Patent Publication Number: US-2021188239-A1

Title: System and method for force compensation in a robotic driving system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 62/951,153, filed Dec. 20, 2019, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally directed to a robotic driving system and method of compensating for any forces induced by components of the robotic driving system. 
     BACKGROUND 
     Automated Driving Systems have become increasingly prevalent equipment on modern automobiles. Accordingly, there is a need to develop testing equipment that can cooperate with these complex systems in order to observe and evaluate their performance. Specifically pertaining to Automated Steering Systems (e.g., Lane Keep Assist Systems), there is difficulty in testing such systems without the Automated Steering System behaving as if it is being manually overridden by a driver (i.e., as if the driver was applying a torque the steering wheel to manually maneuver the vehicle). The present disclosure describes a system and method for preventing testing equipment from overriding of Automated Steering Systems by compensating for any forces induced by the componentry of the testing equipment in order to observe and evaluate the performance of Automated Steering Systems. 
     SUMMARY 
     The present disclosure is directed to a robotic driving system for rotating a steering wheel of a vehicle including an automated steering system. The robotic driving system includes a turntable defining a steering axis and configured to be mounted to the steering wheel of the vehicle such that the turntable and the steering wheel rotate concurrently about the steering axis. The robotic driving system also includes a robot frame including a support member and configured to be mounted to the vehicle. The robotic driving system further includes a transmission device coupled to the support member and operatively coupled to the turntable to transmit a steering torque to the turntable for rotating the turntable and the steering wheel. The robotic driving system also further includes a steering motor in driving engagement with the transmission device to generate and apply the steering torque to the transmission device. Additionally, the robotic driving system includes a load sensor mounted between the support member and the transmission device at a known distance from the steering axis with the load sensor generating a load signal corresponding to a force experienced between the transmission device and the support member. Furthermore, the robotic driving system includes a controller in communication with the steering motor and the load sensor with the controller calculating a resistive torque experienced by the turntable based on the load signal and the known distance from the steering axis, and the controller is capable of determining a compensatory torque to be applied to the steering torque based on the resistive torque to compensate for any forces induced by the robotic driving system for preventing an override of the automated steering system. 
     The present disclosure also includes a method of operating the robotic driving system to prevent an override of the automated steering system. The method of operating the robotic driving system includes a step of generating the steering torque using the steering motor. The method of operating the robotic driving system also includes a step of applying the steering torque to the transmission device. The method of operating the robotic driving system further includes a step of generating the load signal corresponding to the force experienced between the transmission device and the support member. The method of operating the robotic driving system also further includes a step of calculating the resistive torque experienced by the steering wheel based on the load signal and the known distance from the steering axis using the controller. Additionally, the method of operating the robotic driving system includes a step of determining the compensatory torque based on the resistive torque using the controller. Furthermore, the method of operating the robotic driving system includes a step of adjusting the steering torque generated by the steering motor based on the compensatory torque to compensate for any forces induced by the robotic driving system for preventing an override of the automated steering system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages of the present disclosure will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a robotic driving system. 
         FIG. 2  is an exploded view of a turntable of the robotic driving system. 
         FIG. 3  is a perspective view of the robotic driving system installed in a vehicle. 
         FIG. 4  is a perspective view of the robotic driving system mounted to a steering wheel of the vehicle. 
         FIG. 5  is a front view of the robotic driving system mounted to the steering wheel of the vehicle. 
         FIG. 6  is a side view of the robotic driving system mounted to the steering wheel of the vehicle. 
         FIG. 7  is an opposite side view of the robotic driving system mounted to the steering wheel of the vehicle. 
         FIG. 8  is a fragmented front perspective view of the robotic driving system. 
         FIG. 9  is an exploded perspective view of the robotic driving system. 
         FIG. 10  is another fragmented front perspective view of the robotic driving system. 
         FIG. 11  is a fragmented section view of the driving robot of  FIG. 10 . 
         FIG. 12  is yet another fragmented front perspective view of the robotic driving system. 
         FIG. 13  is a fragmented exploded perspective view of the robotic driving system. 
         FIG. 14  is a fragmented sectional view of a load sensor of the robotic driving system. 
         FIG. 15  is a fragmented rear perspective view of the robotic driving system. 
