Robot platform on legs and method for use thereof

Abstract

The invention relates to a robotic platform, comprising: a platform (117); at least four legs (119, 121, 123, 125) connected to the platform (117), each leg comprising three cylinders, a first cylinder (127) and a second cylinder (129) having first ends rotatably connected to the platform (117) at about a first height (H1). A third cylinder (167) has a first end connected to a bottom of the platform (117) at a second height (H2) substantially lower than the first height. A leg of the robotic platform includes an ankle (139) fixedly connected to a second end (133) of the first cylinder (127), a second end of the second cylinder (129) being pivotally connected to the ankle (139). In particular, the first and second cylinders move substantially in a vertical plane. The third cylinder extends at an angle laterally with respect to that vertical plane.

Description

[0001] ROBOT PLATFORM ON LEGS AND METHOD FOR USE THEREOF

[0002] FIELD OF THE INVENTION.

[0003] The invention relates to a robotic platform on legs and to a method for use thereof. The use relates, for example, to carrying a load. The load is, for example, another robot. In particular, the platform can propel itself like a quadruped.

[0004] BACKGROUND OF THE INVENTION

[0005] One of the main advantages of a walking robot is its ability to traverse very rough, uneven and indistinguishable terrain. This feature is an important one in various applications. For example, maintenance of dangerous structures such as nuclear reactors, exploration of planets and other celestial bodies, and transportation in places where there are no paved roads. All these applications require a reliable and mobile machine that can adapt its movement pattern to changes in the environment.

[0006] For example, such a robotic platform can be used to carry another robot through rough terrain. The other robot usually has some functionality. For example, WO- 2023 / 046295 discloses a fruit-picking robot. Harvesting fruit requires the robot to drive through an unpaved field, which may be muddy or uneven.

[0007] To achieve the highest degree of reliability and availability, the harvesting robot usually includes an industrial robot arm based on proven technology. Such robotic arms are available on the market and are widely used in the automotive industry, for example. However, an industrial robot arm can only achieve maximum performance if the arm is mounted on a (very) stable surface, such as a virtually inflexible base. Typically, therefore, the robot arm is firmly anchored to a floor in a factory.

[0008] However, when robots are mounted on a movable platform, it is not uncommon for the robot to break down due to vibrations caused by backlash or deflection in their support. Damage can manifest itself, for example, in the form of mechanical fatigue of the robot arm. Electronic damage can also occur, such as the drives or actuators overheating due to the need to make constant motion corrections. In any case, instability in the supporting frame will result in higher energy consumption of the functional robot because of the requirement to constantly correct movements.

[0009] Here, the motion and control of the robot can be tailored to the specific situation. However, this will almost always result in reduced motion performance. The soil in orchards is typically uneven and can be boggy. However, soil damage and excessive compression should be avoided. Wheeled vehicles can compress the soil and get stuck. Tracked vehicles may damage the ground when cornering. Wheeled and tracked vehicles usually consist of many different parts, making the vehicles relatively complex to maintain and repair. As the number and variety of parts increases, availability usually decreases. However, a robot's number of parts and complexity increase as more functionality is required.

[0010] In this regard, wheeled or tracked vehicles do not have a fundamentally rigid structure. To create a rigid platform, height-adjustable legs are often added to the vehicles. This results in even more parts, which does not improve the availability of the overall solution.

[0011] The addition of legs not only provides more stability, but also allows the vehicle to be aligned with a conveyor system, for example, to transfer a harvest box to or from an external conveyor system.

[0012] Walking vehicles have the full attention of the market, especially with Boston Dynamics' developments. Boston Dynamics has focused entirely on walking robots that all use rotary drives and joints. However, the developments are focused on maximum maneuverability and certainly not rigidity. Also, the robots are built so that there is little room for a payload. There is much attention from the market for Boston Dynamics' four-legged robot, called Spot®, which is primarily used for observation purposes. Remarkably, Boston Dynamics' heaviest humanoid robot is a hydraulic robot with stunning dynamics. However, these robots have a limited ability to carry loads and are relatively unstable.

[0013] W02008084480 describes a relatively simple robot with legs controlled by linear actuators that is capable of performing a variety of tasks, including moving loads long distances to predetermined destinations and moving autonomously over rough terrain. Each of the legs of the robot is driven by means of three linear actuators, each comprising a long hollow body with an opening at one of its ends from which a movable shaft can be drawn along a longitudinal axis thereof, wherein the leg of the robot is composed of a first linear actuator attached to the body of the robot by means of a joint capable of providing two degrees of freedom to the leg and wherein the second and third linear actuator are attached to the leg at points more or less at the same level along its length in selected angular positions relative thereto, so that it can be moved within the two degrees of freedom provided by the joint. This configuration can be used to change the length of each leg by lengthening or shortening the first linear actuators, and to rotate the leg about two axes of rotation relative to the robot body by means of the second and third actuators.

[0014] However, the construction of the legs of the robot on legs of W02008084480 limits the payload capacity. Each leg has two cylinders, typically linear actuators, which engage another cylinder around its center. Thus, the latter cylinder is at least partially loaded in a direction perpendicular to its length. However, cylinders are specifically designed to resist load in the longitudinal direction, and this construction thus limits the load capacity and poses a potential risk of failure.

[0015] CN-104308839-A reveals a platform with legs that each have three cylinders. The construction of the legs has the same drawbacks as indicated above, as one of the three cylinders engages with the center of one of the other cylinders.

[0016] CN-107284548-A and the article “A novel six-legged walking machine tool for in-situ operations” by Jimu LIU, Yuan TIAN, Feng GAO, Front. Meeh. Eng. (https: / / doi.org / 10.1007 / sl l465-020-0594-2) describe a six-legged machine developed to perform in-situ maintenance on large components, such as trains, ships and aircraft. The machine uses a 6-DOF (degree of freedom) manipulator and a six-parallel-legged robot as a mobile platform. The upper manipulator has high rigidity and precision, which are crucial for machining tasks. Meanwhile, the lower-legged robot offers a system with higher mobility and better adaptability for locomotion tasks compared to wheeled or tracked vehicles. Each leg of the lower-legged robot is driven by three cylinders, providing the leg with high payload and accuracy during the walking phase.

[0017] However, the platform of the above article is still relatively unstable. For example, the leg structure is more suitable for vertical forces than horizontal forces. The ball joints at the bottom of the legs make the leg assembly relatively unstable. As mentioned above, any instability in the platform on which the functional robot is based will limit the performance of the functional robot. For the example of the fruit-picking robot, the performance limitation due to instability in the walking platform usually results in a reduction in the amount of fruit picked per unit time, such as fewer apples per hour. Moreover, platform instability can and often will result in damage to or failure of the functional robot.

[0018] The object of the invention is to provide a more stable walking platform. SUMMARY OF THE INVENTION.

[0019] Aspects of the present invention are set forth in the accompanying claims. The invention provides a robotic platform, comprising: a platform; at least four legs connected to the platform, each leg comprising at least three cylinders, wherein a first cylinder and a second cylinder having first ends are connected to the platform via first and second pivot joints at about a first height (Hl), and wherein a third cylinder having a first end is connected to the platform via a suspension at a second height (H2) substantially smaller than the first height (Hl).

[0020] The invention provides a robotic platform, comprising: a platform; least four legs connected to the platform, each leg comprising at least three cylinders, wherein the first cylinder and the second cylinder of each leg extend substantially in a vertical plane, and wherein the third cylinder extends laterally at an angle with respect to the first cylinder.

[0021] Extending substantially in a vertical plane herein may include deviations from that plane with the vertical of, for instance, about 10 to 20 degrees in a lateral direction.

[0022] In an embodiment, the angle is greater than 45 degrees, for example greater than 50 degrees, for example greater than 60 degrees. The angle may be less than 90 degrees, for example, less than 85 degrees, for example, less than 80 degrees.

[0023] In an embodiment, the angle is in a range from about 60 to 80 degrees.

[0024] In an embodiment, the robotic platform includes an ankle fixedly connected to a second end of the first cylinder, wherein a second end of the second cylinder is pivotally connected to the ankle.

[0025] In an embodiment, a second end of the third cylinder is pivotally and pivotally connected to the ankle.

