Angle lag control methods and apparatus for long ground vehicles

The method of automatically steering the steerable wheels of an unmanned wheeled support pivotally connected to the trailing end of a center frame forming part of a long articulated ground vehicle in response to overall vehicle dynamics including the vehicle dynamics of a controlled power driven wheeled support having steerable wheels and pivotally secured to the leading end of the center frame of the articulated vehicle;

• said method comprising the steps of:
• (a) measuring a parameter indicative of the distance traveled by the vehicle;
• (b) measuring the leading angle .alpha..sub.1 between the longitudinal centerlines passing through the center frame and the controlled support as the vehicle traverses a path which is, at least in part, curvilinear so as to produce a first signal representative of the leading angle .alpha..sub.1 ;
• (c) delaying the first signal representative of the leading angle .alpha..sub.1 for a time increment sufficient to permit the articulated vehicle to move a distance substantially proportional to the longitudinal spacing between the points of pivotal connection of the center frame to both the controlled support and the unmanned support;
• (d) measuring the trailing angle .alpha..sub.2 between the longitudinal centerlines passing through the center frame and the unmanned support so as to produce a second signal representative of the trailing angle .alpha..sub.2 ;
• (e) comparing the second signal representative of the trailing angle .alpha..sub.2 at the end of the time increment with the delayed first signal measured at the beginning of the time increment and producing a third signal representative of the angular difference between the trailing angle .alpha..sub.2 and the delayed leading angle .alpha..sub.1 ;
• and,
• (f) utilizing the third signal to govern a steering controller in the unmanned support for steering the unmanned support through a steering angle .beta. sufficient to maintain the trailing angle .alpha..sub.2 at the end of the time increment substantially equal to the delayed leading angle .alpha..sub.1 as measured at the beginning of the time increment so that the unmanned support travels over substantially the same path as the controlled support as the articulated ground vehicle traverses the path.

In a power driven relatively long articulated ground vehicle of the type having a central frame, a first steerable wheeled support pivotally connected to and supporting the leading end of the central frame, and a second steerable wheeled support pivotally connected to and supporting the trailing end of the central frame, an improved steering control guidance system for maintaining the first and second steerable wheeled supports on substantially the same path, irrespective of curvature, as the articulated vehicle traverses a prescribed path which is, at least in part, curvilinear having curved portions defined by radii of curvature at least equal to the minimum turning radius of the vehicle;

• said control guidance system comprising, in combination:
• (a) means for providing motive power to at least said first steerable wheeled support for driving said vehicle;
• (b) control means for steering said first wheeled support;
• (c) means for measuring a parameter representative of the distance traveled by said vehicle;
• (d) means for measuring the leading angle .alpha..sub.1 between the longitudinal centerline passing through said frame and said first support and for producing a first signal representative of said leading angle .alpha..sub.1 ;
• (e) means for averaging said first signal over time and as a function of the distance traveled to produce a delayed first signal representative of the time average of said leading angle .alpha..sub.1 ;
• (f) means for measuring the trailing angle .alpha..sub.2 between the longitudinal centerlines passing through said frame and said second support and for producing a second signal representative of said trailing angle .alpha..sub.2 ;
• (g) comparator means for comparing said second signal representative of said trailing angle .alpha..sub.2 with said delayed first signal representative of the time average of said leading angle .alpha..sub.1 and for producing a third signal representative of the angular difference between said trailing angle .alpha..sub.2 and the time average of said leading angle .alpha..sub.1 ;
• and
• (h) control means responsive to said third signal for automatically steering said second support through a steering angle .beta. sufficient to maintain said trailing angle .alpha..sub.2 substantially equal to the time average of said leading angle .alpha..sub.1 so that said second support travels over substantially the same path as said first support as said articulated ground vehicle traverses said prescribed path.

A control guidance system for automatically steering the steerable wheels of an unmanned wheeled support pivotally connected to the trailing end of a center frame forming part of a long articulated ground vehicle in response to overall vehicle dynamics including the vehicle dynamics of a controlled power driven wheeled support having steerable wheels and pivotally secured to the leading end of the center frame of the articulated vehicle;

• said control guidance system comprising, in combination:
• (a) means for measuring a parameter indicative of the distance traveled by said vehicle;
• (b) means for measuring the leading angle .alpha..sub.1 between the longitudinal centerlines passing through said center frame and said controlled support as said vehicle traverses a path which is, at least in part, curvilinear so as to produce a first signal representative of said leading angle .alpha..sub.1 ;
• (c) means for delaying said first signal representative of said leading angle .alpha..sub.1 for a time increment sufficient to permit said articulated vehicle to move a distance substantially proportional to the longitudinal spacing between said pivotal connections of said center frame to both said controlled support and said unmanned support;
• (d) means for measuring the trailing angle .alpha..sub.2 between the longitudinal centerlines passing through said center frame and said unmanned support so as to produce a second signal representative of said trailing angle .alpha..sub.2 ;
• (e) means for comparing said second signal representative of said trailing angle .alpha..sub.2 at the end of said time increment with said delayed first signal measured at the beginning of said time increment, and for producing a third signal representative of the angular difference between said trailing angle .alpha..sub.2 and said delayed leading angle .alpha..sub.1 ;
• and,
• (f) control means responsive to said third signal for automatically steering said unmanned support through a steering angle .beta. sufficient to maintain said trailing angle .alpha..sub.2 at the end of said time increment substantially equal to said delayed leading angle .alpha..sub.1 as measured at the beginning of said time increment so that said unmanned support travels over substantially the same path as said controlled support as said articulated ground vehicle traverses said path.