         FIG. 16  is a front view of the robotic driving system mounted to the steering wheel of the vehicle illustrating a method of compensating for any forces induced by components of a robotic driving system. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the Figures, wherein like numerals indicate like parts throughout the several views,  FIGS. 1-16  generally show a robotic driving system  20  for testing a vehicle  22  including an automated steering system  24 . The robotic driving system  20  is capable of rotating a steering wheel  26  of the vehicle  22 . The robotic driving system  20  may also include an accelerator actuator  28  configured to be coupled to and actuate an accelerator pedal  30  of the vehicle  22 . The robotic driving system  20  may further include a brake actuator  32  configured to be coupled to and actuate a brake pedal  34  of the vehicle  22 . The robotic driving system  20  is capable of driving the vehicle  22  with the same functionality as a human. For instance, the robotic driving system  20  may be capable of performing coordinated actuation of the steering wheel  26 , accelerator pedal  30 , and brake pedal  34  of the vehicle  22  to perform typical tasks associated with driving. Such tasks include actuating the steering wheel  26  to direct the vehicle  22  into a parking spot, navigate the vehicle  22  around a corner, change the lane of the vehicle  22 , etc. Importantly, there is a need to effectively observe and evaluate the performance of automated steering systems  24 . 
     The automated steering system  24 , for example, may be a Lane Keep Assist System (LKAS). It is contemplated, however, that as autonomous driving technology progresses, the automated steering system  24  may be a fully autonomous steering system. For safety purposes, automated steering systems  24  typically allow a driver to manually “override” the automated steering system  24  by applying a manual torque to the steering wheel  26  to indicate the driver&#39;s desired direction of the vehicle  22 . This functionality presents a challenge for using current robotic testing equipment to observe and evaluate the performance of automated steering systems  24 . Particularly, automated steering systems  24  may unintentionally perceive any forces induced by components of current robotic testing equipment as a driver manually overriding the automated steering system  24 . Due to this phenomenon, the ability to effectively observe and evaluate the performance of automated steering systems  24  is reduced. Therefore, the robotic driving system  20  and method of compensating for any forces induced by components of the robotic driving system  20  of the present disclosure is needed to address the problem of unintentional overriding of automated steering systems  24 . In order to manipulate the vehicle as little as possible, it is desirable that any forces induced by components of the robotic driving system  20  be compensated within the robotic driving system  20 . 
     Referring to  FIGS. 1-7 , the robotic driving system  20  includes a turntable  36  defining a steering axis  38  and configured to be mounted to the steering wheel  26  of the vehicle  22  such that the turntable  36  and the steering wheel  26  rotate concurrently about the steering axis  38 . In a preferred embodiment, such as shown in  FIGS. 1 and 2 , the turntable  36  may include separate portions assembled together with fasteners  37 . For example, the turntable  36  may include a first upper portion  36   a , a second upper portion  36   b , a first lower portion  36   c , and a second lower portion  36   d . The first and second upper portions  36   a ,  36   b , may be assembled to the first and second lower portions  36   c ,  36   d , using the fasteners  37  to form the turntable  36 . Advantageously, constructing the turntable  36  from separate portions  36   a ,  36   b ,  36   c ,  36   d  allows the turntable  36  to be mounted behind the steering wheel  26  without removing the steering wheel  26 . For example, the first upper portion  36   a  and the first lower portion  36   c  may be shaped such that they may be positioned around a steering column of the vehicle  22  and behind the steering wheel  26  without removing the steering wheel  26 . Subsequently, the second upper portion  36   b  and the second lower portion  36   d  may be assembled to the first upper portion  36   a  and the first lower portion  36   c  using fasteners  37  to form the turntable  36 . In some embodiments, the first upper portion  36   a  may be permanently coupled to the first lower portion  36   c , and/or the second upper portion  36   b  may be permanently coupled to the second lower portion  36   d . Conversely, in other embodiments, portions  36   a ,  36   b ,  36   c ,  36   d , may be completely separable from each other. Additionally, a key  39  may be disposed between the portions  36   a ,  36   b ,  36   c ,  36   d  to facilitate alignment of the portions  36   a ,  36   b ,  36   c ,  36   d , such as shown in  FIG. 2 . Also, in an ideal embodiment, such as shown in  FIG. 2 , the second upper portion  36   b  may define a longer arc length than the second lower portion  36   d  such that the second upper portion  36   b  may be fastened to both the first lower portion  36   c  and the second lower portion  36   d.    