[0026] In an embodiment, the second height (H2) is less than or equal to about 60% of the first height (Hl), for example less than or equal to 40% of the first height (Hl), for example less than or equal to 35% of the first height (Hl), for example less than or equal to 30% of the first height (Hl), for example less than or equal to 25% of the first height (Hl), for example less than or equal to 20% of the first height (Hl), for example less than or equal to 15% of the first height (Hl), for example less than or equal to 10% of the first height (Hl).

[0027] In an embodiment, the first cylinder and the second cylinder have first ends which are connected to a side of the platform, and the third cylinder has a first end which is connected to a bottom of the platform.

[0028] In an embodiment, the robotic platform includes a foot connected to the ankle.

[0029] In an embodiment, the foot is connected to the ankle via an ankle joint that allows rotation (Rx, Ry) relative to the ankle.

[0030] In an embodiment form, the foot includes a flat portion for grip on relatively soft ground.

[0031] In an embodiment, the flat portion of the foot includes an upwardly rounded edge.

[0032] In an embodiment, the robotic platform includes a third connecting piece fixedly connected to the second end of the second cylinder, the third connecting piece being pivotally connected to the ankle.

[0033] In an embodiment, the robotic platform includes a fourth connecting piece pivotally connected to the second end of the first cylinder and pivotally connected to the second end of the third cylinder.

[0034] In an embodiment, during use, the respective first cylinder and the second cylinder of each leg extend substantially vertically, and the respective third cylinder extends substantially horizontally.

[0035] In an embodiment, each leg includes a telescopic shaft.

[0036] In an embodiment, the first ends of the first cylinder, the second cylinder and the telescopic shaft are connected to a beam, which is rotatably connected to the platform.

[0037] According to another aspect, the invention provides a leg for a robotic platform, comprising: at least three cylinders, wherein a first cylinder and a second cylinder are arranged to the pivotally connected to a side of the platform and therein extend substantially in a vertical plane, and wherein a third cylinder extends laterally under an angle with respect to the first cylinder. In an embodiment, the angle is greater than 45 degrees, for example greater than 50 degrees, for example greater than 60 degrees. The angle may be less than 90 degrees, for example, less than 85 degrees, for example, less than 80 degrees.

[0038] In an embodiment, the angle is in a range from about 60 to 80 degrees.

[0039] In an embodiment, the first cylinder and the second cylinder have first ends arranged to be pivotally connected to the platform via first and second pivot joints at about a first height, and wherein the third cylinder has a first end arranged to be connected to the platform via a pivot and rotatable suspension, the leg comprising an ankle fixedly connected to a second end of the first cylinder, wherein a second end of the second cylinder is pivotally connected to the ankle.

[0040] In an embodiment, a second end of the third cylinder is rotatably and pivotally connected to the ankle.

[0041] In an embodiment, the leg includes a foot connected to the ankle via an ankle joint hinged in at least one dimension.

[0042] In an embodiment, the suspension is arranged to be connected to the platform at a second height substantially smaller than a first height at which the first ends of the first cylinder and the second cylinder are arranged to be connected to the platform.

[0043] According to a further aspect, the invention provides a method of moving a robotic platform, the method comprising the steps of: providing a platform having at least four legs connected to the platform, each leg comprising three cylinders, a first cylinder and a second cylinder having first ends pivotally connected to a side of the platform and a third cylinder having a first end connected to a bottom of the platform, and an ankle connected to a second end of the first cylinder, a second end of the second cylinder being pivotally connected to the ankle; and moving the robotic platform by alternately extending and shortening the first and second cylinders of the respective legs.

[0044] The ankle may be fixedly connected to the second end of the first cylinder. Alternatively, the leg may comprise a telescopic shaft having an end fixedly connected to the ankle.

[0045] In an embodiment, the step of moving includes hinging and rotating a second end of the third cylinder relative to the second end of the first cylinder. In an embodiment, the step of moving includes rotating (Rx, Ry) a foot relative to the ankle via a hinge joint.

[0046] In an embodiment, the step of moving includes unwinding the foot on a surface by rotating and through a flat portion of the foot provided with up rounded edge.

[0047] In an embodiment, the step of moving includes pivoting the second end of the second cylinder relative to the second end of the first cylinder through a third connecting piece fixedly connected to the second end of the second cylinder and pivotably connected to the ankle.

[0048] In an embodiment, the step of moving includes rotating and rotating a second end of the third cylinder relative to the second end of the first cylinder of a respective leg through a fourth connecting piece pivotably connected to the second end of the respective first cylinder and pivotably connected to the second end of the corresponding third cylinder.

[0049] In an embodiment, during the step of moving, the respective first cylinder and the second cylinder of each leg extend substantially vertically and rotate in the plane of a respective side of the platform, and the respective third cylinder extends substantially horizontally and rotates in the plane of the bottom side of the platform.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Reference is made to the figures on the accompanying drawings. The figures are schematic in nature and are not necessarily drawn to scale. Similar reference numbers indicate similar parts. On the accompanying drawings:

[0052] Figure 1 shows a perspective view of an example of a functional robot in an orchard;

[0053] Figure 2 shows a perspective view of an example robotic platform;

[0054] Figure 3 shows a right side view of a running robot platform;

[0055] Figure 4 shows a right side view of a robot platform including examples of forces during walking;

[0056] Figure 5 shows a top view of the robot platform at the beginning of making a turn;

[0057] Figure 6 shows a top view of the robot platform at the end of making a turn;

[0058] Figure 7 shows a perspective view of the right rear leg;

[0059] Figure 8 shows a side view of a detail of the right rear leg; Figure 9 shows a front view of a detail of the right hind leg;

[0060] Figure 10 shows a perspective view of the right hind leg;

[0061] Figure 11 shows a front view of a detail of the right hind leg;

[0062] Figure 12 shows three perspective views of a robotic platform including an indication of respective movements of a paw during locomotion;

[0063] Figure 13 shows the right side view of an embodiment of a robotic platform;

[0064] Figure 14 shows the rear view of the robot platform;

[0065] Figure 15 shows a robot bearing mounted in the chassis

[0066] Figure 16 shows the rear view of the robot platform including examples of forces while the platform is stationary and a robot mounted on it is moving maximally;

[0067] Figure 17 shows the rear view of a robot platform including examples of forces on a cylinder mounted under the vehicle at different heights;

[0068] Figure 18 shows a perspective view of a detail of the right rear leg;

[0069] Figure 19 shows a perspective view of a detail of the right rear leg;

[0070] Figure 20 shows a perspectival view of a detail of the foot of the right rear leg;

[0071] Figure 21 shows a schematic right side view of a robotic platform including examples of a paw movement of the right rear leg during locomotion;

[0072] Figure 22 shows an exploded view of an embodiment of the right rear leg;

[0073] Figure 23 shows a perspective view of an execution form of a robotic platform;

[0074] Figure 24 shows a perspective view of an embodiment for suspending a first cylinder and a second cylinder to the platform; and

[0075] Figure 25 shows a perspective view of an embodiment of a leg.

[0076] DETAILED DESCRIPTION

[0077] The invention will be further explained using the examples described below.

[0078] A Cartesian coordinate system will be used to illustrate the invention. The Cartesian coordinate system has three axes, namely an x-axis, a y-axis and a z-axis. Each of the three axes is perpendicular to the other two axes. A rotation around the x- axis is called an Rx rotation. A rotation around the y-axis is called a Ry-rotation. A rotation around the z-axis is called an Rz-rotation. The x-axis and the y-axis define a horizontal plane, while the z-axis runs vertically. The Cartesian coordinate system does not limit disclosure and is used only for clarification. The orientation of the Cartesian coordinate system may be different, for example such that the z-axis has a component along the horizontal plane.

[0079] The term “joint” as used herein refers to a component that allows movement of one part relative to another in at least one degree of freedom.

[0080] The term “hinge joint” as used herein refers to a joint that allows movement in one direction. The movement of two parts connected by a hinge joint is similar to a knee of a (e.g., human) body. A hinge joint can include a pin-hole joint, where a first part is connected to the second part through the pin-hole joint. The hinge joint generally allows rotation of a part connected to the pin with respect to another part connected to the openings, while restricting movement in other degrees of freedom.

