26. When the plunger 24 contacts the test head 20 via the ball 71, the displacement transmitted by the plunger 24 via the spring 74 moves the test head. The floating connection between the ball 71 and the test head allows the test head to rotate to counteract the aforementioned uncontrolled / undesirable rotation.

[0047] Figure 7A It includes similar to Figure 2A The front view of the test head manipulator arm of the component. Figure 7B It shows Figure 7A A side view of the example arm shows the different linear positions of plungers 24 and 25 under various rotation angles of cam components 23a and 23b, and under different levels of torque applied to the handle. As described above, the tension / force on the handle 30 rotates the cam 23. Figure 7BAs shown, the loads on plungers 24 and 25 vary at different rotation angles of cam 23. Therefore, when cam 23 has rotated to a specific angle, the load on plunger 24 is different from the load on plunger 25.

[0048] Although this specification describes exemplary implementations in relation to “testing” and “testing system”, the apparatus described herein can be used in any suitable system and is not limited to testing systems, or to the exemplary testing systems described herein.

[0049] The tests performed as described herein can be implemented and / or controlled using hardware or a combination of hardware and software, including at least some control over the test head manipulator. For example, a test system similar to the test system described herein may include various controllers and / or processing devices located at various points. A central computer can coordinate the operation of the various controllers or processing devices. The central computer, controllers, and processing devices can execute various software routines to achieve control and coordination of the tests and calibrations.

[0050] The test, including control of the manipulator, can be at least partially controlled by using one or more computer program products, such as one or more computer programs tangibly embodied in one or more information carriers (e.g., one or more non-transitory machine-readable media), to be executed by one or more data processing devices or to control the operation of one or more data processing devices, such as programmable processors, computers, multiple computers and / or programmable logic components.

[0051] The components of the different specific embodiments described herein can be combined to form other embodiments not specifically illustrated above. Multiple components can be excluded from the structures described herein without adversely affecting their operation. Furthermore, individual components can be combined into one or more single components to perform the functions described herein.

Claims

1. A test head manipulator, the test head manipulator comprising: A tower section having a base and a track, the track being perpendicular to the base; and An arm, capable of supporting a test head, is connected to the rail for vertical movement of the test head relative to the tower. The arm is configured to control rotation of the test head. Each arm includes a rotatable cam and at least one plunger that contacts the cam and is configured to contact the test head. Rotation of the cam is controllable to move the at least one plunger to counteract uncontrolled rotation of the test head. The at least one plunger mentioned therein comprises two plungers; The two plungers are oriented in opposite directions relative to the test head, such that each of the two plungers is configured to contact a different portion of the test head; and The rotation of the cam causes longitudinal movement of the two plungers, which is transmitted to the test head to counteract the uncontrolled rotation.

2. The test head manipulator according to claim 1, wherein the cross-section of the cam has a radius that varies continuously along at least a portion of each cross-section.

3. The test head manipulator according to claim 1, wherein the two plungers comprise: A first plunger located on a first side of the cam, the first plunger including a first roller that contacts the cam; and A second plunger located on a second side of the cam, the second plunger including a second roller that contacts the cam; The cam is located between the first plunger and the second plunger, and the cam is controllable to rotate relative to the first plunger and the second plunger, such that different portions of the cam contact the first plunger and the second plunger at different rotation angles.

4. The test head manipulator of claim 3, wherein the cam includes a first angular structure and a second angular structure rotatable about the same axis, the first angular structure having a first radius varying along a portion of the first angular structure, and the second angular structure having a second radius varying along at least a portion of the second angular structure.

5. The test head manipulator of claim 4, wherein the first radius increases in a first angular direction and the second radius increases in a second angular direction, the first angular direction being opposite to the second angular direction.

6. The test head manipulator of claim 5, wherein at the maximum radius of the first corner structure, the first corner structure includes a straight-edge discontinuity connecting the maximum radius of the first corner structure to the minimum radius; and Wherein, at the maximum radius of the second corner structure, the second corner structure includes a straight-edge discontinuity connecting the maximum radius of the second corner structure to the minimum radius.

7. The test head manipulator according to claim 6, wherein the first corner structure and the second corner structure are each constrained to rotate less than 360°.

8. The test head manipulator according to claim 6, wherein the first angle structure and the second angle structure are each constrained to rotate between 0° and 145°.

9. The test head manipulator of claim 3, wherein the first plunger and the second plunger are separated by approximately 180° such that the first plunger is oriented toward the top of the arm of the test head manipulator and the second plunger is oriented toward the bottom of the arm.

10. The test head manipulator of claim 1, wherein the at least one plunger comprises: A ball configured to contact a portion of the test head, the ball being rotatable at least in the tumbling and θ directions relative to the arm of the test head manipulator.

11. The test head manipulator of claim 10, wherein the ball is supported by a plurality of balls, each of the plurality of balls being rotatable relative to the ball, and wherein the ball is rotatable relative to each of the plurality of balls.

12. The test head manipulator of claim 10, wherein the at least one plunger comprises: A housing that contains the ball; Shaft, the housing is connected to the shaft; and At least one spring, said at least one spring being at least partially compressible to change the longitudinal dimension of said at least one plunger.

13. The test head manipulator of claim 12, wherein the at least one plunger comprises: A roller that contacts the cam, the roller being configured to transmit the displacement generated by the rotation of the cam to the plunger.

14. The test head manipulator according to claim 1, further comprising: A handle, at least a portion of which is external to the arm of the test head manipulator, is mechanically connected to the cam and can be controlled to manually rotate the cam.

15. The test head manipulator of claim 1, wherein the cam is controllable to move the at least one plunger to counteract ±1.5° rotation or less of the test head.

16. The test head manipulator of claim 1, wherein there are two arms and two plungers, each of the arms having one plunger.

17. The test head manipulator according to claim 1, further comprising: One or more motors are used to drive the arm to move along the track.

18. A test head manipulator for conveying a test head, the test head manipulator comprising: A tower section having a base and a track, the track being perpendicular to the base; and An arm, capable of supporting a test head, is connected to the rail for vertical movement of the test head relative to the tower. The arm is configured to control rotation of the test head, and each arm includes means for counteracting uncontrolled rotation of the test head. The device for counteracting the uncontrolled rotation includes: Two plungers oriented in opposite directions, each plunger configured to contact a different portion of the test head; and A rotatable cam, wherein each of the plungers is configured to contact the cam; The rotation of the cam causes longitudinal movement of the plunger, which is transmitted to the test head to counteract the uncontrolled rotation.

19. The test head manipulator according to claim 18, further comprising: A handle, at least a portion of which is external to the arm of the test head manipulator, is mechanically connected to the cam and can be controlled to manually rotate the cam.

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