     The turntable  36  may be mounted to the steering wheel using one or more braces  40 . In the preferred embedment, such as shown in  FIG. 2  and  FIGS. 4-7 , the braces  40  include a brace member  41  (shown in  FIG. 2 ) constructed from stainless steel or any other suitable material, and configured to straddle the steering wheel  26  and be secured in place with a fastener, for example, to mount the turntable  36  to the steering wheel  26 . However, other means of mounting the turntable  36  to the steering wheel in a secure and releasable manner are contemplated, such as, but not limited to, clamps, clasps, fasteners, or straps. Additionally, the braces  40  may be adjustable such that the turntable  36  may be mounted to differently sized/shaped steering wheels  26 . For example, the braces  40  may include an adjustment for mounting the turntable  36  to steering wheels  26  having different radii. Also, the braces  40  may also include an adjustment for mounting the turntable  36  to steering wheels  26  having different thicknesses. Further, the braces  40  may by assembled to various locations on the turntable  36  such that the braces  40  are not aligned with spokes of the steering wheel  26 . Also further, the braces  40  may include covers  43  (shown in  FIG. 2 ) arranged about the braces  40  to cover any shape edges for driver comfort. 
     With continued reference to  FIGS. 1-7 , the robotic driving system  20  also includes a robot frame  42  that is configured to be mounted to the vehicle  22 . The robot frame  42  includes a support member  44  for supporting a transmission device  46  and a load sensor  48  (described in further detail below). Referring to  FIG. 3 , the robot frame  42  may also include a base  50  configured to be mounted to a floor  52  of the vehicle  22 . Alternatively, the base  50  may be configured to be mounted elsewhere on the interior of the vehicle  22  (not shown). For example, the base  50  may be mounted to a dashboard, windshield, seat, or center console of the vehicle  22 . The support member  44  may extend upwardly from the base  50  toward the transmission device  46  to support the transmission device  46  and/or the load sensor  48  (described in further detail below). Additionally, the accelerator actuator  28  and brake actuator  32  may be mounted to the robot frame  42 . 
     The transmission device  46  (shown throughout the figures) is coupled to the support member  44  such that the support member  44  provides support to the transmission device  46 . More specifically, the transmission device  46  may include a transmission housing  54  mounted to the load sensor  48 , and the load sensor  48  may be disposed between the support member  44  and the transmission device  46  (described in further detail below). Referring to  FIGS. 8-11 , which illustrates the transmission device  46  with the transmission housing  54  partially hidden, the transmission device  46  may include a plurality of bearing members  56  arranged to rotatably support the turntable  36  for rotation about the steering axis  38 . Particularly, referring to  FIG. 10  and  FIG. 11 , the bearing members  56  may be arranged to accommodate an inner lip  58  and an outer lip  60  of the turntable  36  such that the inner lip  58  and outer lip  60  roll on the bearing members  56  and constrain the turntable  36  to rotational movement about the steering axis  38 . In the preferred embodiment, the first lower portion  36   c  and the second lower portion  36   d  of the turntable  36  may define the inner lip  58  and the outer lip  60 . 
     The robotic driving system  20  further includes a steering motor  62  capable of generating a steering torque ST. The steering motor  62  is in driving engagement with the transmission device  46  to generate and apply the steering torque ST to the transmission device  46 . The steering motor  62  may be mounted to the transmission housing  54 . For example, referring to  FIG. 15 , in some configurations, the steering motor  62  may be solely supported by the transmission housing  54 . The transmission device  46  is also operatively coupled to the turntable  36  to transmit the steering torque ST to the turntable  36  for rotating the turntable  36  and the steering wheel  26  of the vehicle  22 . For example, referring to  FIGS. 8-10 , the transmission housing  54  may include a drive member  64  partially disposed within the transmission housing  54 . The drive member  64  may be rotatably mounted to the turntable  36  and operatively coupled to the steering motor  62  to transmit the steering torque ST from the steering motor  62  to the turntable  36  for rotating the turntable  36  and the steering wheel  26 . In  FIGS. 8-10 , the drive member  64  is directly mounted to the steering motor  62 . However, it is contemplated that intermediate componentry may be included, such as, but not limited to, a reduction gearset, to operatively couple the drive member  64  to the steering motor  62 . 
     To rotatably mount the driving member  64  to the turntable  36 , the drive member  64  may include a first torque transfer interface  66  and the turntable  36  includes a second torque transfer interface  68 . The first torque transfer interface  66  and the second torque transfer interface  68  may cooperate to transmit the steering torque ST generated by the steering motor  62  from the drive member  64  to the turntable  36  for rotating the turntable  36  and the steering wheel  26 . It is contemplated that various types of torque transfer interfaces may be utilized to transmit the steering torque ST from the steering motor  62  to the turntable  36  to actuate the steering wheel  26 , such as, but not limited to, teeth. In the preferred embodiment, as shown in  FIG. 10  for example, the first and second lower portions  36   c ,  36   d  of the turntable may include the second torque transfer interface  68  in the form of teeth configured to mesh with the first torque transfer interface  66  of the drive member  64 , which is also in the form of teeth. 