[0081] There may be joints with OD, ID, 2D and 3D degrees of freedom. For example, an immobile ankle joint may be a O-dimensional, OD, joint. For example, a OD joint can rotate about a center line but is secured against twisting in other directions. A piston rod of a cylinder can be secured against twisting and is then a OD joint (adjustable longitudinally). A piston rod can be non-secured against twisting and is then a ID joint. For example, a ID joint has one center line around which rotation can take place. A 2D joint, for example, has two center lines that cross or intersect at a point. A 3D joint, for example, has three center lines that cross or intersect in a point. Joints can be arranged in series.

[0082] “Paw” and Teg’ herein refer to a limb of a body that can be used to support and propel that body. The body as referred to herein is essentially the chassis of the robotic platform.

[0083] The development of a robotic platform according to the invention is discussed step by step below. First, the requirements and boundary conditions.

[0084] PRIMARY REQUIREMENTS.

[0085] 1) Stability. The platform should provide maximum stability to a robot mounted thereon while moving over an uneven and so here and there slack surface so that the latter robot can perform as maximally as possible.

[0086] SECONDARY REQUIREMENTS.

[0087] 2) Reliability. The platform should have a high degree of reliability and availability.

[0088] 3) Weatherproofing. The vehicle should be suitable to operate in weather conditions corresponding to those during apple harvesting (autumn) and pruning of apple trees and other similar fruit trees (during winter). The platform is preferably suitable for operating during wind and rain. The platform does not need to operate during frost.

[0089] OTHER REQUIREMENTS

[0090] 4) The surface should preferably not get damaged by the vehicle.

[0091] 5) Alignment. It would be convenient that the top of the vehicle can be aligned with an external transport system, so that, for example, a harvest box can be automatically attached and removed.

[0092] Concerning the primary requirement 'stability' it should be noted that normally the manufacturer of the robot specifies in his product specification values for the reaction forces of the robot on its surface as well as a value for the minimum surface stiffness.

[0093] The following is a technical description of the robot platform.

[0094] See Figure 1. An orchard with apple trees in hedge form is common, especially in the Netherlands. Apple trees 101 then stand in straight rows 103 of several hundred meters long at a pitch of about 3,000 mm between rows. The possible nominal width of a row of trees is given as 1,200 mm, the pitch between the trees 1,000 mm and the height 2,750 mm. A vehicle or platform 109 is provided with a robot 107 for picking apples. A tree normally contains many apples 105. This allows the robot 107 to transfer apples from a tree to a harvesting box 111 present on the vehicle 109 in multiple cycles when the vehicle 109 is stationary.

[0095] In our case, as an example of a robot, we have chosen an industrial robot that can cover a tree from top to bottom. The robot is then also large enough to harvest apples both to the left and right of the vehicle. The reason for choosing an industrial robot is that it meets the requirement for maximum reliability and availability. For example, the robot is not at the front but at the back of the vehicle 109. The reason for this is that sensors mounted on the vehicle 109 can already provide preliminary information to the robot regarding actions to be taken.

[0096] The length of the vehicle 109 is as short as possible. For example, the length is roughly 2,000 mm. Growers indicate that they want to keep the width of the vehicle as minimal as possible. For example, that would be a minimum of 1,000 mm for the chassis of the vehicle 109. This is based on the width of a standard harvest box 111 which is also 1,000 mm. In order for the robot 107 to reach a tree from top to bottom, it will need to be mounted at a certain height above the ground. For example, this is about 1,000 mm. We estimate that the height of the chassis of the platform 109 should not be less than, say, 600 mm. This is determined by the height of the equipment to be housed in the chassis including the robot controller which we estimate to be the component with the greatest height.

[0097] STANDSTILL AND MOVEMENT OF THE VEHICLE

[0098] With current knowledge, we estimate that using an industrial robot 107 to transfer apples collected during a harvest cycle to a harvest box 111 will take on the order of 10 seconds. This time was measured between two consecutive harvest cycles. Has the robot harvested all the apples in its reach that it should harvest, then we state that the vehicle 109 will move over about 500 mm within the before mentioned 10 seconds to get enough apples in reach of the robot. Thus, moving the vehicle does not negatively affect the picking capacity. A low movement speed, of say about 50 mm / sec, is sufficient. This low speed of the robot platform 109 is technically a very low speed. If desired for other applications, the speed will be able to be higher without directly running into technical limits.

[0099] In order to collect as many apples per unit time as possible during a harvest cycle, the functional robot 107 will move at maximum speed. This will generate considerable reaction forces on the vehicle 109. Thus, this is a justifiable reason for the robotic platform 109 to be stopped during a harvest cycle of the functional robot 107. When putting away the collected apples, the robot 107 can move much more quietly and the reaction forces will correspondingly also be much lower. So putting away the apples while moving the vehicle seems possible.

[0100] DRIVING

[0101] As alternatives to drive the robot platform or vehicle 109, propulsion by wheels, tracks and legs were considered. Vehicles with wheels and tracks (which is also basically a solution with wheels) have not been developed from the outset to give a high degree of stability to the vehicle they are part of. Also, wheels or tracks are relatively likely to damage the ground. Especially when rounding curves and on soft ground. We should also mention that a solution with wheels gives a greater ground load than a solution with tracks.

[0102] It is quite possible to give stability to a vehicle with wheels or tracks by adding outriggers to the vehicle which, when the vehicle is stationary, support it on the ground and take some or all of the vehicle's weight. Outriggers can also be used to align the vehicle to transfer a harvest box 111 to an external conveyor system, for example.

[0103] Wheel assemblies consist of many different parts. When outriggers are added to this, it only becomes more complex and the availability of the vehicle only decreases.

[0104] We see a solution with legs as the best solution for driving the vehicle. For example, a solution in accordance with a four-legged creature whose legs are basically implemented with cylinders without the use of a skeleton. We can meet all the requirements and wishes mentioned at the beginning with this solution.

[0105] We specifically chose a solution with cylinders instead of rotary actuators because it is plausible that a solution with cylinders will lead to a more stable solution.

[0106] The following is a step-by-step description of the construction of the vehicle.

[0107] BASIC SOLUTION

[0108] Figure 2 shows the basis of a solution according to the invention. Thereby, two legs 119 and 121, 123 and 125, respectively, are attached to each parallel long sides 113 and 115 of an example rectangular box-shaped chassis 117.

[0109] Leg 119 is the mirrored version of leg 121. Leg 123 and 125 are the mirrored implementation of legs 121 and 119, respectively.

[0110] Figure 2 shows one of the situations during propulsion of the vehicle 109 where two legs 119 and 121 on a first side of the chassis meet halfway across the vehicle and the other two legs 123 and 125 are extended on the opposite side of the chassis.

[0111] Figure 3 shows the enlarged right side view at the rear of the vehicle 109 taken from Figure 2 with leg 121 in the foreground and leg 123 in the background which can make exactly the same motion as leg 121.

[0112] For a purely straight-line movement of the vehicle 109, only two cylinders, cylinders 127 and 129, are needed per leg. Each cylinder, or linear actuator, includes a cylinder body 131 and a piston with piston rod 133.

[0113] The cylinders 127 and 129 are each separately suspended from the chassis 117 using, in this case, a pivot joint, 135 and 137, respectively.

[0114] Fixed to the end of the piston rod 133 of cylinder 127 is a head 139 which is connected to the piston rod of cylinder 129 by a hinge joint 141. This is to accommodate the small angular change between cylinder 127 and 129 during a step of the leg 121. We call the joint 141 the knee joint and the fixed head 139 the ankle. Attached to the ankle 139 is fixed and quickly interchangeable, for example by means of a single pin or bolt connection 145, a foot 147. The foot may be relatively simple in design. Connection 145 is henceforth referred to as the ankle joint. In this embodiment, the ankle joint may still be immobile. For example, the foot is rigidly attached to the ankle to provide maximum stability to the foot. During a bearing step, the foot rolls off over the surface 149.

[0115] A first embodiment assumes the use of electro cylinders to move a leg. These could also be pneumatic or hydraulic cylinders. We assumed electro-cylinders in the design because they take up the most space and we always want to be able to continue to choose between electro-, pneumatic- and hydraulic-cylinders depending on the situation.

[0116] Cylinders 127 and 129 are identical in construction size and in this case, because of the maximum space available, each has a stroke length of 350 mm. The design is based on an electrical cylinder which is freely available in the market. The distance between the suspension points 135 and 137 is chosen as 350 mm. In this situation, the cylinders and the parts connected to them are precisely not touching each other. In this arrangement the foot when lifted 100 mm can make a non-bearing step, see the dash-dot line 151, of about 1,000 mm forward or backward, it is just from where the step is initiated. A vertical movement of 100 mm seems to us sufficient for a step movement in an apple orchard. If a higher vertical movement is desired then the horizontal length of the step will decrease which may be seen from the area bounded by the dashed contiguous curved lines 153 which indicate the boundary within which the center of the ankle joint 145 can move. The boundary is formed by the maximum extension and retraction of the two cylinders.

[0117] FORCE PLAY

[0118] Figure 4 shows the force play on the vehicle for the situation outlined so far where the weight of the vehicle is equally distributed among the four legs. For convenience, we assume that all of the forces shown on a leg converge directly at the ankle joint 145. The forces are determined between the suspension points 135 and 137 of the cylinders of a leg and the ankle joint 145. The forces acting in a leg are in the same plane as the center lines of the cylinders and the pivot points of the leg in question. This is most ideal. The estimated total weight of about 17,000 N shown includes all components which also include the industrial robot 107 with its controls, a harvest box 111 filled with apples, and even a piece of transportation to automatically load and unload a harvest box 111. To be clear, this assumes only static forces for now.

[0119] While moving forward, the robot platform or vehicle 109 will rest on at least three legs each time. If one of the four legs is detached from the ground, the forces shown in the legs will increase. It is even conceivable that the entire weight of the vehicle 109 will rest almost on two legs and that in the case the center of gravity of the vehicle 109 will be close to the straight line between two feet.

[0120] We have assumed for convenience that the center of gravity of the vehicle 109 will be exactly in the middle of the vehicle. In practice this will be different but we will try by distribution of components to locate the center of gravity as much as possible in the middle. The center of gravity will not be a fixed point, this because the robot 107 changes position during movement but also because a harvest box I l l is first empty and later full.

[0121] For the play of forces it is positive if the suspension 135 and 137 of the cylinders are chosen as high as possible above the ground. This is because then the stroke length of a cylinder can be chosen at its maximum. It is not absolutely necessary that the suspension of the cylinders be situated on a horizontal line next to each other, but it is better. If one suspension point is chosen lower than the other the step size will decrease which is not immediately desirable.

[0122] Figure 4 may show that by increasing the distance between the suspension 135 and 137 of the cylinders, the forces in the cylinders will decrease. However, the step size will also decrease. Also, decreasing the step size will decrease the forces in the cylinders.

[0123] STEERING

[0124] Relatively small track corrections during movement can be made by playing with the step size of the legs on either side, left and right of vehicle 109. However, this method can result in relatively large lateral forces on the cylinders and their suspension points. Running the piston rods of the cylinders between fixed guides mounted to the chassis could partially absorb lateral forces. This solution will not be described further here. Eventually, when reaching the end of a corridor with trees, the vehicle will have to move to the next corridor with trees. Thus, the vehicle will have to be able to make a 180-degree turn.

[0125] See Figure 5. A turn can be made by having legs move sideways in addition to moving forwards and backwards. First, for example, leg 121 is raised, moved sideways and then placed on the ground. Then leg 125 does this in the opposite direction.

[0126] See Figure 6. When all legs rest on the ground, legs 121 and 125 are then moved toward the chassis and legs 119 and 123 are moved away from the chassis. For example, a turn can be made around the center of the vehicle. Remarkably, in the situation described above, the feet do not move during the turn.

[0127] All kinds of scenarios are possible for turning. The turning point can also be outside the vehicle.

[0128] CHOICE OF SUSPENSION CYLINDERS AND KNEE JOINT.

[0129] See Figure 7. For example, to move cylinders 127 and 129 of leg 121 laterally away from chassis 117, cylinder 129 will move not only about center line 153 but also about a center line 155 perpendicular to centerline 153. The same is the case for cylinder 127.

[0130] See Figure 8. In all situations, except when cylinder 127 is moved purely straight sideways, a lateral movement of a leg 121 creates a situation in which the ankle 139 fixed to the piston rod of cylinder 127 twists to a greater or lesser degree and thus also the knee joint 141 which is at some distance from the center line of cylinder 127. This creates a situation where the centerlines of both cylinders 127 and 129 will no longer lie in one plane. The centerlines will not intersect but cross each other at some distance. This is not desirable from a load engineering point of view.

[0131] Cylinders are specifically designed to absorb tensile and compressive forces. They are not designed to absorb lateral forces although they can often withstand them to some degree. However, what cylinders, and certainly electric cylinders that are secured against piston rod twisting, certainly cannot withstand well is torsion around the centerline and that is precisely what is involved in our outlined situation. It need not be a major problem when forces are low but that is not the case in our situation. See Figure 4.

[0132] To allow cylinder 129 to follow the motion of cylinder 127 without creating unwanted stresses, the piston rod of cylinder 129 is provided with a knee joint 141 with the main component being a so-called rod head with ball joint 157. This allows twisting in three directions. Rod heads as described are a standard option for cylinders. The rod head is permanently connected to the piston rod of cylinder 129.

[0133] See Figure 9. As a result of the twisting of the ankle 139, it can be observed in the figure that the piston rod of cylinder 127 is visible behind the piston rod of cylinder 129 and the rod head 157 is clearly twisted around the ball.

[0134] The ball of the rod head is slid over a shaft 159 that is fixedly mounted in the ankle on two sides. The center of the ball is in the center of the shaft. The rod head 157 and the shaft 159 together form the ankle joint.

[0135] The situation outlined above applies only to cylinders whose piston rod is secured against twisting as is often the case with electric cylinders. In pneumatic and hydraulic cylinders, the piston rod is usually not secured against rotation. The solution with the rod head with ball joint does not work at all because the anklel39 of cylinder 127 will immediately twist due to the unstable situation because the rod head cannot stop the twisting when the cylinder 129 delivers a pressure force.

[0136] We prefer a solution where the cylinders are not secured against twisting. Then there is less chance of wear and possibly damage. This improves the availability of the overall solution. The use of pneumatic and hydraulic cylinders is therefore preferred. This is not to say that you should constantly rotate these cylinders around their piston rod. In fact, this is not good for the seals.

[0137] See Figure 10. The situations described above are easily solved by making the suspension 135 and 137 of both cylinders 127 and 129 each as ball joints. Now a cylinder can rotate not only around centerlines 153 and 155 but also around its own centerline 161.

[0138] See Figure 11. If we replace the rod head with ball j oint 157 with a head 163 that can only rotate about axis 159, it is noticeable that everything at the level of the foot is again neatly aligned. A great advantage of the purely hinged knee joint is that the centerlines of cylinders 127 and 129 intersect again and this knee assembly can be heavily loaded as is the case in our situation. In contrast, the centerlines of cylinder 129 and axis 159 do not have to intersect. The knee joint will have to be implemented very stably. The design of the knee joint now chosen will ensure that the cylinders cannot touch the chassis when piston rods are secured against twisting. In the case of nonsecured piston rods, provision will have to be made to prevent the cylinders from touching the chassis. For example, consider limiting the twisting of the cylinders about their centerline by incorporating a restriction in the ball joint of both cylinders.

[0139] ADDITION OF A THIRD CYLINDER

[0140] See Figure 12. To allow controlled side movement of a leg, we are going to add a third cylinder to each leg. The third cylinder has a piston rod that is coupled with the piston rods of the previously mentioned cylinders of the legs.

[0141] In situations where a high degree of maneuverability is required, the suspension points of the cylinders are usually all located more or less at the top of the chassis, and a suspension point 165 for the third cylinder is also located at the leading edges of the vehicle. So the suspension points are more or less all in one and the same horizontal plane. So there are suspension points on all sides of the vehicle. Should a foot be able to move under the vehicle due to maximum maneuverability, it appears that the chassis can contain little space under the upper surface. See Figure 12, the leftmost figure therein.

[0142] If the same leg design is used but the feet no longer pass under the vehicle then the space of the chassis is still, but less, reduced because the third cylinder will still move under the upper surface. See Figure 12, the middle figure.