     Referring to  FIGS. 5-16 , the load sensor  48  is mounted between the support member  44  and the transmission device  46  at a known distance D from the steering axis  38  with the load sensor  48  generating a load signal corresponding to a force F (shown in  FIG. 16 ) experienced between the transmission device  46  and the support member  44 . It is desirable that the support member is rigid such that the support member has minimal deflection when experiencing the force F. Referring to  FIGS. 13 and 14 , the load sensor  48  may include a first portion  70  (best shown in  FIGS. 12-14 ) mounted to the support member  44 . The first portion  70  may, for example, be mounted to the support member  44  with hand fasteners  45  (shown in  FIGS. 13 and 14 ) or any other suitable means. A second portion  72  (best shown in  FIGS. 7, 13, and 14 ) may be mounted to the transmission housing  54  using fasteners or any other suitable means. It is contemplated that any suitable members may be used as the first portion  70  and the second portion  72 , such as, but not limited to, brackets. Importantly, the first portion  70  and the second portion  72  are arranged to transmit the force F experience between the transmission device  46  and the support member  44  to a load cell  74  mounted between the first portion  70  and the second portion  72  to measure the force F experienced between the transmission device  46  and the support member  44  and to generate the load signal. The load cell  74  may be mounted to the first portion  70  and the second portion  72  using any suitable means, such as fasteners  79 . Notably, as illustrated in  FIGS. 13 and 14 , the load cell  74  may be contained within a load sensor housing  75 . The fasteners  79  may be arranged to limit rotation of the load cell  74  and the load sensor housing  75 . The load sensor  48  may also include a load cell cover  77  mounted to the second portion  72  for sealing the load senor and accommodating fasteners  79 . The load cell  74  may be any suitable device to measure compression or tension between the first portion  70  and the second portion  72 , such as, but not limited to, strain gauge load cells, pneumatic load cells, hydraulic load cells, piezoelectric load cells, etc. Notably, the load sensor  46 , robot frame  42 , and support member  44  may be arranged offset from the steering axis such that a driver may comfortably fit their driving leg in the footwell of the vehicle. 
     The robotic driving system  20  further includes a controller  76  (shown schematically in  FIGS. 15 and 16 ) in communication with the steering motor  62  and the load sensor  48 . The controller  76  is configured to calculate a resistive torque RT experienced by the turntable  36  based on the load signal corresponding to the force F and the known distance D from the steering axis  38 . The resistive torque RT is indicative of any forces induced by the robotic driving system  20  that may lead to an unintentional override of the automated steering system  24 . Forces that may be induced by the robotic driving system  20  include friction of internal components and inertial resistance to rotation of the turntable  36 . Additionally, based on the resistive torque RT, the controller  76  is also configured to determine a compensatory torque CT to be applied to the steering torque ST to compensate for any forces induced by the robotic driving system in order to prevent an override of the automated steering system  24 . Advantageously, adjusting the steering torque ST based on the compensatory torque CT enables the robotic driving system  20  to internally compensate for any forces induced by its componentry (such as the steering motor  62 , or the transmission device  46 ), and thus provides an integrated solution to prevent the overriding of the automated steering system that is problematic with current robotic testing equipment. 
     The present disclosure also includes a method of operating the robotic driving system  20  to prevent an override of the automated steering system  24 . The method of operating the robotic driving system  20  includes a step of generating a steering torque ST using the steering motor  62 . The steering torque ST may be generated as a result of the controller  76  transmitting a motor signal to the steering motor  62  to generate the steering torque ST in a particular direction and at a particular magnitude. The method of operating the robotic driving system  20  also includes a step of applying the steering torque ST to the transmission device  46 . As mentioned above, the transmission device  46  is also operatively coupled to the turntable  36  to transmit the steering torque ST to the turntable  36  for rotating the turntable  36  and the steering wheel  26 . Thus, applying the steering torque ST to the transmission device  46  will result in rotation of the steering wheel  26  to change the vehicle&#39;s  22  trajectory. 
     The method of operating the robotic driving system  20  further includes a step of generating a load signal using the load sensor  48  corresponding to a force F experienced between the transmission device  46  and the support member  44 . For example, referring to  FIG. 16 , if the vehicle  22  is drifting out of a desired lane, as indicated by the automated steering system  24 , the automated steering system  24  may urge the steering wheel  26  in the proper direction to correct of the vehicle&#39;s  22  the trajectory. However, the automated steering system  24  may unintentionally perceive any forces induced by the components of the robotic driving system  20  as a driver manually overriding the automated steering system  24 . In this scenario, the driver is not applying a manual torque to the steering wheel  26 . In fact, the automated steering system is experiencing a resistive torque RT experienced by the steering wheel  26  due to any forces induced by the components of the robotic driving system  20 . Thus, the method of operating the robotic driving system  20  also further includes a step of calculating the resistive torque RT experienced by the steering wheel  26  based on the load signal and the known distance D from the steering axis  38  using the controller  76 . For example, the resistive torque RT may be the product of the force F and the distance D; however, other methods of calculating the resistive torque RT are contemplated. 