[0143] A chosen form of implementation is the solution shown in the rightmost drawing in Figure 12, where a suspension 165 of the third cylinder of each leg is located under the chassis.

[0144] Figure 13 shows the right side view of the vehicle 109 with under the chassis 117 the four respective mounted third cylinder 167 per leg.

[0145] Figure 14 shows a corresponding rear view.

[0146] Situating the third cylinder 167 per leg under the vehicle gives a large number of advantages, namely:

[0147] 1) It does not limit the length of the chassis;

[0148] 2) It allows a boxy chassis with high volume;

[0149] 3) A vehicle-mounted robot thus obtains more working range;

[0150] 4) The vehicle is easier to interface with other equipment;

[0151] 5) The vehicle-mounted robot can now be mounted at a lower level;

[0152] 6) The build size of the cylinder can be much smaller than that of load-bearing cylinders; and

[0153] 7) Increased lateral stability of the vehicle; Because the length of the chassis 117 is not limited, it can be chosen as long as necessary. This has the great advantage of making it possible to accommodate especially weather-sensitive equipment in the chassis 117. For example, at least the controls of the vehicle 109 and the robot 107. That the chassis 117 can be rectangular in shape makes it possible to maximize the available space and use it more efficiently.

[0154] To harvest apples at a low level above the ground, the vehicle-mounted robot will move in front of the rear of the vehicle to move the harvesting tool toward an apple to be harvested. The closer the robot can move along the vehicle with its tools the more working range the robot has at its disposal. Thus, the fact that the back does not contain any obstructing parts is advantageous.

[0155] To maximize the working range of the robot 107, it is placed against the edge of the rear of the chassis 117.

[0156] The fact that the front and rear of the chassis 117 do not contain any obstructing parts also makes it easier to couple the vehicle 109 to other equipment. For example, coupling to another vehicle, a transport system that can carry a harvest box 111 or a charging station that can supply fuel or electricity to the vehicle.

[0157] See Figure 15. Because the front and rear of the chassis 107 are completely free of obstructions, an additional advantage is that a robot mounted on it can now also be placed lower than the upper deck. Thus, instead of maximizing the vertical working range of the robot, the robot can be used for work where, for example, more horizontal working range is more convenient. Consider, for example, ground-level work. It is notable that the construction and dimensions of the legs do not need to be modified. Thus, the good running characteristics of the vehicle are not affected.

[0158] Mounting the robot at a lower level has a beneficial effect on the interplay of forces on the vehicle (described below) and thus on stability.

[0159] In order for a leg to be able to make a 1,000-mm step when the vehicle is moving straight forward or backward, cylinder 167 in our case only needs to make a stroke of 250 mm. In addition, cylinders 167 in this situation only need to direct the rectilinear motion of a leg. Virtually no force is required for this. The advantage of this construction is that forces supplied by the respective third cylinders are relatively small.

[0160] The third cylinders 167 do need to provide some force when rounding a curve, for example. The third cylinders 167 provide the greatest force when, for example, the vehicle 109 is stationary and the robot 107 is moving high-dynamically. Figure 16 shows the occurring forces at rear view of the vehicle 109. According to the rules for static force plotting, a rotating layup point 169 which is fixed to the ground surface and a layup point 171 which is free to move parallel to the ground surface were assumed.

[0161] In orchard applications, such as apple harvesting, the industrial robot 107 mounted on the platform 117 will usually operate in a lateral direction on both sides of the vehicle and thus will also cause mainly lateral forces on the platform. Rotational forces will also be applied by the robot to the vehicle in the horizontal plane but will have less impact on the vehicle.

[0162] The examples of forces 173 (for example, about 2,330 N, 1,420 N and 3,360 Nm) are the maximum reaction forces in the vertical plane of the selected industrial robot 107 on the chassis 117 during operation. For convenience, all the acting forces have been collected and plotted in one plane.

[0163] Thus, in a third cylinder 167, only a force of 2,760 / 2 = 1,380 N occurs (divide by two because of two trailing legs per side of the vehicle). Cylinders 167 can thus be taken in terms of build size significantly smaller than cylinders 127 and 129.

[0164] See Figure 17. In the most ideal force situation for a third cylinder 167 would be placed horizontally. The resulting force is then 2,330 / 2 = 1,165 N. In our opinion, this is not a good position for a cylinder 167 because the cylinder could then drag through any vegetation or hit elevations in the ground during propulsion.

[0165] If we were to choose a suspension point 165 at the top of the chassis 117, the force acting in a cylinder 167 will be about two times higher than in our chosen situation, namely 4,450 / 2 = 2,225 N. Also, the cylinder 167 will be longer. And also, the bending forces in the chassis 117 will increase the closer the suspension point 165 is to the suspension points of the cylinders of the legs 123 and 125. Also, as in our case, a high chassis 117 gives better resistance to bending than a low chassis. We can safely say that our solution gives a certainly four times better stability than a solution where the suspension points of the cylinders are located high in the chassis.

[0166] CONNECTION OF THIRD CYLINDER WITH BASE AND CHASSIS

[0167] Ideally, the ends of all three cylinders of a leg would come together in a single point. However, it is proving difficult to provide a solution that meets the requirement for high reliability and availability. In an implementation form, the ends come together as close as possible, with the required structures being robust and simple. This led to the construction shown in Figure 18.

[0168] Figure 18 shows a situation of leg 121 where the structures mounted at the ends of the piston rods of cylinders 129 and 167 are just not touching each other. The knee joint 141 is located at minimum distance from the center line of cylinder 127 in order to minimize lateral forces on cylinder 127.

[0169] At the end of the piston rod of cylinder 167, for example, a bushing 175 with two collars is fixed mounted. This bushing, for example, is rotationally mounted around its center line in a joint 177 that can tilt relative to a bushing 179 that can rotate around the center line of the ankle 139 mounted at the end of cylinder 127.

[0170] For example, the connection of the cylinder 167 to the ankle is designed to ensure that the centerline of the third cylinder 167 intersects the centerline of the first cylinder 127. See Figure 18. Similarly, the centerline of the second cylinder 129 intersects the centerline of the first cylinder 127.

[0171] In one embodiment, the knee joint 141 hinged in ID, i.e., the hinged connection of the second cylinder 129 to the ankle 139 that is fixed connected to the first cylinder 127, causes the centerlines of the two cylinders to intersect. In use, the forces in the second cylinder 129 are nearly equal to the forces in the first cylinder 127. In practice, this means a relatively high force. To withstand these forces, a number of joints are possible. What matters relatively much is the stability brought by the joint 141 hinged in ID. In other words, the stability of the respective legs is significantly increased when the centerlines of cylinders 127 and 129 intersect rather than cross. With crossing centerlines, the high forces can go wrong very quickly during operation. The conventional solutions for robot platforms with legs are mostly provided with joints at the foot with more than ID degree of freedom, which wobble and are therefore not suitable for high loads, at least not for the loads as mentioned with respect to the present invention.

[0172] The same applies to the construction of the connection between the third cylinder 167 and the first cylinder 127. This in fact ensures that the centerline of the third cylinder 167 also intersects the centerline of the first cylinder 127. The forces during operation are significantly lower in the third cylinder 167 than the forces in the first cylinder. Therefore, for the joint 179, 177 it is acceptable that it is ultimately a 3D joint. However, the chosen solution with the rotating bushing 179 around the centerline of the first cylinder 127 again ensures that the centerline of the third cylinder 167 must intersect that of the first cylinder 127 and cannot shoot away. The pivot joint 177 then coupled to the bushing 179 is again constructed in such a stable manner that it is similar to the knee j oint 141.

[0173] The respective joints are selected and implemented such that these center lines intersect. It is prevented that the centerlines of the respective cylinders cross each other, that is, that the centerlines pass each other at an interval. This prevents wobbling, in other words uncontrolled deflection of the respective leg. Consequently, the robot platform 109 as a whole is considerably more stable than conventional platforms. Its ability to carry a load is therefore significantly greater. Due to the stability of the legs, a functional robot mounted on the platform 109 can operate at relatively high power.

[0174] The point of engagement of cylinder 167 on cylinder 127 is preferably higher than that of cylinder 129 on cylinder 127. This is because cylinder 167 operates at much lower forces than cylinder 129.

[0175] See Figure 19. For examplejoint 177 and bushing 179 can be united in a spherical plain bearing 181 when the tilt of joint 177 does not exceed 30 degrees in total. In a practical embodiment, the latter is the case. Spherical plain bearings with a tilt angle of 30 degrees are supplied worldwide by major bearing brands which increases the reliability and availability of this overall solution. Standard spherical bearings with a tilt angle greater than 30 degrees are more difficult to obtain. In the design, for example, we stay with the earlier solution because it allows greater design freedom so that a vehicle is also conceivable with a greater tilt angle of joint 177 than 30 degrees.

[0176] See Figure 14. As a suspension 165 of a cylinder 167 to the chassis, a pivot point is provided that can rotate a cylinder 167 in the horizontal plane with, perpendicularly, a pivot point that can rotate a cylinder 167 in the vertical plane. For example, two suspension points of two opposite legs 121 and 123 and 119 and 125, respectively, are located as close together as possible. This is to provide for as rigid a structure as possible.

[0177] As shown in Figure 14, the suspension 165 of the third cylinder 167 is arranged considerably lower than the first and second pivot joints 135, 137 of the first and second cylinders 127, 129 respectively.

[0178] In a practical embodiment, the first and second hinge joints 135, 137 are connected to the chassis 117 at an approximately equal first height Hl. Herein, the first height Hl is measured from a bottom of the respective legs. Said underside of the legs rests on ground 149. Thereby, the third suspension 165 is provided at a second height H2. The second height H2 is chosen as small as possible in order to thereby maximize the stability of the robot platform 109. On the other hand, the second height H2 is chosen large enough to keep the robotic platform usable in a practical application.

[0179] In a practical implementation, the second height H2 is less than or equal to about 60% of Hl. For example, the second height H2 is less than or equal to 50% of Hl. For example, the second height H2 is less than or equal to 45% of Hl. For example, the second height H2 is less than or equal to 40% of Hl. For example, the second height H2 is less than or equal to 35% of Hl. For example, the second height H2 is less than or equal to 30% of Hl. For example, the second height H2 is less than or equal to 25% of Hl. For example, the second height H2 is less than or equal to 20% of Hl. For example, the second height H2 is less than or equal to 15% of Hl. For example, the second height H2 is less than or equal to 10% of Hl.

[0180] A minimum value of H2 is determined by the situation in which a third cylinder is horizontal under the vehicle and thus precisely does not touch the underside of the chassis 117. In a practical embodiment, in our outlined case, this is about 150 mm. the clearance that must remain free between the surface and the suspension 165. H2 is thereby greater than 1% of Hl, for example, greater than 5% of Hl, for example, greater than 10% of Hl. H2 is for example greater than 5 to 10 cm, in order to maintain sufficient clearance for uneven surfaces. In a practical embodiment, for example for application in an orchard, H2 is in the order of 10 to 40 cm, for example about 20 cm.

[0181] First height Hl and second height H2 are independent of the width of the robot platform 109. Taking into account the width of the robot platform, the height difference between Hl and H2 can also be expressed as an angle between the centerline of the cylinder to which the ancle is fixed, and the centerline of the third cylinder 167. Said cylinder typically is the first cylinder 127, but it may also be a telescopic shaft (see Fig. 25). In use, the centerlines of the first cylinder 127 and the second cylinder 129 extend primarily in a vertical plane, and the centerline of the third cylinder 167 extends in a lateral direction at angle with respect to that vertical plane in which the first cylinder extends. Said plane wherein the first and second cylinder move may deviate from vertical, for instance to enable to turn. The deviation may be on the order of 10 to 20 degrees. Preferably, the angle is greater than 45 degrees, for example greater than 50 degrees, for example greater than 60 degrees. Preferably, the angle is smaller than 90 degrees, for instance less than 85 degrees, for instance less than 80 degrees. In an embodiment, the angle is in a range from about 45 to 90 degrees. In a practical embodiment, the angle is in a range of about 60 to 80 degrees.

[0182] For example, the angle is about 73 degrees in a position where the first cylinder 127 is in a vertical position and fully retracted. Would the suspension point 165 of the third cylinder 167 be at the same height as the hinge joint 135 of the first cylinder 127, where H2 is equal to Hl, then the enclosed angle would be about 36 degrees.

[0183] An advantage of the relatively low position of the suspension of the third cylinder and the connection of the third cylinder to the ankle is relatively high efficiency. While propelling the vehicle 109 through the often hundreds of meters of corridors in an orchard, the third cylinders 167 need do little more than keep the legs in line. In other words, the third cylinders theoretically do not have to provide power while running. In the aisles of the orchard, the third cylinders 167 provide significant force only when the vehicle 109 is stationary. So during harvesting, wherein the functional robot arranged on the platform 109 is in operation. This is then only a static force.

[0184] FOOT FOR PROPULSION OVER UNEVEN AND SLACK GROUND

[0185] The permissible surface pressure on the ground applicable in the agricultural sector is set at, for example, 1 kilo per cm2. With a total mass of the vehicle of, say, roughly 1,700 kg, this would mean that a support surface of 1,700 cm2would be required. If, in the worst-case scenario, the vehicle 109 were to rest on two of four circular flat feet on the ground then the calculated diameter of each flat foot would be about 32.9 cm. For convenience, we set the diameter of each flat foot to, say, 35 cm.

[0186] See Figure 20. To allow a flat foot 183 to set itself to the ground, a highly flexible cardanic ankle joint 145 has been chosen for application in, for example, an orchard instead of the previously mentioned immobile ankle joint connecting a foot 183 to an ankle 139. The edge 187 of a flat foot 183 is slightly curled upward to prevent as much as possible, for example, mud from accumulating on the foot during stepping.

[0187] In the event that the vehicle makes a turn, as shown for example in Figure 6, and the cardanic ankle joint 145 would connect the flat foot directly to the ankle 139 then torsion will occur in the ankle 139 because the cardanic ankle joint 145 cannot eliminate the torsion created by friction of the flat foot 183 with the surface. This is undesirable. This will be the case, for example, when the sole of the flat foot has a profile to prevent slipping of the foot.

[0188] To prevent torsion, a bearing plate 189 is placed between the flat foot 183 and the cardanic ankle joint 145. The foot can now rotate around center line 191 which passes through the center of the ankle joint 145.

[0189] For example, a pair of upright supports 193 fixed mounted to the bearing plate 189 that are each located on one side of the cross 195 of the cardanic ankle joint 145 enable rotation of the bearing plate 189 and thus of the flat foot 183 in the transverse direction of the robot platform 109 around center line 197.

[0190] For example, the other axis of the cross 195 is located in the ankle 139 so that the flat foot 183 can also rotate around centerline 199 in forward and backward directions of the vehicle.

[0191] As an ankle joint, it would also have been possible to use a ball joint instead of a cardanic joint. This would have solved the problem of torsion immediately. In a practical implementation, a cardanic joint was chosen because it allows much more movement. The latter is desirable in many cases.

[0192] See Figure 21. To prevent the vehicle from tripping when taking a step because the edge 187 of a flat foot 183 gets stuck in the ground 149 or gets caught behind something on the ground, for example, a brake 201 (see also Figure 20) mounted on the center line 199 of the cardanic ankle joint 145 can ensure that the front of the flat foot 183 points forcibly upward.

[0193] Figure 21 shows several successive positions of the flat foot 183 of leg 121 when taking a forward step. When the flat foot 183 is put down, it sets toward the ground surface because the brake may slip. For example, the required braking force is preset. This can be done, for example, with an adjustable spring. Also, the brake can for example be operated with compressed air or electromechanically. Then the brake force can also be controlled during running.

[0194] We could also add a brake to a movement of the foot 183 in the transverse direction. We think that this is not necessary because the lateral motion of a foot 183 is only small, it is at least smaller than the diameter of the foot 183.

[0195] Figure 22 shows an exploded view of an implementation form of the leg 121 with all its components. In order to prevent environmental influences, think of mud, water, sap from plants and fruits and the like, from damaging the joints, an implementation form of the design takes into account that specially designed covers can be placed over the joints. Where possible, we apply commonly available seals, for example. For example, consider placing a seal ring between the flat foot 183 and the bearing plate 189. The cylinders used, for example hydraulic cylinders, are available as standard with seals suitable for use in relatively harsh conditions.