     Additionally, the method of operating the robotic driving system  20  includes a step of determining a compensatory torque CT based on the resistive torque RT using the controller  76 . To determine the compensatory torque CT, the method of operating the robotic driving system  20  may further include the steps of determining a current rotational speed of the steering wheel  26 , and determining an operational mode of the controller  76  based on the current rotational speed of the steering wheel  26 . The operational mode of the controller  76  may be selected from a dynamic operational mode and a static operational mode. The controller  76  may select the dynamic operational mode when the current rotational speed of the steering wheel  26  is sufficient to change the vehicle&#39;s  22  trajectory. For example, the controller  76  may select the dynamic operational mode when the robotic driving system  20  is rotating the steering wheel  26  at a rotational speed sufficient to direct the vehicle  22  into a parking spot, navigate the vehicle  22  around a corner, change the lane of the vehicle  22 , etc. Conversely, the controller  76  may select the static operational mode when the current rotational speed of the steering wheel  26  is nominal such that the vehicle&#39;s  22  trajectory remains unchanged. For example, the controller  76  may select the static operational mode when the vehicle  22  is traveling straight down a straight road. 
     When the controller  76  is operating the robotic driving system  20  in the dynamic operational mode, the compensatory torque CT is determined based on an identified friction profile of the robotic driving system  20 . Thus, is it necessary to ascertain the identified friction profile of the robotic driving system  20 . To ascertain the identified friction profile, the controller  76  may initiate a friction identification routine. The friction identification routine may include the steps of applying an identification torque (not shown) to the steering wheel  26  using the steering motor  62  and calculating the identified friction profile based on the load signal corresponding to the force F during the friction identification routine using the controller  76 . The identified friction profile may be indicative of any forces induced by the robotic driving system  20  throughout the rotational range of the steering wheel  26 . Thus, when operating in the dynamic operational mode, as the steering wheel  26  is rotating, the controller  76  may determine the necessary compensatory torque CT to prevent the resistive torque RT experienced by the steering wheel  26  due to any forces induced by the components of the robotic driving system  20  from overriding the automated steering system  24 . 
     When the controller  76  is operating the robotic driving system  20  in the static operational mode, the compensatory torque CT may be determined to be a value equal and opposite the resistive torque RT such that the compensatory torque CT counteracts the resistive torque RT. Therefore, the sum of torque experienced by the steering wheel  26  is controlled to zero when the controller  76  is operating the robotic driving system  20  in the static operational mode. Importantly, with the resistive torque RT counteracted, the automated steering system  24  is capable of urging the steering wheel of the vehicle in the proper direction to correct of the vehicle&#39;s  22  the trajectory without being unintentionally overridden. 
     To achieve this end, referring again to  FIG. 16 , the method of operating the robotic driving system  20  includes a step of adjusting the steering torque ST generated by the steering motor  62  based on the compensatory torque CT to compensate for any forces induced by the robotic driving system  20  for preventing an override of the automated steering system  24 . In other words, prior to the controller  76  transmitting a motor signal to the steering motor  62  to generate the steering torque ST, the controller  76  may adjust the magnitude and/or direction of the desired steering torque ST in view of the calculated compensatory torque CT such that the robotic driving system  20  to internally compensates for any forces induced by its componentry to prevent overriding of the automated steering system  24 . 
     It is contemplated that the controller  76  may operate the robotic driving system  20  in other operational modes. For example, the controller  76  may operate the robotic driving system  20  in a fully active mode. In the fully active mode, the robotic driving system  20  may rotate the steering wheel  26  to actively perform typical tasks associated with driving the vehicle  22  (e.g., directing the vehicle  22  into a parking spot, navigating the vehicle  22  around a corner, changing the lane of the vehicle  22 , etc.) without regard to any forces induced by the componentry of the testing equipment. Also, for example, the controller  76  may operate the robotic driving system  20  in a fully passive mode. In the fully passive mode, the robotic driving system  20  may not apply any steering torque ST to the steering wheel  26  whatsoever, as to allow a driver to assume full control of the steering wheel  26 , for example. 
     Several embodiments have been discussed in the foregoing description. However, the embodiments discussed herein are not intended to be exhaustive or limit the present disclosure to any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the present disclosure may be practiced otherwise than as specifically described.