[0196] Figure 23 shows the vehicle 109 with all its components as suitable for use in an orchard.

[0197] Figure 24 shows an alternative to the solution shown in Figure 10 with ball joints 135 and 137. For suspension of the first cylinder 127 and the second cylinder 129 to the chassis 117, it is also possible to first hinge each of the two cylinders separately to a joint beam 203. For example, the beam 203 is attached to the chassis 117 via two rotating bearings 205 and 207. The beam 203 can rotate around centerline 209. Second centerline 211 of the hinge belonging to the second cylinder 129 is thereby perpendicular to centerline 209. The beam may be implemented as a rotatable element, such as a tube, beam, bar, etc.

[0198] Preferably, the centerlines 209, 211 and 213 (i.e., the centerline of the second cylinder 129) intersect in a single point.

[0199] A similar description is applicable to the first cylinder 127.

[0200] As with previous embodiments, in the solution described here the centerlines of the first cylinder 127 and the second cylinder 129 intersect. As an additional advantage, a more stable solution is created than with ball joints 135 and 137. An additional advantage of the alternative implementation form shown in Figure 24 is that piston rods need not be secured against twisting. The suspension of the cylinders to the beam 203 is preferably torsionally rigid.

[0201] Figure 25 shows a further embodiment of a leg. As previously described, cylinders are not in principle designed to absorb lateral forces. Research has shown that cylinders specifically designed to absorb lateral forces are made heavier, therefore more expensive and less readily available. In order to circumvent these objections and be able to use relatively inexpensive and identical cylinders for cylinders 127 and 129, it is possible to mount the ankle 139 not rigidly to the piston rod of the first cylinder 127, but fixed to, for instance, an externally toothed shaft 215. The shaft 215 can slide in an internally toothed bushing 217. The anti -rotation secured combination of shaft 215 and bushing 217 may also be called spline shaft 219. A spline shaft is also available with a different configuration, such as, for example, a linear ball bush guide. The functionality of the aforementioned spline shaft can also be performed by any other telescopic shaft, which preferably is secured against twisting. For example, the telescopic shaft may be a multi-angular (for example, having three of four corners) or an oval shaft that can slide in a corresponding tube.

[0202] Like cylinders 127 and 129, the telescopic shaft 219 can be connected to the rotating beam 203, see Figure 24. Direct suspension to the chassis by means of a 2D joint is also possible. Preferably, the suspension is sufficiently secured against twisting around the centerline 221 of the telescopic shaft.

[0203] A great additional advantage of using the telescopic shaft 219 is that the knee joint 141 can be implemented with a standardly available rod head. The first cylinder 127 is attached to the ankle 139 in the same manner as the second cylinder 129. Since torsional rigidity is now obtained with the telescopic shaft, it is not necessary to implement torsional rigidity in the suspension of cylinders 127 and 129 to the beam 203.

[0204] The solution outlined in Figure 25 has advantages in that it can be made from standard parts to a greater extent. The standard parts are relatively easy to obtain commercially and have proven themselves, giving these parts a higher degree of reliability and availability to the structure. The first cylinder is thereby relieved of lateral forces by adding the telescopic shaft.

[0205] Electricity can be generated with a generator or can be drawn from a battery. The robotic platform 109 and / or the functional robot 107 can operate on this electricity.

[0206] If hydraulics are used to drive the cylinders, one solution is to use a so-called power-pack with an electrically driven pump. The use of batteries and their charging is already advanced and widely available. The great advantage of using a battery in this case is that braking energy can also be stored. So the choice for our solution was to use a battery as an energy source.

[0207] A generator can be powered by an internal combustion engine. For example, the fuel used is a relatively clean fuel such as LPG or natural gas. Refueling of fuel in this case is done manually. The vehicle 109 may be equipped with a battery. The vehicle may be equipped with a connection that allows automatic charging. To charge the battery, the robot automatically couples to a charging station. Pairing and charging solutions are available on the market.

[0208] For the vehicle to make its way through an orchard unmanned, GPS and Lidar are used. Lidar also works when the GPS signal is insufficient, such as under hail nets. Since GPS and Lidar do not provide direct directional information, the use of a compass is considered.

[0209] To keep the vehicle level, a so-called inclination sensor is used.

[0210] If the vehicle is on three legs, it is always stable. However, we prefer to use four legs during a harvest cycle for maximum stability. Pressure sensors are needed to optimally load all legs. This is easily integrated with a hydraulic system.

[0211] It is to be expected that, especially in the beginning, impasses will occur (situations where the vehicle cannot continue execution of work for any reason). To resolve impasses, intervention is expected from an operator in a control room in charge of multiple vehicles. Communication with the control room is via Wi-Fi or telecommunications, for example.

[0212] The cylinders are equipped with a position sensor, for example.

[0213] During a harvest cycle, the vehicle will be stationary. The accuracy of apple harvesting is determined with sensors.

[0214] Even in a field, it may be necessary to manually operate the vehicle from time to time. Consider driving the vehicle to a starting position before it can perform its tasks autonomously. Manual operation will then require a remote control, such as that used with construction cranes, etc.

[0215] If the vehicle is to be able to operate unmanned, then a safety system must be in place to ensure that the robot waits to perform tasks if a human comes too close to the vehicle. It is not yet legal to operate a vehicle unmanned, but there are safety systems under development that will allow this in the near future. One possibility is a Lidar- or radar-based safety system.

[0216] To make the investment in a harvesting robot (the total solution) more interesting, it is also being considered to use the robot for other applications that fall in a different season than the harvest season. Pruning is initially being considered. This is done in the winter period. Thinning (removing blossoms or small apples) is also mentioned as a possibility or removing wild shoots at the base of a tree's trunk. Disease and pest detection and spraying are also mentioned.

[0217] Growers also show interest in monitoring an orchard during the growing season. Drones are already being used for a quick scan.

[0218] One of the questions repeatedly asked by growers is mapping the exact position of trees in an orchard. There is no solution for this yet. The vehicle 109 without a robot could do this task just fine. For example, the Lidar scanner could then be held horizontally. For applications without a robot, a rigid vehicle is not a necessity. But it is convenient to have one vehicle for everything.

[0219] Currently, there are no commercially successful robots on the market for harvesting in orchards. The main reason is that, in particular, the required sensorics (mostly vision-based technology) and software (artificial intelligence) are still under development. This also applies to safety. However, developments are moving fast and investments are in full swing. It is estimated that within five years there will be enough satisfactory working solutions of fruit-picking robots that can be carried through an orchard using the robot platform of the present disclosure.

[0220] To protect the environment, only environmentally friendly materials are chosen. For example, consider food-grade lubricants and hydraulic oil.

[0221] The vehicle or robotic platform of the present disclosure is a four-legged vehicle called a quadruped. The four legs each consist of three cylinders without a skeleton. The legs are relatively rigid and stable so that an industrial robot mounted on the platform can perform optimally.

[0222] The vehicle can be optimized for unmanned use in an orchard. The robotic platform can move through long narrow corridors with trees on either side and can automatically move to an adjacent corridor. In a given corridor, the vehicle can stop and restart several times in a row, taking the most suitable and stable position at each stop so that the functional robot can perform optimally. When the vehicle moves forward, the movement speed can be relatively slow. The vehicle can move forward and backward.

[0223] The vehicle is suitable for irregular terrain and weather conditions such as in orchards. The payload the vehicle can carry is relatively large. The platform has a relatively simple construction that achieves a high degree of availability. Repair and maintenance can be performed by the end user himself and applied parts are generic and readily available worldwide. For practicality, the design assumes a payload of the robotic platform in the order of 850 kg. The platform can carry a fruit-picking robot consisting of a robot arm (275 kg) with controller (150 kg), a harvesting tool (10 kg), a harvesting box filled with apples (300 kg) and a conveyor for transporting the box (100 kg). The power consumption of the robot platform is estimated at 900 W at maximum load.

[0224] New developments in industrial robots show that robot arms and controllers are becoming much lighter. It is expected that the weight of the robot arm will be halved and the weight of the controller will be only one-third. The total weight of the payload could then be around 600 kg. Controllers are becoming increasingly compact. For today's application, controllers can be about 500 x 400 x 500 mm (W x D x H) in size. As robot arms become lighter, the maximum power consumption is approximately halved (450 W).

[0225] The scope of this disclosure is not limited to the embodiments described above. Many modifications are conceivable without departing from the scope of the present invention as defined by the attached claims. In particular, combinations of features of respective embodiments or aspects of the disclosure may be made. An aspect of the invention may be further advantageously improved by adding a feature described with respect to another aspect of the invention. Although the present invention has been illustrated and described in detail by reference to the figures, these illustrations and descriptions are merely illustrative or exemplary.

[0226] In the claims, the word “comprising” does not exclude other steps or elements, and “one” does not exclude a plural. The mere fact that certain features are mentioned in mutually distinct dependent claims does not mean that a combination of these features cannot be used to advantage. Characteristics of embodiments may be combined, for example. Reference numbers in the claims should not be interpreted as limiting the scope of the present invention.

Claims

CLAIMS1. A robotic platform, comprising: a platform (117); at least four legs (119, 121, 123, 125) connected to the platform (117), each leg comprising at least three cylinders, wherein a first cylinder (127) and a second cylinder (129) having first ends are connected to the platform (117) via first and second pivot joints (135, 137) at about a first height (Hl), and wherein a third cylinder (167) having first ends is connected to the platform (117) via a suspension (165) at a second height (H2) substantially smaller than the first height (Hl).

2. The robotic platform according to claim 1, wherein the second height (H2) is less than or equal to about 60% of the first height (Hl), for example less than or equal to 40% of the first height (Hl), for example less than or equal to 35% of the first height (Hl), for example less than or equal to 30% of the first height (Hl), for example less than or equal to 25% of the first height (Hl), for example less than or equal to 20% of the first height (Hl), for example less than or equal to 15% of the first height (Hl), for example less than or equal to 10% of the first height (Hl).

3. A robotic platform, comprising: a platform (117); at least four legs (119, 121, 123, 125) connected to the platform (117), each leg comprising at least three cylinders, wherein the first cylinder (127) and the second cylinder (129) of each leg extend substantially in a vertical plane, and wherein the third cylinder (167) extends laterally at an angle (Q) with respect to the first cylinder (127).

4. The robotic platform according to claim 3, wherein the angle (Q) is greater than 45 degrees, for example greater than 50 degrees, for example greater than 60 degrees.

5. The robot platform according to claim 3 or 4, wherein the angle (Q) is in a range from about 60 to 80 degrees.

6. The robotic platform according to any of the preceding conclusions, wherein the first cylinder (127) and the second cylinder (129) are connected with first ends to a side of the platform (117), and wherein the third cylinder (167) is connected with a first end to a bottom side of the platform (117).

7. The robotic platform according to any of the preceding claims, wherein during use, the respective first cylinder (127) and second cylinder (129) of each leg extend substantially vertically, and wherein the respective third cylinder (167) extends substantially horizontally.

8. The robotic platform according to claim 7, wherein the third cylinder (167) extends laterally at an angle (Q) with respect to the first cylinder (127).

9. The robotic platform of any of the preceding claims, comprising an ankle (139) fixedly connected to a second end (133) of the first cylinder (127), wherein a second end of the second cylinder (129) is pivotally connected to the ankle (139).

10. The robotic platform of claim 9, wherein a second end of the third cylinder (167) is pivotally and pivotally connected to the ankle (139).

11. The robotic platform of claim 9 or 10, comprising a foot (147) connected to the ankle (139).

12. The robotic platform of claim 11, wherein the foot (147) is connected to the ankle (139) via an ankle joint (145) that allows rotation (Rx, Ry) relative to the ankle (139).

13. The robotic platform of claim 11 or 12, wherein the foot (36) includes a flat portion (54) for engagement on relatively soft ground.

14. The robotic platform of claim 13, wherein the flat portion of the foot includes upwardly rounded edge (187).

15. The robotic platform of any of claims 9 to 14, comprising a third connecting piece (163) rigidly connected to the second end of the second cylinder (129), the third connecting piece being pivotally connected to the ankle (139).

16. The robotic platform of any of the preceding claims, comprising a fourth connecting piece (179) pivotally connected to the second end of the first cylinder (127) and pivotally connected to the second end of the third cylinder (167).

17. The robotic platform according to any of the preceding claims, each leg comprising a telescopic shaft (219).

18. The robotic platform according to any of the preceding claims, wherein the first ends of the first cylinder (127) and the second cylinder (129) are connected to a beam (203), which is rotatably connected to the platform (117).

19. The robotic platform of claim 17 and 18, wherein a first end of the telescopic shaft (219) is connected to the beam (203).

20. Leg for a robotic platform, comprising: at least three cylinders, wherein a first cylinder (127) and a second cylinder (129) are arranged to be pivotally connected to a side of a platform (117), extending approximately in a vertical plane, and wherein a third cylinder (167) extends laterally at an angle (Q) with respect to the first cylinder.

21. The leg according to claim 20, wherein the angle (Q) is greater than 45 degrees, for example greater than 50 degrees, for example greater than 60 degrees.

22. The leg according to claim 20 or 21, wherein the angle (Q) is in a range from about 60 to 80 degrees.

23. The leg according to any one of claims 20 to 22, wherein the first cylinder (127) and the second cylinder (129) have first ends arranged to be pivotally connected to the platform (117) at about a first height (Hl), and wherein the third cylinder (167) has a first end arranged to be connected to the platform (117) via a pivot and pivot suspension (165), the leg comprising an ankle (139) permanently connected to a second end (133) of the first cylinder (127), wherein a second end of the second cylinder (129) is hingedly connected to the ankle (139).

24. The leg of claim 23, wherein a second end of the third cylinder (167) is rotatably and hingedly connected to the ankle (139).

25. The leg of claim 23 or 24, comprising a foot (147) connected to the ankle (139) via an ankle joint (145) hinged in at least one dimension.

26. The leg of any of claims 23 to 25, wherein the suspension (165) is arranged to be connected to the platform at a second height (H2) substantially smaller than a first height (Hl) at which the first ends of the first cylinder (127) and the second cylinder (129) are arranged to be connected to the platform.

27. A method of moving a robotic platform, the method comprising the steps of: providing a platform (117) having at least four legs (119, 121, 123, 125) connected to the platform (117), each leg comprising three cylinders, a first cylinder (127) and a second cylinder (129) having first ends pivotably connected to a side of the platform (117) and a third cylinder (167) having a first end connected to a bottom of the platform (117) and an ankle (139) connected to a second end (133) of the first cylinder (127), wherein a second end of the second cylinder (129) is pivotably connected to the ankle (139); and moving the robotic platform by alternately extending and shortening the first and second cylinders of the respective legs.

28. The method of claim 27, wherein the step of moving includes hinging and rotating a second end of the third cylinder (167) relative to the second end of the first cylinder (127).

29. The method of claim 28, wherein the step of moving includes rotating (Rx, Ry) a foot (147) relative to the ankle (139) via a hinge joint (145).

30. The method of claim 29, wherein the step of moving comprises unwinding the foot on a surface by rotating and through a flat portion (54) of the foot provided with an upwardly rounded edge (187).

31. The method of any one of claims 27 to 30, wherein the step of moving includes pivoting the second end of the second cylinder (129) relative to the second end of the first cylinder (127) via a third connecting piece (163) fixedly connected to the second end of the second cylinder (129) and pivotally connected to the ankle (139).

32. The method of any one of claims 27 to 31, wherein the step of moving includes rotating and rotating a second end of the third cylinder relative to the second end of the first cylinder of a respective leg by means of a fourth connecting piece (179) rotatably connected to the second end of the respective first cylinder (127) and hingedly connected to the second end of the corresponding third cylinder (167).

33. The method of any one of claims 27 to 32, wherein during the step of moving, the respective first cylinder (127) and the second cylinder (129) of each leg extend substantially vertically and rotate in the plane of a respective side of the platform (117), and wherein the respective third cylinder (167) extends substantially horizontally and rotates in the plane of a bottom side of the platform.

34. The method according to any one of claims 27 to 33, wherein the third cylinder (167) extends laterally at an angle (Q) relative to the first cylinder (127), wherein the angle (Q) is greater than 45 degrees, for example greater than 50 degrees, for example greater than 60 degrees.

35. The method according to claim 34, wherein the angle (Q) is in a range from about 60 to 80 degrees.

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